One of the occupational hazards of working in the environmental trades is that your head is soon stuffed with acronyms.
Well, heres one more to fit into your vocabulary. Get familiar with it, because understanding it will be critical for evaluating energy choices as oil brushes against $110 per barrel, coal prices surge, and politicians cast around for alternatives.
The acronym is EROEI. Heres why its worth knowing: When oil was at $20 per barrel, alternatives to conventional fossil technologies seemed like pie in the sky. At $110 per barrel, the pie is on the shelf at a competitive price. But how do we know which flavor to buy?
EROEI can help us decide. EROEI stands for Energy Return On Energy Invested. For clarity, lets just call it E-Roy.
Every source of energy has an E-Roy rating. To get energy, you have to invest energy in order to produce it, process it, transport it, and store it.
Another way of expressing E-Roy is your return on energy investment. A high net means you get much more energy back than you put in. The bigger the surplus, the more energy at our disposal to create economic wealth.
In 1930, wildcatter Columbus Dad Joiner drilled an exploratory well in Rusk County, Texas, that set off one of the great oil booms of the 20th century. Within a few months, more than 100 wells per day were going into production. The National Guard was called in to keep order in the fields.
For every barrel of oil that was expended producing oil from the East Texas oilfield, 100 barrels went to market, a net surplus of 99 barrels.
The huge energy surpluses produced from East Texas and other supergiant oilfields with high E-Roy ratings fueled the industrial machine that won World War II and set the stage for the postwar economic boom.
But that was then. Diminishing returns have set in. Resources like the East Texas oilfield that produce very large energy surpluses with very high E-Roy ratings are much harder to come by today. In the future, absent an unforeseen technological breakthrough, its likely well have to spend more energy to get energy. That goes for fossil fuels and for their renewable and nuclear competitors.
In the U.S. today, the E-Roy for conventional oil is anywhere from 11:1 to 18:1. For every barrel of oil expended for production, 11 to 18 barrels go to market. Thats not bad, but its not East Texas in its glory years either.
E-Roys for alternative fuels are worse. Some politicians wax poetic about the vast size of oil sands and oil shale resources, but getting useful fuel out of the Alberta tar pits requires a great deal more energy than carting off the gusher from Dad Joiners well did.
The numbers vary depending on whom you ask, but a safe guess is that the E-Roy of oil sands is around 3 to 1. For every unit of energy you invest, you get only three back, producing a marketable surplus of only two barrels.
Corn-based ethanol is another dreg. For every unit of energy growing and processing corn, only one and a half units of ethanol go to market. Cane-based ethanol is better, with an E-Roy of 8 to 1.
E-Roy is not the only criterion for making wise energy choices. Other considerations include the impacts of energy resources on human health and the environment, their usefulness, and whether they are easily moved or stored.
Solar photovoltaic systems, for example, have a lower E-Roy than coal. The need to cap and reduce carbon emissions may be the factor that enables solar to cut into coals market share.
But E-Roy is an important reason why energy difficulties will be with us for the long term and why yesterday's thinking about solutions won't work. So when you pull into a gas station this summer and the price reads $4 per gallon, youll know that E-Roy was here.
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