Two of the greatest challenges facing humanity this century are climate change and the need to produce enough energy to meet the demands of a growing and developing population. This blog shows how lignocellulosic bioenergy crops can help to mitigate and adapt to current climate change.
Potential for lignocellulosic bioenergy crops
Lignocellulosic bioenergy crops are a potential option for meeting the climate mitigation targets of the Paris Agreement in Europe. Bioenergy has been proposed as a feedstock for delivering energy security and for closing the gap between our current dependency on fossil fuels and the time after 2050 when other renewable energy sources, e.g. solar, wind, wave, are technologically and operationally fully developed and energy will be produced solely from renewable sources. Through substitution of fossil fuels, lignocellulosic bioenergy crops help reducing net greenhouse gas emissions from energy production. Recent analyses suggest that up to 20% of global energy demand could be met by biomass without negative impacts on food supply.
Lignocellulosic bioenergy crops – an alternative crop for marginal lands
In order to improve the effectiveness of bioenergy, the development of second-generation bioenergy technologies based on the conversion of lignocellulosic plant materials from fast-growing tree and grass species to various energy feedstocks has received a lot of attention recently1. These energy crops, such as poplar, willow and Miscanthus are not as dependent on favourable climatic and soil conditions as food crops, inputs of agrochemicals are only required during establishment year and there is less soil disturbance compared with food crops which get harvested several times a year2. Lignocellulosic bioenergy crops like poplar can therefore be planted on more marginal land, unsuitable for growing food crops, which reduces their direct competition with food production. Poplar, willow and Miscanthus are often planted as wind barrier between conventional and organic fields to keep the organic food free from pesticides and herbicides. Because most of the harvested aboveground biomass can be converted into energy (not just the grain or oil as with maize or rapeseed), per-area energy yields are innately greater1.
Coupling lignocellulosic bioenergy crops with carbon capture and storage
Although bioenergy is not without potential trade-offs, its potential for low carbon energy production has led to considerable attention over recent years 2. A potential way to improve the carbon balance of bioenergy production, and carbon sequestration by poplar, is the use of bioenergy coupled with carbon capture and storage. Although many scenarios show that CO2 continues to rise and will not peak before 2030, the bioenergy sector coupled with carbon capture and storage could help limiting global warming to 2 degrees, thus, making it possible to meet the targets of the Paris Agreement.
Focus on poplar as lignocellulosic bioenergy crops
Poplar is a suitable lignocellulosic bioenergy crop for large parts of Europe and already widely planted. Due to its physiological traits, it is fast growing and poplar clones are widely adaptable to different site conditions, which makes poplar an ideal candidate for short rotation coppice or forestry 3. Another factor in favour of poplar in Europe is, that in contrast to other bioenergy crops, e.g. Switchgrass, there are no concerns about it being an invasive species because poplar is native all over Europe 3,4.
Models to assess yield and climate change mitigation and adaptation potential
Knowledge about potential future poplar yields in Europe will allow for optimum use of these bioenergy crops. Currently, many medium and long term field experiments with different genotypes produce yield and phenotype data that can be used as a basis for model parameterisation 1.
Process-based models are useful tools for assessing potential yields, plant traits and evaluating environmental interactions, especially in lignocellulosic bioenergy crops where long growth cycles over multiple rotations make data collection expensive and time consuming 2–4. Bioenergy crop models can provide insights to support policy for renewable energy development and can be used to predict yields and climate change mitigation and adaptation potential under different climatic and soil conditions 2–4.
Poplar physiological traits, e.g. water use, leaf area, biomass development or partitioning and radiation use efficiency, change greatly with genotype and environment. The recently published process of finding the optimum set of parameters for the PopFor model, especially in the very dry area of Brandenburg, Germany, or similar areas like Southeast Styria, added to the existing knowledge around bioenergy crops 3.
For assessing the full climate change mitigation and adaptation potential of lignocellulosic bioenergy crops, further research towards a sustainable system of use – including potential synergies but avoiding trade-offs like indirect land use change – will be necessary to improve current and future bioenergy policy.
1. Clifton‐Brown, J. et al. Breeding progress and preparedness for mass-scale deployment of perennial lignocellulosic biomass crops switchgrass, miscanthus, willow and poplar. GCB Bioenergy 11, 118–151 (2019).
2. Richards, M. et al. High-resolution spatial modelling of greenhouse gas emissions from land-use change to energy crops in the United Kingdom. GCB Bioenergy 9, 627–644 (2017).
3. Henner, D. N. et al. PopFor: A new model for estimating poplar yields. Biomass Bioenergy 134, 105470 (2020).
4. Henner, D. N. The potential for second-generation bioenergy crops in Europe and their impact on soil carbon changes and erosion. (University of Aberdeen, 2019).