ImechE report on Geo-Engineering

Many people are now talking about Geo-engineering - interventions which can control the planet's climate. This is a controversial topic because they present many risks and challenges of their own, but many top climate scientists (and others) now feel we need to consider such options seriously.

The Institute of Mechanical Engineers recommends a strategy for removing CO2 using ‘artificial trees’, rooftop algae-growing tubes, and reflective roofs. These are not as a replacement for lower emissions but to buy us time since relevant technologies (like large-scale renewables-based electrification) will take some time to develop. Their ‘front runner’ is 5 million ‘artificial trees’ that filter CO2 out of the atmosphere for storage..But they also recomment rooftop algae-growing tubes that extract CO2 by photosynthesis and are subsequently burnt for energy (similar/better than coal, wood etc). Because this creates Biochar as a by product (valuable for soil fertility) it has the net effect of locking useful amounts of carbon away long-term, as well as reducing fossil fuel demand. The rooftop reflectors work to reduce the ‘heat island’ effect of buildings (especially grouped in cities like LA or London) – rather than warming the planet, this energy reflects back off into space. They also cut air-conditioning use in warmer weather/climates. ImechE feels other approaches like space-based reflectors, seeding clouds ocean algae etc, would have higher capital cost and less predictable/controllable effects.