Renewable Energy

This has been one of the most thorough yet broad books on Renewable Energy that I have read. It is written in a very technical and fundamental science lens which gives it a lot of potential. Do be warned that this is a very hard read. My most favorite parts were all the interjections that the author makes, since it contrasts the technical-heavy tone of the book. Examples:

“One wonders when consumers will, instead, respond with the thought that, “If a product needs to be advertised, there must be something wrong with it”?”

In reference to fossil fuels being “cheap”: “As long as they are cheap, they cannot be scarce!”

Fixed nitrogen is limitng factor of plants. Can be helped by nitrogen fixing plants. Nitrogen fixing plants enhanced by fertilizer. Fertilizer by fossil fuels. So plants grown on fossil fuels than solar energy.

In these notes, page numbers are PDF page numbers, so book page number is PDF page number subtracted by 13. This is the 2017 edition.

Chapter 1

• Only 0.02% (might be 0.2%) of renewable energy is used by humans
• Fossil fuels are often cause of national conflicts: disparity b/w geographic availability and demand
• Woodfuel is most common biofuel. Claims of CO2 neutrality is false because replacement rate is super slow
• Food crops for energy is economically unacceptable (food corps for energy uses too much energy in its own process)
• Cost of fossil fuels is not strongly coupled with production prices; mainly market and politics
• Coal, oil, natural gas: $10^{23}$ J recoverable
• Deutrium for fusion: $10^{31}$ J recoverable
• In practice, energy always gets converted to heat
• Stored energy of any form that may be converted to heat that is ultimately lost to space could then be called a non-renewable energy resource.
• The term renewable energy resource is used for energy flows that are replenished at the same rate as they are “used.”
• energy stores, which are part of the natural process of converting solar energy into heat re-radiation, are also considered renewable energy resources.
• Human bodies need “new biomass continues to be produced to replace “respiration losses.””
• parts of the population today use no more energy than theaverage person during the Neolithic period.
• Low-latitude regions: houses were built partly underground and the evaporation of soil moisture was utilized to create cool environments for living
• High-latitude regions: keeping livestock within the living area of the houses, so as to benefit from their respirational heat release.
• Fig 1.17 and 1.18 are pretty important
• It is clear, however, that the energy basis for human societies has been renewable energy sources until quite recently.
• the average European or Japanese uses about half as much energy as the average North American, but the former have a living standard no lower than that of the average North American.
• Nuclear fuel resources are no more abundant than oil or gas
• nothing suggests that fusion reactors, should they become workable, would have fewer radioactivity problems than fission reactors.
• Sustainability means exploiting flows, rather than stocks.
• Human interference includes land-use change, emission into the atmosphere of light-absorbing gases, emission of particulate matter with different size distributions, and injection of chemical pollutants into the atmosphere at various levels.
• The true variables may be split into the sum of a mean value and a deviation from the mean value, but the latter is neglected in all climate models.
• 32 Many low-latitude deserts are examples of local human climate change
• 32 Global average fossil fuel energy in 1970 was 0.015 W/m²; average of solar is 240 W/m²
• 32 If [all the nuclear] weapons were detonated within a 24-hour interval, the average energy flux would be 5×10^15 W, and if the target area were 10^12 m² , the average heat flux would be 5000 W/m²
  • Additional deaths from stratospheric ozone shield being destroyed
• 33 energy habits have been formed largely by those who sell fossil energy and energy-using equipment. They are responsible for consumer behavior biased toward buying an additional kWh of energy instead of saving one by efficiency measures, even if they are cheaper
  • Common fallacy: “As long as they are cheap, they cannot be scarce!”
• 34 for practical purposes geothermal energy behaves as a renewable resource

Chapter 2

• 54 energy in sun is produces in core, up to 0.25R; half of all mas is in here
• 55 In universe, helium content is above 25% almost everywhere
• 56 temp of sun surface: 4300 K to 8000 K. Approx 6000 K
• 57 Sun has period of 22 years
• 57 Eclipses can showcase sun’s chromosphere as red light
• 58 corona extends into a dilute, expanding flow of protons (ionized hydrogen atoms) and electrons known as solar wind
• Fig 2.9 is super useful to show all radiation coming on earth
• 2.2.1-2 is helpful to know what time of year, location, etc. has how much solar energy
• 80 Blue light (high frequency) is scattered more, so sky looks blue
• Fig 2.20 useful for understanding what happens to incoming and outgoing radiation
• 84 Seawater albedo 0.07. Ice cover albedo 0.3. Land albedo 0.15-0.20 (0.05-0.45). Snow closer to 0.95 if clean, 0.4 if dirty.
• 91 Availability of solar radition decides deep water photosynthesis
• 93 Atmospheric water content ~0% near poles by volume; 4% near tropics.
• 97 Rainout = in-cloud absorption of particles into water droplets. Washout = scavenging of particles by falling rain/ice
• 97 Stratosphere particles detectable since they modify solar radiation transmission
• Fig 2.48 Energy flux due to radiation, atmospheric motion, and ocean currents
• 113 Only potential energy and sensible heat create energy flows
• 115 Meteorological forecast period of predictability is 2-5 days
• 115 Zonal wind = wind parallel to latitude circles, averaged by longitude
• 115 Meridional cell motion is closed-loop streams that move southwards close to ground and northwards higher up. Does not transfer particles across latitudes (pg 119)
• 116 Hadley cell, similar to Meridional cell, but for equator
• 117 Zonal winds + meridional transport toward equator = trade winds
• 120 Transport of angular momentum is critical of general circulation. See fig 2.51
• 126 Frictinal dissipation also happens above ground in atmosphere
• 132 Evaporation of seawater leaves salt particles in air, which creates condensation nuclei for water vapor that haven’t yet been carried away
• 148 Equation intransitive if dependent on time: non-unique climate functions
• 148 Equation transitive if not dependent on time: unique climate functions
• 149 Talks about transitive/intransitive earlier, and how “climate” consequently is defined to be 30 years
• 150 If more than one stable climate, system is intransitive; here, magnitude of perturbation needed to change stable point is of concern
• 159 Condensation does not happen where evaporation happened
• 160 Transfer of energy due to run-off water and ocean water being different temps is negligible
• Fig 2.90-1 are both useful for energy cycle
• Fig 2.92 Carbon cycle
• 166 “Practically all the oxygen present in the atmosphere has been formed by photosynthesis. The same seems to be true for the oxygen present in the lithosphere.”
• 167 Regarding CO2 emissions: “Part of this surplus is absorbed by the oceans, but the process seems unable to keep pace with the rapid growth of CO2 in the atmosphere, so the net result is that about half the extra CO2 injected into the atmosphere is accumulating there. Also, the mixed upper layer of the oceans has a turnover time that is longer than the time scale of human interference with the carbon cycle, so the additional CO2 absorbed by the oceans largely accumulates in the mixed layer, rather than reaching the long-term sink provided by the deep ocean”
• Fig 2.93 Nitrogen cycle
• 168 Leafy vegetables useful for nitrogen fixation, and cultivation of these contributes to 50% of nitrogen fixation
• 169 Fixed nitrogen is limitng factor of plants. Can be helped by nitrogen fixing plants. Nitrogen fixing plants enhanced by fertilizer. Fertilizer by fossil fuels. So plants grown on fossil fuels than solar energy.
• 169 Ammonifying bacteria = dead organic matter to ammonia. Nitrifying bacteria = oxidize ammonia to nitrite/nitrate. Denitryfing bacteria = undoes nitrogen fixing, converts to gaseous nitrogen on N₂O.
• 170 Some of the fertilizer administered to agricultural soils runs off with surface water even before it has been absorbed by plants, and some is carried away by ground water flows
• 171 Human intervention to climate may be considered to stop natural climate changes
• 171 Using flows for energy delays re-radiation back to space, but could also end up altering climate. “agriculture is a way of utilizing solar energy that involves changes of large land areas and almost certainly has had climatic impacts during the history of cultivation.”
• 174 the formation and dissolution of large continents near the poles may explain the late Paleozoic glaciation and its subsequent disappearance.
• 174 dust-triggered temperature drops of 5~10°C for several decades may have been responsible for the extinction of certain animal species (in particular species of dinosaurs, which appear to have had no thermoregulatory mechanism).
• 175 variations in solar output to small to cause ice age
• 176 Early anthropogenic practices could have been enough to keep the atmospheric CO2 con- tent so much above 210 ppmv that the previous mechanism of generating a new ice age no longer works
• 176 most stable state of the Earth is one of complete glaciation: “white earth” has albedo greater than 0.7. (178) However, this is unlikely to be the case of the earth, the albedo is either lower or greehouse effect was stronger
• 177 a decrease as small as 1.6% in the solar constant would cause the ice caps to exceed a critical size, beyond which they would continue to grow until the entire Earth was covered.
• 178 solar constant must have been increasing regularly from a value about 25% lower than the present value during the 4.5 3 109 years since the Sun became a main-sequence star.
• 179 showcases Bowen ratio, defined as the ratio of sensible and latent heat fluxes
• 179 savannah grasslands in the tropical regions are entirely man-made, since the natural vegeta- tion of these semi-humid regions is dry, deciduous forest.
• 179 Rajputana desert in India was as fertile as a tropical forest only 1000 years ago
• 180 When a tropical forest is being removed, the soil is no longer able to retain its humidity. Then precipitation runs off along the surface, and the soil becomes still drier. The humus layer is washed away and a solid crust of clay is developed. Weathering of this dry soil may greatly increase the particle content of the atmosphere
• 182 silver iodide crystals for cloud making. Particle emissions (e.g., from industry) in a certain size range may provide an unintended source of cloud condensation nuclei.
• 183 aerosols in air can heat up or cooldown earth. “cooling effect dominates if the albedo as of the Earth’s surface is below 0.6 and that the heating effect dominates if as is above 0.6 (snow and ice), fairly independently of other parameters” (shortwave radiation). “increase in atmospheric aerosol content will lead to a decrease in temperature”. However, (184) infrared radiation to space is little affected by the presence of an aerosol layer
• 185 “present content of CO2 is already big enough to imply a nearly total absorption at λ=1.5E-5 m. It is therefore unlikely that even a dramatic increase in CO2 could have consequences similar to the addition of a small amount of NH3”
• 186 “temperature change of just 1 or 2 globally may have serious effects on climate, particularly if the local temperature change is amplified in sensitive regions, such as the polar regions. “ While temp increases 2-3K for surface in mid-heights, in poles it can be as much as 10K.
• 186 Heating also causes water vapor, which also acts like greenhouse gas
• Fig 2.100 shows what happens if CO2 doubles in northern hemisphere
• 190 laminar flow is horizontal near ground, so vertical transport is likely through eddy motion
• Eq 2.34 is horizontal velocity wrt height
• 191 friction velocity description
• 193 turnover time for underground water is 200-300 years
• 196 average heat flux from interior of Earth is only 3E12W or 8E-2W/m². “most of the heat generation takes place within the rocks present in the Earth’s crust.”
• 196 for winds to ocean water, “ large fraction of the kinetic energy is transformed into wave motion rather than directly into currents “
• 197 “Waves may be defined as motion in which the average position of matter (the water “parti- cles”) is unchanged, whereas currents do transport matter. “
• 199 geostrophic wind = horizontal average wind
• 205 large gap in wind frequency between 0.5/h and 20/h
• 206 Talks about why weather forecasts are poor, especially due to turbulence
• 206 Only two ways of energy conversion in atmosphere: potential to kinetic energy, and heat to kinetic energy due to pressure gradient
• 218 “Governments may nominate good scientists to the IPCC working groups, but they may also nominate some that can advance a particular government’s attitude toward acting on the warming threat. “
• 220 tides responsible for deceleration of Earth
• 221 Waves are flatter at bottom. Fig 2.112 shows wave profile, and earlier math shows why this is the case
• 223 “ about 80% of the momentum transfer from the wind may be going initially into wave formation, implying that only 20% goes directly into forming currents. Eventually, some of the energy in wave motion is transferred to the currents. “

