BECCS may well prove to be invaluable in minimizing climate change, but policy action is needed to limit the inherent scaling risks. The UK is leading BECCS development, so must also demonstrate robust policy leadership.
The slow pace of global decarbonization has created an inevitable need to turn to removing CO₂ from the atmosphere to prevent the overshooting of carbon budgets and runaway climate change. A worst-case scenario of over reliant and poorly implemented BECCS policies could delay or deter emissions reductions, fail to deliver the removals being baked in by policymakers and net zero pledges, and result in ‘imagined offsets’ that fail to materialize. One analysis indicates that this could result in an additional temperature rise of up to 1.4°C. The UK is leading efforts to develop policies and market frameworks to support BECCS. The UK must do so cognisant of striving towards realistic and robust targets, otherwise it would risk undermining global efforts to decarbonize.
This is particularly pertinent given the ‘middle-of-the-road’ 2050 IPCC global pathway towards 1.5°C compliant scenarios that envisages 1.5 GtCO₂/yr of BECCS removals, which if supplied solely by wood pellets would require a scaling of supply by more than 120 times, relative to what Drax currently combusts at its Selby facility. Due to the potential scaling pressures on wood pellet supply chains, the risk of carbon debt remains of concern. As one recent study points out, ‘in the US coastal southeast there were fewer live and growing-stock trees and less carbon in soils with every year of milling operation than in the rest of the eastern US’. As such, a diversity of feedstocks should be pursued.
In influential IAMs, particularly the six reviewed by Butnar et al. (2020), biomass is assumed to be carbon neutral, efficiency and capture rates are exogenous inputs to the models, and the models lack transparency. In the real world, biomass supply chains embody non-marginal emissions and there is a clear trade-off between the efficiency and capture rate. While scientists treat models as ‘experimental sandpits’, policymakers tend see them as ‘truth machines’. Forging ahead with policy and market support mechanisms risks policy decisions leading the scientific and engineering evidence. In the UK, wheat straw may provide the optimal carbon efficiency: 74–72 per cent of CO₂ is geologically stored, and 26–28 per cent emitted to the atmosphere. As such, for a finite land area, wheat straw based BECCS would remove more CO₂ from the atmosphere. Based on the UK’s CCC 2050 target for BECCS-to-power, if 100 per cent of the feedstock were provided by domestically grown wheat straw, an uplift of 57–83 per cent of current wheat production would be required, and 27–31 per cent of the UK’s current agricultural land area, a substantial proportion that could have implications for food prices. This should be treated as an indicator, given that other agricultural residues could compliment wheat straw, and the genetic potential exists to raise wheat straw yields and minimize or eliminate additional land requirements.
Based on the UK’s CCC 2050 target for BECCS-to-power, if 100 per cent of the feedstock were provided by domestically grown wheat straw, an uplift of 57–83 per cent of current wheat production would be required, and 27–31 per cent of the UK’s current agricultural land area, a substantial proportion that could have implications for food prices.
There are indications that first generation BECCS-to-power facilities will exhibit lower efficiencies than that envisaged by the CCC. Inefficient facilities would remove more CO₂ for an equivalent generating capacity, but would likely require a greater carbon removal subsidy as power revenues would be relatively lower than efficient equivalent facilities.
If BECCS is to play the crucial role that models, policymakers and net zero targets imply, then the carbon efficiencies and the energy output–capture rate trade-off needs to be at the heart of policy development, or else there is a risk that already tight carbon budgets become unresolvable, leading to runaway climate change. As such, policymakers should:
- Enforce tighter supply chain emission regulations that are well monitored and verified; likely to be more attainable if feedstocks are domestically grown.
- Prioritize reductions over removals, ensuring that proven low-carbon technologies are deployed with earnest, options for demand reduction are given political priority, and green hydrogen is swiftly developed.
- Legislators should consider separating net zero targets into reductions and removals, with an appropriate split that represents the current ambiguities in BECCS performance. Overtime, a regular review cycle could expand the role of removals as BECCS performance moves from being masked behind commercial confidentiality to meeting key performance indicators.
In assessing the merits of implementing a more stringent set of criteria for achieving net zero, policymakers should keep in mind that monitoring, reporting and verification of CO₂ is challenging enough, but that as the system becomes ever more complex the risks increase of a mismatch between what is claimed and real-world atmospheric CO₂ concentrations. Furthermore, all crises involve scarcity of some form or another. In the case of the COVID-19 pandemic, PPE and then vaccines became the commodity of scarcity, with profiteering, counterfeits and fraud swiftly following. The climate crisis is no different: the commodity of scarcity being the remaining units of the global carbon budget. But while PPE and vaccines are tangible goods, CO₂ in the context of removal offsets is, in many ways, a more gameable system, ripe for exploiting crisis driven profit.
