Ron You're possibly mixing up a perceived critique of biochar with my response to the dark algae system under discussion.
Biochar is practical at small scale where the fuel assets are stranded, eg on-farm systems with low density fuels far from bulk transport infrastructure. Its costs really aren't comparable with the dark algae farms under discussion. This hydrogen-based system would obviously require a hydrogen energy infrastructure. This just isn't practical until we've stopped using fossil fuels, but may one day be a useful way of dealing with waste renewable energy. As regards the speed point: releasing co2 from saline aquifer storage slowly enables biochar to pick up the carbon from the air and lay it down in soils, without shocking ecosystems. Quite why you'd bother when the co2 is sitting peacefully in a saline aquifer is beyond me. To provide perspective : The only CDR scheme I hold out much hope for is olivine beaches. The reaction energy goes the right way, and the process energy is supplied by the sea without any expensive contraptions being needed. By contrast, everything else is hideously expensive, polluting or enormously land hungry. A On 18 Sep 2014 19:48, "Ronal W. Larson" <[email protected]> wrote: > Andrew and list cc Greg and Michael > > See inserts below. > > On Sep 18, 2014, at 2:21 AM, Andrew Lockley <[email protected]> > wrote: > > All CDR schemes that reduce carbon before sequestration sacrifice the > energy available from it. > > *[RWL1: I will restrict my response to biochar, which I believe does not > fit the “All” of this sentence. First, biochar is receiving almost all of > its intellectual progress now for soil, not sequestration, reasons. There > is no conflict between these; improving soil comes at no expense > to sequestration. Yes one can get more energy output from biomass > combustion than pyrolysis - but only if you stop the analysis in the first > year. Reports of increased bacteria and fungus as well as increased above > ground productivity fill biochar technical papers these days (a rate of > about one per day). My guess is that pyrolysis beats combustion (BECCS) > within 2-4 years based on both sequestration and energy terms. > Unfortunately, I know of no CDR comparison that has included these > out-year benefits. Biochar will always lose in both energy and > sequestration comparisons if soil improvement issues are ignored.* > > While we still burn carbon fuels this doesn’t make sense, as you have to > input energy to reduce the carbon (unless you use photosynthesis) , > > *[RWL2: Biochar always uses photosynthesis - and of course the free > nature of solar energy is the key to biochar’s favorable economics.* > > and sacrifice the energy available from oxidizing the resulting fuel, as > well as lose all the process costs and energy involved in incidental > materials handling and preparation. > > *[RWL3: Yes, one can make char and ignore the roughly half of the > available energy. And that is happening right now. But it is not with > those conversion approaches seen as most promising (see www.coolplanet.org > <http://www.coolplanet.org> for a liquid fuel example with plentiful > funding and exuberance about the char - the part that provides carbon > negativity.) Better yet is that BECCS economics assumes huge facilities > that do not allow combined heat and power. And BECCS seems likely to > follow CCS with coal, not precede or accompany it. And the requisite > geology is not everywhere, while soil problems are.* > * Process and energy costs (even transportation costs) have not appeared > large in the LCAs I have read. Biomass energy density is as good as many > coals (because of lower ash content) - about 18 GJ/tonne.* > > Sequestration of oxidized carbon is fundamentally more efficient. > > *[RWL4: Not understood. BECCS takes a 30-40% hit over combustion - same > as why we are seeing reluctance to CCS. When viewed over 30 or 100 year > time period, biochar comes out way on top. Proof is in today/s land > productivity (factor of 3-4 X) of the terra preta soils of the Amazon - > untouched for 500 + years.* > > If we really want to reduce it, releasing it from storage slowly whilst > creating biochar slowly would seem a more sensible approach than the > suggested scheme, and doesn’t require a large technological infrastructure. > > *[RWL5: Also not understood; does “it from storage” refer to stored > biomass or stored CO2? I presume “suggested scheme” is that of Michael > Hayes; please clarify. Doing anything slowly sounds like a sure way to > increase costs.* > * The technological infrastructure is tiny for all forms of biochar > production I have seen proposed - including Michael’s. Even the Cool > Planet refineries are tiny - and projected to have lower drop-in fuel costs > than those starting with fossil fuels. Villages of a few thousand people > are projected to be enough with transportation distance under 20-25 km > (much larger for BECCS). So virtually every square meter of earth is > available to provide both inputs and receive inputs from any biochar > operation. There are economies of mass production as well as of size in > the sequestration business. You are assuming something about biochar > operation size I have never seen in print.* > > *Ron* > > A > On 18 Sep 2014 03:54, "Ronal W. Larson" <[email protected]> wrote: > >> List cc Greg and Michael: >> >> 1. This note relates to Michael’s submission (geoengineering category) >> to MIT at >> http://climatecolab.org/plans/-/plans/contestId/1300209/planId/3710 . I >> just >> > > <snip as not being pertinent to Andrew’s comments, except for my > mentioning biochar a few times.> > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. 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