CCS, an 'Airbag Technology' -- the technology is ready
A UN Intergovernmental Panel on Climate Change (IPCC) report on the potential to mitigate the effects of climate change recognized that reducing CO2 emissions from power plant will be vital and that technologies such as CCS (Carbon Capture and Storage) will have a key role in meeting the challenge.
Separating CO2 from industrial and energy-related sources, transporting it to a storage location and isolating it from the atmosphere is the key to large-scale de-carbonisation and sustainable long-term use of fossil fuels. Now the idea is no longer a dream. The technology is ready to go.
A 2004 paper by Robert Socolow and Stephen Pacala of Princeton University's Carbon Mitigation Initiative, funded by BP and Ford, identified 15 existing technologies that could each prevent 1bn t/y of carbon emissions by 2054. Carbon Capture and Storage (CCS) technology is one of them. The CCS technology can capture and safely store about 90% CO2 that would otherwise be emitted into the atmosphere, and is widely regarded as a long term solution to low-carbon power generation.
As such, says George Peridas, a climate scientist at the Natural Resources Defense Council, an environmental NGO, it is an 'airbag' technology. This can refer to both its capacity to store captured CO2 and its function to ease and cushion the green house gas effect.
How to store CO2?
According to research and development works so far, there are three main approaches to CO2 capture, namely post-combustion processes, pre-combustion processes and Oxyfuel-combustion processes.
Post-combustion, as the name suggests, processes separate CO2 from the exhaust gases produced by the combustion of fuel and captures CO2 by using a liquid solvent. Pre-combustion processes convert fuel into a gaseous mixture of hydrogen and CO2. The CO2 can then be separated either by absorption by liquid solvent or solid adsorbent, and released either by heating or reducing pressure. Compared with post-combustion processes, the pressure and concentration of CO2 in pre-combustion processes is relatively high – making CO2 separation easier to achieve and offering the potential to apply novel CO2-capture technologies. Oxyfuel-combustion processes use oxygen rather than air for combustion of the fuel. This produces exhaust gas that is mainly water vapour and relatively high concentration of CO2. Oxyfuel-combustion systems are being developed on a small scale, in laboratory or pilot projects.
There are three main types of geological storage. The most attractive are existing oil and gas fields: their ability to hold hydrocarbons indefinitely is already proved and the geology of producing fields is well defined. More importantly, reinjecting gas can help enhance oil recovery rates by up to 15%. Some companies have had experience of enhancing oil-recovery operations through the reinjection of gas. The second category is geological traps that do not contain hydrocarbons, but have similar characteristics to oil – or gas-bearing structures, or coal seems. The third possibility is aquifers - deep saline reservoirs. Less well understood than oil reservoirs, saline formations are an attractive long term solution because of their size.
The significance of the CCS technology
Power generation fired by fossil fuels accounts for over 40% of man-made greenhouse gas emissions in the energy industry, while almost 75% of the CO2 power emissions come from coal. Of the new power plants to be built in the next few decades, more are now expected to be fuelled by coal. According to the IEA (International Energy Agency), global primary energy demand may grow by as much as a half by 2030, with fossil fuels remaining the dominant source of energy. By then, the world will need over 50% more electricity than it does today, according to some forecasts. To make matters worse, much of the new capacity will be powered by coal.
As CCS is playing a key role in reducing emissions from power generation, business practices linking the technology to hydrogen power are on the rise. Hydrogen is used to produce green power while CO2 is separated, captured and reinjected to enhance oil and gas recovery. The projects, some of which can even link emission reduction and production efficiency, mark the initial steps in the commercialization of CCS, the road that leads to the application of the "airbag" technology.
Industry leads the way
As a pioneer in the pursuit of CCS and its commercial application, BP and Rio Tinto formed Hydrogen Energy, a new jointly-owned company, in 2007 to develop decarbonised energy projects around the world. Proposed projects include the capture and storage of 4m t/y of CO2 from a 500 MW power project at Kwinana in Western Australia, which envisages breaking new ground by storing CO2 in a deep geological formation.
Hydrogen Energy, along with partner Edison Mission Energy, is also planning the Carson project in California, an industrial-scale project using petroleum coke to manufacture hydrogen for power generation while also dramatically reducing greenhouse gas emissions by CCS. The hydrogen will be used to fuel a power station capable of providing the California power grid with 500 MW of low-carbon electricity – enough to power about 325,000 Southern Californian homes. At the same time, about 4 million tons of carbon dioxide a year will be captured, then transported by pipeline to the California oil fields and stored in oil reservoirs thousands of feet below the surface, where it will flush out additional oil that traditionally could not be recovered.
Other companies are joining the race. Germany's RWE is investing in a 450 MW coal-fired power plant integrated with CCS technology and says the facility could be operational by 2014. Sweden's Vattenfall, meanwhile, is building a 30 MW oxyfuel pilot plant in Germany, which is scheduled to start operating next year.
The way forward
"There are no technical or physical barriers to CCS", says Carbon Capture and Storage Association's (CCSA) Jeff Chapman: "The only thing that stands in the way of progress at the moment is policy." Environmental think-tank World Resources Institute (WRI) agrees: The capital exists and the technology exists; what is required is a regulatory framework that allows financial intermediaries to earn a sufficient return on investment."
The role of governments in putting in place appropriate regulatory and support mechanisms is essential to enable this to happen. The demand for low-carbon or carbon-free energies, particularly cleaner use of coal, has motivated related technology research and development work in China. This is not only expected to enhance China's capability to produce and commercialize clean energies, but also will contribute to the sustainable development of the country.
This story is developed on the basis of Robert Socolow (Princeton University), Tom Nicholls (Petroleum Economist), Chris Brown (BP) and Jonathan Forsyth (BP) 's works.
