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The importance of bio-CCS to deliver negative emissions
The Global CCS Institute has published its annual major report on the latest developments in carbon capture and storage (CCS). The Global Status of CCS: 2015 presents the most comprehensive overview of large-scale CCS projects and policy developments, the importance of the upcoming international climate discussions, new technology developments and further progress towards the emergence of coordinated industrial hubs and clusters. In the latest report the growing importance of negative emissions technologies is highlighted. Net negative emissions technologies including Bio-CCS or bioenergy with CCS (BECCS) are a group of technologies that result in an overall decrease in atmospheric greenhouse gas concentrations. In this Insight the Institute's Alice Gibson, Principal Manager Capacity Development, introduces bio-CCS.
What is ‘negative emissions’?
The Global Status of CCS 2015 report states that many of the climate models examined by the International Panel on Climate Change (IPCC) indicate the world is likely to temporarily ‘overshoot’ the atmospheric concentrations of carbon dioxide (CO2) required to achieve the world’s climate goals. The world is therefore likely to need to achieve ‘net negative emissions’ to meet our climate goals in the future.
Negative emissions occur where there is net removal of CO2 from the atmosphere. Not emitting more CO2 into the atmosphere is the aim of most emission reduction technologies, but bioenergy associated with carbon capture and storage (bio-CCS, or often called BECCS) is one of the few technologies that can deliver a net removal of CO2 from the atmosphere.
What is bio-CCS?
Bio-CCS is where a carbon capture and storage (CCS) project is combined with an industrial facility that burns biomass to create energy, or uses biomass as part of an industrial process (like a pulp factory for instance). Biomass comes from living, or recently living, materials; usually this is wood or other plant matter.
Plants absorb CO2 from the atmosphere and use this CO2 to grow, through a process called bio-sequestration. This is part of the natural carbon cycle. When these plants are combusted to produce energy, or are processed in an industrial facility (e.g. pulp plants), the CO2 is released back into the atmosphere. Energy produced from biomass is usually accounted for as ‘carbon neutral’, because it absorbs the CO2, but then that CO2 is released back into the atmosphere when combusted or processed.
However, when the CO2 from the combustion or processing of the biomass is not released into the atmosphere, but is captured and then stored in geological formations, this results in the net removal of CO2 from the atmosphere. Refer Figure 1 below for a diagram of this cycle.
How important is bio-CCS?
Eighty-five per cent of IPCC scenarios (or 101 of 116 scenarios) consistent with the 2°C goal, require global net negative emissions before 2100, typically through bio-CCS and afforestation (Sabine Fuss et al, Betting on negative emissions, 2014).
The potential role for negative emissions from bio-CCS could be in the order of 10 gigatonnes of CO2 by 2050 (The Climate Institute, 2014). The longer the delay in climate change action, the greater the need for net negative emissions technologies like bio-CCS.
Is bio-CCS already happening?
There is a large-scale, integrated CCS project associated with bioenergy that is currently in the construction phase. This project is called the Illinois Industrial Carbon Capture and Storage Project and is located in Decatur, Illinois, USA. It is a corn-to-ethanol plant, which was commissioned in 1978 and is being retrofitted with CCS. There have also been several smaller scale bio-CCS projects in Kansas, USA. (GCCSI, Global Status of BECCS, 2010)
What challenges does bio-CCS face?
The Climate Institute’s report on bio-energy identifies four major challenges to implementing bio-CCS. The first is incentive structures: incentives are needed to encourage large-scale deployment of all low-carbon technologies, but incentive mechanisms for carbon removal technologies in particular are in their infancy.
Bioenergy sustainability is essential. Biomass needs to be sustainably and reliably sourced to avoid the negative effects outweighing the positive climate change benefits. This includes ensuring land use is not diverted away from forest and food production and into bio-energy crops.
A key technical challenge for bio-CCS is that biomass-fired power plants are usually smaller and more dispersed than coal plants, which may result in reduced economies of scale when compared to larger CCS plants.
The last key challenge identified in the Climate Institute report is public perception. Public knowledge about bioenergy and CCS often lags behind other low-emission technologies like solar. This is a key area that needs to be addressed.