It appears to be more than just my definition.
Federal Energy Subsidies
Direct and Indirect Interventions in Energy Markets
http://tonto.eia.doe.gov/FTPROOT/service/emeu9202.pdf
"There is no universally accepted definition of what constitutes a subsidy. A typical textbook definition of a subsidy is a transfer of economic resources by the Government to the buyer or seller of a good or service that has the effect of reducing the price paid, increasing the price received, or reducing the cost of production of the good or service. The net effect of such a subsidy is to stimulate the production or consumption of a commodity over what it would otherwise have been."
Types of Energy Subsidies Reviewed
Provision of energy and energy services.
Provision of loans.
Tax exempt interest on debt.
Assumption of environmental, safety, and health liabilities.
Research and development.
Provision of Regulatory Services.
I guess we can keep beating this dead horse.
a subsidy is a transfer of economic resources by the Government
Precisely. Here, there is no transfer of economic resources by the government.
At any rate, I don't see how anything you quoted defines 'subsidy' so as to include the tax exemptions enjoyed by the ethanol industry. The government has decided to not tax something. Instead of grousing about it, I'd think a conservative might find reason to rejoice.
Back to the definition, I found this relevant sentence in that document:
Tax policy can achieve subsidy-like effects in energy markets.
Note the careful wording, "subsidy-like"; in other words, although the effect may be subsidy-like, it's not a subsidy.