Chapter 3

Radiation

• 3.1 Talks a lot about reflected radiation
• 235 talks about why measured values of radiation is better.
• Fig 3.3 - turbudity is not very consistent across months and days
• Fig 3.4 and 3.6 Effect of different clouds on radiation flux
• Fig 3.7 Radiation on inclined surface, for different albedo and Fig 3.8 for different cloud cover
• 245 “radiation decreases with increasing cloud cover, but for north-facing [opposite of sun] slopes the opposite takes place. “
• Fig 3.10 useful to show effect of climate on radiation, even for similar latitudes
• 248 Estimating radiation on inclined surfaces requires separating total radiation into direct and scattered if we only know horizontal plane’s radiation
• 249 scattered radiation is not very isotropic
• 250 maximum direct average flux is obtained at a tilt angle closer to φ plus or minus the Sun’s declination, which are about ±23° at summer and winter solstices
• 3.1.4 talks about emission and absorption. Emission and absorption coefficients are typically identical; emittance is property of surface, and absoptance is not necessarily. This section has a lot of content similar to a heat transfer due to radiation course.
• 253 Typically emittance is 0.95 for most surfaces
• 253 “main absorbers in the long-wavelength frequency region are water vapor and CO2”, and since CO2 is fairly constant, H2O primarily is responsible for altering long-wavelength flux
• Eq 3.20 effective temperature of the long- wavelength radiation

Wind

• 3.2.1.1 describes amount of horizontal wind based on different height
• Fig 3.27-28 shows wind energy based on location
• 267 Wind-height relationship is less apparant in summer where wind is more turbulent due to rising air
• 3.2.2 Wind energy is significantly higher at higher altitudes (~10 km above sea level), and over oceans.
• 271 Power is dependent on wind speed by a factor of a cube. So “average” wind speed cannot simply be plugged in to estimate average power. Average power is significantly higher.
• 271 Wind can yaw, so have a yawing device to get more accurate data
• 272 seasonal variations in wind is higher based on height
• 273 gusts are frequent, but cancel out if you have multiple wind collection devices spaced apart
• Fig 3.36 Daily changes in wind are less prominent higher up; yearly changes are more prominent higher up
• Fig 3.37 Horizontal wind speed frequency has peaks at 1 day, and 4 day, and the region near 4 day is just pretty high
• 275 Frequency of wind speed can have different peaks due to wind from sea vs land, but frequency for wind power typically shows only one peak due to cubic dependence

Oceans

• 278 Most places do not have stable ocean currents
• 279 Ocean currents differ based on height. See “Ekman spiral” also (mentioned somewhere else)
• 282 Like wind, ocean currents follow cubic laws
• 283 Ocean currents are pretty in-tune with wind. Higher in January, less in July
• 283 Power in currents is no greater than that of wind found in low heights

Other water

• 284 Many streams and rivers originate due to ice melting
• 284 The area from which a given river derives its input of surface run-off, melt-off, and ground water is called its drainage basin.
• 284 Global hydropower potential = 2.9×10^13 W
• 285 626 GW is realistic reserve of hydropower, of which 70 GW is already being used (1995 data)
• 287 Dams suffer from increased evaporation and spreading diseases higher up
• 288 The energy storage in waves may be varying more smoothly than the storage in wind (both waves and wind represent short-term stored solar energy, rather than primary energy flows)
• 289 If the wave field is “fetch-limited,” i.e., if the wind has been able to act over only a limited length, then the energy spectrum will peak at a higher frequency, and the intensity will be lower
• 295 renewable energy flows and stores can be utilized in quantities exceeding present technological capability, without worry about environmental or general climatic disturbances.
• 297 Talks about resonance condition of tidal energy; bays and inlets that have resonance condition have high tidal ranges
• 297 Tidal range can have a half-day or full day period
• 298 Potential tidal energy: 2-3GW in Europe, and 20-50 GW in North America

Other

• 300 food intake accounts only for 25%-30% of man’s total acquisition of energy during a summer day in central Europe

Salinity, Currents, etc.

• 301 over half the solar energy absorbed by the oceans is used to evaporate water
• 301 water stays where it is longer the deeper it is; can be hundreds of years in deepest parts
• 301 if water is brought up from deep seawater, more CO2 will transfer from ocean to atmosphere
• 304 Water currents are warm only when they pass through equatorial region; most of north gets warm and south gets cold (because water originates from Antarctic to up and then to North)

Geothermal

• 305 energy extraction by using soil/rock temperature is negligible
• 306 energy extraction by using air temperatures is negligible (would require several kilometers of air)
• 307 hot springs or underground steam happens in very places. Superheated brine is more common but hard to find
• 307 dry rocks accumulate heat, but have low surface area. reservoir may not be large enough to be renewable: 240E9W for 50 years
• 307 radioactive materials more common in granite-containing continental shields
• 308 radiogenic heat (heat due to radiation) decreases with depth; very little happens in mantle or core
• 309 short-lived isotopes are absent; this is supported by constant-temperature earth during formation theory, since they’d be responsible for heat
• 310 geothermal is renewable because relative heat outflow of earth is 2.4E-10/year; similar to sun - sun also does change, but in order of billions of years (in case of sun, it actually increases)
• 311 circulating water is most appealing heat transfer method for geothermal

Salt concentration

• 314 chemical energy: solutions < pure solvent
• Fig 3.70 shows osmotic pump
• 315 Harnessing energy via osmotic pump is about 3E12 W

Nuclear

• 316 Infamous Einstein equation
• 316 minimum atomic energy is for iron
• 316 most heavier-than-iron elements don’t decay to iron since potential barriers exist to reach iron state; the barrier is hard to overcome due to temps on earth
• Fig 3.71 very useful for nuclear energy
• 317 even in uranium, quantum tunelling has to happen
• 317 using radiation to force radioactive material to fission is called induced fission
• 318 The reason why further fission processes yielding nuclei in the Fe region do not occur is the high barrier against fission for nuclei with Z2/A <= 30 and the low probability of direct fission
• 318 10E22 J of energy from fissile material recoverable
• 318 the recoverable amounts of fissionable elements do not appear large compared with the possible requirements of man during the kind of time span for which he may hope to inhabit the planet Earth.
• 319 The potential nuclear energy released by one of the deuterium to helium fusion chains is thus 10E13 J per meter cube of seawater, or over 10E31 J for all the oceans
• 319 Nuclear fission for energy is a concern with respect to wastes, however, “ These dangers exist equally for the use of nuclear reactions in explosive weapons, in addition to the destructive effect of the explosion itself, and in their case no attempt is made to confine or to control the radioactive material.”
• 319 “very limited amounts of fissile resources available for this mode of operation, comparable at most to those of oil. Nuclear fusion research has been ongoing for more than 50 years, so far with little success. Commercialization is still predicted to happen some 50 years into the future, just as it was at any earlier stage.

