Ron (cc Greg, list),
Perhaps biochar is another C-separation process for biochar Ocean Macroalgal Afforestation (as opposed to anaerobic digestion OMA). There may be more processes.
Any process which separates the energy (carbon & hydrogen) from the plant nutrients (organic nitrogen, phosphorous, iron, and others) and then recycles them to grow more macroalgae (while selling the renewable energy) can be sustained over sufficiently large earth surface area. Microbial digestion is the most common process in nature.
I haven't gotten into ocean albedo effects when converting large ocean areas from nutrient deserts to macroalgal forests.
---------- Original Message --------
Subject: Re: Oceans? RE: [geo] Natural land air capture nutrient
limited
From: rongretlar...@comcast.net
Date: Wed, October 03, 2012 4:59 pm
To: markcap...@podenergy.org
Cc: r...@llnl.gov, geoengineering <geoengineering@googlegroups.com>
--Mark (cc Greg, list)
See insert responses below.
From: markcap...@podenergy.org
To: rongretlar...@comcast.net
Cc: r...@llnl.gov, "geoengineering" <geoengineering@googlegroups.com>
Sent: Wednesday, October 3, 2012 5:59:17 AM
Subject: RE: Oceans? RE: [geo] Natural land air capture nutrient limited
Ron,How perfect is the nutrient recycling when you convert macroalgae to charcol?[RWL: A good question that I am not qualified to answer.
One thought is that it seems the present ocean has considerable excess nitrogen and phosphorus, and that land-based agriculture and forestry need these in large amounts. So, to the extent that conversion of the macroalgae is to char which ends up on land, recycling these two excess nutrients out of the ocean - would seem to be entirely desirable.
A second train of thought going around the biochar community is that coupling char with appropriate sea-salts will add to biochar's value. I can conceive, but this needs checking, that char from ocean-based macroalgae would find favor among biochar users because of a larger amount of many micronutrients.Is there any energy left over after you lift the macroalgae (and some water) out of the water and remove all the water from the macroalgae in order to make char?
[RWL: Again, I do not claim to be expert on this. But I have seen the concept of macroalgae being used for conversion to biofuels since the mid-'70s. Indeed in one major 100% RE study from that period (MITRE or SRI?) most of the world fuel liquid market was projected to come from macroalgae. Sure, micanthus, sugar cane, etc are "woodier", but the main issue is the photosynthetic carbon productivity (kg C/sqm-yr). In my experience, pyrolysis can handle anything that biogas can. I think the Cool Planet pyrolysis approach gives a larger total of valuable C product - as there is little CO2 production.
I hope we can hear from anyone thinking the idea of macroalgae cannot be both a major energy and sequestration option.
Ron]Mark-------- Original Message --------
Subject: Re: Oceans? RE: [geo] Natural land air capture nutrient
limited
From: rongretlar...@comcast.net
Date: Tue, October 02, 2012 9:32 pm
To: markcap...@podenergy.org
Cc: r...@llnl.gov, geoengineering <geoengineering@googlegroups.com>
Mark, Greg, List
I like your idea and will start looking up the macroalgae citations found at your site.
But I suggest (as did Greg Rau) that you investigate the biochar alternative to your proposed conversion through biogas. I see three main benefits to biochar over your CCS option as it impacts the Carbon Dioxide Removal portion of this list. First is that liquifying and deep-sequestering the accompanying CO2 seems unlikely to be ready soon - and will always be pretty expensive (especially at small scale). More importantly, char obtained from pyrolyzing your macroalgae will provide out-year benefits from up to millenia. Lastly, natural gas transport to the mainland seems likely to involve considerable expense - more so than moving a solid or liquid.
Your possible project in Fiji could have a valuable char side immediately, while a BECCS approach seems likely to be many years away - so you will be foregoing the promising sequestration potential of ocean biomass that Greg is looking for.
A good place to see the current status of pyrolysis and biochar at what seems to be the leading commercial biochar (and biofuel?) entity is only 20 miles east of you. Look at (I have no connection):
www.coolplanetbiofuels.com
Ron
From: markcap...@podenergy.org
To: r...@llnl.gov, "geoengineering" <geoengineering@googlegroups.com>
Sent: Tuesday, October 2, 2012 7:05:42 PM
Subject: Oceans? RE: [geo] Natural land air capture nutrient limited
Greg,Another solution is rapid nutrient recycling, as happens in the Ocean Afforestation ecosystem.Deploying the Ocean Afforestation ecosystem over 4% of the world's ocean surface would imply cycling about 16 times the global artificial nitrogen plant fertilizer production. The recycle will happen over distances of a few kilometers and time scales of a few months. The ecosystem would also be cycling proportional masses of all the other nutrients needed to grow macroalgae.Perhaps more important than nutrients, land plants are limited by fresh water and the timing of fresh water (no good to rain in August if the corn kernel silks lacked water to deploy July).---------- Original Message --------
Subject: [geo] Natural land air capture nutrient limited
From: "Rau, Greg" <r...@llnl.gov>
Date: Tue, October 02, 2012 10:53 am
To: geoengineering <geoengineering@googlegroups.com>
--Possible solutions:fertilizegenetically select/modifyreduce CO2 recycling (CROPS, Biochar)all of the above.GregNature | NewsEarth’s carbon sink downsized
Abundance of soil nutrients a limiting factor in plants’ ability to soak up carbon dioxide.01 October 2012Plants need enriched soil to make use of increasing carbon dioxide.As carbon dioxide levels in the atmosphere continue to climb, most climate models project that the world’s oceans and trees will keep soaking up more than half of the extra CO2. But researchers report this week that the capacity for land plants to absorb more CO2 will be much lower than previously thought, owing to limitations in soil nutrients1.Because plants take up CO2 during photosynthesis, it has long been assumed that they will provide a large carbon ‘sink’ to help offset increases in atmospheric CO2 caused by the burning of fossil fuels. Some scientists have argued that the increase might even be good for plants, which would presumably grow faster and mop up even more CO2. Climate models estimate that the world’s oceans have absorbed about 30% of the CO2 that humans have released in the past 150 years and that land plants have gulped another 30%.But the latest study, by ecologists Peter Reich and Sarah Hobbie at the University of Minnesota in St Paul, suggests that estimates of how much CO2 land plants can use are far too optimistic. Plants also need soil nutrients, such as nitrogen and phosphorus, to grow. But few studies have tested whether soils contain enough of these nutrients to fuel growth in proportion to rising CO2.“This work addresses a question that’s been out there for decades,” says Bruce Hungate, an ecosystem scientist at Northern Arizona University in Flagstaff. "It's a hard question to answer, because it takes a long time to see how ecosystem carbon and nitrogen cycles change."Long-term growth
In a 13-year field experiment on 296 open-air plots, the researchers grew perennial grassland species under ambient and elevated concentrations of both atmospheric CO2 and soil nitrogen.“Rather than building a time machine and comparing how ecosystems behave in 2070 — which is hard to do — we basically create the atmosphere of 2070 above our plots,” says Reich.Reich and Hobbie found that from 2001 to 2010, grasses growing under heightened CO2 levels grew only half as much in untreated as in enriched nitrogen soils.Researchers do not have a firm grasp on the complexities of nitrogen and carbon cycle interactions, so “the vast majority of models do not adequately reflect nutrient limitation”, says Adrien Finzi, a biogeochemist at Boston University in Massachusetts. “The real strength in this study is that now we have this 13-year record of a single ecosystem. It provides a really strong case for the claim that soil resources and nitrogen limitation in particular can impose a major constraint on carbon storage in terrestrial ecosystems.”A study published in March modelled nutrient cycling across the globe to predict how much carbon plants could sequester over the next 100 years when nutrient limitations are taken into account2. Those simulations, which included nitrogen limitations in northern hemisphere soils and phosphorus limitations in the tropics, predicted that land plants will absorb 23% less carbon than is projected by other models.Researchers say that much more work is needed to understand how nutrient dynamics will affect carbon uptake — particularly in forest ecosystems, which are expected to be important carbon sinks. Often, says Hungate, these ecosystems seem to offer a “partial, natural, easy solution” to the climate problem. “But it turns out that in reality, ecosystems are complex and only have limited flexibility.”Naturedoi:10.1038/nature.2012.11503References
1. Reich, P. B. & Hobbie, S. E. Nature Climate Change advance online publication, http://dx.doi.org/10.1038/nclimate1694 (2012).2. Goll, D. S. et al. Biogeosciences 9, 3547–3569 (2012).
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