DECARBit - Zero-emission pre-combustion power plants

The following conclusions from DECARBit can be used when considering different CCS routes both regarding capture cost and advanced pre-combustion capture techniques.

This is a summary of the results. For a full overview, please see the Final Publishable Summary.

Executive summary

The following conclusions from DECARBit can be used when considering different CCS routes both with regards to capture cost and advanced pre-combustion capture technologies.

During the project, Integrated Gasification Combined Cycle (IGCC) models were created, incorporating the processes investigated in DECARBit. The first model was the so-called Base Case, which was developed within the activities of the European Benchmarking Task Force (EBTF) and published in a report. As a result of heat and mass balance studies from these models, boundary conditions and operational requirements were provided to the other SPs, for the development and evaluation of the novel processes. These first cycles were developed including the novel processes as black boxes, as they were created in the first year of the project. Such cycles were the starting point for three different avenues of activities. The first being the analysis of operability of the Base Case power station. Variations of a large number of conditions were considered, with their responses in the cycle. Implications of these responses on the efficiency and on the design of control systems were also investigated. The second was the assessment of costs of critical components, total investment costs, and operational and maintenance costs. Very important results here are the cost of electricity of the new cycles, cost of capture of CO₂ and cost of CO₂ avoidance. The third avenue of activities was the risk analysis of the novel cycles, based on failure mode, effect and criticality analysis. Here, the study involved the participation of partners from SP1, SP2, SP3 and SP4. 

Independently from these three activities, EBTF produced a technical and economic common framework, and a set of three test cases – IGCC (the Base Case of DECARBit), Super Critical Pulverized Coal (from the CESAR project) and Natural Gas Combined Cycle (from the CAESAR project).In the last year and a half of the project period, DECARBit focused on the establishment of four selected pilots, with the aim of providing more correct figures for the CO₂ capture cost analysis for the selected and most promising DECARBit processes. The following table, Table 1, gives the main techno-economic results obtained in DECARBit. The colours emphasize the comparative situation of each technology regarding each of the investigated parameters, orange fill colour being the worst and light blue being the best in the group.

Table 1 The main techno-economic results obtained in DECARBit. The DECARBIT cases (PSA, MDG, LT and ITM) are compared to the EBTF base case.

PSA: Pressure Swing Adsorption, MGD: Membrane Gas Desorption, LT: Low Temperature separation, ITM: High temperature membrane air separation, Contingency 15% - higher values recommended for novel cycles, BESP: Break-even Electricity Selling Price = Cost of Electricity, Specific Investment (SI) includes construction costs, year of reference is 2008

The main finding is that the LT technology seems to be the most economic one, able to capture at 19.5 € per ton closely followed by PSA and MGD at 25.1 € and 25.7 €, respectively. ITM achieved the highest capture costs of 29 € per ton. However, it should be noted that the capture rate for the selected cases is inversed with regards to capture cost, where the most economic LT technology only has a capture rate of 76.5%. Then again the LT comes out as the best alternative in terms of efficiency, total plant cost, specific investment, net electricity output, variable operation and maintenance costs, break-even electricity selling price as well as cost of CO₂ avoided. Variations in capture rate for the different cases are trade-offs and have been selected based on each systems currently known optimum operation. In comparison, the base-case developed by EBTF have a capture cost of 23.9 € per ton and a capture rate of 91%.

One reason that the LT technology was able to obtain quite low capture costs is that it has been optimized throughout the DECARBit project. Further optimization of the competing alternatives might possibly lead to somewhat lower capture costs. Regarding the Oxygen Transfer Membrane (OTM) integrated IGCC technology, it has still room for improvement, especially when it comes to improved power plant configuration, increased flux rates and novel cycles i.e. ITM integration in power generation sector. When it comes to the MGD alternative, improvements could be achieved by increasing the flux rates from the constructed pilot plant significantly. Finally, the PSA alternative needs improvement in both efficiency and capture rate to become a viable alternative.

Pilots

An important part of the project was the pilot studies. Four pilots were chosen, and they are explained below.

	Based on the solvent-membrane combinations that have been proven to work by TIPS Novel solvents and/or membranes will be tested in the proposed pilot as soon as they become available. Testing of a Shell propriety solvent is currently being discussed. Benchmarking of the different solvent systems, including ionic liquids and optimized chemical or physical solvents, will be performed by TU Delft.
Pilot 1: The general view (left) and the scheme (right) of pilot membrane unit for HPT MGD process
	A successful demonstration of an OTM lab scale pilot as proof-of-principle is a realistic goal. A pilot based on the principles in this work will benefit from the advantage of inexpensive support material, chemically stable membrane material and fabrication procedures which can be scaled up beyond the planned development. Technology is in the early stages of development The involvement of both a manufacturer and a possible end user benefits this activity Pilot will give a significant contribution towards the overall targets of DECARBit.
Pilot 2: Various membrane modules, single- and multitube
	A pilot plant is proposed for determining the performance of concentrically heat integrated distillation stages, used for the separation of an air-like mixture at cryogenic conditions. The economic feasibility of applying this technology in an air separation unit will be assessed. The organization of the construction and operation of the pilot plant will be done by SINTEF-ER and the NTNU. Air-Liquide will have an advising role The pilot will be located at the facilities of SINTEF-ER in Trondheim, Norway.
Pilot 3: a) Concept of heat integrated distillation column (HIDiC) & b) Experimental setup for the HIDiC
	High pressure combustion tests with H2  rich fuel types needs testing in order to quantify the trade-offs of various GT engine performance criteria. This kind of data is essential for the computation of the cost of electricity and as a result, for any forecast on CO2 capture and storage costs. This pilot was evaluated as the one which is closest to demonstration scale testing and development. The results are expected to contribute directly towards the overall targets of DECARBit, as the work will be performed by a manufacturer (ALSTOM)
Pilot 4: New hydrogen combustor tested in Alstom's high-pressure reheat test rig