On the carbon intensity of ethanol

One of the fastest ways to decarbonize transport is to reduce the carbon intensity of the fuel – whether it be through use of renewable electricity for increasing share of battery powered vehicles, or fossil fuels for majority of the fleet today.  Major countries have set CO2 targets for light- and heavy-duty vehicles, but these aim to regulate fuel consumption through tailpipe-standards. The true extent of decarbonization and the success of these policies can be measured through a well-to-wheel (or better still a cradle-to-grave) analysis including the carbon intensity associated with production of the upstream fuel. 

To reduce its carbon footprint, gasoline is routinely blended with up to 10 – 15% of ethanol, with even higher levels available (85%) for flex-fuel vehicles. Heavy-duty engines are also developed to run exclusively on ethanol, with performance similar to diesels.  Ethanol is even being considered as a feedstock for sustainable aviation fuels (SAFs). In countries such as  Brazil and India, the addition of ethanol is further seen as a way to reduce dependence on imported oil.   

It is important, of course, to assess the carbon intensity of this fuel. Many debates rage about the correct intensity – naturally so, given the various inputs that go into such a calculation, including farming practices, quantity and type of fertilizer, processing to make ethanol, any by-products, land use change, and of course the end use efficiency, etc. This article doesn’t provide a definitive answer but covers some recent developments on the topic.