The Tidal Irrigation and Electrical System

Microbes for biofuels need carbon dioxide, sunlight, water, space to grow in and fertilizers. The last of these can come from several different places. People can make fertilizer with heavy industry out of fossil fuels or they can collect animal waste or they can collect their own waste or they can pump water from deep in the ocean to the surface. It is such a shame then that The Energy Biosciences Institute (EBI) should focus soley on the potential for harvesting municipal waste in the service of growing algae for biofuels. As reported at Physorg.com on November 2, 2010 “Algae for biofuels: Moving from promise to reality, but how fast?” the EBI has looked at five conceptual facilities for algae growth, all of which use sewage as the source material for the fertiliser. In fact, the report goes on to point out that other “co-products” like animal feeds have low value and limited markets.

This is a major oversight by the EBI because of the limitations of municipal waste as source material for fertilising algae or “co-product”, as it refers to it. The first major obstacle for any open pond using municipal waste is the availability of flat ground on which to build the ponds. The EBI estimates that 1000 acres would be needed to break even economically. That is a huge area for any city to acquire. Most flat land close to big cities was long ago used for houses.  The second major obstical to using municpal waste as the source material for algae is due to its limitted potential. Despite the vastness of the world wide human populations only about half of us live in what could be described as cities and it will be a long time before any significant proportion of those people will have sewage systems capable of being converted to biofuel making.

Most importantly there are two conceptual failures of the EBI’s report best illustrated by a couple of metaphors; No animal can live on it’s own waste and you do not collect rain with a thousand cups, you collect rain by building a dam in the valley. Our waste simply is not sufficient to power our industry, no more so than any animal could live on it’s own waste and as most of our food is ultimately derived by turning fossil fuels into fertilisers or by pumping fresh water for irrigation, this means we are recouping some by turning municipal waste into feed for algae but it will not replace the ultimate source material, the fossil fuels. The rain metaphor is more to the point of looking at the nutrient cycle from a macro-scale as opposed to the micro-scale. From the point of view of the earth a single city no matter how big is still fairly small. On the big scale nutrients generally move from continental interiors down rivers to the sea or are blown to the oceans in the form of dust storms. In the oceans the nutrients sink in to the deep and there they remain until they are eventually recycled in the form of mountains built as a result of subduction. Of course, there are countless eddies in this nutrient flow where plants utilise them and these take form in the shape of a blade of grass, a sandwich, a swamp, a forests, a single cell of blue green algae, the polar oceans in spring, deep ocean water upwellings, etc., but these are merely slowing down points in the long term trend.

The largest reservoir of free nutients for plant growth on the planet are the deep oceans. The ocean below the direct influence of light is unbelievably vast and it is the perfect medium for biofuel growth. It is the closest thing there is on earth to a limitless resource. The Tidal Irrigation and Electrical System harnesses the tidal flux on the surface to pump DOW, deep ocean water, into a thermodynamic exchange in order to generate electricity and then it is held in the tidal barrage as the source material for algae growth (please see the sections on how the TIE System works on the right side of this page or http://demo.seavac.org/ for a flash based audio/visual tour of the project) This gets around the two major issues of land based ponds that are fertilised by municipal waste. Being built on the continental shelf the TIE System does not require the all too scarce flat land and the potential for scaling up to meet the huge demand is also possible.

By not paying attention to the large scale issues of the nutrient cycle the EBI has focussed on expensive and ultimately limited biofuel systems. DOW based systems are a much better bet.