There is, however, a whole different set of problems created by having an excess of CO2 in the air. This is about how the atmosphere and the oceans interact to create carbolic acid and is known as ocean acidification. I blogged about it here. The long and the short of it is that as the ocean becomes more acidic, corals and some planktons find it harder and harder to grow until they die off. As the effect increases, the whole oceanic food web breaks down. The major geologic models we have eventually resulted in extinction events, the largest of which killed off 95% of  the life in the ocean. We are a long way off of that but even a slight change can have remarkably deleterious effects on the ocean’s ability to produce food. Some of the latest horrifying figures can be found in this article, which details a report from the UN and this one about a model of surface uptake.

One biologist, Ronald Osinga, presented an interesting idea at a symposium involving the growing of sea lettuce (ulva lactuca) to combat the acidification of the ocean.  Roelof Kleis wrote an article about the symposium which was held at Wageningen, the Netherlands by the International Society for Reef Studies (ISRS). It had an emphasis on climate change and the deleterious effects it will have on coral reefs. Presented on the last day, Osinga pointed out the pollution caused by current fish farming techniques could be utilised to grow sea weeds for human consumption or for food for fish.

Osinga and his colleagues have calculated that a ‘marine garden’ of 180,000 square kilometres could provide enough protein for the entire world population. A sea lettuce bed of such gigantic proportions would raise the pH (acidity level) of the Mediterranean Sea by one tenth. That may not seem much, but according to Osinga, it would be enough to compensate for the rise in acidity that started with the industrial revolution.

My criticism of the scheme is that it fails to account for the eventual nutrient loss if either the fish or the sea lettuce are taken from the system for consumption by humans. This aside, the proposal does have huge implications for the Tidal Irrigation and Electrical System (TIE System), the subject of this blog. One of the key components of a TIE System is its ability to deliver the nutrients necessary to a lagoon isolated from the surrounding ocean, in order to create a sustainable aquaculture. It does this while producing electrical power.

The TIE System is driven by tidal action and so it is difficult to estimate the amount of power generated by Osinga’s 180,000 square kilometre figure. But, if there was a tidal swing average of 2.33 meters and each TIE System had a diameter of 20 kilometres, the 573 aqua farms should produce about 36.3 TeraWatt Hours every flux. This is on top of producing the sea weeds necessary to change the pH of the oceans to offset the consequences of fossil fuel use AND feed the whole population of the world.

It is worth noting that 36.3 TeraWatt hours per flux is about 23,849 TeraWatt hours per year. In 2007 world consumption of electricity was 17,109.7 TeraWatt hours. The economic and societal imperative to develop the Tidal Irrigation and Electrical System seems to become increasingly evident as time passes.

As to the specifics of how the report dealt with the Tidal Irrigation and Electrical System; to put it simply it didn’t. It generalized all systems which utilize deep ocean water (DOW) into one broad category and in that category they only looked at the potential to transport CO2 from the atmosphere to the seabed. This is a great shame because systems which exploit DOW produce power and biomass on large scales. The Tidal Irrigation and Electrical System is the first renewable energy system which has proposed trying to capture the biomass component of the OTEC process. The utilization of these biomass resources can lead to less fossil fuel use and this is because they go into everything from fertilizer to food to plastic to the lights in our city’s and the fuel in our cars. However, this does mean that the biomass generated is not being stored on the sea floor so by the logic of the report it did not do much to offset climate change in that manner.

One idea that the Royal Society is interested in that this author feels desereves special derision is that of “artificial trees”. In proposal, these man made structures would litter our planet by the million. Their sole job is that of absorbing CO2 from the air. They produce nothing and rely on energy intensive processes in their construction and in either the storing of CO2 or the manufacture of the chemicals which are used to absorb the gas. The same problems that face other mechanical or chemical storage methods for capturing atmospheric carbon such as the ones that are proposed for coal burning power stations. A further criticism of artificial trees is that there is only a small economy of scale in the in industrial processes which underpin the concept. None of the designs become more efficient as they grow in scale. It does make this author wonder if it wouldn’t be better to build wind turbines in everyplace they are thinking of constructing one of these things. That might mean that the carbon emitted by the burning of fossil fuels was never released into the atmosphere in the first place.

It says in the press release that it was achieved by “microfabricating” the stack structure. These processes are notoriously difficult to “scale up”. There is little detail as to the cost of manufacture so we shall see. The Fuel Cells site has lots to say about methanol in fuel cells.

Methanol is a potential product of the Tidal Irrigation and Electrical System’s biomass. (see Algae/Marine Plants)