A growing body of research, including that from the first AVOID programme, has shown that the probability of being able to limit future global warming to levels such as 1.5°C or 2°C above pre-industrial times is strongly dependent on the implementation of, so called, negative emissions technologies. Here, the basic idea is that greenhouse gases, especially carbon dioxide, might be removed from the atmosphere at a quicker rate compared to that of natural processes alone. This could allow for a slower reduction of fossil fuel use whilst still keeping open the options of meeting ambitious warming limits. Several technologies have been suggested that could enable enhanced carbon dioxide removal but so far most emphasis has focussed on the combination of biomass and carbon capture and storage. This combination has not yet been demonstrated on a large, commercially viable scale.
What do we already know?
We have already estimated how much negative carbon emissions would be needed in order to meet given temperature limits with a chosen probability. Essentially the negative emissions buy time, allowing a later peak in fossil fuel emissions and/or a slower rate of emissions reduction after the peak. Crude estimates have been made of the capacity for combined biomass and carbon capture and storage, but these have typically lacked consideration of key processes and limitations, such as the amount of available water for biomass crops. Some studies have examined the joint needs of land for biofuels and land for food production, although usually in a highly simplified manner. There has been less work to date on other barriers to negative emissions technologies, including many technical aspects and societal attitudes.
What will this research achieve?
Firstly this work will provide a review of the recent literature on negative emissions, synthesising existing knowledge. It will then use expert judgement to provide new and additional information focused on the barriers to implementation and realistic scenarios of deployment. The second aspect of our work in AVOID2 will use a state of the earth system model to examine the maximum capacity for biofuels, assuming a range of resource limitations and other land use needs. Until recently earth system models have not had the complexity needed to perform this type assessment in a credible manner.
What is the policy relevance?
This work has a direct impact on determining the mix of mitigation methods that would need to be used for a given temperature target. It will also provide useful information on the barriers that will need to be overcome in order to make implementation of negative emissions a reality on a large-scale.
Research area description and outputs
D1. Review of negative emissions technology
A significant issue when considering the feasibility of limiting warming to values such as 2°C is the availability of technology to artificially remove greenhouse gases from the atmosphere. So far most consideration has been of combining biofuels with CCS (BECCS) – but even this is very uncertain. This project will first provide a literature review of current thinking on greenhouse gas removal (View report D1.a). It will then hold a workshop to update knowledge on the capacity, deployment rates and side effects of bio-energy with carbon capture and storage. View report D1.b
D2. The role of BECCS in mitigating climate change
A report on climate feasibility of bio-energy and carbon capture and storage, based on new earth system model experiments. Unlike earlier work this will include the impact that climate change might have on bio-energy capacity (feasibility based on bioenergy production: due Dec 2014). The second phase of this will see an assessment of global and regional climate under emission pathways that assumed availability of BECCS, but then experience a failure to partially or fully deploy BECCS (implications of non-deployment:View report). The final phase will deliver a report on the interplay between biofuel needs, food security and future potential crop yields. This will include discussion of the implications for existing emission scenarios. View report)