Coal-fired power plants are the single biggest source of greenhouse gases in the US, according to a new report by the National Research Council.

In 2005, the total annual external damages from nitrogen oxides, sulphur dioxide, and particulate matter generated by burning coal at 406 coal-fired power stations hit nearly $62bn.

These non-climate damages average nearly 3.2 cents for each kilowatt-hour (kWh) of energy generated.

Coal-based power plants emitted about a ton of CO2 per MW/h of electricity produced during the period, according to the report.

Nearly 10% of the total number of plants represented 43% of the damages. By the year 2030, non-climate damages are expected to decline to 1.7 cents per kWh.

Climate-associated monetary damages vary from 0.1 cents to 10 cents per kWh, based on earlier modelling studies.

Burning natural gas resulted in far less damage than coal, both overall and per kWh of electricity produced.

In 2005, a sample of 498 natural gas-fired stations generated $740m in non-climate damages, an average of 0.16 cents per kWh.