* To establish feasibility, it is necessary to include some items in the energy invested term that are normally not thought of as investments. For example, the cost of sequestering such carbon dioxide as will be produced by the energy technology under investigation should be added to the energy invested term because feasibility requires that our society be sustainable (until astronomical events intervene). In this thought experiment, the support of an alternative energy technology would be the sole concern of every citizen.

Saturday, December 1, 2012

Comment on Computing ER and EI


It's easy to compute the quantity of energy (really availability, which is energy corrected for entropy) we expect to be produced over the life of the project for any energy production installation we wish to investigate - in particular, to determine whether or not it produces more than it consumes. We consider energy spent to prevent or repair environmental damage caused by the installation, embodied and direct energy purchased with money paid to the stakeholders in the system, and the many other direct and indirect energy costs discussed in eroeistar.htm all to be part of the energy consumed by the process over the life of the installation. The energy produced is denoted ER for Energy Returned and the energy consumed to produce it is EI for Energy Invested. Clearly, if ER/EI < 1.0 (ER < EI), the installation should not be built. In a fossil-fuel economy, if the installation is built - usually because subsidies hide its true nature from analysts who go by monetary costs - it will result in the combustion of more fossil fuel not less. Thus, the computation of ERoEI* should be done way before the installation is built using our best estimates of things like the amount of energy required to hold the supply of materials in steady state, the energy costs to rehabilitate the plant site to a pristine condition if the plant becomes obsolete, demographics change, or for some other reason the installation abandons the planned plant site, etc. If you do this computation for any given nuclear plant taking proper account of every negative effect, you will probably determine that ERoEI* for nuclear is less than 1.0. If it is less than 1.0 for solar, it shows that more research should be done, as we have not reached our goal yet of a sustainable renewable energy technology. But, we must eventually succeed and we will.

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