Mettais was speaking at the Bioenergy North America conference organised by Bioenergy Business in Chicago last week. He suggested that the CCS process should be renamed carbon capture and recycle, as the CO2 would be continuously drawn out of the underground gas reservoirs to fuel algae farms.
Capturing the CO2 for use would not only be more productive than simply storing it but would also help address concerns about possible leakage of the gas from the underground rock formations causing damage to property or contaminating water supplies. The possibility of building a grid of pipelines carrying CO2 from a network of CCS sites to algae farms is currently being discussed by US politicians, he disclosed.
CCS facilities are currently being promoted by politicians and industrialists around the world as a way of sequestering power plant CO2 emissions which are deemed to be a major cause of global warming. Some countries have already said that new coal-fired power plants must have a CCS facility built alongside them.
“The CO2 problem becomes an opportunity” for algae farms, Mettais said. He estimated that one tonne of CO2 could yield net revenues of around $165 if used as the feedstock for an algae farm.
Only a small part of this would be from the biofuel produced, he noted, with the bulk of the revenues coming from sales of protein for animal feed. Other valuable products from the process would include methane, fertiliser and potentially tradable carbon credits. In his presentation, he assumed an input cost of $25/tonne of CO2 and estimated the various components of the revenue stream as: biofuel $30; protein $80; methane $27; fertilizer $28; and carbon credits $25.
One acre of an algae farm could removeabout 100 tonnes of CO2 each year, he said.
A2BE plans to build a full-scale experimental algae bioreactor next year and aims to start building a commercial scale facility in 2012.