Patrick Brandl, Imperial College London, Ruiqi Wang, Newcastle University, Ayub Golmakani, Cranfield University and Olajide Stephen Otitoju, University of Sheffield, write about the Core Research Carbon Capture session, on day one of the UKCCSRC Autumn Programme Conference.
The University of Edinburgh hosted the UKCCSRC programme conference on the 4th and 5th September. It saw national and international experts come together to discuss the recent advantages in CCS research. The session of Core Research Projects on day one of the UKCCSRC Programme conference in Edinburgh was kicked off with updates on Carbon Capture.
Mohammed Pourkashanian, head of Energy Research at the University of Sheffield and Director of the Pilot-scale Advanced Capture Technology (PACT) national facilities provided insights into his groups’ research work on advanced cycles and Bioenergy with CCS.
Mohammed started by explaining the direct-fired sCO2 cycles and its high efficiency and integral ability to capture CO2 at high pressure. He stated that sCO2 cycle with oxy-fuel high-pressure combustion strategy is a next-generation technology that is capable of providing an effective solution for the full integration of power-to-gas, CCS, and sCO2 pumping. He further stated that this technology will particularly be useful where improved efficiency and plant flexibility are desired.
He stressed that the availability of detailed reaction schemes is essential to the design of the high-pressure combustor component of the sCO2, but the uncertainties associated with the validated reaction schemes at high pressure constitutes a technical challenge of the sCO2 power cycle for stationary power generation. According to Mohammed, efforts at addressing this challenge are underway as available validated reaction schemes are being assessed for high-pressure natural gas combustion. He also stated as part of the future plan that they are building a heated high-pressure shock tube that is capable of operating up to 270 atm and a supercritical heat exchanger test bed to examine:
- The ignition behaviour of a large range of fuels at high pressure.
- The chemical kinetics of various fuels under homogeneous conditions of temperature and pressure.
- The heat transfer mechanism at sCO2 system.
Mohammed then moved on to talk about bioenergy facility coupled with CCS. Bioenergy in this sense refers to electricity and gas generated from biomass, which he stated was critical to achieving the UK and global CO2 reduction targets. He explained that the pilot-scale testing at PACT is assessing air-and oxy-combustion of a range of fuels, including:
- North AMERICAN Grade A white wood
- Short-rotation coppice (SRC) willow
- Grade A recycled (waste) wood from clean pallets
He opined that practical trials are important to building industrial confidence in the technology. Moreover, he explained that identifying the key species and pollutants from combustion and evaluating their impacts on solvents and capture plant operation through extensive analysis of combustion gases, assessment of entrained metal aerosol release, and examination of submicron particulate matter formation, including online particle size and concentration, are important for the bioenergy process with CCS.
He demonstrated that, although the analysis of the combustion gas shown that the SRC willow and the waste wood have a similar concentration of Oxygen and CO2, the concentrations of pollutants such as SO2 and NO in the gas are however higher in SRC willow than in waste wood. He also added that out of the three woods, the waste wood had the highest numbers of transition metal released due to its heterogeneous nature. These metals can negatively impact capture solvents through initiating/catalysing oxidative degradation.
Mohammed concluded by discussing the next step in their research to include:
(a) the full integration of the combustion and the capture plants to assess the impacts of alkali/transition/heavy metals on the oxidative solvent degradation, corrosion of capture solvents, and contamination of high purity CO2.
(b) the assessment of wastes and more contaminated fuels with a higher concentration of trace elements that can be detrimental to solvent integrity and plant performance.
Solid Adsorbents Looping Technology (SALT) is one of the most cost-effective CO2 capture technologies for both power plants and industrial processes, compared to amine scrubbing. Professor Hao Liu from University of Nottingham, who has rich experience in the field of CCS, presented the work of pilot-scale operation of solid adsorbents for CO2 capture. In the pilot-scale testing, basic polyethylenimine (PEI) adsorbents and activated carbon (AC) are being scaled-up to 5-100 kg. KOH-ACs potentially offer the most energy efficient technology, but moisture co-adsorption and heat recovery are much more of issues than those for silica-PEI. Next step, a tonne scale of adsorbent will be demonstrated, however, we should notice that the scaling up materials preparation from a gram to a tonne scale will still be a major challenge.
Linked with the systems work and focused on the problem of comparing one estimate for different capture technologies, Dr Ewa Marek shed light on the research at University of Cambridge in the field of modelling solids-based carbon capture processes. From the model, we found that the governing equations which are used to describe post-combustion capture and air separation are almost identical including the underlying equations and rate expressions. Will that be a solution of single estimate of cost and energy penalty? Maybe we can find the answer from the future work of Dr Ewa Marek and her team.
Ben Anthony and Paul Fennell
Cranfield University and Imperial College London are working towards development and testing of novel oxygen carrier materials. Professor Paul Fennell’s group at Imperial has developed materials at grams level in their bench scale batch co-precipitation unit whereas Professor Ben Anthony’s group are manufacturing materials at kilogram levels (~10’s kg) for pilot-scale testing. The fluidised/packed bed reactor test for the materials at both the institutions have shown no degradation of the materials which is a promising sign. The total time for producing materials at lab scale was roughly two days and the final product was palletised particles at different grain sizes between 70-500 µm. The characterization of materials by SEM, TGA and SEM-EDS is ongoing.
Professor Paul Fennell gave an overview of the activities being done by each member in the Capture group. The university of Imperial College is working on developing novel materials for CO2 capture at lab scale and they plan to scale up their production which is ongoing. The Sheffield University tests the materials at PACT facilities. Another member of this group has built GT with sCO2 or direct oxy-fired CCGT-CCS models, with interesting divergence of results observed based on thermodynamic models. The different integration possibilities in the field of hydrogen/clean power for the aim of uplifting in efficiency is under investigation by another member of capture group.
Dr David Danaci presented the recent advances in solid adsorbent and chemical looping research carried out at Imperial College London. Imperial developed a rapid screening tool that ranks and evaluates adsorbent materials e.g., MOFs, based on their physical properties and performance. Danaci feeds the properties as well as the operating conditions into a pressure vacuum swing adsorption process topology (non-isothermal, equilibrium model). Subsequent sizing and costing allows him to rank the different materials based on their projected capture cost.
He found that most adsorbents require a process that is more expensive than a solvent based MEA capture plant for atmospheric flue gases. The major costs are vacuum pumps and columns. It is a common theme in CO2 capture material research to increase the selectivity for CO2. However, Danaci found decreasing N2 selectivity is equally important to increase the CO2 working capacity. The key aspects in solid based CO2 capture are purity and recovery – both of which can be optimised via CO2 selectivity and cyclic capacity. Future work sees him analysing temperature swing adsorption cycles and increasing the number of analysed materials.
This blog was co-authored by Patrick Brandl, Imperial College London, Ruiqi Wang, Newcastle University, Ayub Golmakani, Cranfield University and Olajide Stephen Otitoju, University of Sheffield.