Wesley Bruce writes,
The Sargasso appears to be light and grazing limited.
I have seen that claim, and the data for it is weak. Plus, but once again, this is based on the assumption of harvesting but not replenishing the bio-system after harvesting.
As you probably are aware from looking at proposals, this is the ecosystem where iron-ore dispersal has been demonstrated to do amazing things as a growth stimulant.
At the current prices of iron ore and ethanol the value increase is quite dramatic compared with having to use ammonium fertilizers. Instead of 10-1 return you get semething like 500-1. Plus subgrade mineral ores can be theoretically used as ocean fertilizer - ores that are not valuable for metal extraction.
Nutrients don't produce a bloom unless there is a nutrient shortage for some other reason.
The ideal situation is to conitnually harvest and disperse iron and other minerals in the "just-harvested" or depleted water, astern. You would need a continuous parade of tenders bringing in mineral ore and taking away ethanol.
Let's make it clear that any proposal that cannot be made sustainable over century-long time spans, should not even be considered. All of these plans should both "add" as they "substract". In the case of Sargasso seaweed, which is spanning the most solar-intensive part of the globe (and thus its high density) - the removal of biomass is like the removal of solar energy... and just might possibly serve the added ecological goal of "lowering" ocean temperatures slightly if done on a massive scale. Certainly the Sargasso removes more CO2 than any coherent ecosystem I know of and this will be boosted, not lessened, with sustainable harvesting.
All biomass projects must recover all non atmospheric nutrients and return them to the soil. Otherwise they will not be sustainable.
Couldn't have said it better... except here we are returning nutrients to an ocean which is functioning as soil. And ,as for the carbohydrates in seaweed not being the optimum makeup for ethanol, that is probably just a matter of genetically modifying the fermentation bacteria - which is a technology that we seem to have mastered pretty well.
Jones
