Industry looks to boost CCS technology

Carbon capture technology works and is being demonstrated at scale around the world — at natural gas processing plants, oil refineries, fertiliser plants, and most recently power stations.

However, established technologies are energy intensive and expensive, so research efforts across the UK and beyond are directed at more efficient technologies.

Most capture systems at scale are based on amine solvents that temporarily react with carbon dioxide from flue gases.

Once heated to around 120 degrees Celsius, the CO₂ is liberated in a pure enough form to be sent to storage or be used, and the regenerated solvent is cooled to begin the cycle again.

Research is under way to improve processes, develop new solvents and new capture mechanisms.

These include fuel cells, chemical looping combustion, and specialised membranes that selectively allow carbon dioxide to pass through. Construction of a pilot plant in Texas in the US is under way to remove CO₂ from oil production using a ceramic membrane.

The UK's Leeds University spin-out C-Capture has developed a novel solvent, with details firmly under wraps. Its pilot facility is capturing up to 1 tonne per day from biomass combustion at the Drax power station in North Yorkshire, making it Europe’s first negative emissions technology demonstrator.

Loaded with CO₂, the solvent is less corrosive, allowing less expensive construction materials to be used, according to founder Chris Rayner.

C-Capture has improved upon every aspect of the capture process, with temperatures and pressures kept to a minimum, so reducing energy demands.

Rayner is confident the solvent is flexible enough to take CO₂ out of any gas stream.

Biogas

The company has already carried out a lot of work on biogas, and discussions with other industries are expected to lead to pilots over the next 12 months.

Now a £5 million ($6 million) grant from the UK government will allow C-Capture to "do the final tweaking to optimise the process" and look at how its solvents perform over a prolonged period.

Energy requirements and emissions will be verified by Norwegian research institute Sintef, and if all goes to plan it will begin a trial at the CO₂ Technology Centre in Mongstad of up to 100 tonnes per day, so providing the data needed for scale-up.

The idea, says Rayner, is to have a plant capable of capturing 10,000 tonnes per day on Drax by 2025 or 2026. "We want to push on as fast as we can," he says.

Drax has also been exploring the feasibility of using a molten carbonate fuel cell to produce electricity — as a hydrogen fuel cell does — while also capturing CO₂ from its flue gases.

In the fuel cell, CO₂ from the flue gases and oxygen from the air combine to form a carbonate, which is transported across the electrolyte to react with hydrogen produced by reforming natural gas with steam.

Oxygen and hydrogen combine, producing water and CO₂.

Lab studies suggest the fuel cell will generate around 1.7 megawatts of electricity for the power station whilst consuming 3.8MW of natural gas.

All of the CO₂ from the gas used in the process is captured, as well as 70% of the CO₂ from the biomass flue gases. The process also reduces nitrogen oxide emissions.

France ’s Institute of Petroleum Research (Ifpen) is working on a range of capture technologies from incremental to breakthrough.

"Climate change is now ongoing — we have to implement solutions in a very short time, but we also have to have longer term solutions," says carbon capture manager Florence Delprat-Jannaud.

Ifpen is preparing to deploy its DMX solvent technology at Accelor Mittal’s steel plant in Dunkirk, providing the anchor for industrial decarbonisation there.

Delprat-Jannaud explains the objective is to cut capture costs by 40% to around €30 ($33.6) per tonne.

In contact with CO₂, its solvent has two phases. One is CO₂ rich, and only that gets regenerated.

Pilot plant

Energy requirements are cut further by using heat from the industrial processes, and because the CO₂ is produced at pressure, less energy is required to compress it for transport.

Construction of the pilot plant is expected to begin next year. The plan is to use storage provided by Norway’s Northern Lights project.

Ifpen is also developing chemical looping combustion in conjunction with its partner, French supermajor Total.

Here only oxygen is delivered to the fuel combustion process, meaning an almost pure CO₂ gas is produced.

Oxygen delivery is achieved though a metal oxide reaction in a specially designed reactor.

During combustion, the oxygen reacts with the carbon to produce CO₂ and the metal particles revert to their pure form to be recycled.

The steam produced by the oxyfuel combustion can be used for industrial processes or to generate electricity.

Ifpen’s design has been tested on a 10 kilowatt pilot unit, but through a joint European Union–China venture it will be developed into a 3MW per hour demonstration project in China using petcoke.

If all goes to plan, the project developers anticipate that an industrial facility could be operating by 2025.