The world’s first cement plant to be fitted with industrial-scale carbon capture technology is currently under construction at Brevik in Norway. The second – and the UK’s first – is likely to be Hanson’s Padeswood plant in Flintshire, north Wales.
“We are neck-and-neck with another Heidelberg Materials project in Edmonton, Canada,” says Iain Walpole, Hanson’s head of process and sustainability for carbon capture. “But it doesn’t matter who comes second. We just want to start capturing CO2 at our plant as soon as we can.” Subject to necessary consents and government funding, Hanson hopes to start construction of the new carbon capture plant in 2024. So how will it work?
Walpole says that Padeswood, which opened in 1949, is fairly typical of the dozen or so major cement manufacturing plants in operation in the UK. Its kiln is a state-of-the-art five-stage precalciner, and it currently represents about 10% of UK cement production. The carbon capture unit will be built next to the existing plant, covering a similar footprint to the kiln line. It is set to cost around £400m to construct, and will capture some 800,000 tonnes of CO2 annually.
Padeswood will use the most mature and proven technology, based on amine, an organic solvent derived from ammonia. This involves circulating the flue gases through an 80m-high absorber column, where the CO2 bonds with the amine. This prevents 95% of the CO2 in the exhaust gases from escaping into the atmosphere. CO2-rich amines are then pumped to a regenerator column and boiled to release near pure CO2, which is then compressed and purified its work.
Then the amine has to be reboiled at 120°C to release the CO2, and after that, cooled again so it can be reused. Around 1,000 tonnes of amine solvent needs to be circulated every hour to capture 100 tonnes of CO2.” Walpole says that the carbon capture plant will use as much energy to capture 1 tonne of CO2 as the cement consumes to produce 1 tonne of cement: “Roughly 85% of the extra energy is used to heat and cool the amines, and around 15% is electricity needed to power pumps, fans and compressors.”
This will be supplied by a dedicated combined heat and power (CHP) unit, which will be powered by natural gas, with its exhausts fed through the carbon capture stack too. “To minimise the heat demand from the CHP, we plan to use waste heat from the cement plant for about 20% of our amine heating requirement,” says Walpole. He adds that the cement produced at the plant could be carbon negative: “Although the technology only captures 95% of the CO2 we produce, some of this comes from biofuels which are already classed before being piped away
from the site.
Carbon capture is an energy-intensive process, says Walpole. “Our gases start out at 120°C, but have to be cooled to 40°C – the optimal temperature for amine to do as zero-carbon. The net figure could be around -200kg of CO2 for every 100 tonnes of cement produced.” Once captured and compressed, the CO2 will be taken via a dedicated new 10km, 16” diameter pipeline to connect to HyNet’s 36” diameter pipe, which will collect CO2 from the entire HyNet area (see main copy). This will then link to a repurposed natural gas pipeline that will take the CO2 for permanent storage 1km below the seabed of Liverpool Bay in the Irish Sea.
“This was established to help start-up companies with great new ideas on how to improve our industry, including on carbon capture,” explains Lorea. “Our accelerator programme gives them direct access to academic advice, along with the labs and know-how of our members.”
Among the participants is Carbon OrO, which is exploring the potential of biphasic amines to make carbon capture more efficient. These can save energy by absorbing and releasing CO2 at lower temperatures than traditional amine solvents. On a different tack, Carbon BioCapture is using algae to capture CO2 directly from industrial waste gases; the algae, which thrive on CO2, can then be sold as agricultural feedstuff.
Fortera’s technology, meanwhile, combines CO2 emitted from cement plants with calcium oxide to make reactive calcium carbonate; Carbon Upcycling uses a low-energy process to chemically activate and capture CO2 within solid waste to produce supplementary cementitious materials; and MOF Technologies has harnessed a new class of solid sorbents called metal-organic frameworks in a filtration system that removes CO2 from flue gas using pressure rather than heat, reducing the energy required by up to 80%.
“There’s a huge amount of real innovation happening – but realistically it will take time for costs to fall,” says Casey. In the meantime, government will need to step in to ensure UK producers can compete on a level playing field: “Costs cannot currently be passed on to customers, because they will simply buy cheap, higher-carbon imports instead,” she points out.
The UK government is aware of these challenges and is starting to address them. Understanding that CCUS cannot operate in isolation, it is taking forward the technology in two initial “clusters”, areas where carbon capture plants can be joined to a new network of pipelines to transport compressed CO2 from a range of sources to permanent storage destinations off the coast of Britain.
The clusters already announced are in north-east England and around Manchester, Liverpool and Cheshire. Known as HyNet, this latter cluster will collect CO2 from new hydrogen production plants, the petrochemical industry in the Ellesmere Port region, and Padeswood. David Parkin is director of Progressive Energy, HyNet’s originator and project coordinator. “HyNet is sized to collect about 10 million tonnes of CO2 per year,” he says. “About half of this will come from new plants producing hydrogen from natural gas, with the rest coming from large industrial contributors such as Padeswood.
The CO2 will be stored under the Irish Sea in depleted gas fields which are coming to the end of their useful lives. We can repurpose the reservoirs, the platforms and the pipelines which now bring gas to shore, to send back CO2 to permanent storage beneath the seabed.” The existing pipeline effectively stops at Connah’s Quay in Flintshire, so HyNet plans to build a 35km extension to enable CO2 to be collected from Stanlow.
"THE NET FIGURE COULD BE AROUND -200KG OF CO2 FOR EVERY 100 TONNES OF CEMENT PRODUCED"