Thank you for your comprehensive reply. Let me address your points one by one.
- Oil Rigs are mobile. We could move them to whichever area we desire. Currently about one-third of them are not under contract, ie they sit idle and could be put to any job.
- As ypu probably know, areas that suffer from dead zones are typically relatively shallow and stagnant (do not have a lot of current), or have special conditions like salt water and sweet water layers that prevent water mixing. A lot of the high-nutrient, low-chlorophyll areas that would benefit from iron addition, are deeper than 2000 meters (6500 feet), and have currents. As, I am sure you know (but our readers might not), algae do not consume the oxygen themselves, they produce it. The oxygen is consumed during the algal blooms because a lot of algae die, sink and decompose at once, and the decomposition uses up oxygen. Down at 2000 meters at any random spot, there isn't much life to decompose the potential sinking algae (except around thermal vents). This is why carbon sinking into the deep sea is conventionally considered "sequestered". But even if not:
- The catastrophic blooms happen because the nutrient runoff is unintended, and uncontrolled. If we dredge up the nutrients from the sea floor "by hand", we can control how much -- and what exactly -- is released into the environment. The platform could be used as a research base to study the effects in the entire water column as well as downstream. We wouldn't have to rely on asumptions or accidents: we could directly observe the results, and modify the inputs.
- I agree that we should grow more algae in a controlled environment as well. However, this will not solve the main problem: 120ppm too much of CO2 in the air -- that is also acidifying the oceans and killing life. One of the problems is scale. We had 150 years to build the infrastructure that pollutes the world. Trying to solve that by building more infrastructure is not going to happen overnight. Even open algae ponds require a lot of up-front work and constant care. Doing it on land will also require a lot of surface area -- and energy, if you want to grow algae the year over in a bioreactor. Otherwise you will be limited to 9 months a year, or to tropical areas. In Iceland this can be done with hydrothermal, but in a lot of the world, most energy still mostly comes from burning hydrocarbons: Oil, coal and gas. We will be putting more CO2 into the air trying to capture CO2.
- And finally, using algae to capture CO2 to then produce biofuel -- or better, food -- from it, is not capturing the CO2, it is simply recycling it: the results will be eaten or burned, and end up right back in the air. And of cpurse it will be exactly the same amount of CO2 (conservation of mass and energy). To really capture that CO2, we would have to pump the produced hydrocarbons straight back into the oil wells -- again, using some form of energy, which will release some CO2.
Using the entire carbon cycle of Earth, and life, to capture the CO2, has the advantage that it can be done with relatively minimal input from us compared to any other solution that I have seen so far. As a bonus, having more algae in circulation will also trap the excess nitrogen and phosphorus that we have been dumping into the oceans for decades uncontrolled due to our agricultural run-offs. If they die and sink below 2000m, good, we have trapped the excess, it will hopefully mineralize there and be removed from circulation. If they don't, we can introduce salps or fish or zooplancton into the area and see how to make them thrive. They consume the microalgae, and drop the "pellets" down into the deep sea. This is just a matter of research and experimentation, which could. in my humble opinion, very well be done in-situ, not in theory, and have a lot less damaging effects than anything we are already doing to the oceans.
And of course, we will still have to stop burning the hydrocarbons. What I am proposing is not a replacement strategy, this is a mitigation strategy. But at least the snail pace at which we are implementing the CO2 control measures right now won't threaten our collective survival.
