Turn over a new leaf for using CO2
Carbon dioxide is bad. That’s the common thread in public discourse. We’re constantly told of the need to reduce the amount of CO2 in the atmosphere and that it’s destroying the planet.
Of course the reality is that carbon dioxide is a key part of the natural cycle of energy and vital to the survival of all life on this planet. It also has a wide range of commercial uses. So should we see CO2 as more of a resource than a problem?
Our supplies of the gas are set to increase massively as carbon-capture power plants become a reality, and scientists and industry are increasingly looking for new ways to use and hopefully monetise it.
Carbon dioxide is already used in food preparation and preservation, in drug and chemical processing, in water treatment, welding and pneumatics. None of these applications will soak up all the CO2 we’re going to produce in the next fifty years, though at least CCS power stations could become more cost-effective if they sell the gas on.
But what if we could develop a use for carbon dioxides that actually helped the climate change cause and made a big impact on greenhouse gas emissions?
Injecting CO2 into oil wells as they dry up keeps it out of the atmosphere but also helps get more oil out, meaning we have more fossil fuels to burn and even more CO2 to deal with.
A different idea, as highlighted in our recent feature, is to mineralise CO2 to create products for use in the construction and food industries. If we can make it economical and energy efficient, we could even take the waste materials of existing cement-making processes – ash and carbon dioxide – and combine them to make a stronger form of cement.
Nature, as so often is the case, could also provide a solution – photosynthesis. It gives plants their own wonderful use for CO2, but unless we literally go back to living in forests by covering the whole world in trees, there’s really only so much they can do for us.
Instead, some scientists are hoping to deliver an artificial version of photosynthesis that effectively turns carbon dioxide into an energy storage medium. If we can efficiently use sunlight to power the reaction, we can transform the pesky gas (and water) into usable fuels.
Of course, we are already turning plants into fuel with serious consequences for food prices. Around 40 per cent of corn grown in the US is now used to make ethanol instead of feeding humans and animals, according to the Department of Agriculture.
Photosynthesising algae could provide one alternative to this. Another idea is to do the energy conversion ourselves. Scientists at MIT have already developed a ‘practical artificial leaf’ that uses solar energy and inexpensive catalysts to produce hydrogen from water with efficiencies much greater than those of real leaves.
Find a way of efficiently adding carbon dioxide to this artificial process and we could create biofuels to use in our existing fuel infrastructure without the need to rely on growing plants (and impacting food production).
Though all these ideas are still at the laboratory stage, the business world is taking notice. Spanish research institute MATGAS, which is majority-owned by industrial gas company Air Products, is coming to the end of a €26m project examining these very ideas.
Speaking this week at MATGAS’s tenth anniversary conference, institute director Dr Lourdes Vega said the challenge was now to move the concepts to market and the biggest areas of potential were increased use of water pH treatment, new materials and bio-energy.
Alongside the technology issue, however, cost remains a major problem. Some fear that without a global carbon pricing system or a major rise in oil prices, using CO2 to produce fuels won’t be economically attractive for most companies.
Vega admitted that the size of the market for carbon dioxide still wasn’t clear, and that industrial uses wouldn’t provide an alternative to reducing emissions or storing them in large quantities.
‘The amount of CO2 emitted two to three years ago was 25 gigatonnes and the amount used for all industrial applications was 125 megatonnes,’ she said.
‘But there is room for everything. If you use different sources of energy you will have less CO2 in the atmosphere. If you find ways to use CO2 you are converting a residue into a resource with added value.’