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Forget solar panels, it's time for rooftop slime-tanks

And offshore 'artificial tree' forests. Apparently

Rip the solar panels down, we're going to put slime-tanks up there instead

The next brilliant plan is "algae on buildings", or "the large scale introduction of algae into the built environment".

The rough plan would be to fix sealed tanks of algae known as "photobioreactors" (PBRs) to "available vertical and horizontal surfaces" - ie walls and roofs. You need a sealed unit, apparently, as it "guards against infestations" - whether of or by the algae inside isn't clear.

The PBR-clad buildings would seemingly yield a rich crop of algal biofuel as well as "biochar" which is excellent fertiliser, while extracting CO2 from the atmosphere in fine style.

Bottom line, then? Would having our cities clad in bottled scum be better or worse than covering them in solar panels? Which would cost more? Is it, in fact, the time for slime?

At this juncture, this geo-engineering solution is very much at a conceptual stage [no shit] and has attracted little if any assessment of its technical feasibility [not even from us at the engineering institution] ... implementation on a large scale is a plausible outcome.

Oh really.

Finally, the report suggests that it could be a good notion to use more reflective materials to build - or at least cover - our cities. At present, there's a known "urban heat island" issue whereby roads, buildings etc. get hot on sunny days and further heat the air above them. If they reflected heat rather than absorbing it, this effect could be lessened.

But it seems that this idea isn't actually much use in a saving-the-planet context.

It is clear that ... urban albedo modification does not produce a large enough effect to contribute significantly to balancing global warming.

However, in hot places where air conditioning gets used a lot, like Los Angeles, shiny roofs might cut cooling demand by up 60 per cent. Again, you have to wonder if there might not be some argument from people wanting to put solar panels there instead, or maybe algae PBRs. The IMechE offers no comparison of the various plans.

To sum up, then. Option one is a £60bn plan for huge fields of roadside or offshore carbon-sequestering machines which would consume colossal amounts of energy on top of what we now use. Option two is a vague suggestion that it might be nice to cover our cities in biofuel slime tanks instead of solar panels. Option three is to cover them in infrared-reflective paint instead, though this last would apparently have very little effect.

Frankly, it seems difficult to see how the IMechE's original objections to more conventional green plans - that the tech isn't ready, that the skills don't exist, that the market isn't interested - don't apply with hugely increased force to these plans.

Even by the standards of summer news-drought barrelscrape notionry reports, this is poor stuff. Those interested can read the whole report here (warning - troublesome image pdf). ®

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