The Last Drops: How to bridge the gap between oil and green energy

For all our talk of an online future unbounded by physical limits, life in our increasingly global economy still requires the movement of actual people and things, often over long distances. And without a steady supply of prehistoric hydrocarbons, that movement would come to a halt. More than 95 percent of the vehicles on Earth--from cars to trucks to freighters to jumbo jets--run on oil products, and without them we’d be hard-pressed to commute to the office or import our gadgets, much less till our fields or get food from the farm to our kitchens. For now, we must have oil.

Our dependence on oil is driven less by the political might of the oil industry than it is by the fact that oil itself is a terrific source of power. It packs more energy into less space than any other commonly available resource, and it requires much less energy to produce. In the Middle East, where “easy” oil remains most plentiful, drillers need only invest a single barrel’s worth of energy to produce a full 30 barrels of crude. That is among the highest ratios of energy returned on energy invested, or EROEI, for any widely available source of power on the planet. (That same barrel’s worth of production energy, for instance, would get you fewer than two barrels of corn ethanol.) Oil’s amazing efficiency is one reason it remains in such high demand, especially for transportation, and it’s also why finding an alternative will be so difficult.

But find one we must. We have already burned our way through most of the world’s easy oil. Now we’re drilling for the hard stuff: unconventional resources such as shale and heavy oil that will be more difficult and expensive to discover, extract, and refine. The environmental costs are also on the rise. Oil production remains a significant local ecological hazard—as we were reminded by the disastrous failure of the Deepwater Horizon well in the Gulf of Mexico last year--even as oil’s large carbon footprint threatens the global environment as a whole.

Bridging the gap between our current oil economy and an as-yet-undefined clean-energy economy will not be easy. Alternative systems, such as hybrid cars powered by biofuel drawn from oceanic algae farms, may be vastly more sustainable someday. But “sustainability” is an economic concept as much as it is an environmental one. People will always prefer cheap energy to expensive energy. (Indeed, many people in less-wealthy nations require cheap energy simply to survive.) And the process of making alternative energy systems affordable will be long and uncertain, in part because the oil-based systems they must compete against (internal combustion engines, for instance) will themselves become even more efficient and alluring.


/Popular Science/