Atmosphere

• 320 the energy input for the strong dynamo currents observed at mid-latitudes is believed to derive mainly from absorption of ultraviolet solar radiation by ozone
• 321 “ charge of the Earth, as well as the tropospheric current system, constitutes energy sources of very small magnitude, even if the more concentrated return flux of lightning could be utilized”. On order of 3E10 W

Biology

• 321 standing crop biomass = 1.5E22 J
• 321 Biomass on land surface is 7.6E13W or 0.51 W/m²; 0.999 W/m² for standing crops
• 321 fossil fuel deposits = 6E23
• 321 “suggesting that fossil energy resources are not very large compared with the annual biomass production”
• 322 old biofuel such as firewood requires drying, which is by solar
• 3.5.1 is big chapter on photosynthesis, for plants and bacteria
• 338 Copper is at core in plants; could be because iron was less abundant during evolution
• 343 could be possible to genetically modify plants to produce hydrogen gas
• 345 overall maximum efficiency of hydrogen producing using plants is 0.14
• 345 bacteria photosynthesizes in a single step unlike plants
• 346 instead of using photosynthesis for glucose production, bacteria can produce H2S (sulfur bacteria), ethanol (fermentation); often absorb different light
• 346 bacterial photosynthesis often don’t have stored energy
• 3.5.2 talks about ecological systems
• 346 higher up the trophic level, there is more long-range stability
• Fig 3.93 shows energy flow of different trophic levels
• 347 older ecosystems → higher diversity → more likely to withstand external changes for longer
• 347 “energy extraction serving human society diminish along the food chain”
• 348 mature ecosystem could reach stable situation where growth of whole community is zero
• 349 sudden frost during growing period can do damage
• 349 “If human intervention can be achieved without changing the trophic relationships within the community, it would appear that a harvest (energy extraction) corresponding to the net production could be sustained”
• 350 water content of plant is 4x compared to that done by photosynthesis
• 352 biomass production difficult on worldwide scale due to fresh water limitation
• 354 “nutrients suitable for uptake are being depleted from the soil so rapidly that increasing amounts of fertilizer must be added in order to maintain a constant productivity.”
• 355 maximum efficiency possible for plants is 10%. Most plants realistically are at 2%; higher for mature wood forests, cultivated crop, and coral reefs
• Fig 3.88 photosynthesis efficiency

Chapter 4

Basic principles of Thermodynamic Cycles

• Figure 4.1 shows Carnot cycles
• 4.1.1 Talks about the fundamental Carnot processes
• 4.1.1.1 Talks about Gibbs free energy, Helmholtz potential, enthalpy, linearization, etc.
• 372 in order to go through a thermodynamic engine cycle in a finite time, one has to give up reversibility and accept a finite amount of energy dissipation and an efficiency that is smaller than the ideal
• 374 First law efficiency, and (375) second law efficiency
• Fig 4.3 Several thermodynamic cycles summarized: Brayton (gas fuel, typically open cycle, or geothermal), Otto (automobile), Diesel (automobile, bigger cargo rail, ships, and trucks), Stirling (similar to Carnot, but no use explained), Ericsson (for solar), Rankine (power plants, heat pump, and refrigerator)
• 378 Coefficient of performance
• 379-381 showcases different generators to get direct solar energy into electricity such as thermoelectric, thermionic, etc. These typically have fundamentally low efficiencies.
• 385 heat pump max COP higher for smaller temperature differences, but real heat pumps can’t keep up with this increasing COP (they still increase overall)
• 385 weather-related temperature variations disappear as one goes just a few meters down into the soil
• Fig 4.7 super useful COP carnot vs real
• 389 Brayton cycle for geothermal only if steam is produced, but this is not common. In some regions, geothermal sources provide a mixture of water and steam, including suspended soil and rock particles, so that conventional turbines cannot be used
• 389 In general, geothermal is not very ideal (the ‘typical’ geothermal). Most places don’t get hot enough for direct use.
• 390 Even when hot geothermal exists, “heat extraction rate deemed necessary for practical applications is often higher than the geothermal flux into the region of extraction, so that the temperature of the extracted heat will drop. This non-sustainable use of geothermal energy is apparent in actual installations in New Zealand and Italy (where temperatures of extracted steam are dropping by something like 1°C per year “
• 390 Ocean thermal energy for electricity also not ideal because “overall efficiencies around 0.02 may be achieved “

Basic principles of wind turbines

• 4.3.1 talks about rotational shaft power from non rotational (i.e. turbine)
• 393 Turbines induce rotational component
• 395 Typically ignore radial component of wake. Upper power limit coefficient is 16/27 (0.59, “Betz limit), but may be exceeded if vortex rings are around converters and does not contribute to wake
• 395 “sailing vessels of the type used in the 19th century would have converted wind energy at peak rates of a quarter of a megawatt or more.”
• 395-396 talks about how boats can move towards wind (not directly)
• 397 for boats with sails, it is possible to increase force by 10 or 100 compared to drag by using actual airfoils. Called “setting” of the airfoil (carefully choosing parameters)
• 4.3.2 is about traditional wind turbines and their calculations, their losses, etc.
• 403 air behind wind turbine can be reversed or have recirculating flow if massive tip losses
• Fig 4.17 Effect of power coefficient based on tip speed ratio. This will never exceed Betz limit
• 406 Asynchronous electricity generator. Turbines where angular speed is kept constant, but power/torque/etc can be changed
• 407-409 High pitch angle to start prop, and then lower it to ideal angle; if too low of an angle, then torque goes below maximum
• 409 Synchronous DC generators continuously ramp up power with spin speed
• 4.3.2.3 deals with cases where wind comes at an angle. Talks about coning as well to reduce effect of too much wind
• 413 wind is turbulent in wake (behind turbine), but gets quickly restored. See fig 4.28 and 4.29. Restoration is much faster than model predicts.
• 415 for placement of turbines in wind farm, “suitable distance would seem to be 5-10 rotor diameters”. However, If, on the other hand, several wind directions are important, and the converters are designed to be able to “yaw against the wind,” then the distance required by wake considerations should be kept in all directions.
• 417 chained wind turbines (one behind another) isn’t very ideal, because accumulative effect of wind reduction. This could cause climate change.
• 417 3D CFD model needed to understand shadow model because of difference between theory and reality. E.g. Fig 4.29
• 419 Blades supposed to last 25 years, so flexing blades are bad idea
• 4.3.2.6 discuses offshore wind tubines and having them also potentially float and their challenges. See Fig 4.30 for some ideas
• 421 One of the leading alternative type of non-conventional wind turbine is the Darrieus rotor
• 422 Like regular turbine, Darrieus rotor does not benefit from large chord being near axis
• 422 Shape of Darrieus = troposkien curve (shape of hanging chain)
• 422 symmetric airfoil for Darrieus
• Fig. 4.32 Power coefficient of Darrieus
• 423 Darrieus does not have optimial blade orientation for all rotations
• 423 Torque while stationary is zero, so needs small Savonius rotor to start spinning
• 424 Darrieus is self-regulating: will reduce its speed if there’s too much wind
• 424 Multiple rotors with different optimum wind performance may be beneficial for getting more operating hours (Vestas 4-rotor design)
• 425 Betz limit can be exceeded by having crosswind, like with ducted rotors.
• 4.3.4 talks about ducted rotors, and they increase coefficient of power over 1, but have too much material needs
• 4.3.5 simulates a ducted rotor by having angular blades at wing tips, which acts like a duct
• 427 Ratio of vane velocity over duct velocity maybe 10 or higher typically. Can make coefficient of power be 1.2, twice the Betz limit
• 429 Artificial tornado induced wind turbines; however, they seem to need massive structures
• 430 Putting turbines on buildings induces vibrations in buildings
• 430 Turbines can be mounted on balloons and have them counter rotate; will require power transmission wires of sufficient strength.
• 430 Gearbox and induction-type generator common of wind energy converted has constant velocity
• 430 For variable velocity wind energy converted, synchronous generator and variable frequency AC would be common. This would require frequency conversions, especially for arrays of wind turbine
• 431 Thyristors for converting AC to DC then DC to AC
• 431 If heat needed instead of electricity, connect turbine to compressor of heat pump, or create friction-based heating; if water is used in friction based heating, it is called water-brake
• 431 Pumping of water, and oxygenating lakes is very suitable for wind turbine
• 431 Hydrogen can be produced via wind turbine

Basic principles of hydro and other

• 4.3.7 talks about hydro
• 432 Pelton, Francis, Nagler, and Kaplan are common water turbines. See Fig 4.37
• 432 Pelton and Francis are for rapid descent
• 433 Hydropower has typically been the largest power plant, even more so than fossil and nuclear
• 433 Kaplan/Nagler are for low water heads
• 435 Magneto-hydrodynamic converter is converting heat into electricity, such as using ionized gas in magnetic field. This has several challenges.
• 435 for magneto-hydrodynamic, cooling is needed, seeding is needed, and high temp of 2500 K is needed, and more
• Fig 4.40 shows a lot of wave energy converters
• 437 weight-to-power ration of WEC is ≥2 compared to wind, and more likely to be about 5
• 437 power obtained by using WEC is 13× less than off shore wind
• 438 Wave power has more seasonal variations; 6× instead of 2× for wind
• 441 For pneumatic WEC, efficiency is very high if tuned to resonant frequency of wave, but this gets complicated
• 442 Oscillating vane VEC can almost completely absorb almost all wave energy within a certain frequency, especially if an entire row of them is made. However, wave period has to be selected to be a certain radius divided by wavelength to have max efficiency.
• Fig 4.4.3 Efficiency of oscillating vane WEC; surrounding figures show what this looks like
• 443 Backbone of oscillating vane WEC is a weakness

Basic principles of solar (electro-chemical)

