Category: Carbon capture, storage and use

Sucking out the carbon from the atmosphere- can negative emissions technologies help reach climate goals?

A blog post from Dr Jasmin Cooper, Research Associate at the Department of Chemical Engineering and Sustainable Gas Institute.

The atmospheric concentration of carbon dioxide is continuing to rise despite global efforts to decarbonise energy systems and economies. There was a dip in emissions during periods of national lockdown in the 2020 COVID-19 pandemic but as lockdown measures ease, emissions are returning to pre-pandemic levels (Met Office, 2021). It has become evident that the rate of decarbonisation is not matching the pace needed to meet the climate change goals set in the Paris Agreement and therefore cutting fossil fuels alone is not enough to keep global warming to below 2°C or 1.5°C (McGrath, 2020). Therefore, negative emission technologies (NET), such as those which ‘suck’ carbon dioxide out of the atmosphere, have an important role to play in meeting emission targets.

What are NET?

There are a number of emerging NET being used or are emerging, including afforestation and reforestation, direct air capture and bioenergy with carbon capture, some of which are on display in the Science Museum’s Our Future Planet exhibition. These are different to carbon capture for a coal power plant as they remove pre-existing carbon dioxide from the atmosphere, therefore reducing the atmospheric concentration.

Each NET has its pros and cons; afforestation is simple yet effective but requires large numbers of trees (and therefore land) to be planted in order for significant carbon removal. Bioenergy with carbon capture is multifunctional as it generates heat, electricity or liquid fuels, but the feedstock requirements could conflict with other agricultural needs.

Our work on the environmental impacts of NET

At the Sustainable Gas Institute, we have been examining the environmental impacts of NET. Important factors of all NET are their embodied emissions (emissions from the production of materials and energy used by a NET) and life cycle impacts (impacts from all activities, materials and energy consumed by a NET over its entire lifespan). If these are high, then the overall climate change mitigation effectiveness of a NET could be severely reduced. For example, if a NET emits 400 kg CO2eq. per one ton of carbon dioxide removed from the atmosphere, then the total amount of carbon dioxide removed is 600 kg. Emissions occur in the materials and energy supply chains, as well as during activities in the life cycle such as maintenance, construction and waste management. Emissions are not limited to greenhouse gases.

Other chemicals are released into the atmosphere that can have negative impacts to air quality, land and water. No NET is emission free, and the magnitude of emissions ranges greatly both between and within NET, depending on the quantity of materials and energy used and the level of decarbonisation within the materials and energy supply chains. Therefore, it is important that these emissions are taken into consideration when developing NET strategies.

Rate of carbon dioxide removal

Another important factor to consider is the amount of carbon dioxide removed over time. Afforestation and reforestation and enhanced weathering can remove large quantities of carbon dioxide from the atmosphere, but the rate of removal is slow and dependant on factors such as temperature. Direct air capture and bioenergy with carbon capture, on the other hand, can remove large quantities of carbon dioxide from the atmosphere quickly, with capacities of one to four megatons of carbon dioxide per year per facility. However, they are the most sensitive to emissions from their supply chains. Hence, forward planning is an important factor that should be taken into account when devising NET strategies so that variations in rate of carbon dioxide removal are taken into account.

Weighing up the evidence

Overall, NETs do result in a net removal of carbon dioxide across their life cycle but under particular circumstances, the impact of embodied emissions can be so great that there is limited net carbon removal. Therefore, we need to maximise the effectiveness of NET as this is crucial for ensuring no repercussion are experienced from expanding their uptake globally and that there are no further delays to reaching Paris Agreement targets.


McGrath, M. 2020. ‘Not enough’ climate ambition shown by leaders. BBC News, 12 December 2020.
Met Office. 2021. Mauna Loa carbon dioxide forecast for 2021 [Online]. London, UK. Available: [Accessed June 2021 2021].


BLOG: Reducing the costs for Carbon Capture and Storage

12235378406_e25379dc47_o copyThis event blog was written by Sara Budinis, a research associate at the Sustainable Gas Institute (SGI). 

Last Thursday, I attended a thought-provoking event which covered the role for research and development (R&D) in delivering cost-competitive Carbon Capture and Storage (CCS) projects in the UK in the 2020s.

This particular topic was of special interest to me as the SGI’s second White Paper (due to be published in the Spring of 2016) will review and discuss the costs of CCS when applied to power generation and industrial applications.

The workshop was arranged by KTN Knowledge Transfer Network together with the APGTF, CCSA, Coal Research Forum and UKCCSRC.

It explored the challenges associated with second and third generation CCS projects and how R&D could help to solve these challenges, reduce costs and support the development of a sustainable supply chain.

The cost of CCS is one of the main challenges to its development in the UK and worldwide. There is a variety of metrics to express CCS costs. The most common ones include the cost of carbon (£/CO2, which can be avoided, captured or abated carbon) and cost of electricity (£/MWh), which is used when you are dealing with CCS applied to power generation.

When delivering new technology, its cost decreases along a “learning curve”.  So, a First Of A Kind (FOAK) plant obviously involves a high economic risk. Exploring ways to reduce the capital and operating costs of CCS from the FOAK level to the NOAK (nth of a kind) level is of great interest for industry, government and academia.


Below are some highlights from the day:-

  • Luke Warren, from CCSA, highlighted the lack of an enabling policy framework as one of the main challenges to the development of CCS in the UK, which must move toward a low carbon economy. He commented on the need for a long term sensible energy policy. Because of the strong interest of the UK Government towards the consumers, CCS and carbon reduction in general must be cost effective and represent a good “value for money” as an investment for the future.
  • Jeremy Carey from UKCCSRC talked about the role of academics in the development of Carbon Capture and Storage and pointed at the importance of basic research at every stage. Moreover he believes that current technology rather the new technology must be involved in order to achieve concrete outcomes. This is because of the little time window between the present and 2020.
  • Andrew Green from Energy Technologies Institute: CCS is less expensive than other option for the reduction of CO2 emissions and moreover can be combined with biomass technologies in order to have negative carbon emissions. CCS must be applied to the power sector as well as to the industrial sector. He highlighted some key actions including the implementation of both Peterhead and Whiterose CCS projects, and the need for early investment in storage appraisal and further investments by 2020.

If you want to hear more updates from SGI or receive a copy of our next White Paper, sign up to our new bimonthly newsletter by emailing us at: