The Importance of Energy Return on Investment

1 / 2
These bars represent the estimated maximum energy return on investment of both renewables and fossil fuels. Oil's ratio has declined over time with the increased difficulty of bringing it to consumers. Note its EROI value in 1930, 1970, 2000, and 2005.
These bars represent the estimated maximum energy return on investment of both renewables and fossil fuels. Oil's ratio has declined over time with the increased difficulty of bringing it to consumers. Note its EROI value in 1930, 1970, 2000, and 2005.
2 / 2
The energy return on investment for firewood includes what you spend cutting and splitting it. However, after some rest and a good meal it's 100 percent renewable!
The energy return on investment for firewood includes what you spend cutting and splitting it. However, after some rest and a good meal it's 100 percent renewable!

The future of our finite supply of fossil fuels is uncertain at best, and development of new energy options continues to gain speed. It’s likely we’ll use a combination of renewable energies and fossil fuels for the foreseeable future.

If you listen to some representatives of the alternative energy industry, you’d think every renewable fuel source out there is the No. 1 candidate to meet the world’s future energy needs — the most qualified to replace oil, coal, and natural gas. So, which type of renewable energy will provide us with the highest net gain in energy?

Energy return on energy invested is more commonly stated as energy return on investment (EROI). The term was coined by Charles Hall, professor of environmental science and forestry at the State University of New York (SUNY), and is presented as a ratio of energy produced to the energy consumed during production. An energy source that yields positive net energy has an EROI ratio of more than 1:1. Anything less than that constitutes an energy sink, or net loss. 

Focusing on the Future

It takes energy to find, extract, refine and transport energy commodities. The energy cost of energy wasn’t a topic worthy of study throughout most of the era of fossil fuels because coal, oil, and natural gas were so accessible and easy to deliver that their EROI ratios were very high.

  • Published on Oct 29, 2010
Comments (0) Join others in the discussion!
    Online Store Logo
    Need Help? Call 1-800-234-3368