With net zero separated into reduction and removal targets, and as BECCS and other GGRs prove themselves, their role, and our reliance upon them to avert climate change, could be expanded.
As the previous sections have highlighted, future reliance on BECCS is not necessarily flawed, but rather is fraught with complex trade-offs regarding feedstock choice, the supply chain embodied energy and emissions, as well as the optimization towards energy production or CO₂ removal. If handled poorly, these trade-offs will likely result in either competition with food production, high costs, impaired energy security, or a failure to meet the global carbon budget and ultimately prevent runaway climate change. This is particularly pertinent as countries’ net zero pledges remain vague and potentially allow for offsetting traditional decarbonization with CO₂ removals. In addition, the risks and trade-offs will be more acute as BECCS is scaled to the global level, which is likely to place significant pressure on biomass supply chains – not unimaginable given the number of countries now pledging net zero targets. This section discusses the potential solutions that could enable a future of BECCS (and more broadly GGRs) contributing to achieving net zero in a manner that minimizes the risks. Figure 10 illustrates these potential solutions (green box) that stem from the initial need for negative emissions (orange box) and the risks of BECCS (red box), as discussed in the previous chapters.
It is worth remembering that much of the optimism and hence increasing future reliance on BECCS stems from the IAMs and IPCC pathways. Furthermore, in the six IAMs that Butnar et al. (2020) reviewed, biomass is assumed to be carbon neutral, efficiency and capture rates are exogenous inputs, and the IAMs lack transparency around the technical functionality of BECCS. 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 modellers and scientists treat models, such as IAMs, as ‘experimental sandpits’, policymakers tend see them as ‘truth machines’. A worst case scenario of poorly implemented BECCS policies could delay or deter emissions reductions, fail to deliver the removals currently being baked in by policymakers and net zero pledges, and result in ‘imagined offsets’ that fail to materialize, which one analysis indicates could result in an additional temperature rise of up to 1.4°C.
In the real world, biomass supply chains embody non-marginal emissions and there is a clear trade-off between the efficiency and capture rate.
Many companies are planning on using CO₂ removals from BECCS to offset their emissions (see section 1.5). As a recent paper by prominent academics highlighted, ‘Carbon offsetting is a widespread tool in efforts to achieve net zero emissions. But current approaches to offsetting are unlikely to deliver the types of offsets needed to achieve global climate goals’. The report recommends that countries minimize the need for offsets, prioritize reducing emissions, and where offsets are used they should be of high quality, namely ‘verifiable and correctly accounted for and have a low risk of non-additionality, reversal, and creating negative unintended consequences’.
This is likely to have three primary consequences, as per Figure 10. The first two are intimately connected: prioritizing reductions over removals and minimizing reliance on removals by ensuring the deployment of proven low-cost renewables, reducing energy demand, incentivizing green hydrogen and ensuring a diversity of future GGRs, inclusive of NBS. Secondly, in order to achieve high-quality offsets in the context of BECCS, both the carbon payback periods associated with the different feedstocks and their supply chain emissions need to be accounted for robustly. Given the issues highlighted in section 4.1, this would require the tightening of regulations and enforcement along the length of biomass supply chains. Furthermore, enforcement is likely to be significantly easier if countries ensure that the biomass they use is grown domestically.
Part of the solution could be to separate net zero targets into emission reductions targets and removals targets, which as a lead author to the 6th IPCC assessment report has indicated in a recent paper – could prevent ‘offsetting the effects of both approaches’. The authors go on to recommend a 90:10 split between reductions and removals, and that the reduction target should be seen as a minimum target, which if GGR methods (including BECCS) improved or demonstrated breakthroughs, could lead to net zero being achieved earlier. Another approach could see countries not only separating net zero targets, but also legislating a regular review cycle that adjusts the split between reductions and removals as BECCS (and other GGRs) is deployed and demonstrates its whole system operational performance, such as verifiable net negativity inclusive of supply chain emissions.
Currently the performance of BECCS is poorly understood, due in part to the understandable commercial confidentiality of the companies developing the technology. This, unfortunately, means there is a disconnect between the information available to policymakers – which is based on assumptions within models, such as the IAMs – when planning net zero inclusive of BECCS, and the risk that BECCS fails to meet the assumed level of performance. The review cycle of the split between reductions and removals could go further, including stringent key performance indicators that if met as BECCS is scaled up, could lead to BECCS being allocated a greater aggregate role within the net zero future.
