Sustainability challenges of lignocellulosic bioenergy crops

Alternative fuels Life-cycle analyses

This briefing paper reviews evidence on the environmental risks of growing lignocellulosic energy crops for biofuel production. The sustainability of energy crops such as Miscanthus, switchgrass, and short rotation poplar is a growing concern as the European Union (EU) considers ambitious targets for advanced biofuels.

Energy crops could represent a lower-carbon alternative to food-based biofuels that can potentially deliver much greater volumes of biofuel than waste and residue feedstocks. On the other hand, similarly to food crops, energy crops require land to grow and so their cultivation leads to induced land use change (ILUC). While most ILUC modeling studies estimate that total land use greenhouse gas (GHG) emissions from energy crops are minimal, these studies also predict that energy crops are likely to cause some degree of direct and indirect deforestation. It is clear that directly converting forest to energy cropping for biofuel will lead to a net increase in GHG emissions compared to burning petroleum, as well as causing other negative environmental impacts. If energy crops displace food and fiber crops on agricultural land, they can cause indirect deforestation by inducing expansion of food and fiber crops elsewhere. On the other hand, there are some circumstances under which growing energy crops can deliver net environmental benefits: significant GHG emission savings are likely achieved when growing these crops on recently abandoned agricultural land.

Policies can promote energy crop biofuels while limiting negative environmental impacts. Sustainability criteria excluding policy support for energy crops grown on converted forestland or actively used agricultural land would effectively curtail the greatest environmental risks of using these crops. This would be a pragmatic approach particularly in the EU, where sustainability criteria already apply for biofuel feedstocks.