• 445 Both nuclei and electrons are affected by charge, but electrons are significantly lighter, and consequently, electrons are considered to be moving in a potential
• 446 Number of energy levels that an electron can take can be on the order of $10^{24}$ for solid crystals, so this forms a practically continuous energy level, called energy band
• 446 If atom-atom spacing is large, the energy spectrum is identical to being an individual atom
• 446 In the 3s and 3p region of silicon, near the band crossing point, it is possible to find energy gaps between adjacent bands that are much smaller than in the non-overlapping region
• 447 By Pauli exclusion principle, at most one electron in each quantum state
• 448 If particular band is completely filled, and massive distance from that band to the next one, then it is an insulator
• 448 If particular band is partially filled, then it is a conductor
• 448 If distance between highest filled band and empty band is small, it is semiconductor: conductance of silicon increases by a factor of $10^6$ between 250 K and 450 K.
• 448 Introducing higher atom number impurity in semiconductor makes it n-type: electrons in donor level are very easily excited into conduction band
• 448 Introducing lower atom number impurities in semiconductor makes it p-type
• Fig 4.48 showcases p-type and n-type and non-doped
• 449 p-n junction provides elecrical field to cause solar energy to move electron from p-type to n-type
• 453 Constant current called dark current is present in photovoltaics
• 455 Total current given by equation 4.102
• 455 Wavelengths not absorbed by material is transparent to that wavelength
• 457 Voltage and current are not fixed to obtain max power.
• 458 Eq 4.105 is open-circuit voltage
• 459 Max efficiency is smaller than 1 because of radiation not being absorbed when outside of semiconductor band gap, and max power ≠ max volt * max current; as others, to get energy in finite time, non-ideal ratios have to be used. External potential has max value.
• Fig 4.53 Max efficiency of p-on-n cell
• 460 scatterd solar radiation is still useful
• Fig 4.54 Efficiency between p and n component in cell
• Fig 4.56 efficiency-temperature dependence for different cells
• 462 positive temperature coefficient can be obtained by annealing
• 463 monocrystalline silicon cells formed from single crystals
• 463 light capture can be improved by minimizing reflections and trapping light
• 463 Thin oxide layer prevents electrons is cell to get to rear contact. See Fig 4.57 for cell structure
• 465 multicrystalline is less efficient, but simpler to make
• 466 stacked cells allow wider range of sunlight frequencies and lower quality material
• 466 although stacked cells achieved 15.2% efficiency, it couldn’t scale due to difficulty in electron transport
• Fig 4.63 structure of most common a-Si cell. These are common in calculators and other small devices
• 469 a-Si:H have great long-term stability
• 469 GaAs, CdS, and CdTe are better than silicon and common for use in space
• 470 cells receiving concentrated solar have to be actively cooled
• 470 two efficiencies relevant to consumers: cell efficiency, and module efficiencies
• 470 amorphous cells can be integrated into windowpanes, since only 10-30% is converted only
• 470 energy not converted to electricity can be converted to heat: hybrid photovoltaic and thermal device: PVT
• 471 max electrical efficiency of single junction PV device is 40%; 95% can be approached by absorbing different lights and stopping reflections; infinite stack can reach efficiency of 87%
• 471 PVT can add another 40% in efficiency
• 471 organic solar cells, photo-electrochemical (PEC), use organics for creating electricity or chemicals.
• 471 Carbon capture with ruthenium catalyst. Better to also add titanium di-oxide.
• 472 Monolayer of PEC dye only absorbs less than 1% of solar radiation; 10% can be achieved by increasing absorption (forcarbon capture)
• 473 most catalysts are based on platinum
• Fig 4.65 shows photo-electrochemical solar cell
• Fig 4.67 shows spectral sensetivity of different dyes for electricity production
• 476 ab initio calculation
• 476 software by Frisch et al. 1998 can be used to get molecular states. Also check Hartree-Foch calculation
• 480 The photo-electrochemical dye and nanostructure technique has several applications beyond the formation of solar cells. Among them are smart windows, energy storage, environmental monitors, hydrogen production, computer and TV screens also suitable for outdoor use (using the dye as light emitter rather than absorber), and three-dimensional data storage
• 480 perovskite, halide with ABX3 form where X is halogen, can transport electrons and holes

Basic principles of solar (thermal)

• 482 solar energy to heat requires a collector, and that energy has to be transported
• 482 passive system naturally creates heat flow (e.g. windows allow more heat in than out)
• Fig 4.76 to 4.79 shows several passive solar heating and cooling system
• 485 high absorptance implies high emittance for all wavelengths, so surface treatments used to make the value high in short-wave, and low in long wave: selective surface. See fig 4.80
• 489 back side and edge sides of collector are described by same way as building heat losses
• 4.4.3.2 has lot of calculations for flat-plate calculators
• 491 stalled collector is when energy is not collected; important to know max temp it can withstand
• 491 maximum temperature is independent of the heat capacity of the collector, the time scales linearly with C’
• 493 The short response time of the collector is also relevant in situations of variable radiation (e.g., caused by frequent cloud passage).
• 494 if heat storage present, then heat transfer coefficient can be taken to infinitely large if same fluid is circulated
• Fig 4.84 solar heating system with storage
• 495 accumulating stored energy diminishes efficiency
• 496 pump energy of heat transfer fluid is negligible for low fluid speeds, but not for higher since resistances increase with speed
• 497 Because the time distribution of the load is, in general, barely corre- lated with that of solar energy collection (in fact, it is more “anti-correlated” with it), an instantaneous efficiency, defined as the ratio between the amount of energy delivered to the load area and the amount of incident solar energy, is meaningless. A meaningful efficiency may be defined as the corresponding ratio of average values, taken over a sufficient length of time to accommodate the gross periodicity of solar radiation and of load, i.e., normally a year:

Basic principles of solar (concentrators)

• 498 maximum average gain from a fully tracking system (less than a factor 2) would rarely justify the extra cost, which, at least at present, exceeds the cost of doubling the collector area.
• 498 Evacuation of the substantial space between absorber and cover is not practical
• 499 One extreme is a point-focusing device, such as the parabolic reflectors
• 499 absorber dimension would have to be chosen so that it covered the bulk of the image under most conditions.
• 499 either the collector has to fully track the Sun or the absorber has to be moved to the focal point corre- sponding to a given direction to the Sun
• 499 scatter radiation is not available for use
• Fig 4.87, 4.88, and 4.89 shows some concentrators
• 4.4.4.3 talks about photo-thermoelectric energy generation
• 505 radiation reaching the absorber of a focusing collector is perhaps half of the total incident flux Es;γ SW and ηw is maybe 60% of the Carnot value
• Fig 4.94 reflection for cell with different coatings
• 507 For large-factor concentration of light onto a photovoltaic cell much smaller than the aperture of the concentrator, the principles mentioned for thermal systems apply unchanged
• 507 very difficult to accept scattered light even if concentration is reduced
• 508 in general, almost always, PV cell without concentrating device preforms better

Basic principles of solar (other uses)

• 512 solar ponds used in desert areas to get ice even when temperature is above freezing
• 512 Radiative cooling is very dependent on the clearness of the night sky
• 512 reflect as much sunlight as possible by an integrated photonic reflector consisting of several layers of HfO2 and SiO2 with individually optimized thickness, and 97% reflection has been achieved
• Fig 4.100 is solar absorption cooling system
• 513 “only one kind of storage is necessary, but, with both hot and cold storage, the sys- tem can simultaneously cover both heating needs (e.g., hot water) and cooling needs (e.g., air conditioning).” This sounds like conversation between Type 4 and Type 5 Geothermal energy
• 513 absorbent-refrigerant mix can be LiBr-H2O or H2O-NH3. lithium—bromide—water mix is more suitable for flat-plate solar collector systems, having a higher efficiency than the water—ammonia mix for the temperatures characteristic of flat-plate collectors
• Fig 4.101 solar water pump using Stirling cyle
• 514 cooling by means of solar energy may also be achieved by first con- verting the solar radiation to electricity then using the electricity to drive a thermodynamic cooling
• Fig 4.102 solar water pump using Rankine cycle
• Fig 4.103 solar still for water purification

Fuel cells

• 515 A device that converts chemical energy into electric energy is called a fuel cell
• 517 driven cell if inverse conversion (electrolysis of water to hydrogen) happens
• 517 regenerative/reversible fuel cell if both driving and forming can happen
• Fig 4.104 basic schematic of fuel cell
• 519 phi is the quantity usually referred to as the electromotive force (e.m.f.) of the cell, or standard reversible potential of the cell,
• 520 ideal efficiency of hydrogen-oxygen fuel cell is 0.83
• 520 loss mechanisms are blocking of pores in the porous electrodes [e.g., by piling up of the water formed at the positive electrode in process (4.145)], internal resistance of the cell (heat loss), and the buildup of potential barriers at or near the electrolyteelectrode interfaces. Most of these mechanisms limit the reaction rates and thus tend to place a limit on the current of ions that may flow through the cell
• Fig 4.105 Fuel cell electric potential w.r.t. current
• 521 optimum fuel cell current is less than max; this is where max efficiency is obtained
• 521 If a fuel cell is combined with an electrolysis unit, a regenerative system is obtained, and if hydrogen and oxygen can be stored, an energy storage system, a battery, results. The electric energy required for the electrolysis need not come from the fuel cell, but may be the result of an intermittent energy conversion pro- cess (e.g., wind turbine, solar photovoltaic cell, etc.).
• 521 Directly using light to electrodes is possible using p- and n-type semiconductors
• 522 hybrids between either battery electric vehicles or fuel cell vehicles and conventional inter- nal combustion engine vehicles may smooth the transition.
• 522 some fuel cell technologies include: phosphoric acid cells (needs high temp, alkaline cells (these struggle with CO2 presence), and proton exchange membrane (PEM)
• 523 membrane material for PEM can include polyperfluorosulfonic acid
• 523 platinum or Pt—Ru alloy catalyst is used to break hydrogen molecules at negative electrode
• 523 The efficiency of conversion for small systems is between 30% and 50%, but a 50 kW system has recently shown an efficiency in the laboratory of near 60% . HIgher efficiency for partial loads
• Fig 4.106 show PEM schematic
• 524 hydrogen storage is a problem. Metal hydride or carbon nanofiber stores could be used.
• 524 methanol could be used instead of hydrogen despite much lower energy density than gasoline. This is quite acceptable owing to methanol’s higher efficiency of conversion. Hydrogen is then produced onboard, by a methanol reformer, before being fed to the fuel cell to produce the electric power for an electric motor.
• 524 PEM fuel cells that accept a mixture of methanol and water as feedstock have been developed but still have lower energy conversion efficiency than hydrogen-fueled PEM cells.
• Fig 4.108 shows methanol-to-hydrogen vehicle
• 525 molten carbonate fuel cell uses carbonate as hydrogen and oxygen converter
• 526 solid oxide fuel cell uses high temps, and Current conversion efficiency is about 55%, but it could reach 70—80% in the future
• 526 there is a need for new safety-related studies, particularly where hydrogen is stored onboard in containers at pressures typically of 20—50 MPa.

