How is the Net Energy of Ethanol Determined?

The amount of energy gained or lost through the production and use of fuel ethanol continues to be questioned. Some recent studies have estimated positive energy gains of 25% to over 100%, while others show a net energy loss.

The variation in the estimated values is typically caused by different methods for the estimation and allocation of energy consumption throughout the production process. More complete analysis of the net energy efficiency of ethanol production include the following when being compared to other fuel sources:

  • the amount of energy used to produce the raw feedstock including the energy for the processing, manufacture, and transport of all inputs
  • the amount of energy used in the ethanol production process
  • allocation of energy used between the production of ethanol and the production and/or use of co-products and by-products (burning waste lignin to produce electricity, for instance)

Some links to studies on the net energy balance of ethanol