Clean and green: A Californian kelp forest.
Credit: iStockphoto
We have calculated that less than three per cent of the world's oceans — that's about 20 per cent of the land area currently used in agriculture — would be needed to fully substitute for fossil fuels. A small fraction of that sea area would be enough to fully substitute for biofuel production on land.
As with land-produced biofuels, the contribution to carbon dioxide reduction would come from cutting net carbon dioxide additions via equivalent decreases in fossil fuel combustion. This happens because biofuels — fuels derived from recent photosynthesis — are basically carbon neutral because all carbon released by burning has recently been taken from the atmosphere.
In contrast, fossil fuels come from ancient photosynthesis, thus the carbon released by burning had been stored for ages and thus represents a net addition into the atmosphere.
Wastewater solution
The main input needed for the large-scale farming this would require is nutrients, because large quantities of them will be removed at harvest. Common agricultural fertilisation — costly and energy consuming — could add large amounts of nutrients to the oceans, with unknown results.
But there is a great and grossly misused nutritional source on hand: domestic wastewaters or the product after their treatment.
Growing large seaweed fields for energy using nutrients from wastewater could be an economically-sound use for the millions of tonnes of untreated wastewater dumped daily into our seas worldwide, and the seaweed helps clean it up in the process.
This idea has been tested successfully using human wastewater in experiments at U.S. institutions, including the Woods Hole Oceanographic Institution and the Harbour Branch Oceanographic Institution.
As with agriculture, considering that seaweed production is economical for food and other products, it follows that at least some of the options should also be economical for biofuels and bioenergy. However, the analogy with agriculture does not stop there, and a careless farming of the seas could be as damaging as careless agriculture.
But the greatest spin-off from switching biofuels production to the oceans would be the return of land to food production, making food and nutrition more easily available to the world's poor.
Ricardo Radulovich is director of the Sea Gardens Project at the University of Costa Rica in San Pedro. The project is funded by the World Bank.
This opinion piece was originally published on SciDev.net
Is voting on this kind of question relevant?
Any idea for alternative energy should be evaluated based on its technical and economic feasibility as well as its benefits for the environment. As in the case of ethanol, and of wind and solar power, too much weight is given to the misperceptions of laymen.
misperceptions
And the willful misperceptions of scientists...
i see no reason to vote on this
i agree, there is absolutely no reason for this to be a vote. the idea should be taken up on its merits not the marketing power of Cosmos.