These are just two of the geoengineering ideas that the Inst. of Mechanical Engineers (IMECHE) have suggested in their report on geo-engineering. Geo-engineering is the manipulation of our built environment to counter the effects of global warming, such as taking up carbon dioxide from the atmosphere artificially, and reflecting sun back into space. The highly efficient artificial trees would filter carbon dioxide and store it in underground in disused mines. They look a bit like large solar panels and are already in prototype. The report suggests that hundreds of thousands of them could be positioned along motorways and around wind farms.
Another idea is the use of bioreactors. Bioreactors contain green algae and they photosynthesise, taking carbon dioxide from the atmosphere and convert it to starch and sugar. The algae could be harvested and put to a number of uses, not least as a source of carbohydrate and protein. This idea is not new and there are a number of companies, especially in California that are pioneering bio-reactors, biofences and the like. However the engineers envisage tubes of algal being attached to the outside of buildings where they could take up carbon dioxide generated by traffic.
These and many other ideas will not solve the problem of global warming but they will reduce the rate at which the carbon dioxide levels are rising, giving us a bit more time to tackle the real issues.