Avoiding Negative Impacts from a Biomass Energy Strategy

At first glance the conclusion drawn by a new report from the European Environment Agency (EEA) sounds like an impossibly tall order. The report argues that, while biomass is an important part of the renewable energy mix, more should be done to ensure that the maximum amount of energy is extracted from the same material input, while avoiding any negative environmental effects potentially associated with its production.
On closer reading the report makes clear that bioenergy production could and should follow EU resource efficiency principles, which means reducing the land and other resources needed per unit of bioenergy produced.
According to the EEA’s analysis, the most efficient energy use of biomass is in combined heat and power (CHP) applications as well as second generation biofuels. Conversely, the report finds, first generation transport biofuels, for example biodiesel based on oilseed rape or ethanol from wheat, are shown to be far less efficient.
Furthermore, says the report, extensively using mature trees for energy purposes may have a negative effect on the climate, due to the period it takes for the trees to regrow. This ‘carbon debt’ does not arise if bioenergy uses other forest biomass instead, for example material left over from forest harvesting by-products or waste products from timber and paper production. And, inevitably, using organic waste and agricultural or forestry residues as feedstock is more resource efficient than many others.

Hans Bruyninckx, EEA Executive Director, explains: “Bioenergy is an important component of our renewable energy mix, helping to ensure a stable energy supply. But this study highlights the fact that forest biomass and productive land are limited resources, and part of Europe’s ‘natural capital’. So it is essential that we consider how we can use existing resources efficiently before we impose additional demands on land for energy production.”
In conclusion then, the analysis finds that bioenergy's GHG efficiency and ecosystem impacts can vary significantly depending on the economic and policy constraints in place and the resulting bioenergy pathways. Where feedstock is sourced from waste or agricultural residues, it implies zero land use change and substantial advantages over fossil fuel energy in terms of both greenhouse gas efficiency and ecosystem impacts. Conversely, where biomass is derived from energy cropping, some bioenergy pathways lead to additional GHG emissions and other environmental impacts. Indirect land use change effects are particularly important in this regard and need to be addressed by the EU bioenergy policy framework.
From a resource-efficiency perspective, the core message from this study is clear: bioenergy can play a valuable role in meeting society's energy needs but only if it focuses on the most resource-efficient use of biomass through the whole biomass-to-energy production chain.
Noting that the energy crop mix in Europe is currently not environmentally favourable, the authors recommend a broader mix of crops to reduce environmental impacts. They also highlight the advantages of perennial crops, which are not harvested annually, for example SRC willow and energy grasses.
It’s no surprise that the report argues that different energy cropping systems can vary hugely in their productivity, as well as in environmental impacts. Indeed the EEA claims that high-yielding systems with efficient conversion can deliver over 20 times more energy per unit area than low-yielding and inefficient systems. And with bioenergy delivering  approximately 7.5 percent of the total energy used in the EU in 2010 – a figure which is expected to rise to around 10 percent by 2020 – making the right choices for bioenergy adds up to a whole hill of climate change beans.

http://www.renewableenergyworld.com/rea/blog/post/2013/07/avoiding-negative-impacts-from-a-biomass-energy-strategy