Andrew Walsh, Flickr Creative Commons

Thanks to Anthropocene for this summary of the latest findings on how far we can expect renewable resources to take us in our efforts to reduce our carbon footprint:

Bioenergy has its limits for cutting emissions

by Prachi Patel

Many climate policies and models consider biomass carbon-neutral. The argument is that carbon emitted during burning the biomass is balanced out by the carbon that plants and trees sequester. But that understanding is flawed.

Biomass is indeed renewable, and burning biomass or biomass-derived fuels can offset fossil fuel use. However, cultivating and harvesting biomass, transporting it, and processing it for energy or to make liquid fuels all emits greenhouse gases. Exactly how the biomass is used—whether directly or turned into fuel—also makes a difference.

Now researchers at MIT have calculated the extent to which bioenergy can cut greenhouse gas emissions from fossil fuel use when bioenergy’s emissions are taken into account. In a new study published in the journal Nature Energy, they also quantify the best use of global bioenergy resources to replace fossil fuels…

…These findings indicate that “[greenhouse gas] emissions mitigation via the use of bioenergy is constrained not only by the availability of biomass, as considered in previous assessments of bioenergy potential, but also by the [lifecycle] emissions of final bioenergy,” the researchers said.

The researchers caution that these are maximum numbers. Bioenergy adoption faces additional constraints such as existing investments in fossil fuels, as well as economic and policy factors.

Source: Staples MD, R Malina, and SRH Barrett. The limits of bioenergy for mitigating global life-cycle greenhouse gas emissions from fossil fuels. Nature Energy. 2016.