Nanotechnology could help bring down costs of CO2 capture
A European project called 'Nanomembranes against Global Warming' (NANOGLOWA) is attempting to find a new way of capturing CO2 emissions from power plants with the help of nanotechnology. Nanostructured membranes could reduce carbon capture's energy consumption and costs, making it more attractive than current technology. Europe produces one gigaton of carbon dioxide annually and wafts it into the atmosphere. Around one-third of this stems from fossil-fuelled power plants. Carbon capture and storage (CCS) could reduce those emissions by up to 90%. The idea is to store the carbon thus captured underground in, for example, empty gas fields and aquifers. Existing capture methods include absorption and non-selective cooling. During the absorption process, flue gasses - mainly consisting of nitrogen, water, dust particles and, of course, CO2 - flow through several baths in which the carbon dioxide is bound with amines. However, this 'scrubbing' technology is far from being energy- or cost-effective, as it can consume up to 25% of the energy actually produced, and large installations as well as chemicals are needed, says the NANOGLOWA team. CO2 separation through membranes, on the other hand, would consume only up to 8% of the energy produced, and bring down installation costs. Suitable membranes must first be developed, however. Currently, five different types of nanomembranes are simultaneously being designed in the framework of the project: - polymer membranes: - - diffusion transport membranes, block copolymers; - - fixed-site carrier-type membranes, cellulose acetate or polyamides; - - ionomeric high voltage membranes, electrically modified materials; - carbon membranes: - - carbon molecular sieve membranes; - ceramic membranes. While polymeric membranes are cheap, they seem to dilate when brought into contact with CO2 at higher pressure, so that selectivity and hence efficacy may be significantly reduced. Carbon membranes, on the other hand, are well developed and have good selectivity, says the NANOGLOWA team, but they may be contaminated by the power station's flue gasses. Finally, ceramic membranes are very stable and have great longevity as they respond well to extreme conditions such as high temperatures. After development in academic laboratories, the membranes will be tested in pilot power plants in the fifth and final year of the project (2011). The NANOGLOWA project unites 26 organisations, including six universities and five power plant operators, as well as industry and small and medium-sized enterprises (SMEs) from 14 European countries. The project receives €7 million in funding from the European Commission under the Sixth Framework Programme. Total costs amount to €12.5 million.