Until such a time exists that clean, renewable energy can provide sustainable energy for cheaper than gas or coal, we can expect that producing energy will continue to generate a carbon footprint. However, the energy industry has been been touting the benefits of carbon capture and sequestration (CCS), which they claim can make traditionally dirty forms of energy much cleaner.
Thus far, few of the project have worked out as planned. But now, the US Department of Energy has started construction on a CSS project using proven technology that will be the largest system in existence. All the action is happening at a coal-fired power plant near Houston where – with the help of NRG Energy and JX Nippon – the DOE hopes to build a carbon capture system that can put 90% of the CO2 output of coal back into the ground where it can’t affect the climate.
The Petra Nova refit was originally going to be a modest DOE project that would retain 60 megawatts of energy generation, but the extra engineering muscle from NRG Energy and JX Nippon boosted the plan dramatically. Petra Nova will now be built with the intention of capturing the carbon output from 240 megawatts. The whole idea of carbon capture is to get the energy out of fossil fuels like coal and oil without releasing the carbon at the same time.
By taking carbon out of the ground and putting it in the atmosphere, the overwhelming majority of scientists believe we are causing global temperatures to increase. Putting the carbon back underground removes it from the atmosphere and maintains the environmental balance we currently enjoy. However, carbon sequestration might need to expand beyond new energy production.
Petra Nova will be using a scaled-up version of smaller amine-based CO2 CC systems. In these, CO2 is routed into a chamber where an amine-based solvent absorbs the gas. The resulting carbon-rich solution isl then sent through another chamber where low pressure steam is used to break the bond holding the carbon in solution so it can be captured while the solvent is reused.
The last step in any CCS system is to get the carbon back underground, but the Petra Nova is doing that in an unusual way. Instead of simply pumping it down in any old place, it will be transmitted via pipeline to the West Ranch oil field about 130 km (80 miles) away. There, it will be used for so-called “enhanced oil recovery”, which means it will be pumped into an oil reservoir deep underground to push previously unreachable oil closer to the surface.
The carbon dioxide does end up underground at the end of the day, but the hydrocarbon fuel cycle keeps on churning with increased oil output from the field. Naturally, the amount of carbon released by oil recovered from the West Ranch oil field will be far greater than what is recovered by this one power plant. Still, the Petra Nova project is a good way to subsidize the development of carbon capture tech until such time as it’s installed in all suitable facilities.