Other Electrochemical

Real page number in 517, pdf page number is 527

• 527 Salinity gradients can be used to drive electricity directly, unlike osmotic pump: dialytic battery see Fig 4.109
• 528 Internal and external losses are present in this
• 528 Salinity gradient cells have to be stacked to get adequate current
• 529 Highest power is when freshwater has 3-4% of seawater salinity, because the salinity allows ion exchange
• 529 Salinity gradient conversion device difficult on large scale because large membrane needed

Bioenergy

• Fig 4.111 shows biomass uses (non-food)
• 530 Biomass is also nutrients, so interferes with biosphere when used as just fuel
• 530 Fossilization increases energy density of biomass from 10-30 MJ/kg (living) by a factor of 2×
• 531 In future, fossil fuel may still be used, but for non-energy purposes (lubricants, plastics)
• 531 Low-grade fossils such as coal, shale, tar cause extreme pollution to soils and waterways during extraction
• 531 Captured CO2 has challenge of storage; only deep ocean seems viable for storage
• 531 CO2 capture from flue gas is costly+inefficient
• 532 Cow dung needs more energy or drying than what can be obtained by burning
• 532 Firewood and others act like stores of energy since they can be dried in summer, used in winter
• 532 Heat efficiency from wood/straw is at most 0.6, since a lot of it is lost as vapor and smoke
• 532 Only 5% of heat reaches pot in 3-stone stoves in rural countries for cooking
• 532 Indoor air quality is extremely poor when using chulas.
• 533 Early European stoves had at most 25% efficiency. Typically 10%.
• 533 Industrial burners reach up to 60% efficiency
• 533 Crushing, pelletizing, etc. make biomass more versatile
• 533 charcoal is more efficient, even if wood-to-charcoal has losses
• 533 Talks about waterwall incinerator, where biomass is used for district heating in a way where air pollution is minimized
• 534 Environmental impacts of biomass via combustion is similar to that of coal and oil combustion. Sulfur and NOX values are lesser.
• 534 Electrostatic filters can remove up to 99% particulates
• 534 “When a wood boiler is started, there is an initial period of very visible smoke emission, consisting of water vapor and high levels of both particulate and gaseous emissions. After the boiler reaches operating temperatures, wood burns virtually without visible smoke. When stack temperatures are below 60°C, during start-up and during incorrect burning, severe soot problems arise.”
• 534 benzo(a)pyrene emission is 50× more in biomass than fossil fuel. Severe problem with chulas.
• 535 for biomass, CO2 emissions combusted is balanced by CO2 assimilated by plants, especially if fast biomass crops are used
• 535 fluid manure has ≤10% dry matter. Solid manure has 50-80% dry matter
• 535 composting involves bacterial decomposition with air flow
• 535 heat produced by decomposing carbs in composting
• 537 composting stops if too much heat, so getting high heat is difficult
• 537 final composted product is valuable as fertilizer
• 537 heat from livestock can be used, but heat pump needed. Not feasible if newborn/young animals present. Best with dairy farms.
• 537 dairy cow converts 25% fodder into milk, 25% into manure. More energy is in form of heat if temperature is colder.
• 538 Fischer-Tropsch process for converting coal to hydrocarbon, in inefficient manner. Sulfur has to be removed to improve catalyst functionality
• 538 Fischer-Tropsch process efficiency = 21% to 55%
• 539 different names for Fischer-Tropsch process when process tweaked: solvent refining, H-coal, donor solvent
• 539 biological material can be converted to hydrocarbons or hydrogen using anaerobic fermentation
• 539 lots of waste and ocean-grown algae/seaweed can be used for biogas
• 539 anaerobic digestion is particularly suited for getting biogas in wet process
• Fig 4.116 “Simplified” anaerobic digestion of biomass
• 539 Last paragraph and next 3 describes the exact process of fig 4.116. Useful!
• 540 Anaerobic digestion can be done in single chamber, but multiple chambers improve efficiencies: third stage takes weeks, while first two takes hours or days
• 541 Talks about challenges and solutions to anaerobic digestion; useful to mix and match different biomass for biogass production
• 541 biogas conversion efficiency from manure of grown cows and pigs = 42% and 61% efficiency respectively
• 542 anaerobic fermentation removes pathogens, so useful for cleaning sewage
• 543 biogas + fertilizer very common in rural India and China
• Fig 4.117 shows biogas reactor plant energy flow
• 544 biogas is 23 MJ/m3, medium quality; CO2 removal necessary, ideally by water spraying
• 544 volume penalty for methane storage (vs oil) is 9×
• Fig 4.118 New Zealand methane production and vehicle use
• 545 if residues are recyled, little environmental impact from anaerobic digestion. Contaminants that come out are simply returned to soil
• 545 because biological organisms used to make biogas, poor performance will warn about problems with source and contaminants.
• Fig 4.119 biogass single chamber in China
• Fig 4.120 conversion efficiency of biogas. Pig is highest for simple biogas plants.
• 547 pathogenic bacteria+parasites not removed as much when composting happens
• 547 citiy sewer can use biogas as energy source to drive sewer cleaning procedure, and even gain energy
• Fig 4.121 biogas plant diagram, that takes sewer and gets many different things out
• Fig 4.122 energy efficiency over the years for biogass per biomass production. As much as 90%! (and as little as 20%)
• 549 129 kg of CO2 reduced for every m³ of biomass converted to biogas!
• 549 other environmental effects are possible, but can be easily mitigated (NOx emissions, nutrient emissions, odors, etc.)
• 550 photolysis exists, but better if biology is used for photolysis
• 550 in many cases, making fossil fuels ‘cleaner’, like coal to gas, creates more emissions.
• 550 methane could be synthesized in sites of coal mining by directly converting the carbon to methane and water. Lurgi fixed-bed gasifier and Keppers-Totzek gasifier; both have low efficiencies
• Fig 4.123 making synthetic natural gas using coal
• 552 equivalenc ratio is ratio of oxygen available to oxygen that would have allowed complete combustion
• 552 0.1 and less equivalence ratio is pyrolysis; inefficient
• 552 0.2 to .4 equivalence ratio is gasification; max energy transferred into gas
• 554 turning wood to biogas: updraft not ideal; downdraft better; fluidized superior for large scale
• 554 wood gasification produces ash, char, liquid wastewater, and tar. Char can be recyled in gasifier. Ash and tar can be used in road building
• 555 ethanol produced by yeast fermentation on glucose; ethanol continuously removed when concentration reaches 12%
• 555 hydrolysis can be used to reduce other stuff going into fermentation
• 555 theoretical max of glucose-to-ethanol conversion is 97%, but realistically only 25%
• 556 food oils readily burn in diesel engines
• 556 using crops foir fuel oil interferes with food production, except palm oil; palm oil can help with other crops if intercropping done
• 556 places where food trees can’t be grown could grow fuel oil trees
• 556 rubber is hyrocarbon-water emulsion, with lot of hydrocarbon; latex has slightly lower molecular weight, and can yield diesel fuel
• 556 sterols in gopher plant (50%) can be feedstocks to replace petroleum in chemical applications
• 556 hydrocarbon could be produced from plants, but research is not super optimistic
• 557 cost of ethanol from bio is equal to gasoline
• 557 lignin provides structural rigidity, such as wood and straw. Has to be broken down for bioenergy.
• 557 historically acid used for hydrolysis of breaking down lignin, but very ineffective.
• 557 using enzymes for hydrolysis is better: bacteria and fungi have these and can convert 80% of lignin to glucose (rest is cellodextrins)
• 557 residue can be used for fertilizer or animal feed; alternatively burnt for heat for distillation
• 557 fermentation product = water-ethanol mixture. If alcohol is 10% or higher, fermentation halts. So distillation needed to remove ethanol, but ends up needing energy
• 557 energy input is 1.5× than energy output of bio ethanol. Could still be viable if agricultural waste used and intention is to stop imported oil
• 558 more sophisticated designs could get efficiency of 55%-65% of inputs
• 558 Fig 4.127 LOT of distillation energy needed if ethanol in final product is higher (especially greater than 90%)
• 559 ethanol can completely replace gasoline for vehicles, and has very high octane number. Can blend gasoline and ethanol 10% without engine modification
• 559 ethanol-diesel would require emulsifier. alternatively, use diesel with plant oils
• 559 sugar cane and cereals are ideal for biomass, but these also need good land, so compete with food: “first generation biofuels”. However, waste sugars and cereal residues could be used: “second generation biofuels”
• 559 acids for hydrolysis poses several risks. Enzymatic hydrolysis is less risky, but can harm if they escape with waste water
• 560 “ethanol combustion in modified ignition engines has lower emissions of carbon monoxide and hydrocarbons, but increased emissions of nitrous oxides, aromatics, and aldehydes”
• 561 carbon monoxide + hydrogen gas + some CO2 + catalyst = synthesis gas
• Fig 4.129 shows how to get methanol from biomass
• 562 using synthesis-gas-to-methanol, wood to methanol efficiency is 40-45% by energy

