The US Department of Energy has announced the start of construction work near Houston Texas on what is set to be the world’s biggest post-combustion carbon capture and sequestration (CCS) facility.
The $470 million Petra Nova project is a joint venture between the US Department of Energy, NRG Energy and JX Nippon. It is expected by its backers to capture as much as 90 per cent of the emissions produced by 240 megawatts of power generation capability.
The project represents a major expansion of the DOE's original plans, which envisaged the capture of carbon produced by 60 megawatts of capacity, following the provision of additional assistance by NRG Energy and JX Nippon.
CCS technology is considered by advocates to be a highly viable means of reducing the carbon footprint of conventional fossil fuel plants by capturing and storing the greenhouse gas emissions which are released during the combustion process used to generate energy.
While the method is appealing in theory, given its ability to permit the environmentally sustainable usage of coal and oil, its deployment has thus far been hampered by a number of dilemmas, including the high cost of facilities and the additional burden that CCS technology places on power plants in terms of energy usage.
Questions have also arisen over the long-term effectiveness of the technology due to concerns that CO2 cannot be stored permanently beneath the earth or in artificial wells without subsequent leakage.
The DOE and its joint-venture partners are confident, however, that the CCS technology they are employing for the Petra Nova project will overcome these concerns following a trial in another project located in the American South.
The DOE sponsored a three-year pilot-scale test project in Alabama which proved capable of capturing 150,000 metric tons of CO2 per annum from a coal power plant. The Alabama test project used an amine-based CO2 capture system to collect the greenhouse gas emissions produced following combustion.
According to the DOE, the amine-based solvent employed by this system requires less energy to extract carbon emissions from the flue gas stream of a plant.
The method used for the disposal of the capture carbon also marks a departure from conventional technology. Instead of pumping capture carbon into an underground reservoir where it serves no purpose, it will be sent by means of a pipeline to the West Ranch oil field, located around 130 kilometres away from Petra Nova.
The carbon will be used for "enhanced oil recovery," which involves pumping it into the depths of an oil reservoir to shift oil which was previously inaccessible closer to the surface.
The final outcome is that the carbon ends up underground as originally intended, yet achieved improved overall economy by facilitating the extraction of oil from the West Ranch field.