A coal-fired power station in Canada is launching carbon capture and storage on a commercial scale. Could this make burning fossil fuels guilt-free?
RISING above the endless plains of Saskatchewan, Canada’s Boundary Dam power plant looks like any other: giant boxes, tall red-and-white striped chimneys, and a mess of pipes and power lines.
But appearances can be deceptive. In the coming months, it will become the first power plant to suck the carbon dioxide out of its flue before the gas reaches the air. It is blazing the trail for carbon capture and storage (CCS) around the world. Not bad for Canada’s largest coal power plant.
Each year, Unit 3 of Sask Power’s Boundary Dam plant emits 1.1 million tonnes of carbon dioxide. But from this summer, 90 per cent of that CO2 will never see the light of day. Instead, the gas will be piped to the nearby Weyburn oilfield and Dead water saline aquifer, and pumped several kilometres underground.
“The resulting 110 megawatts of power produced will be some of the world’s most environmentally clean power from fossil fuels,” says Sask Power’s Robert Watson.
“2014 is a pivotal year for CCS,” says Stuart Haszeldine of the University of Edinburgh, UK. “The technology is going from zero to something. It’s terrific.”
Boundary Dam is CCS’s first big success story, and more must follow. The International Energy Agency (IEA) says that, to have a 50 per cent chance of avoiding 2 °C of global warming, which is probably too dangerous to adapt to, the energy sector can only emit 884 gigatonnes of CO2 between 2013 and 2050 (Redrawing the Climate-Energy Map, 2013). Burning proven reserves of coal, oil and gas would release 2860 Gt. So we must leave two-thirds in the ground (Technology Roadmap: Carbon Capture and Storage, 2013).
Here’s the rub: the IEA says we will build enough power plants by 2020 to burn our budget by 2050. “Climate change mitigation can and should start by lowering consumption and increasing energy efficiency,” says Ruben Juanes of the Massachusetts Institute of Technology. “But the reality is that fossil fuels will continue to dominate the world’s primary power for decades to come.”
That is where CCS comes in. Exhaust from a power plant is passed through a solvent that binds to CO2. While the rest of the gas is vented, the CO2-rich solvent is drawn off and heated to release the gas. Then the CO2 can either be used (see “Don’t junk CO2, turn it into bottles and glue”) or pumped underground, beneath impermeable layers of rock .
Boundary Dam will be the first CCS project built on a commercial-scale power station. The process is already up and running in 12 industrial installations like fertiliser factories and natural gas processing plants. Also, for some time the oil and gas industry has been injecting flue gas into old oil and gas seams to push out the last drops of fuel. But power stations are the big daddies. They are the single largest source of greenhouse gases, accounting for 26 per cent of our emissions.
Later this year, Kemper County power station in Mississippi will become the second CCS power station. It is a coal gasification plant, so will test CCS on a different energy source. And last week the UK announced funding to draw up detailed plans for full-scale CCS at the Peterhead power plant. That is a significant move: Peterhead is gas-fired and, while coal remains a major source of power in China, Europe and the US have been switching to gas.
“The success [of these projects] is very important for the future of CCS,”.
A key question is whether there is enough room underground to safely store all that CO2. “Curbing CO2 emissions worldwide is a daunting task,” . We pump out 30 billion tonnes each year, which amounts to 60 billion cubic metres of compressed CO2 under the typical conditions in Earth’s crust . “That’s more than 10 times the volume of oil that is transported around the globe on a daily basis. Of course we don’t expect that one single technology will take our emissions to zero, but this gives a sense of the scale of the problem.”
CCS is only a bridge technology. It could buy time to make the switch from fossil fuels to renewables. The question is, “how long is that bridge”, and will it be enough?
They studied 11 US saline aquifers, geological formations that could store CO2, and calculated that they could hold 100 years’ worth of US emissions (PNAS, doi.org/rqs). The North Sea is said to have room for 100 years of European emissions.
The big hurdle for CCS is money. Adding chemical scrubbers to a power station uses about 20 per cent of its power output. Power companies are unlikely to pay that hefty cost without incentives.
For now the cost of electricity from a CCS power plant is higher than normal fossil fuels but close to wind energy . The most pricey bit is reheating the solvent to release captured CO2. Researchers are now looking into scrubbing reactions that use less energy. If that works, power plants could use residual heat alone to drive the reaction.
That is still in the R&D phase, with tangible results 10 to 15 years away. But a similar technology – scrubbing sulphur dioxide pollution from power station emissions – was once dismissed as impossibly expensive, but now runs on most power stations for little extra cost.
We need to do more than CCS to save ourselves from climate change. But how many technologies can vanish gigatonnes of CO2each year? “The answer is none ” .