Chapter 5: Energy transmission and storage

PDF 579 = 570 actual

• 579 Equation for heat loss along pipeline that is transferring heat. Excludes friction
• 580 Average heat loss in pipelines is 10 to 15%; economical to have transmission be less than 30 km long, except perhaps geothermal
• 581 For long distance electricity, converting to DC and then back is common
• 581 Uninsulated electric lines have losses depending on the state of air (leak current)
• 581 Loss for 138 to 400 kV transmission line 15 to 40 m above ground is ≤1% per 100 km. Transmission line only
• 581 Grid loss is 12% to 15% per 1E4 km² of land for old networks; 5 to 6% for post 2000s, and 2 to 3% for newer ones
• 581 Cooling transmission lines for higher efficiency is illogical due to higher energy needed to reduce heat
• 582 Current offshore wind farms use AC cables of up to 150 kV, but will likely use DC in the future
• 583 Super conductors (niobium, niobium-tin) could be used for ultra long distance DC
• 583 Even with super conductors, AC has losses due to electromagnetic field variation
• 584 Natural gas distribution lines made of plastic use 103 kPa to 400 kPa. Steel ones use 5 to 8 MPa. These lines can also transfer hydrogen if valves are upgraded
• 585 fossil fuel and nuclear power plants have long start-up times, whereas pumped water has satrt up time of less than a minute
• 586 For storing and distributing energy as heated water in a home, 45 to 50°C is good for water-filled radiators, and 25 to 30°C for heated flooring and vetilation.
• 587 0.3 m³ water storage tank is sufficient for storing heat for daily fluctuations in single family home
• 588 Adding more solar collectors for water heating produces less and less gains in energy collected
• 591 large warm water tanks (5 m to 20m radius) can be kept uninsulated if heat storage of few days is needed; otherwise insulation required
• 592 for centralized hot water storage, central solar collector more beneficial because it can operate at higher efficiencies; individual solar collectors already receive warmed up water so not efficient
• 592 if no surrounding natural water flow is present (e.g. ground water), very much makes sense to have hot water storage be under ground, and surrounding earth mass also acts like storage
• 593 in hot water storage reservoirs, temperature stratification is preferred
• 596 Example of solar pond using salt density, shallow waters, and heat exchanger at bottom
• 597 solar ponds and stores can be modelled easily since water is very stable in heat
• 597 in industry, medium temp is 100 to 500°C, and high is above 500°C. Lower-medium is 100 to 300°C.
• 598 transfer fluid can be passed multiple times for heat conductivity, especially for air which has low conductivity
• 598 surface area for air ca be increased by using granular storage material
• 598 advection = moving entire fluid. convection = turbulent transport
• 598 liquid sodium is very conductive, and acts as both heat storage and transport; serious safety problem. Used in solar collectors and nuclear breeder reactors, with storage temps of 275°C and 530°C.
• 598 equation for ganular mass diameter
• 599 Table 5.1 heat capacity, range, and conductivity of some materials
• 599 optimum particle diameter for granular heat storage is few centimeters and void diameter of 0.5
• 600 energy can be stored in phase transitions. These could be simple structural changes such as solid sulfur changing crystalline forms, or lithium sulfate storing a lot of energy. Hydrates can also be used which allows higher latent heat capacities (see Table 5.2 and 5.3)
• 601 chemical heat pump separates two chemicals, one which absorbs heat and other which gives
• Figure 5.12: Chemical heat pump. Text surrounding it describes the actual process.
• 605 In chemical heat pump, the heat store can literally be moved to a different location, and the heat loss is about 3 to 4%
• 606 cost of chemical pump in regular production is 4 to 5 euro per kWh. Can be used for both heating and cooling.
• 606 using chemical reactions to store and use heat is technically (temp, pressure, energy density, etc.) and economically difficult
• 607 reactants have to be stored in different chambers to prevent unwanted reaction; exception is catalyst, where the catalyst can simply be taken out
• 607 chemical reaction based storage has near infinite storage time, and compounds are not consumed, and has high energy densities
• 607 EVA-ADAM transmission line uses chemical reaction principle, where carbon monoxide and hydrogen gas can just be transported from nuclear facility to use site. Significantly higher energy density than storing water

• 608 Metal hydride systems are another chemical reaction stores that can be used for heating

• 609 “Quality” of energy storage is important. Typically mechanical or electrical energy have high quality
• 609 converting heat into mechanical or electrical is limited by Carnot limit and other losses
• 609 reversible storages have much lower volumetric energy density than solid/liquid fossil fuels
• 611 hydro storage (dams) can be used to store energy of intermittent wind/solar
• 611 artificial reservoirs can be made for storing hydropower
• 611 artifical reservoirs can cover up to 24 hours, but natural ones can cover a whole year
• 611 if overhead reservoirs not possible, underground can be made
• 613 large heads use Francis and Pelton turbines; these have 0.95 efficiency for strong flows, but 0.8 for decreasing flows.. Small heads use Kaplan or Nagler. Francis can be multistage, where efficiency is 0.7. Changing from pumping to generating takes about 1 minute.

• 613 for underground stores, cost scales about linearly with capacity

• 5.5.1 talks about flywheel mathematics
• Equation 5.23 gives the optimal disc thickness for constant stress flywheel: it is infinitely extending and exponentially declining in thickness.
• 618 tangential stress in flywheel is highest in inner rim

• Equation 5.32 describes the shape for a miximum stress and storage density. Using this, the maximum angular velocity can be found.

• 619 infinite flywheel isn’t possible, so has to be truncated, leading to shape factor of 0.8.
• 619 low material cost is key factor for flywheels
• 619 filament type flywheels (multiple rod-like) disintegrates individually and gets contained, so is safer
• 620 solid flywheels expel large fragments, so unsafe for vehicles; maybe used for stationary storage
• 620 constant stress infinite flywheel is not volume efficient
• 621 flywheels would need friction mitigation; can be done by placing in vacuum and using magnetic suspension made of cobalt compounds and electromagnets

• 621 for stationary flywheels, 3000 kJ/kg possible

• 621 small scale compressed gas storage can be done in steel containers
• 622 larger scale compressed gas storage can be done in salt deposits (flushed with water), rock cavities (natural or excavated), and aquifiers (regions above the water). See Fig 5.19
• 622 in all underground compressed gas cases, cavities ability for storage is not fully known until after installation
• 623 air-aquifier/water case could be viable as it does both compressed gas + lifting hydro storage
• 624 pressure difference for compressed air can be up to 70×, and reach temperatures of 1000 K, so cooling needed; heat can be moved to thermal energy storage
• 624 compressed air loss is 5 to 10% due to compression, and more from heat. Overall cycle efficiency is less than 65%, unless thermal loss can be less than 10%
• 629 aquifier type compressed air storage has to have high permeability to fill and unfill. Permeability at the borders however causes leaks.

• 629 loss from pressure is 15% + losses from machinery

• 629 hydrogen gas produced by methane/gasoline + H₂O at 850°C, 2.5 MPa under catalyst. typical process
• 630 emerging process is high-temp plasma-arc gasification at 1600°C that produces high purity at lots of useful products. 48% efficient
• 630 hydrogen can be produced cleanly using electrolysis (70% efficiency) or reversible fuel cells 90% efficient
• 630 “Electrolysis conventionally uses an aqueous alkaline electrolyte, with the anode and cathode areas separated by a microporous diaphragm “
• 630 cooling has to be applied in electrolysis due to over voltage from polarization effect
• 631 electrolysis has inefficiencies, so solid-state electrolyzers can be used, but they are just fuel cells in reverse
• 631 thermal decomposition of water not possible since it requires 3000 K, but could be done by using the three-stage reaction which requires at most 850°C instead, though it is still corrosive
• Table 5.8 showcases danger of hydrogen (very low minimum energy for ignition, high flame temperature, high flame velocity, high diffusion coefficient in air)
• 632 commercial hydrogen storage at 20-30 MPa, and still less than 10% energy density of oil
• 632 Carbon fiber needed to reduce permeability of hydrogen for compressed
• 632 even for liquid hydrogen at -253°C, energy density is 4 to 5 times lower than regular fuel
• 633 hydrogen can be stored as metal hydride, but still has 10% less density than conventional fuels. Highest density is two hydrogen atom per metal atom by Toyota 1996. Has benefit of cleaning gas.
• 633 methanol fuel cells is better than methanol to hydrogen to hydrogen fuel cell

• 633 carbon nanotubes can be used to store hydrogen, but no existing design

• 634 “Rechargeable batteries are called accumulators or secondary batteries, whereas use-once-only piles are termed primary batteries”
• 634 cell voltage in galvanic cell depends on electromotive force subtracted by the polarization factor of current and internal cell resistance
• 5.5.11.1 lead-acid battery
• 637 “ The energy density of the lead-acid battery increases with temperature and decreases with discharge rate”
• 5.5.11.4 lithium-ion batteries
• 638 environmental concern of LiIon battery is cobalt, which is very toxic and needs a lot of recycling to be acceptable
• 640 “ If many household appliances become battery operated, the stringent requirements placed upon the electricity system to meet peak loads may become less burdensome”

• 640 “Freedom from having to always be near an electric plug to use power equipment is seen as a substantial consumer benefit, which many people are willing to pay a premium price for.”

• 641 Supercapicators can be used to smooth out energy fluctuations using rapid charge/discharge
• 642 reaction of using metal to convert CO₂ + H₂O into methanol using light also favors reverse reaction very readily because of close proximity of reactants+products, and both reactions are similar
• 642 if using photochemical reaction, would be beneficial to separate reactants and products using charge or hydrophilia
• 643 photo-induced chemical reactions have same limitations as photovoltaic cells due to limited light absorption range
• 643 magnetic fields are form of stored energy. CERN uses supercooled superconductors to store energy as magnetism slowly, which can be used very fast. 1 GJ power storage, but 10 to 100 TJ needed for commercial viability.
• 644 superconductivity can disappear if too much magnetic field; only type II superconductors are useful

Mini Projects

• Massachusetts Total Potential for Solar 2023.
  • Map. Link.
  • Documentation. Link.

