Apparently carbon emissions from coal plants were previously underestimated by half by British scientists advising the British government on the best ways to reduce electricity demand. That revised rate is 0.69 kilograms of carbon dioxide per kilowatt hour of consumed electricity, not 0.43 kilograms.
They were using an estimated figure for emission rates that the new study shows was 60 percent lower than the actual rates observed between 2002 and 2009. The error came partly because they were averaging nationwide emissions. The numbers were to determine how much carbon would be saved by policy encouraging all Britains to, for example; change their light bulbs.
But, just as here, some regions of the UK are powered by clean energy that emits no carbon, while others are powered by relatively dirty energy. Here, for example Wyoming is over 95% powered by coal and every year, Hawaii spends over $5,000 for oil to power each homeowner while Maine is 55% clean powered by a variety of non carbon-emitting sources, including 30% hydro-power.