Accounting for carbon emissions can be tricky

The July edition of Scientific American gives a great example of some of the difficulties in tracking and accounting for carbon emissions. Most larger business now track their carbon emissions, and in most developed countries have to pay to emit carbon dioxide. So it makes business and environmental sense to reduce emissions.

The article in Scientific American tells the story of plug-in hybrid and electric cars (a plug-in hybrid has a small normal engine which means it still uses more carbon based fuel, whereas an electric car has no engine at all). A plug-in hybrid you might think is emits less carbon than a normal hybrid, and in turn a full electric car would gave zero emissions. But it’s not that simple as you have to consider how the electricity is produced. As noted in the article, the vast majority of electricity is produced by oil, coal and natural gas in the United States. Coal is the worst in terms of carbon emissions and in some states it is the main fuel source for electricity production. So in Illinois or Ohio, a zero-emission electric car would contribute more carbon emissions than a normal hybrid like a Toyota Prius. In both regions coal is used to generate 65-75% of the electricity.

What this example shows is how tricky it can be to determine your own carbon emissions or that of a business. You really have to trace things back to source to be sure you’re counting is correct. Another example I came across recently really surprised me. It was in a book called ‘ In Defence of Food ‘ by Michael Pollan. The raising of lambs for meat in the UK uses a lot of energy and carbon as land is treated with chemical fertilisers. In New Zealand, lush natural meadows remove the need to fertilise. As the manufacture of chemical fertilisers consumes a large amount of energy, it may actually be more environmentally sound to import lamb by air from New Zealand to the UK. Crazy I know, but it shows the type of thinking needed when trying to account for carbon use.