A few weeks ago I attended an excellent seminar at work given by a Professor from Cranfield University about the future for marine renewable energy in the UK. A key point that he made was that because there is a time lag between us humans putting “Greenhouse gases” such as carbon dioxide (CO2) into the atmosphere and the effects of these gases showing up in the global climate change signal we need to be thinking not about carbon neutral technologies (which don’t add CO2 to the atmosphere) but rather what we actually need are carbon negative technologies that actively reduce the concentration of CO2 in the atmosphere.
A recent article in New Scientist (“Clearing the Air” – Issue 2690: 10 January 2009) picks up on this point and describes attempts to develop systems for scrubbing CO2 out of the atmosphere. Currently, a number of prototype CO2 scrubbing devices have been developed and although the challenge is great, the prospects for producing larger and more efficient versions seem to be encouraging. I found it interesting to read that CO2 is a commodity that some parts of industry pay good money for (e.g oil companies use CO2 to flush out old oil-fields and fruit and vegetable growers use CO2 to enrich the air in greenhouses) – apparently CO2 can cost as much as $300 per tonne.
However, it occurs to me that nature does already possess an excellent piece of technology for removing CO2 from the atmosphere – namely the tree. So, perhaps what we need to do is to plant a lot more trees (and, of course, stop chopping down those that already exist). A diagram that accompanies an article in this week’s New Scientist (“Hacking the planet: The only climate solution left” – Issue 2697: 28 February 2009) seems to back this idea up. It shows various different methods of geoengineering that might help to cool the Earth, ranging from placing mirrors in space, growing reflective crops, seeding clouds and fertilising the oceans with iron. Each method is given a pair of ratings to show when the technology might be ready to make a difference and what the technology will cost and guess what, “Foresting” is, arguably, the best bet, having low cost and a relatively fast timescale (“within decades”) with the only drawback being the amount of land area needed. Still, there’s lots of unused land around the place, so why don’t we all get planting. It might not have an instant and dramatic effect but as long as we don’t use lots of energy maintaining the resulting trees it would be a step in the right direction.
Tim O'Hare 