Minimising and eventually eliminating carbon dioxide emissions from fossil fuel power generation is a vital pillar of the global effort to limit the warming of the earth's temperature to less than 2°C higher than pre-industrial levels. Carbon dioxide represents the vast majority of greenhouse gas emissions around the world, and around 50% of man-made carbon dioxide emissions can be traced back to the burning of fossil fuels in power plants and factories.
Carbon capture and storage (CCS) has been touted as the most likely candidate to make the world's fossil fuel power plants more environmentally sustainable for many years. The technology proposes to separate carbon dioxide from the flue gas that is a by-product of fossil fuel combustion and transport it via pipe or ship to sites where it can be stored without any release into the atmosphere.
Proponents of the technology note that future CCS-enabled power plants could provide electricity with next to no carbon emissions. The main appeal of CCS is the potential to make a positive impact on carbon emissions while renewable energy generation is refined and made viable - according to the Intergovernmental Panel on Climate Change, CCS could make up more than half of the global carbon reduction effort by 2100.
Although on paper CCS seems like the perfect stopgap in the challenge to produce energy in a cleaner way, the technology has its critics. Here we examine both sides of the CCS debate and what place this method has in the future carbon reduction picture.
Proponents of carbon capture
Many governments around the world are embracing carbon capture and storage as a large chunk of short-term carbon reduction measures. In April 2011, the Canadian province of Saskatchewan approved the construction of a C$1.24bn CCS demonstration project. The province plans to rebuild Unit 3 of the existing Boundary Dam power station near Estevan to integrate a new carbon capture capability.
Shell subsidiary Cansolv has been contracted to install the carbon capture system at the plant, with Hitachi providing a new steam turbine. Although the increased energy requirements of the carbon capture process will mean that the unit's generating capacity will be reduced from 139MW to 110MW, the CCS system will reportedly capture around a million tonnes of carbon dioxide.
The sequestered carbon dioxide is expected to be sold to enhanced oil recovery projects being carried out by the oil and gas industry.
Rob Norris, the Government of Saskatchewan's minister in charge of SaskPower, the government-owned power company responsible for the Boundary Dam CCS project, emphasised the role of carbon capture as a way to start cutting emissions immediately.
"This project will forge an environmentally sustainable path for the production of coal-fired electricity in Saskatchewan," he says. "By proceeding with the carbon capture project at Boundary Dam while continuing to add wind power and investigating other renewable energy options such as biomass, SaskPower is helping to build a greener future for Saskatchewan."
In other regions, CCS is being promoted not just as an important environmental step, but also as a boost to local economies and labour markets. A report by Scottish Enterprise published on 18 May 2011 at the All Energy conference highlighted the potential local and national benefits if three proposed CCS demonstration projects are given the green light.
According to research by the organisation, which is a public body of the Scottish Government, the three projects - located at Longannet, Peterhead and Hunterston - could create more than 5,000 jobs for the construction and operation of the plants, as well as adding £2.75m to the Scottish economy and up to £535m per year of the plants' operational lifetime.
"CCS is acknowledged as having an important role to play in supporting Scotland's ambitious emission reduction targets," says Scottish Enterprise's Adrian Gillespie. "However, to become commercially viable, demonstration projects such as the three proposed Scottish projects are critical."
The arguments against CCS
The aforementioned comment by Gillespie is central to one of the prime arguments made by detractors of carbon capture technology. Although there is now a healthy number of large scale projects now operating around the world, like Vattenfall's 30MW pilot plant at Schwarze Pumpe in Germany, this technology is still very much in the testing and demonstration phase.
There has been little confirmation as to carbon capture's industrial-scale viability. Saskatchewan's 110MW demonstration plant might be the closest that the technology has to truly commercial scale generation, and first operations are not scheduled to begin there until 2014. Scaling CCS up to make it commercially and environmentally relevant requires colossal investment into a technology that is, for all intents and purposes, unproven.
A potent example of the knowledge that is yet to be gleaned about the carbon capture process comes from the nearly completed Technology Center Mongstad (TCM) in Norway, a facility that intends to contribute to research and testing on carbon capture technology, according to the Oil & Gas Journal.
Once the building is complete (it is now 70% finished), one of the projects TCM will undertake is to test the separation of carbon dioxide from flue gas using an amine-based process that has become controversial due to the possible build up of carcinogenic compounds as a by-product of the process. Although TCM managing director Tore Amundsen says he is confident there will be no health risks from the emissions, he admits: "We don't know the impact of large-scale amine technology."
From the perspective of production and profit, carbon capture involves significant sacrifices. On top of the up-front investment, the increased energy needed to separate carbon dioxide from the flue gas means plants will have to reduce capacity to avoid negating their carbon savings, as has been seen at the Boundary Dam project. This means that CCS-enabled power plants might struggle to compete with their more-polluting rivals.
In an interview with Canada's Globe & Mail, University of Calgary physicist and CCS expert David Keith stated that unless assertive legislation or regulation is brought in to make sure all power companies are conforming to the same set of sustainability rules, there will be little incentive for them to sacrifice profit margins for the sake of the environment. "If there is no price for using the atmosphere as a waste dump, then there's no reason to waste your time on it," he says. According to Keith, the major deciding factor for the future of CCS is "climate policy, climate policy, climate policy".
CCS: the global debate
Some environmental groups have also come out against carbon capture as an expensive diversion from the true hope for the ozone layer: renewables. A memorable example is the reaction from Greenpeace after the opening of the Global CCS Institute in Canberra, Australia in 2009. The institute is a collaborative organisation whose mission is to advocate CCS as a means to cut carbon emissions, as well as promote the sharing of expertise and to conduct research into making the technology commercially viable.
According to the Greenpeace statement in response to the opening of the institute, CCS is a costly folly that diverts much-needed funds away from the development of a long-term, renewable power solution.
The environmental group also cited a 2008 survey in the Carbon Capture Journal, in which 64% of climate decision makers expressed serious doubts concerning the retrofitting of clean coal technology to existing power plants to reduce carbon dioxide emissions within the next 25 years.
The global debate concerning the strategy to cut carbon emissions is one of optimism and pessimism, of pragmatism and idealism. Just as CCS advocates might be prematurely optimistic about a technology that has yet to prove viable, CCS detractors may be equally premature with their staunch belief in equally unproven - and equally expensive - renewable options.
The fact remains that both renewable technology and methods of making existing power stations cleaner must both play a significant role in our approach to cleaning up the earth's atmosphere. Exclusively supporting one over the other makes little sense. Without technologies like CCS, carbon dioxide reduction would likely be too slow to meet international targets. Without renewable energy, there would be no long-term strategy. Simultaneously refining all possible avenues of carbon reduction is the only logical way to meet our environment's demanding, and essential, requirements.