There is a growing and significant dependence on biomass energy with carbon capture and storage (BECCS) in future emission scenarios that do not exceed 2°C warming; over a hundred of the 116 scenarios associated with concentrations between 430–480 ppm CO2 depend on BECCS to deliver global net negative emissions in the IPCC Fifth Assessment Report (AR5) (Fuss et al., 2014). Wiltshire et al (2015) found a median value of around 168 GtC cumulatively removed by 2100 using BECCS in the IPCC scenarios. The feasibility of this dependence on BECCS is coming under increased scrutiny, given the interconnected issues of food production, energy provision, energy system capacity and environmental impacts of large scale bioenergy coupled with large scale carbon capture and storage (CCS).
- Biomass energy with Carbon dioxide Capture and Storage (BECCS) is an emerging technology that combines large scale biomass energy applications (including electricity generation) with the capture and storage of CO2 .
- BECCS has the potential to remove CO2 from the atmosphere (‘negative emissions’).
- Alternative CO2 removal approaches do not provide the co-benefit of energy production.
- BECCS technology is entering the demonstration phase; the first large scale (1 MtCO2 yr-1 ) project is due to start operation in 2015 in Decatur, Illinois, USA. There are around 15 pilot scale BECCS plants globally.
- Most, but not all, IPCC WG3 emission scenarios that, for a mid-range equilibrium climate sensitivity, do not exceed 2°C warming require BECCS at a large scale to reconcile current emission trajectories with cumulative carbon budgets.
- For a given climate target the inclusion of BECCS in emission scenarios allows higher total carbon emissions, and/or a later peak in emissions, by removing carbon dioxide from the atmosphere later in the 21st century.target the inclusion of BECCS in emission scenarios allows higher total carbon emissions, and/or a later peak in emissions, by removing carbon dioxide from the atmosphere later in the 21st century.
- Many scenarios consistent with 2°C use BECCS to achieve global net negative emissions (when negative emissions from BECCS are greater than total emissions from all other sources) by about 2070, with a mean CO2 removal across IPCC WG3 scenarios of 616 GtCO2 by 2100.
- Integrated Assessment Models (IAMs) are based on different assumptions and constraints; some set a maximum limit of 200 EJ yr-1 for BECCS applications, whilst others incorporate explicit land use modelling. IAMs take account of future population, food production and land availability to varying levels of detail.
- The potential global bioenergy resource available for BECCS is a key uncertainty; composed of uncertainties in land and water availability, crop yields and residue availability, each associated with socio-economic assumptions, e.g. future agricultural efficiency gains, population growth, dietary trends and lifestyles.
- Many IAM scenarios assume that BECCS utilises dedicated rain-fed bioenergy crops grown on surplus agricultural land, assuming medium yields and the use of crop and waste residues. This seeks to circumvent issues of competition with food production and other land uses but is strongly dependent on the underlying socio-economic assumptions.
- BECCS may not deliver negative emissions if the biomass energy system is weakly governed and regulated. A poor choice of biomass type and location could lead to a net release of carbon to the atmosphere through direct and indirect land use changes.
- Deployment of CCS adds to the costs of energy generation, without strong climate policy incentives, such as suitable carbon pricing, and regulation there is no driver to establish the technology.
- Almost all scenarios compatible with the 2°C target assume full global participation in delivering emissions reductions; at scales sufficient to deliver global net negative emissions, uptake of BECCS in particular will require new global implementation and governance frameworks in the context of a highly complex supply chain.
- The global potential for negative emissions is estimated to be between 0 and 10 GtCO2 yr-1 in 2050 and between 0 and 20 GtCO2 yr-1 in 2100. Assuming 150 EJ yr-1 bioenergy in 2050, 250 EJ yr-1 in 2100, a 90% capture rate and emissions of 15 kg CO2 GJ-1 from bioenergy production. If BECCS starts in 2020, the maximum values equate to 900GtCO2 (245 GtC) removed by 2100. The lower bounds could result from weak or no climate policy; lack of social acceptability; and/or failure of the BECCS system to deliver net negative emissions. The confidence in this estimate is limited as it is based on one expert team using one particular modelling approach.