Chapter 6: Energy Systems Planning

PDF pages is 7 pages ahead than actual page number

• 656 “real demand is always a product or a service, not the energy in itself”
• 657 “even trend forecasts cannot be expected to retain their validity for very long periods, and it is not just the period of forecasting time that matters, but also changes in the rules governing society.” “The non-linear, non-predictable relations that may prevail in the future, given certain policy interventions at appropriate times, must therefore be postulated on normative grounds”. → Scenario method
• 657 scenarios ≠ predictions. Scenarios are “options that may come true if a prescribed number of actions are carried out”.
• 658 scenarios for tackling one problem such as global warming is of he simpler kind
• 658 for energy systems, short-term fluctuations can be left out in some cases
• 659 flow delays can be ignored for cases like fluids
• 659 flow delays should not be ignored for presence/absence of energy. Mainly true for storage facilities
• 660 transmission times can be included as simple constant delays
• 660 dispatch optimization = how to best use the system at hand
• 660 second way of system optimization is system layout = what structure of conversion systems should/can be changed
• 6.2.1 describes potential scenarios in final energy use (non-quantitive = precursor scenario)
• 663 Catastrophe precursor scenario includes: “In this scenario, there would be a decreased number of people trained in skills necessary for participating in international industrial and service developments, and the opportunity to import people with these intellectual skills would have been lost by the imposition of immigration policy unfavorable to precisely the regions of the world producing a surplus of people with technical and related creative high-level education.”
• 6.2.2.1 Laisser-faire precursor senario actually reduces energy efficiencies and progress
• 6.2.2.2 Rational investment precursor scenario is only partially used in our current age

• 665 average efficiencies over groups of related equipment can be extrapolated reliably

• 666 Maslow’s hierarchy of needs. Energy demand associated with satisfying these needs.
• 666 Natural approach to energy demand is to fulfill needs. Market-driven scenarios focus on commercial interests more. “It is interesting that the basic needs approach is routinely taken in discussion of the development of societies with low economic activity, but rarely in discussions of industrialized countries”
• 666 identify needs → discuss energy to satisfy them by tracing backwards to resources
• 667 typically can ignore the political and economic systems that deliver energy; however, realistically political/economic system alters these, such as by import/export
• 667 9 end-use energy demands and A-F goal categories
• Table 6.1 and 6.2 perform the end-use energy calculation using bottom-up techniques
• 669 most heating/cooling energy comes from buildings
• 671 method to approximate heat loss or cooling
• 673 typically people don’t live in harsh climatic regions (Siberia, Darwin Australia)
• 6.2.3 and subsections talks about the end-use energy calculations
• 679 “the lower limit of energy use for recreation and social visits is between 5 and 6 times less than the upper limit.”
• 681 present day combustion engine efficiency is 20%; future in 2050 is closer to 50% due to electricity (losses are due to numerous conversions)
• Table 6.3 to 6.5 also do end-use calculations
• 685 “It is reassuring that the gross estimate of energy demands associated with full goal satisfaction is much lower than present energy use in industrialized countries. It demonstrates that bringing the entire world population, including little-developed and growing regions, up to a level of full goal satisfaction is not precluded for any technical reason”
• 685 Consumers often choose items that have lower present purchase cost, but significantly higher use cost
• 685 “free consumer choice” is often used as an excuse to sell lower quality and low efficiency equipment

• 686 “One wonders when consumers will, instead, respond with the thought that, “If a product needs to be advertised, there must be something wrong with it”?”

• Fig 6.14 and 6.15 Relative electricity load between days and time of day of different seasons. Bimodal distribution in both cases
• 687 For RE, best loads are those that can be done in a certain time span, irrespective of what day and time.
• 689 Typical = average and the typical variations
• 689 For data on typical values, can use multi year variations, a “reference” year, or generate data if average and standard deviation is known
• 691 Best solar locations = “Sahara, the Arabian Peninsula, the Gobi, and Australian inland locations”
• 691 For PV transmission and storage, 0.75 can be assumed for the losses
• 692 Just 1% of usable land and 5% of desert-ish area can cover MANY times more than the 2050 demand for energy, inclusive of losses!
• 692 “A centralized installation in the huge area of the Sahara Desert would suffice to supply more than the entire world’s need for energy. Of course, it would require intercontinental transmission, which may be realistic by the year 2050, e.g., through superconducting trunk line”
• 694 wind turbine start generating above 5 m/s, and peak at 12 m/s. Wind weather has 2 week period typically.
• 696 wind turbines may claim 10% of land, but realistically only occupy 0.1% of land, to sustain world energy demand; can place PV in between and other things
• Fig 6.25 Power curves for typical wind turbines

• Table 6.6 cost of installing wind turbine

• 709 offshore wind speed measured by using satellite data, measuring the reflected radar signal; these reflections are modified by the wave ripples on ocean, and those are affected by wind
• 710 surface wind info is taken to get wind info at higher heights and also use for wind turbine characteristics
• Fig 6.32 overview of biomass
• Fig 6.33 and 6.44 shows global cropland and rangeland map, and 6.45 is forests. 6.46 shows marginal land. As of 2000s
• 721 changing meat to vegetable ratio is sufficient to use biomass for energy without risking food shortage for growing population
• 721 most African places don’t use cropland for feeding livestock
• Table 6.7 shows biomass growth capability due to several factors
• 724 85% of animal biomass does not go to our food
• 724 biofuel from forestry scraps is 30% of forest collected biomass

• 728 two get to a particular scenario, either set of paths can be taken from present to the scenario, or backcasting (final to current) can be done

• 728 capacity of energy supply determined by max load expected
• Fig 6.43 example supply-demand energy storages
• 729 when changing tech, consider economic effects of early retirement of existing tech
• 731 for PVT, electricity is weaker than thermal
• 731 for PVT, if heat transfer fluid in front of panel then it is air, if behind then it is water.
• 733 for PVT, if water then corrosion protection and seals needed, if air then it has low effectiveness; better to collect heat behind panel
• 734 heat needed in building = heat losses
• 735 naturally ventilated Danish dwellings have lower air-exchange rate than needed for health
• 736 buildings release gasses in first few years after installation
• 736 if heat supplied by: water, then 45°C minimum; air, then 28°C minimum
• Fig 6.47 Solar heat system with switching heat pump between store, load, and collector
• 739 making low-temp side of heat pump during storage mode be soil or air, it becomes an independent energy source
• 739 using heat pump to lower solar collector temp is unsutable
• 745 in general, 6.5.1.5-7 basically states that, attempting to provide heating to individual buildings with their own PVT does not satisfy the building’s heat demand. Small 2 m² solar system never covers energy need, medium covers about 2 months, and large 40 m² covers about 5 months. In general, the larger the system, the better it is. Even if auxiliray power needed in winter, some energy needs still met by PVT.

• Fig 6.58 shows PVT supply-demand stats for the ‘large’ PVT system. There’s more energy generated in brighter months. 1 to 2 month delay between peak solar input and peak energy output

• Fig 6.66 when heat pump is added to large PVT, no aux power needed
• 754 wind turbines over land have 4× more max peaks than average; off shore has 2.3×
• 759 coupling just 3 wind units is similar as coupling 18 wind turbine units in country like Germany since large variations appear all throughout the country. Distances of over 1000 km are needed to tune our low frequency wind fluctuations
• 760 fossil fuel generators take time to start. If time elapsed since last stop is short, then not lot of time is taken to start again: generally 1 to 5 hours. If starting after long time, then over 5 hours, with same taking 2 days
• 760 metereological forecasts can’t do exact wind estimates, but can predict storms
• 762 simple predictions such as ‘high wind’ etc. is feasible, especially with previous wind data within a couple of hours
• 763 to maintain balance between wind and fossil, different fossil units operate at different capacities, and can be brought up or down to match wind. If too much down needed, then one fossil stopped and other fossil increased. No more than 1 fossil unit stopped in any given hour to minimize challenges with sudden loss of wind
• 763 if wind is in severe deficit, then peak-load units needed: storage, hydro, gas turbines, electricity import, etc., which have fast start ups
• 764 when the average energy produced by wind is 30% of average energy produced in total, base load gets replaced by wind. Rapid increase of number of times peak-load units are needed.
• 764 “the additional peak-load usage excluded in this way will be independent of whether the system comprises wind energy converters or not”
• Fig 6.75 even if wind capacity is increased, wind energy must be lost to keep use of non-wind units, since non-wind times have to be met (this was without storage!)

• 768 wind forecasting for power is good for 1 to 2 days

• 771 high storage-cycle efficiency achievable via flywheel storage, pumped hydro storage, and superconducting storage. These are needed for short-term stores.
• 771 setting wind up for peak-load has benefit of being able to pre-emptively charge for peak, and displace peak-load fossil units which are expensive
• 773 “modest storage leads to a substantial improvement in availability, but improvements above availabilities of 75%-80% come much more slowly and require storage sizes that can no longer be characterized as short-term stores”
• Fig 6.82 shows that, as short-term storage capacity increases, the energy fluctuations are decreased at a decreasing rate. However, fig 6.83 shows that as short-term storage capacity is increased, their charge/discharge cycles increase at a decreasing rate.
• 775 “the performance of a store indicate that the improvement per unit of storage capacity is high at first, but that each additional storage unit above ts ts=70 h gives a very small return.”
• 777 peak load operation: “the storage size required to reach an 80% availability increases with the peak-load time fraction, but, relative to the capacity of the wind energy converters, the trend is decreasing or constant”
• 777 if too much peak load, then wind system acts as base-load mode
• 778 mode of operation for wind with long-term energy storage is load-following. For example, wind + hydro, decentralized hydrogen (and using waste heat of the conversion),
• 778 hydrogen can be stored underground in caverns/aquifers, available in many locations
• 778 to fulfil 100% of load using wind, 1250h of storage needed; if 97%, then 730h (1 month) of storage needed.
• 779 in general, it is much better and cheaper to share renewable electricity across countries
• 780 exchange of power/fuel already happens between countries today
• 780 power for heating/cooling per floor space used to be 36, then 24, and in the future 18 W/cap/°C in Denmark 1980, 2005, and future respectively
• 781 food can be assumed to be 120W/cap + 18W/cap for storage. Leisure anh human relations is 100 W/cap. These are old Danish numbers.
• 783 one solution to reducing energy due to transport is making employers be responsible for transporting employees and including that as work hours: this forces employers to choose most energy efficient options
• 783 energy surplus of Nordic countries is as large as the energy deficit in Germany (renewables)
• Fig 6.88 Nordic hydro weekly fillings example
• Fig 6.89 on-shore vs off-shore wind-power production in Northern countries. Off shore significantly better.

