Energy+return+on+investment+(EROI)

Energy return on investment (EROI) is the ratio of the energy delivered by a process to the energy used (the direct and indirect cost and use of energy in the extraction and manufacturing process). The process is defined as:

Quantity of Energy Used in Supply process
 * EROI=** **__Quantity of Energy Supplied__

In other words: How much net energy remains after fuel production. ** Earth is not as saturated in oil as many believe... and claim.

// Another model of the EROI takes the cost in energy of finding fuel, extracting fuel, transporting fuel and the energy costs involved in using the fuel. This is called the **extended EROI** and is a more accurate indicator of all energy needed in the fuel process. We will not discuss the extended EROI in this wiki, but it is helpful to keep all the energy costs in mind when referring to the EROI. //

Energy, with regard to the EROI, is defined as the physical ability to do useful work, where useful work is done when a body is moved by a force. The physical ability to do work is represented by the enthalpy of the fuel, so the numerator and denominator is typically measured in heat in units such as [|joules].

High per-capita energy use is considered desirable because it is associated with a high standard of living based on energy-intensive machines. A society will generally exploit the highest available EROI energy sources first, as these provide the most energy for the least effort. With non-renewable sources, progressively lower EROI sources are then used as the higher-quality ones are exhausted, leading to increasing market values and a positive feedback loop. The current state of the oil EROI is declining. That is, we have extracted all the oil with a high energy return investment (high EROI) and have now moved on to oil that is hard to find, hard to extract and requires more refinement – all aspects use more energy (low EROI). For Example, [|Alberta’s oil sands], which were never exploited before due to the low EROI, is now a major supplier of fossil fuel. The higher cost in Energy during the processing of the oil sands can easily be seen in this diagram.

Predictions of EROI are very helpful and can give the population a much better insight into what the costs relative to the gains are likely to be in the future. If costs go up in the production, so will prices, i.e. the lower the price of oil the higher the EROI ratio and vice-versa. For an economy that is dependent on fossil fuels, such as Canada, this will have a detrimental effect on our society, unless alternate fuel sources are discovered with a high EROI, similar to that of oil.

The lowering EROI for oil 1930-2000 EROI can be used to help evaluate which alternative fuels are likely to be the most economically viable in the future. Environmental issues can be included in EROI analyses, allowing a more comprehensive analysis of EROI. For example if growing a [|biofuel] causes soil erosion the energy cost of making fertilizer to restore the soil's natural fertility can be readily factored in.