Mark Jacobson of Stanford University researched alternative energies to determine which fuels provided the most amount of energy, including inputs and outputs.  In a recent article in the New Scientist by Catherine Brahic, the author writes about Jacobson's detailed study "ranking 11 types of non-fossil fuels according to their total ecological footprint and their benefit to human health. . . . To compare the fuels, Jacobson calculated the impacts each would have if it alone powered the entire US fleet of cars and trucks.

"He considered not just the quantities of greenhouse gases that would be emitted, but also the impact the fuels would have on the ecosystem - taking up land and polluting water, for instance. Also considered were the fuel's impact on pollution and therefore human health, the availability of necessary resources, and the energy form's reliability."

His findings do not mirror conventional wisdom.  Jacobson found wind power to be "by far the most desirable source of energy. . .  The US could replace all its cars and trucks with electric cars powered by wind turbines taking up less than 3 square kilometres - in theory, at least."

The second on the list is called concentrated solar power, new technologies that amplify the amount of energy produced by new types of solar power.  "Biofuels from corn and plant waste came right at the bottom of the list, along with nuclear power and "clean" coal . . .  Jacobson says it would take 30 times more space to grow enough corn to power the US fleet than would be needed to erect enough wind turbines, while bioethanol would produce more greenhouse gases than wind power."

Here's a video of Jacobson talking about his research findings.  And here's the list of energy sources that Jacobson found most promising:

1. Wind
2. Concentrated solar power (mirrors heating a tower of water)
3. Geothermal energy
4. Tidal energy
5. Solar panels
6. Wave energy
7. Hydroelectric dams

As we move forward on alternative energy, it would be useful to focus on the technologies that will be most effective, especially in this time of few resources.