Renewable Hydrogen?

Crunching some numbers on the use of renewables for hydrolysis:

One kilo of hydrogen gas is energetically equivalent to one gallon of gasoline. Granted, a fuel cell or internal combustion engine running hydrogen is a little more efficient than gas, but the energy lost from storing the hydrogen (as a liquid, or in a metal hydride--see next post) more than makes up for this. Anyway 1 kg H_2/gallon gas is convenient.

The hydrolysis process to produce that kg of hydrogen requires about 65 kWh of electricity (practically) though this could be lowered to 40 kWh in the mid-term future. Everything involving hydrogen or renewables takes a 20-year window or so.

In 2005 the US consumed 140 billion gallons of gas. So to replace gasoline with hydrogen would require 8,000 terawatt-hours of electricity, roughly one-and-a-half times the throughput of the current electrical system. Doing so without carbons would require the construction of something like 1000 nuclear power plants.

The US is currently planning three new plants and they're being fought like hell.
The present price of electricity in the US averages (in 2004) about 7 cents per kWh commercially, 5 cents industrially. At these prices a kg of h_2 would cost around $5: perhaps lower if the utility itself got involved in the hydrogen business.

Let's set our sights on electrolysis via solar energy provided by stirling engines. According to Sterling Energy Systems (SES), their 150 kW units currently cost $150,000, 25% of which cost is the solar dish. So the engine itself, provided by a german company who manufactures them for use in ultra-silent submarines, costs over $100k. SES claims that they can reduce the cost, once mass-production is set up, to $50k a unit.

We'll put our generators in the Mojave desert, as SES has, where an average of 6000 Watt-hours per day is produced, implying around 7 hours per day (on average) that the engines will run. So the cost per kWh (using the optimistic engine cost of $50k) over 5 years is a shade over 3 cents, implying a hydrogen cost of $3.50/kg.

Over 10 years, and let's include the cost of keeping the engines running etc, this goes down to maybe $2.50. Are industries willing to sink huge capital into projects that will only turn a profit after ten years (if then)? I dunno.

Here is the breakdown of the cost of a gallon of gas in 2007:
Distribution
Costs, Marketing Costs and Profits $0.20
Crude Oil Cost $1.72
Refinery Cost and Profits $0.63
State Underground Storage Tank Fee $0.01
State and Local Sales Tax $0.23
State Excise Tax $0.18
Federal Excise Tax $0.18
Retail prices $3.16

So we're competing with the crude + refinement cost of $2.30. Even in the best case renewable hydrolysis only competes with $5/gallon oil, or $100 a barrel sweet crude. I don't see that happening anytime in the next 50 years (It's at $73 now).

So far the scheme appears to be possible if unlikely. But now look that the investment required:
Let's take our goal as producing 10% of the 8,000 TWh renewably, and have a look at the SES plant in Mojave:

Seller
Gen. Type
Initial Size (MW)
Possible Expansion Size (MW)
Estimated Annual Energy Based on Initial Size (GWH)
Estimated Annual Energy Based on Expansion Size (GWH)
Initial Phase On-Line Date
Completion Date for Initial Size
Term of Agreement (Years)
Estimated Capacity Factor

SES Solar One LLC
Solar Thermal ( Stirling Dish)
500
850
1,047
1,780
Jan. 2009
Dec. 2012
20
23.90 percent

This plant is composed of some 3,000 individual generators and is projected to go online in 2009. Using SES's numbers (the big one, $150k/generator) I'd guess it'll cost about half a billion dollars.

For 800 TWh you'd need around 1000 such plants at a cost of half a trillion dollars, just to provide the power. Best case, to provide 10% of America's gasoline requirements renewably you'd need around a trillion dollars. That's maybe not excessive in light of the e.g. 70 billion being invested to extract canada's oil sands, but then that's coming from big oil. Who's investing in hydrogen?

All my numbers here have been incredibly idealized, using stirling power as a magic bullet--far superior to photovoltaics--and remember they only seek to supplement transportation by 10%. Conclusion? Gasoline can't be replaced renewably at anything like our current usage levels. And remember that if you're making hydrogen from something other than nuclear power, you're just replacing the delivery system: oil still needs to go into producing electricity (or perhaps coal, but this is dirty, or natural gas, but the US hasn't invested heavily in that).

Extrapolation? Renewables need to be targeted to middle-class families feeling the pinch of increased energy prices. This area (<$10k) takes maximum advantage of government aid and capitalizes on public opinion. But it can't help in the long haul.