• Fig 6.90 power duration curves for northern european countries.

• 791 in Meditarranean region, fixed horizontal solar panels works as well as tilted panels
• 792 African Mediterranean countries could export solar
• Fig 6.95 and 6.96 different solar placement (roof vs centralized) in Mediterranean region
• 795 in Meditarranean, annual solar is more than adequate, but storage needed for winter months for heating
• 795 some Meditarreanean countries have lots of land for solar, while others not; wind can be used to make up for deficit
• Fig 6.103 vs 102 shows that northern Meditarreanean countries have more wind potential than African ones, but still have MASSIVE surplus due to solar
• Fig 6.105 potential power grid connections for Mediterranean Saharan export
• 801 In Mediterranean, potential exists for biofuels from waste food etc. especially France
• 801 Biomass less expensive than battery or fuel cell vehicles, but still has pollution (Mediterranean, also old data)
• Fig 6.113 to 6.116 shows maps of different energy productions in North America
• Fig 6.118 to 6.121 shows how much energy can be produced in different NA countries
• Fig 6.125 to 6.129 describes energy in and out for 2060 for NA countries
• 813 In 2060, Alaska and Canada have potential for bio+electricity export, Greenland has electricity export, and transmission networks needed
• 813 “In winter, the solar panel thermal circulation is shut down due to risk of frost damage, and the heat pumps deliver all heat required.”

• 817 “Hydrogen pipelines have to be built to higher standards than most of the natural gas pipelines currently in operation, which is estimated to add some 25% to cost”. “current estimated cost of GW hydrogen pipelines lie somewhere between the cost of land-line and sea cable electricity transmission costs, at 1.0-1.5 M US$/km”

• 819 Japan has high frequency of clouds that diminish solar. Also SK + Japan suffer from high population density
• 819 Japan and SK has good wind
• 824 “efficiency is an established virtue in the South-East Asia region”
• 824 “the efficiency of charging batteries and delivering traction energy to wheels by an electric motor is higher than the efficiency of hydrogen production by electroly-sis and subsequent fuel cell operation, but the gap may narrow with time.”
• 824 hydrogen preferred for SK+Japan due to greater need for long term storage
• Fig 6.143 SK+Japan renewable energy input chart
• 825 China just has lots of renewables: solar in south; wind (on shore) in west high country, northeast belt from Mongolia to sea, and entire coast; great offshore due to shallow waters; great hydro; great agricultural lands. However, not evenly spaced resource: see fig 6.149
• 833 region in China with energy deficit only needs to import electricity and biofuels; heat obtained from conversion losses

• 833 “China is endowed with sufficient renewable energy to allow the establishment of a stable and unstressed supply system, covering a demand as high as that of the most developed nations, say in Europe.”

• Tables 6.165 to 6.170 shows global energy flow for different regions. Table 6.5 lists the regions (1 through 6): USA, Canada; Western Europe, Jap, Australia; Eastern europe, ex soviet, middle east; latin america SE asian tigers; china and other asia; Africa. Fig 6.171 shows global use case.
• Fig 6.172 shows 2050 all renewable energy trade.

Socioeconomic assessment

PDF 860 = book 853

• 860 “In a socialist economy, the power to produce goods is entirely attributed to the workers”
• 861 “in a capitalist economy, only capital is capable of producing profit, and labor is on the same footing as raw materials and machinery”
• 861 long term price determined by mark-up or full-cost
• 861 flexprice (supply-demand relations) used to determine short-term price
• 862 this page talks about determining net profit for given goods
• 862 one pricing option is using shadow prices, but this needs adjustments often
• 864 Walrus equilibrium
• 865 “(2008+) financial crisis, which was caused by allowing nonproductive sectors, such as the financial sector, to attract a very high fraction of the total investments in society (in itself detrimental) and then to grossly mismanage the assets “
• 865 “ in a capitalist society the members of the capitalist class make individual decisions on the size of investment and the types of production in which to invest. Then it may well be that the highest profit is in the production of goods that are undesirable to society but are still demanded by customers if sales efforts are backed by aggressive advertising campaign “
• 865 “Unemployment is by definition absent in a socialist society. In a capitalist society, the effect of introducing new technology that can replace labor is often to create unemployment. For this reason, new technology is often fiercely opposed by workers and unions, even if the benefits of the machinery include relieving workers from the hardest work, avoiding direct human contact with dangerous or toxic substances, etc. In such cases, the rules of capitalist economy clearly oppose improvements in social values. “
• 868 “For the individual, who has a limited life span, this attitude (of having something in the present be valued more than having it later) seems very reasonable. But for a society, it is difficult to see a justification for rating the present high- er than the future. New generations of people will constitute the society in the future, and placing a positive interest on the measures of value implies that the “present value” (7.7 below) of an expense to be paid in the future is lower than that of one to be paid now “ … “ This places an energy system requiring an amount of nonrenewable fuels to be converted every year in a more favorable position than a renewable energy system demanding a large capital investment now. “
• 868 “A positive interest rate tends to make it more attractive, when possible, to leave the wastes to future management, because the present value of even a realistic evaluation of the costs of future treatment is low “
• Fig 7.2 practically showcases that renewables win in terms of cost
• 877 life cycle assesments can be done, but hard because techniques often determine how much energy and pollution
• 877 energy provided by a system should subtract the energy that was used to make that system in the first place
• Fig 7.3 sketches energy needs and outputs of renewable vs fuel-based system

Scale of analysis

• 879 “people place a high value on having as much control as possible over their lives and specifically over their energy provision, even at a premium cost. “
• 879 “Initially, the distances were seen as a positive development, because homes and children were separated from polluted cities and industrial workplaces, but today, pollution is unacceptable and therefore has been reduced, except for that from automobile exhaust, which is strangely regarded as a necessary evil. “
• 881 global GNP has been increasing. worldwide sum of foreign payments must be 0, so some countries are indebted to others.
• 882 “Hidden unemployment occurs if there is not enough meaningful work available for distribution among the work force”
• 882 “conservation should be given priority, as long as the cost of saving one energy unit is lower than that of producing one “
• 883 “ employment or “work” is in itself not a goal of society, and unemployment can always be eliminated by a distribution procedure that simply shares the available work. However, meaningful work for each individual may well be a social goal”
• 883 “if the investments and choices of energy supply system are made by individual citizens then the government has to use either compulsory regulations or taxation/subsidies to influence the choice of systems.”
• 885 annuity loans are better than index loans for renewables
• 885 many government funds for research is often dual-purpose support, such as offering energy people with military/space tech; the optimality of this is not well defined
• 885 subsidy policy has to be done right. Introduction of wind power in 1975 via subsidies failed in many countries.
• 888 in general, early privatization of energy sector led to poorer service, higher prices, and low development efforts
• 888 to combat challenges with privatilation, power industry separated into producers/transmitters/distributors, and additional legislation imposed
• 890 “the only possible solution to such concerns is to surround the energy supply sector with so much regulation that the owners of the production and grid system do not have any room left to maneuver—in which case it would be simpler to retain public ownership.”

Life cycle analysis/assessment

• 890 LCA = Life cycle analysis/assessment. Analysis is scientific and technical. Assessment is political.
• 7.3.1 talks about how to do life-cycle analysis
• 894 “impacts found in the literature are normally divided into direct and indirect, and the indirect ones are distributed over their origin”
• 894 In general, be careful of double counting! Especially for indirect costs!
• 895 LCA should be limited to a certain region. Effects of goods that are imported/exported should be excluded if the specific effect happens outside of the region
• 896 environmental effects of renewable systems are primarily from manufacturing. This can lead to imports being from countries dis-regarding human rights. To counter this, sometimes LCA can consider effects as if manufacturing done in home country, but problems of technology differences arise.
• Table 7.1 provides LCA consideration points. Bullet points surrounding the table give more explanation
• 901 policy-makers will often ignore warnings that are placed next to fragile data
• 901 fault-tree or event-tree analysis used for rare accidents. Former mitigates probability of individual equipment failures leading to disaster. Latter is from experience.
• 902 for rare events, “probability” is a wrong word
• 7.3.1.3 talks about how to do probabilistic calculations for accidents like air pollution
• 903 studies should consider more than just creation of the technology: should consider short, medium, and long term effects. Also should consider social and spatial effects.
• 905 assesments for planning uses state-of-art technology normally, but problematic because many places still prefers using old tech
• 905 this page has a list of issues for considering the setting
• 906 “No one demands energy, but we demand transportation, air conditioning, computing, entertainment, and so on.”
• 907 Damage can be monetized by substituting how much it would cost for the damage (e.g. hospitalization cost)
• 909 most people are not willing to pay for environmental damage or long term health costs, but are for avoiding accidents