Is rooftop solar more like an independent power producer, subject to societal regulation and policy, such as wholesale-level regulation or retail-level resource planning? Or is the electricity...
From Fuel Cells to a Hydrogen-based Economy
1 For example, a 1992 A.D. Little study estimated that a from-scratch bulk hydrogen supply infrastructure sufficient for 25 million cars would require about $95 billion of investment, or $3,800 per car. This antiquated result is still being quoted, e.g. in the Epyx article in the December 1998 (Derby 1998).
2 e.g., Lomax et al. 1997.
3 Widely quoted efficiency figures around 30-odd percent to 50 percent assume the fuel cell is fed not pure hydrogen, but the more dilute and impure reformate gas converted from a hydrocarbon fuel, and often include the conversion losses in the fuel processor.
4 Obviously, liquid fuels would become potentially interesting reformer feedstocks only if natural gas were not locally available, so that (for example) LPG or biofuels had to be substituted.
5 For illustration, even an $800 per kilowatt fuel cell system, at a 15 percent per year fixed charge rate, would incur a capital charge of only 2.7 cents per kilowatt-hour at a 50 percent capacity factor. Alternatively, the net electrical output efficiency of a PEM fuel cell using reformed methane often is quoted at or above 40 percent (lhv), often with neither heat recovery from the stack to the reformer nor pressure recovery from the stack's hydrogen input and stack output to the air compressor. With both forms of heat recovery, the best technology is now about 50 percent. At 50 percent conversion efficiency, natural gas at $3.70 per gigajoule or $4 per thousand cubic feet would produce electricity at 5.5 cents per kilowatt-hour. That would represent 2.7 cents per kilowatt-hour for the fuel plus 2.7 cents per kilowatt-hour for the cost of a relatively expensive early fuel cell system at about $800 per kilowatt, plus a nominal 0.1 cents per kilowatt-hour for O&M. This would undercut typical commercial-sector U.S. electricity tariffs (averaging 7.6 cents per kilowatt-hour in 1997) by 28 percent, even with no thermal credit and no allowance for the improved power quality and reliability or for other distributed benefits.
6 Lovins & Lehmann 1999, representing the capital and operating costs and the losses of the transmission and distribution systems for the average customer at the average hour. Obviously the actual costs, both total and marginal, depend on who, where, and when.
7 Lovins & Lehmann 1999.
8 Lenssen 1995.
9 Lovins & Lehmann 1999.
10 One-hundred fifty million light vehicles times a minimum capacity of 20 kW-the average could be substantially higher-yields 3 terrawatts (TW), vs. summer-1997 U.S. peak capability of 0.78 TW and 1996 noncoincident peak load of 0.62 TW (neither of which reflects the approximately 14 percent on-peak grid loss).
11 Bain, 1997; Bain, Addison: Personal communication, Nov. 1, 1999.
12 Directed Technologies Inc. 1997.
13 James et al. 1997. Further, a fuel cell Hypercar could travel roughly 200 km on 1 kg of hydrogen: A Taurus-class Hypercar was calculated to drive roughly 925 km fueled by 4.65 kg of hydrogen (Williams et al. 1997).
14 President's Council of Advisors on Science and Technology (PCAST) 1997 at 6-34.
15 Ogden et al. 1997, Thomas et al. 1997, 1998a.