http://www.eurekalert.org/ pub_releases/ 2009-09/ miot-mgl090209.php

It appears that the continental shelves are going to start evolving massive amounts of methane, and that this methane will erupt in plumes adding to ocean acidification, unless we drill down through the gas hydrate deposits and harvest the methane, for power generation and deep injection of the CO2. So we’re going to have massive amounts of methane to deal with, and more than enough energy from these methane releases to power your Saharan forest scheme, I think.

Sorry about the delay in replying, got busy on the job.

I think your scheme is worth a shot.

There aren’t that many ways of “putting the genie back in the bottle” and we shouldn’t neglect this one.

I think you should consider ways of making the carbon storage as permanent as possible. Then, if the worst case scenario occurs, you have still managed to take a lot of carbon out of the system.

I’ve been thinking about a high carbon concrete aggregate, for example, that takes charcoal, and ruins it forever for use as a fuel by adding a geopolymer to it. This results in a hard rock-like substance that is suitable for concrete aggregate, but not suitable as a fuel, and that will hopefully have the long term stability necessary. Difficulties include locating a sufficient source of alkali to create the geopolymer.

I think your scheme is worth trying, especially if coupled with methane hydrate remediation and power generation, from the continental shelves around north Africa, and in-situ mineral carbonation of the resulting CO2 in basalt deposits off the north African coasts.

Nobody can predict the future, and we don’t have that many opportunities to win the whole ball game.

Maybe you all should look at fire resistant species. Eucalyptus supposedly use fire as a weapon against other species, and are some of the top biomass producing species – and might be a bad idea for Saharan forests.

Thank you for your ideas and efforts, and all of your hard work.

Good luck on your scheme.

The bio-sequestration projected for the Sahara and Outback forests is about 8 GtC/yr – ‘forever’ – if eco-neutral conservation harvest is practiced as the forests mature. That, by itself, would almost stop AGW ‘cold’! So with added conservation practices that pay for themselves, “severe global warming scenarios” could be permanently avoided.

These would be irrigated tropical forests, in the Sahara, though.

If the carbon was deep injected as CO2, though, especially if it was deep injected off the African coasts into basalt strata for in situ mineral carbonation, it would be stable. And any carbon stored would be carbon taken out of the climate system, and would tend to help stabilize the climate system.

Perhaps Len’s plan makes sense only if the carbon is stored in a stable form, by deep injection or mineral carbonation, and is more likely to succeed in the near term, with long term feasibility depending on climate change itself, how rapid and severe it becomes? So maybe we have a window of opportunity for Saharan forests, which is rapidly closing?

Maybe instead of growing trees where they grow naturally, we should grow trees where the models predict they will be capable of growing under severe global warming scenarios.

I would have said that was in the Canada and Siberia, until the bark beetle infestation. Once again, the Mississippi/Ohio basin might be a good place to put biomass plantations, and the Amazon Basin, which also looks to have potential hydrate deposits close to the coast of South America. The diversity of the Amazon flora might make it resistant to insect infestations.

In the short term, we need to concentrate on harvesting the beetle killed trees, IMO, and get as much carbon from these trees as possible underground, in converted, carbon negative coal fired power plants.

http://walrus.wr.usgs.gov/globalhydrate/poster.pdf

There appear to be some deposits of methane hydrate off the coast of Africa.

If these are substantial deposits, and they start to dissociate, they could provide more than enough methane to power Len’s Sahara project, I think.

Combining hydrate remediation with carbon sequestration in Saharan forests seems like a good, synergistic idea, which would simultaneously help limit ocean acidification, limit methane release to the atmosphere, and help store carbon in the forests.

The CO2 resulting from burning the hydrate methane should be deep injected, probably, into porous basalt strata below the ocean floor for in situ mineral carbonation. The electricity generated from burning the hydrates could be used to power the desalination units and pumps for groundwater to get the forests started.

Perhaps a lot of the resulting carbon, from the trees, could be turned into biochar and used as a soil amendment, to help build soil fertility.

Incidentally, the GCM simulations in our paper shows that the rainfall over the Sahel is also usefully increased by irrigating the Sahara forest – as a free bonus;-)

If you are going to do that, go the whole hog: use some of the land to grow algae to make biomethane to compete in the world-wide natural gas market. Some of the biomethane could be used locally for the RO and pumping via combined cycle gas turbines.

In support of such policy, rigorous accounting rules will need to be developed that measure the impacts of biofuels on the efficiency of the global food system, greenhouse-gas emissions, soil fertility, water and air quality, and biodiversity. Accounting rules should consider the full life cycle of biofuels production, transformation, and combustion.

But hopefully the accounting rules and environmental permitting process will not be so stringent that it blocks beneficial new development.

This is an emergency, and we might have to give up some loss of soil fertility, for example, to turn the corner on this runaway global warming problem, and “dodge the bullet” from the coming decade or two of radical, self-sustaining and accelerating climate change.

It’s important to not hold biofuels and biomass systems to an impossibly high standard of meeting multiple criteria, with new projects subject to “moving target” multiple rounds of criticism.

No such process is currently implemented for fossil fuels, for example, and this seems to be a double standard- a double standard that fossil fuel companies and those academics in fossil fuel supported programs are likely to want maintained.

Energy return on energy invested (EROEI) is explicitly treated in both papers.

In the Irrigated Sahara project, the yearly EROEI largely depends on what kind of energy source is used for pumping (desalination and water distribution) which is discussed. It ALSO goes down linearly as the amount of irrigation required diminishes as a result of induced rainfall. And the value of an ultimately ‘forever’ sustainable harvest also increases the long-term energy return VERY substantially.

In Substituting Wood for Coal, it largely depends on how far the wood must be transported (but is a small fraction of the value of the wood as fuel). But even if the wood is just safely stored (rather than burned in power plants), the cost of the net sequestration of the 1.5 to 5 GtC/yr is tiny compared to the cost of that amount of CCS from coal-burning power plants!