First article
Second articleThe Big gun
David Keith believes strong arm strategies could soon be our last resort for reversing record levels of carbon in the atmosphere.
In the 1992 film Unforgiven, Clint Eastwood slowly and methodically avoids violet confrontation with the bad guys before finally turning things around with a bloody burst of gunslinging. That's something like the approach of Canadian physicist and environmental scientist David Keith. Except that his villain is climate change, and while he's still doing everything he can to avoid a fight, Keith is also stockpiling ammo.
Keith, a professor at Calgary University in Canada, runs a start up company, Carbon Engineering, that is developing commercial scale devices to capture atmospheric carbon dioxide. That's the slow and methodical. "But if we can't control atmospheric CO2 well enough, then we might want to do the solar stuff." That's the gunfight.
For several years now Keith who has served as a member of Canada's blue ribbon panel on sustainable energy technology, has been the leading voice in the call for serious research into geoengineered schemes for cooling the planet. The most common example would be to scatter sulphates in the stratogsphere to reflect sunlight away from the planet. The cooling would be immediate and global. We know this because it happened before. When Mt. Pinatubo erupted in the Philippines in 1991, the resulting plume of sulphuric ash cooled the planet by about 0.5 celsius for a year. Should we find ourselves faced with an immediate environmental emergency - a shifting Gulf Stream or an impending collapse of the Arctic ice sheets - effective "sunlight mediation" could be a quick retreat from the edge.
The immediate problems with this, however are twofold. First, there's an obvious moral hurdle. Most people reflexively reject notions of geoengineering for fear that they may cause more harm than good, and undermine efforts to reduce carbon emissions. The other drawback is that the method would be cheap and easy enough that even a rogue nation could pull it off, which leaves open the very real possibility of unilateral action with global consequences.
The hope is to refine geoengineering methods and develop standards, while simultaneously working toward a future in which they would never have to be used. That's where Keith's carbon sequestration technology comes in. Most carbon capture systems propose sequestering CO2 from large facilities such as power plants. Keith's plan, however, is more mobile, calling for towers that could be deployed wherever land, climate and labour costs are optimal.
These carbon suckers woudl employ fans to move air through a solution of sodium hydroxide, which absorbs the CO2. Inside, lime bonds with the CO2 to form solid calcium carbonate. The reaction releases the sodium hydroxide for reuse in the first step, while the CO2 could be stored in underground reservoirs that once housed oil and gas to be recycled into petrol [see next article I post].
Keith has proven this process with a test tower 6 metres tall and 1.2 metres wide that can capture 19 tonnes of CO2 per square metre annually, using less than 100 kilowatt-hours of electricity per tonne. HIs company expects to spend about US#5 million over the next three years refining the technology and investigating how best to scale it up. The ultimate goal is for fields of towers some 90 metres long and 18 metres tall, scrubbing up to one million tonnes of carbon a year.
Thoughts?The carbon slayer
Jeffrey Martin's closed loop plan for recycling heat trapping carbon emissions into petrol
Into the category of things that sound too good to be true, add Green Freedom. If the scientists behind this US government funded proposal are correct, we'll be able to continue travelling in petrol powered cars and aircraft indefinitely, in a closed, net zero emissions system that won't contribute to global warming. Green Freedom proposes a netowrk of nuclear power plants that capture carbon dioxide from the atmosphere and chemically convert it into petrol, all with existing technologies. "We're not taking anything out of the ground, not using fossil fuel to create fuel," explains F. Jeffrey Martin, the nuclear scientist behind the proposal. "The whole thing is carbon-neutral." By that, Martin means that the system releases only as much carbon as it captures. Since mobile sources, such as vehicles and planes, account for half of all carbon emissions, his recycling program, could reduce the strain on the environment and allow sequestration technologies to start cleaning up the atmosphere instead of just slowing the rate at which we damage it.
The catch? Collecting and processing enough CO2 to fuel the US alone would require building 500 new nuclear power plants, each with the ability to produce 2.7 million litres of petrol. Today the US has around 104 nuclear plants, the most recent ones built more than 30 years ago; and they would need to be retrofitted. The key is turning nuclear cooling towers into giant CO2 suckers. Nomrally, the towers inhale air to cool hot water from the reactors. With Green Freedom, they woudl pass the air over a solution of potassium carbonate added to the cooling liquid. "Potassium carbonate is like a vacuum for CO2," Martin explains. To extract the CO2 for recycling, he proposes an energy efficient electrochemical process that produces only hydrogen as a by product.
With additional funds secured from the US government, Green Freedom has plnas to build a demonstration facility at a nuclear power plant set for construction in West Texas. If all goes as planned, the plant will begin producing power and petrol in 2018, serving as a model for all to follow.