Project Objectives

CESARs primary objective is to decrease the cost of capture down to 15 €/tCO₂ captured. Translated into technical terms this objective comes down to:

• Reduction of the energy requirement of the capture process (mainly concerns regeneration of chemical solvents) from 3 GJ/t CO₂ 1down to 2 GJ/ton CO₂.
• Reduction of capital expenditures (CAPEX) related to the capture process by a factor of 1.5 per installed MW-e.
• Reduction of the total overall energy efficiency losses (including losses due to integration of the capture process into the plant) from 11 to 6 Percentage points for gas-fired stations and from 13 to 8 Percentage points for coal-fired power or 0.40-0.45 kWh electricity lost per captured kg of CO₂ down to 0.25 kWh per kg CO₂ captured.
• Assessment and comparison of novel integration concepts with mainstream techniques on a pilot plant scale, providing technical and economical proof of technological advancements.
  

The main scientific and technological objectives to be detailed later are:

• High Potential Amine or Amino Acid Based Solvents selected (with input of experience from CASTOR), characterized and finally tested in the Esbjerg Pilot plant.
• Low Energy Hybrid Solvent Systems including novel slurry/precipitating solvents such as activated polymers slurries, precipitating amino acid salts and carbonate systems allowing: better operability, reduced waste, compact equipment, low-energy regeneration.
• High Flux Membrane Contactors that will allow reduction in terms of size and alleviating a number of constraints imposed by the standard equipment (packed columns), and thereby resulting in both lower CAPEX and OPEX.
• CO₂ Capture Process Models and Modifications including novel models and methodology, based upon solvent system properties investigating options like interstage cooling, vacuum or pressure desorption, flue gas cooling, split stream options and utilization of flash tanks.
• CO₂ Capture Integrated Plant Process Configurations with a minimum CO₂ capture energy penalty and a minimum environmental impact.
• Pilot Scale Validation (1% of full scale, 1 ton CO₂/hr) of novel solvent systems in terms of operability and absorption performance, comparison with main stream, thus paving the way for large-scale demonstration.

B1.2.1 CO₂-capture processes and the position of post-combustion capture

There are three basic types of processes for capturing CO₂ from power plants as indicated in the ZEP WG1 final report 1 on Power plant and Carbon dioxide capture:

• Post-combustion processes.
  Carbon dioxide is captured from a flue gas at low pressure (1 bar) and low CO₂-content (3-15 %). The separation task is to selectively remove CO₂ from a mixture of mainly nitrogen and oxygen. These technologies would be applicable to existing power plants and new power plants based on existing designs.
• Pre-combustion processes.
  Carbon dioxide is captured from a gas mixture with predominantly H2 gas at high pressure (15-40 bar) and medium CO₂-content (15-40 %). These technologies would be applicable to new power plants in which hydrogen as an intermediate energy carrier is produced. Combustion of hydrogen in existing gas turbine is an element of the technology chain, which requires significant modifications to the existing gas turbines.
• Oxyfuel or denitrogenation processes.
  A concentrated stream of carbon dioxide can be produced by the exclusion of nitrogen before or during the combustion/conversion process. The difference with the previous process routes is that here the separation is targeted to produce pure oxygen from air (i.e. the selective separation of oxygen from mainly nitrogen), thereby avoiding the need for CO₂ separation. These technologies would be applicable to new power plants where the modification of boiler technologies would require considerable attention.

Figure 1.2.1 CO₂ Capture systems (source: ZEP – WG1 report, 2006)