Effective Adsorbents for Establishing Solids Looping as a Next Generation NG PCC Technology

To achieve the UK’s ambitious target of reducing greenhouse gas emissions by 80% by 2050, it is widely accepted that from ca. 2030 Carbon Capture and Storage (CCS) needs to be fitted to both coal and natural gas fired power plants.

The flue gas characteristics of natural fired gas power plants, mostly operating in a combined cycle of gas turbine and steam turbine (NGCC), differ significantly from those from coal-fired power plants. Comparing to the flue gas of the same size coal-fired power plant, the flue gas of a NGCC power plant contains significantly lower CO2 (3-5 vs. 13-15%) and higher O2 concentrations (12-15 vs. 2-4%) and has ca. 50% higher flow rate, which make the separation of CO2 equally, if not more, challenging. 

The most mature PCC technology, CO2 amine scrubbing, suffers from well-known problems of high energy penalty, oxidative solvent degradation and corrosion, large capture plant footprint and high rate of water consumption. A new generation of PCC technologies for NGCC power plants which overcome these drawbacks need to developed and demonstrated in the next 10 ~ 20 years in order for their commercialisation from ca. 2030. Solid adsorbents looping technology (SALT) is widely recognised as having the potential to be a viable next generation PCC technology for CO2 capture compared to the state-of-art amine scrubbing, offering potentially significantly improved process efficiency at much reduced energy penalty, lower capital and operational costs and smaller plant footprints.

The aim of this project is to overcome the performance barriers for implementing the two types of candidate adsorbent systems developed at Nottingham, namely the supported/immobilised polyamines and potassium-promoted co-precipitated sorbent system, in the solid looping technology specifically for NGCC power plants, which effectively integrates both materials and process development and related fundamental issues underpinning the technology development. The objectives are:

1. To overcome the following major specific challenges:

(a) To examine and enhance the oxidative and/or hydrolytic stability of supported/immobilised polyamine adsorbents and hence to identify efficient and cost-effective management strategies for spent materials.

(b) To optimise the formulation and preparation of the potassium-promoted co-precipitated sorbents for improved working capacity, reaction kinetics and regeneration behaviour at lower temperatures.

(c.) To gain comprehensive understanding of to what degree and how different flue gas conditions, particularly oxygen and moisture, can impact the overall performance of adsorbent materials and related techno-economic performance of a solid looping process.

2. To produce kilogram quantities of the optimum adsorbent materials and then demonstrate their performances over repeated adsorption/desorption cycles and to establish the optimal process thermodynamics in fluidized bed testing.

3. To investigate a novel rejuvenation strategy for oxidised polyethyleneimines involving low temperature hydrogenation.

4. To conduct techno-economic studies to assess the cost advantages of the solids looping technology for NGCC power plants over amine scrubbing based on the improved adsorbent performance and optimised process configuration achieved in the project.

The know-how acquired in this project will be of direct benefit to academics, CCS research community, power generation and energy industries, energy policy makers/regulators, environmental organisations and government departments such as DECC. 

The successful delivery of the proposed project represents a major step forward in the development and demonstration of the novel and cost-effective Solids Adsorbents Looping CO2 capture technology for NGCC power stations.