An interesting question

[Andrew Lockley]

If energy was free, what could we do with geoengineering?  It may seem a daft question, but bearing in mind that fusion power is only 40 years away (and always will be) then it is worth considering.

My understanding is that Lackner's 'fake plastic trees' are energy-hungry, and fusion could make them a lot more attractive.  (Perhaps an alternative technology could be used to remove dissolved C02 from the sea.)

However, there is a potentially serious problem with this.  What if we emit such large volumes of secondary GHGs (eg methane) that we need to reduce CO2 below natural levels to control temperature?  If we take CO2 too low, plants will not grow and we'll all starve.  Wildfires would then act to balance CO2 levels.

Previously, I've outlined my ideas for tackling methane to this list, but what if none of them worked?  What would our options be? How practical would it be to 'overshoot' CO2?  We wouldn't need to worry about stability anymore, as it would be so cheap to draw down the CO2 that we could just dump it in the deep ocean and pump down a bit more when it leaks.  Leakage in an 'overshoot' world would possibly be an advantage - bringing up CO2 levels 'naturally' when the secondary GHGs had decomposed chemically or photochemically in the atmosphere.

I just thought I'd ask for comments as to the kind of geoengineering our grandchildren will be able to engage in once they have the 'Mr Fusion' machines which power the cars in 'Back to the Future', but in a world where secondary GHGs are the primary problem.

Comments please.  I think it's worth a paper on this.

A

[Ron Larson]

Andrew - cc list:

I don't mean to sound flip - and maybe you were asking for this
response: We already have the desired fusion machine: our sun.

The two reasons that Biochar can work in the big way that Peter
Read has commented on a few hours ago are 1) that the sun's energy is
already free (and really already in great abundance compared to the
global need for energy) and 2) Mother Nature has given us many millions
of years of fixing photosynthesis to be pretty good.

The fake trees in your scenario can be replaced by real trees.
We'll need more of them, but they are cheap. The right ones will also
provide food.

I believe the land can be made available. There is also the 75% of
the world's surface in oceans to use as well.

Biochar has been reported to retain methane quite efficiently.
Shifting pasture to trees will save a lot on methane.

The overshoot issue is possibly already also solved with Biochar.
Certainly the main detractor (BFW) claims it won't last in the ground.
We know from Terra Preta studies that some large (but undeterminable)
amount is still effective many millenia after its anthropogenic
placement in Amazonian soils. If we have a billion new hectares of
biomass intended for Biochar, there will be plenty of ways to put all of
its energy content to use - economically - as humans have done for
millennia. Char can also be designed for short lifetimes - and some
proponents believe it should be for better feeding the necessary
bacteria and fungi in the first year or two.

We only need to add about one percent to the world average
photosynthetic efficiency (NPP - Net Primary Productivity). Quite a few
plants already do much better than the average. I think Biologists and
Soil scientists can help almost any plant do better as well.

Ron

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[Eugene I. Gordon]

We also have the desired nuclear reactor; it is just below the Earth's
crust. Someone has called it geothermal. We have deep drilling technology
and geothermal is already being exploited near the surface. It is completely
free of carbon emissions. We also have stores of molten rock heated by
radioactivity near the surface, volcanoes, that it may be possible to
exploit more than it is.

If we don't watch out the CO2-free energy problem will be solved and we
won't need geoengineering. Great solution.

[David Keith]

Air capture does take a fair amount of energy.

 

You may be interested in my recent overview in Science (enclosed).

 

See also http://www.ucalgary.ca/~keith/AirCapture.html, paper #116 which is a longer overview of the engineering design constraints on air capture systems. We do talk about nuclear and solar driven air capture systems. In the long run, I think if air capture makes sense it will be powered by non-fossil energy.

 

Peter Read has asserted that biomass with capture is far cheaper than air capture. He may turn out to be right, but I can say that I've worked on both, and I published cost analyses on both that use the same (relatively conservative) methodologies for cost estimation. I don't think there is a clear-cut winner for large-scale implementation, particularly not when you consider the environmental impacts of biofuels.

 

One paper that compares the two is Frank S. Zeman and David W. Keith (2008). Carbon Neutral Hydrocarbons. Philosophical Transactions of the Royal Society (A), 366: 3901-3918, see #103 on the link above.

 

Yours,

David

---

[Peter Read]

The reason why the biomass route is so much lower cost than mechanical air capture depends on the common practice of discounting cash flows. 

 

If you plant trees (very low cost) then they do the CO2 capture job for a decade or so, depending on the rotation length.  When they are mature you can use them for fuel, leaving fossil fuel in the ground (zero emissions) or in a BECCS set up (negative emissions and likely just as expensive as Air Capture, but at least you get some energy out of it) or in a biochar set up (lower cost than BECCS, but less energy and C stored, though with soil improvement benefits not usually accounted for in geoengineering circles).

