In this edition of In Depth, Fabio Bozzolo from ESB’s Innovation team takes a look at carbon capture, utilisation and storage technologies, and the role they could play in Ireland’s future energy system.
The best way to decarbonise energy is to prevent emissions in the first place through the use of renewables, electrification and energy efficiency. But there are some areas – like cement production or emissions from waste – where residual greenhouse gases may be unavoidable. To reach net zero, we will need to find ways to remove this CO2 from the atmosphere using carbon capture, utilisation and storage (CCUS) and negative emissions technologies.
UCC modelling of Ireland’s future net-zero energy system has estimated that around 3Mt of carbon dioxide equivalent will need to be removed this way annually by 2050. As we work to decarbonise our own operations at ESB by 2040, it’s important that we have a good understanding of CCUS technologies and the role they could play in our energy system – developed through research projects, collaborations and policy forums. This article takes a look at where the technology currently stands, and the work ongoing at ESB in this area.
What is carbon capture, utilisation and storage?
As the name suggests, CCUS refers to a range of technologies that ‘capture’ carbon dioxide from emission streams like industrial flue gas: the CO2 is separated out from the other gases in the mix through processes such as membrane separation or ‘scrubbing’ the exhaust gas with solvents. Once captured, the CO2 can either be transformed into a product – e.g. as a feedstock for chemicals or fuels – or stored away in a durable form that stops it re-entering the atmosphere.
CCUS technologies are carbon-neutral or even carbon-negative, as they lower emissions from current sources of CO2 and/or replace products that would otherwise have been produced with virgin materials.
A brief history of CCUS
The origins of carbon capture date back to the oil and gas industry of the mid-20th century. Climate was not on the radar back then; rather, the aim was to recover CO2 that could be injected back into oil wells to help extract more oil, meaning these systems usually generated more emissions than they mitigated. Yet these early applications helped improve the underlying technology – for example, demonstrating that carbon dioxide can be safely transported and stored underground.
As climate change rose up the agenda in the 1990s, the idea of capturing and storing CO2 to limit overall emissions gained traction. Pilot projects established the technical feasibility of CCUS at industrial scale, and bodies like the International Panel on Climate Change (IPCC) and International Energy Agency (IEA) today recognise that some measure of carbon capture will be needed to deliver net zero by 2050.
Challenges of CCUS
Traditionally CCUS has meant capturing emissions from industrial processes before they enter the atmosphere. There are limitations to this approach, however. First, retrofitting factories with carbon capture technology is expensive, and companies may find it difficult to justify the investment. Second, CO2 transport and storage requires very specific infrastructure and geological conditions which may not be present. Finally, the policy framework can be a challenge: for example, if the carbon captured is not of renewable origin, EU legislation does not promote production of fuels or products where the CO2 is not stored for long periods of time.
An alternative – carbon dioxide removal (CDR) technologies
For these reasons, traditional CCUS technologies may be more difficult to implement in Ireland without extensive investment and international partnerships. An alternative is carbon dioxide removal (CDR), technologies which the IPCC defines as deliberate human activities “removing CO2 from the atmosphere and durably storing it in geological, terrestrial, or ocean reservoirs, or in products”.
Rather than capturing CO2 at the source of generation as CCUS does, CDR actively takes carbon dioxide from the air, generating ‘negative emissions’. These can be sold as carbon credits, and a nascent international voluntary CDR market is fast becoming part of the decarbonisation portfolios of companies.
CDR options for Ireland
A cross-business ESB working group has been investigating potential CDR options that could be implemented in Ireland. These include:
- Biochar: This stable, carbon-rich material is produced by heating biomass (e.g. agricultural waste or wood residues) using a technique called pyrolysis, which locks the carbon in a solid, non-biodegradable form for long periods of time. It offers co-benefits when used in the agricultural sector, and is currently the CDR technology that has delivered the largest share of voluntary market carbon credits.
- Enhanced weathering: Weathering is a naturally occurring process where certain rocks react with carbon dioxide to form stable bonds. By crushing specific types of rocks and increasing their surface area, this natural process can be accelerated.
- Afforestation and reforestation: Trees have the natural ability to capture carbon dioxide and form stable structures within their biomass, and they provide ecological co-benefits if well managed.
Afforestation/reforestation appears to be the most promising option for Ireland currently, in light of its proven carbon removal potential and the technical maturity of available solutions. Looking at CCUS more broadly, other established solutions that perform strongly include bioenergy with carbon capture and storage (BECCS) in ethanol plants.
CDR policy developments
The policy landscape will be an important factor in how utilities engage with carbon removal technologies. It’s an area that is constantly evolving at national and European level at the moment, as policymakers seek to answer questions like which technologies should be recognised as delivering negative emissions, or how can it be ensured that carbon removals meet necessary quality standards?
At ESB, we continue to monitor this landscape as we build our knowledge base on carbon capture and removals, working with partners in Ireland and internationally to understand how this technology can support Ireland’s pathway to net zero by 2050.