carbon reduction technologies

Whenever coal or gas is burned, carbon dioxide (CO2) is produced. Depending on the type of power plant, a large quantity of the gas will dissipate into the atmosphere and contribute to climate change. A hard coal power plant discharges roughly 720 grammes of carbon dioxide per kilowatt hour, a modern gas-fired plant about 370g CO2/kWh. To ensure that no CO2 emerges from the power plant chimney, the gas must first be removed, and then stored somewhere. Both carbon capture and storage (CCS) have limitations. Even after employing proposed capture technologies, a residual amount of carbon dioxide - between 60 and 150g CO2/kWh - will continue to be emitted.

CO2 captured at the point of incineration has to be stored somewhere. Current thinking is that it can be trapped in the oceans or under the Earth’s surface at a depth of over 3,000 feet. As with nuclear waste, however, the question is whether this will just displace the problem elsewhere.

Ocean storage could result in greatly accelerated acidification of large sea areas and would be detrimental to a great many organisms, if not entire ecosystems, in the vicinity of injection sites. CO2 disposed of in this way is likely to get back into the atmosphere in a relatively short time. The oceans are both productive resources and a common natural endowment for this and future generations. Given the diversity of other options available for dealing with CO2 emissions, direct disposal to the ocean, sea floor, lakes and other open reservoir structures must be ruled out.

Because of the lack of experience with CO2 storage, its safety is often compared to the storage of natural gas. This technology has been tried and tested for decades and is considered by industry to be low risk. Greenpeace does not share this assessment. A number of serious leaks from gas storage installations have occurred around the world, sometimes requiring evacuation of nearby residents.

Sudden leakage of CO2 can be fatal. Carbon dioxide is not itself poisonous, and is contained (approx. 0.04 per cent) in the air we breathe. But as concentrations increase it displaces the vital oxygen in the air. Air with concentrations of 7 to 8% CO2 by volume causes death by suffocation after 30 to 60 minutes.

There are also health hazards when large amounts of CO2 are explosively released. Although the gas normally disperses quickly after leaking, it can accumulate in depressions in the landscape or closed buildings, since carbon dioxide is heavier than air. It is equally dangerous when it escapes more slowly and without being noticed in residential areas, for example in cellars below houses. The dangers from such leaks are known from natural volcanic CO2 degassing. Gas escaping at the Lake Nyos crater lake in Cameroon, Africa in 1986 killed over 1,700 people. At least ten people have died in the Lazio region of Italy in the last 20 years as a result of CO2 being released.

Can carbon storage contribute to climate change reduction targets? In order to avoid dangerous climate change, we need to reduce CO2 globally by 50% in 2050. Power plants that store CO2 are still being developed, however, and could only become reality in 15 years at the earliest. This means they will not make any substantial contribution towards protecting the climate until the year 2020 at the earliest. They are thus irrelevant to the goals of the Kyoto Protocol.

Nor is CO2 storage of any great help in attaining the goal of an 80% reduction by 2050 in OECD countries. If it does become available in 2020, most of the world’s new power plants will have just finished being modernised. All that could then be done would be for existing power plants to be retrofitted and CO2 captured from the waste gas flow. As retrofitting existing power plants is highly expensive, a high carbon price would be needed.

Employing CO2 capture will also increase the price of electricity from fossil fuels. Although the costs of storage depend on many factors, including the technology used for separation, transport and the storage installation, experts from the UN Intergovernmental Panel on Climate Change calculate the additional costs at between 3.5 and 5.0 €cents/kWh of power. Since modern wind turbines in good wind locations are already cost competitive with new build coal-fired power plants today, the costs will probably be at the top end. This means the technology would more than double the cost of electricity. The conclusion reached in the Energy [R]evolution Scenario is that renewable energy sources are already available, in many cases cheaper, and without the negative environmental impacts that are associated with fossil fuel exploitation, transport and processing. It is renewable energy together with energy efficiency and energy conservation – and not carbon capture and storage – that has to increase worldwide so that the primary cause of climate change – the burning of fossil fuels like coal, oil and gas – is stopped.