BECCS is often viewed from the perspective of facility level challenges, which risks masking the complexity of the entire system and the inherent trade-offs.
The common narrative surrounding BECCS tends to focus on the capture rate of BECCS facilities. Combined with the assumption that biomass is carbon neutral, this results in a somewhat simplistic conclusion that if the capture rate is high, then the BECCS facility will remove an equivalent amount of CO₂ from the atmosphere to that absorbed by the plants during their growth. As previously mentioned, capture rates are often cited as being 90 per cent or more by BECCS developers, within the IAMs, academic literature and within policy briefings.
BECCS is a complex system, as with all complex systems there are inherent trade-offs between different design criteria (cost vs capture, for example); the trade-offs and nuances need to be front and centre to avoid the downsides and maximize the chance of mitigating climate change. BECCS requires:
- An optimal choice of feedstock, of which there are many, requiring consideration of the supply chain emissions of differing feedstocks and the land required to grow them;
- A balancing of BECCS between energy production or CO₂ capture; and
- The permanent storage of captured CO₂ in underground geological formations.
Given that biomass feedstock supply chains are complex, with countries often importing biomass from other regions, and that the CO₂ needs to be transported to an underground geological formation, there is clearly a need to expand the boundary of the system when analysing the net negativity of BECCS.
The boundary of the system is crucial given the increasing global reliance on BECCS. The UK government would be short-sighted to develop policies without considering the implications of scaling BECCS, as is implicit in the move by so many countries to adopt net zero targets. While the supply chain emissions and land requirements of BECCS might be manageable from the perspective of the UK sourcing biomass to offset its residual emissions, the pressure on those supply chains and land as BECCS is scaled could lead to increasingly sub-optimal outcomes.
2.1 Capture rates are critical, but risk hiding the whole story
Both CCS and BECCS are still very much in development. CCS has been under development for many years, but despite political support, the global roll-out of CCS has not yet occurred. In 2007, the EU committed to deploying 12 demonstration power plants by 2015, and new fossil fuel power plants fitted with CCS by 2020. To date, these projects are yet to materialize.
CCS capture rates require third-party verification to confirm that the technology performs as well as is claimed by those in the industry. This is of particular importance as more BECCS is incorporated into country policies.
CCS capture rates require third-party verification to confirm that the technology performs as well as is claimed by those in the industry. This is of particular importance as more BECCS is incorporated into country policies. The handful of CCS demonstration facilities that have been built, for which there is third-party verification, indicate the real-world, whole system capture net negativity may be substantially lower than the facility level capture rate (often cited as 90 per cent or greater). A third-party study in late 2019 of data from a coal with carbon capture and use (CCU) facility and a synthetic direct air carbon capture and use (SDACCU) facility shows capture rates of less than 11 per cent over 20 years, and 20–31 per cent over 100 years. These significantly lower whole system carbon removal efficiencies are a result of the study factoring in supply chain emissions and emissions associated with powering the CCS equipment. While this is only one study, and the results do not necessarily translate neatly to BECCS, it does demonstrate the need to look beyond the facility level capture rate and consider the wider system.
2.2 Biomass land requirements
The land required to grow biomass for BECCS is significant and dependant on the choice of biomass feedstock, with potential consequences for food production and biodiversity. Furthermore, biomass will be required for other components of the globally decarbonized energy system, such as biofuels for transport and biomass-based heating. Biomass-based energy is already the largest source of renewable energy worldwide. The majority is consumed as fuelwood, charcoal and agricultural residues in developing countries; an estimated one-third of the global population rely on this source of energy to some extent. Traditional uses of bioenergy accounted for an estimated 9.5 per cent of global primary energy supply in 2018.
The IPCC 2019 report on climate change and land concluded that, ‘although estimates of potential are uncertain, there is high confidence that the most important factors determining future biomass supply are land availability and land productivity. These factors are, in turn, determined by competing uses of land and a myriad of environmental and economic considerations.’ The IPCC SR1.5 report indicated that 1.5°C compliant pathways would require around 25–46 per cent of arable and permanent crop land in 2100.