 

A propos having been ticked off for stating the blindingly obvious, I did not say the advanced economies should not aim to reduce emissions, obviously they should.  But whatever OECD countries can achieve by energy efficiency and over-hyped ambient energy technologies is obviously going to be outweighed by industrialization in advanced developing countries that have large reserves of coal. 

 

The world does not end at the Mexican border.

 

Peter

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[Andrew Lockley]

We will still, I suggest, need geoengineering to deal with the existing CO2 and the feedback effects - especially methane.  The challenge is how to effect a permanent solution, and I suggest that fusion + air capture is the only credible method I've seen to date.

A

2009/11/1 Eugene I. Gordon <eugg...@comcast.net>

[jim woolridge]

Andrew: whatever you do don't put your eggs in the fusion basket. Why?
Its always been empty and, as you yourself point out, always 40 years
away. We don't have 40 years...you do the math!

On Nov 4, 3:53 pm, Andrew Lockley <andrew.lock...@gmail.com> wrote:
> We will still, I suggest, need geoengineering to deal with the existing CO2
> and the feedback effects - especially methane.  The challenge is how to
> effect a permanent solution, and I suggest that fusion + air capture is the
> only credible method I've seen to date.
>
> A
>

> 2009/11/1 Eugene I. Gordon <euggor...@comcast.net>

[Veli Albert Kallio]

As per Jim's rebuke about reference to fusion energy as a solution, it is important to note:
 
I do agree that that the big 'X-factors' in the energy equations are: the fusion generators, safe and reliable fast-breeder reactors, and, clean coal projects (to start injecting CO2 into this underground rocks), these can produce massive reduction in the emissions. The problem is that they are unproven techonologies that have not yet done a dent in mainline energy production. As such they may either remain in the twilight zone (fusion energy), or, quite peripherial in volume of the overall energy production (fast breeders, clean coal). 
 
Their successful and quantitatively meaningful proportion in the world energy generation mix would be a positive "x-factor", but we cannot rely on possibilities and wishful hopes. The engineers have not yet come over hurdles to generate more energy out of fusion and after that is still the hurdle the fast breeder reactors face: system reliability and safety. I am quite aware that there is a need to develop new materials for tokamak reactors as the odd stray ions contained in the donough shape magnetic bottle strips materials into fields, this non-fusion stuff accummulates and starts to inhibit the fusion reactions within it.
In fast-breeder the problem is the sodium reactions with most of things and when system needs to be shut down the solidified metal causes problems if trying to repair or restart.
 
I should not be too judgemental on saying that we should not discuss the above positive "X-factors" if human technologies advance and replace polluting generation capacity due to new innovation and technological breakthrougs. But we cannot rely on something that does not exist. Similarly, we should exercise caution on the issue the First Nations told to the UN General Assembly that the ice sheets slid suddenly into oceans instead of melting. That negative X-factor relies on the statement and recollection of the ancient peoples who might be right as well as the might be wrong, so far their concept remains unproven.
 
These are uncertainties we cannot do anything about, except pour more money into R&D in the hope that this would resolve the issues. But as a precautionary principle, it would be best of all if we could be prepared to the point that all these +/- uncertainties would be kept within manageable limits, and that to me should be the goal of geoengineering efforts as well. As we are outside already, and probabilistically runaway events, abrupt changes, are entirely possible the efforts in all areas should continue until we are back in safe harbour and the boat will not tip over by any tall wave the nature might throw at us. 
 
With kind regards,
 
Veli Albert Kallio  
 
> Date: Wed, 4 Nov 2009 09:24:04 -0800

> Subject: [geo] Re: An interesting question

> From: jimwoo...@hotmail.com
> To: geoengi...@googlegroups.com

[Oliver Morton]

In the spirit of Andrew's question, Kim Stanley Robinson's 60 Days..
has teh neat idea of managing sea level (in an energy unconstrained
world) by pumping water onto the East Antarctic ice sheet -- and idea
that stretches back at least to a paper of Mike MacCracken's in the
early 1990s. haven't done the sums, but it mist be a many terawatt
proposition.

And there's also, in the energy unconstrained world, the 50-reverse-
Niles needed for Sahara Afforestation...

o

[Mike MacCracken]

Dear Oliver--When I first mentioned it, the idea was to derive the energy
for snow-making on Antarctic from the difference in temperature of the sea
water (so just above sea level) and the radiating temperature above ice in
the winter, so maybe -40 C (and one could, conceptually do this using
temperature below and above Arctic sea ice to run a snow-making spray to
thicken the sea ice). A key problem, however, is icing up of the
equipment--so one has to find some way to deal with this.

Mike

[Oliver Morton]

Does that give you the 3TW or so you need to pump 3x10^12 tonnes of water up 3km every year?

2009/11/5 Mike MacCracken <mmac...@comcast.net>

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Eating the Sun: How Plants Power the Planet

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