METHANE HYDRATES

Think fresh-frozen natural gas, buried in the Arctic permafrost and under seabeds. In a speech last spring, Fed chair Alan Greenspan sent reporters scurrying when he noted that US methane hydrates reserves are estimated at 200 quadrillion cubic feet - 33 times the global reserves of natural gas. No one has figured out how to tap them, but Canadian researchers, the US energy department, and BP are working on it.

Current cost: $90/b.o.e.*

Environmental friendliness:

Technological maturity:

Carbon emissions:

Potential oil killer: Yes

US reserves: 10,882 gasoline years

Global reserves: 72 quadrillion b.o.e. Global production 2004: 0

HYDROGEN

The ultimate oil killer: Anything from sunshine to nuclear reactors can make hydrogen - the carbon emissions could be zero. It will cost a lot in R&D money to perfect the automotive fuel cell and build a new distribution infrastructure, and the Hindenburg problem remains to be solved, but there's nothing like triple-digit crude prices to focus the mind.

Current cost: $90/b.o.e.*

Environmental friendliness:

Technological maturity:

Carbon emissions:

Potential oil killer: Yes

US reserves: Unlimited

Global reserves: Unlimited

Global production 2004: 902 million b.o.e.

PLUG-IN HYBRIDS

Tank up in your garage - 64 cents' worth of kilowatts will take you as far as a gallon of regular. Too bad the batteries in today's hybrids won't go more than a few miles. Extend the range to 30 miles (cost per vehicle: $10,000) and add the ability to suck power from the grid, and you have a dual-fuel vehicle that kisses gasoline good-bye for short trips. The electrons can come from dirty coal, clean solar, or anything in between.

Fuel cost: $120/b.o.e.* (including battery)

Environmental friendliness:

Technological maturity:

Carbon emissions:

Potential oil killer: Yes

US reserves: N/A

Global reserves: N/A

Global production 2004: N/A

*barrel of oil equivalent

Sources: Electric Research Power Institute, Energy Information Administration, National Renewable Energy Laboratory, World Energy Council, US Geological Survey.

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