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eak
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eak is now following Peter Reinhart
Apr 14, 2019
Some have questioned the lack of an inverter. I think this is meant to be used with a PV system, which will have its own inverter (those with micro-inverters are out of luck). The economics of this using PG&E E-6 TOU rates would be: charge 7 kWh at 90% AC-DC conversion efficiency and 92% battery efficiency is 8.5 kWh x 13.1¢/kWh = $1.11. Return power to grid at 95% DC-AC inverter efficiency = 6.65 kWh x 13.1¢/kWh = $2.15. Profit is then $1.04/d. Breakeven is then 2885 days (again not counting time value of money), or 7.9 years. These things are no where near big enough to provide backup power for a house (a few lighting circuits and a refrigerator could be powered in a blackout if your home were wired just right), or to enable off-grid operation, which is why I calculated its utility for load-shifting, but it doesn't appear to be that cost-effective at that either (especially if you were to include the time value of money).
Concerning the article text, A breakeven analysis showed that an ICEV would need to consume less than 3.9 L/100km (60 mpg US) to cause lower CED than a BEV or less than 2.6 L/100km (90 mpg US) to cause a lower EI99 H/A score. Consumptions in this range are achieved by some small and very efficient diesel ICEVs, the authors noted. It is inappropriate to introduce diesel MPG as equivalent to gasoline MPG. Diesel soot has been found to be the second most important greenhouse pollutant after CO2 (beating out methane) in recent work by Mark Jacobson at Stanford. Also, please note that the authors used the current European electric grid in their study. Unlike ICEVs, BEVs get cleaner with time as we improve the electric grid. In contrast ICEVs get dirtier with time, both as the vehicle components age, but especially as we are forced to turn to dirtier and dirtier sources of crude (e.g. oil sands, coal to liquids, etc.). My last point about the improving grid invalidaes Mannstein's comment. By the time ICEVs reach 60 MPG, the grid will have improved to the point that yet higher ICEV MPG will be required. Mannstein has also apparently not heard of fast BEV charging (e.g. the Nissan Leaf). It is technically possible to charge lithium batteries in 5 minutes (see A123 for example). As for the cost argument, new technology does usually get introduced at a cost disadvantage (e.g. early cell phones or CD players), but the manufacturing learning curve usually solves the problem in a few generations. Mannstein's concern about longer life from an ICEV engine is also wrong. Modern battery technology will soon outlast vehicle lifetimes, creating the problem of how we are going to move batteries from old vehicles to new ones.
Does the book actually work well on the Kindle? I've found books with graphs, charts, tables, etc. are poor candidates for the Kindle as the publishers don't spend enough time making them readable on the small screen.
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Wouldn't salt buildup on the solar cells quickly reduce their effectiveness?
Where would all the crops to create this ethanol come from? Sugarcane doesn't grow well in most of the US. To fuel the US on switchgrass cellulosic ethanol would require planting 18% of the non-Alaska land area. (Alaska probably won't be a good place to grow switchgrass for a few years anyway, but if we let global warming continue, it might be the only place it grows.)
What are the emissions like from this process? At 1000 °C there could be NOx and black carbon formed, as occurs in a diesel engine. If it is clean, how would it compete with the engines in locomotives, which are already used to generate electricity to turn the wheels?
This is not algae taking CO2 out of the atmosphere, it is feeding it the exhaust from a coal power plant, so what it does is use the carbon twice instead of just once, before releasing it into the atmosphere. But the coal still ends up as greenhouse pollution. Also, it would be much better to just burn dried algae in a power plant, generate electricity, and power electric cars, than it would be to convert the algae to CNG. Certainly that was the case for the Pickens Plan.
Quantum efficiency is not a great metric. Plants have high quantum efficiencies, but lousy energy efficiencies (they generally are sub-1% in conversion of sunlight into stored energy). So what is the g H2 produced per MJ of sunlight? Also, what do you do the sulfur oxides or whatever waste?
Henry Gibson, if the world got all of its energy from nuclear, we would still have global warming, because of the blackbody effect. See the analysis in Long-Term Global Heating from Energy Usage, Eos, Vol. 89, No. 28, 8 July 2008 page 253-254. Here is an excerpt: "More realistically, if world population plateaus at 9 billion inhabitants by 2100, developed (Organisation for Economic Cooperation and Development, or OECD) countries increase nonrenewable energy use at 1% annually, and developing (non-OECD) countries do so at roughly 5% annually until east-west energy equity is achieved in the mid-22nd century, after which they too will continue generating more energy at 1% annually, then a 3ºC rise will occur in about 320 years (or 10ºC in ~450 years), even if carbon dioxide emissions end." If you want a long-term solution, solar is the way to go. At 3,850,000 EJ/year of insolation, a single year of sunshine has far more energy than all the reserves of U235, U238, and Th232 combined. Remember that these are a kind of fossil fuel too (coming from the supernova that seeded our solar system).
I'll guess a lower heating value of 30 MJ/L for algae oil, in which case 60,500 L/ha/yr is 504 MWh/ha/yr. After combustion in a 35% efficient diesel engine, you get 176 MWh/ha/yr. Compare to Stirling SunCatcher CSP farm, which has a rating of 989 MWh/ha/yr, which means 773 MWh/ha/yr delivered to the motor (after grid, charge/discharge efficiency). That's 4.4 times better than the algae route. Of course the SunCatcher value is a lower bound (being built today), and the algae number is a "practical upper bound". The SunCatcher value might increase, while the algae number might never be practical.
To add to that last calculation, one can get some more data from their laptop battery data sheet. It looks like you want to discharge at 0.5 C; the 1 C and 2 C discharge rates seem to lose too much. My hypothetical 150-mile BEV using 250 Wh/mi at 70 MPH is 17,500 Watts, or 0.47 C, which works. Their recommended "fast charge" is 1.5 C, about 56 kW. 90 miles at 70 MPH is 1.29 h, recharging the 90 miles of range lost is 22,500 Wh. At 56 kW, this is 0.4 h. So steady state is 90 miles in 1.69 h, or 53 MPH, for cross-country driving. 56 kW is of course beyond J1772's meager 19 kW (240V, 80A, single-phase), but only 74% of the EU charging standard (400V, 63A, three-phase).
Let's run some numbers using a hypothetical 150-mile range BEV. 150 miles at 250 Wh/mi (highway) is 37.5 kWh. This would be 208 kg (459 pounds). Constant power would be 91.7 kW (123 hp). Pulse power would be 312 kW (419 hp). Charging every 90 miles on a highway trip would be 60% DOD, and so you would be 7,000 cycles * 90 = 630,000 miles on a pack. If only they had hinted at the $/Wh and charging time (can it do 5-minute charging like A123?).