The scale of the problem.

Submitted by my friend Richard, and via fivecentnickel.com:

c|net Green Tech Blog: Can renewable energy make a dent in fossil fuels?

Quotes:

4.2 billion.

That's how many rooftops you'd have to cover with solar panels to displace a cubic mile of oil (CMO), a measure of energy consumption, according to Ripudaman Malhotra, who oversees research on fossil fuels at SRI International. The electricity captured in those hypothetical solar panels in a year (2.1 kilowatts each) would roughly equal the energy in a CMO. The world consumes a little over 1 CMO of oil a year right now and about 3 CMOs of energy from all sources.

Put another way, we'd need to equip 250,000 roofs a day with solar panels for the next 50 years to have enough photovoltaic infrastructure to provide the world with a CMO's worth of solar-generated electricity for a year. We're nowhere close to that pace.

But don't blame the solar industry. You'd also have to erect a 900-megawatt nuclear power plant every week for 50 years to get enough plants (2,500) to produce the same energy in a year to equal a CMO. Wind power? You need 3 million for a CMO, or 1,200 a week planted in the ground over the next 50 years. Demand for power also continues to escalate with economic development in the emerging world.

"In 30 years we will need six CMOs, so where are we going to get that?" Malhotra said. "I'm trying to communicate the scale of the problem."

The CMO is a figure you might begin to hear more as utilities and governments map out their renewable energy strategies. SRI's Hew Crane came up with the term as a way to normalize all the different measurements (kilowatt-hours, BTUs, million barrels of oil equivalents, cubic feet of gas, etc.) in the energy business.

It's also a big enough measure to suit the global energy market without saddling everyone with a train of zeros. Many of these stats and a far lengthier discussion of the issue will be found in a book coming from Oxford University Press by Crane, Malhotra, and Ed Kinderman called A Cubic Meter of Oil.

And judging by some of the stats Malhotra gave me, the book will alarm policy makers, environmentalists, and pretty much anyone else interested in weaning ourselves from fossil fuels.

....

If there's a bright spot here, it's that the world has a lot of fossil fuel, he claimed, so we won't be plunged into darkness yet. Oil reserves come to around 46 CMOs, while natural gas reserves total 42 CMOs. There are 121 CMOs of coal out there. These numbers all go up when difficult-to-extract energy such as tar sands are added.

"It's been 30 years of (oil) reserves for the last 50 years," he joked. "It's like your pantry. Do you look at it and say 'Oh, no. I'm going to run out of flour in two weeks'? You go out and buy more."

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The only thing I would add, particularly to his parting comments:

At what price?