Ken, cc List 1. I like your analysis. It seems to be a new and needed analytical methodology. Unfortunately, I think many will take it to be quite discouraging about reaching carbon neutrality in the (2030?) time period proposed by Dr. Hansen, even much later. One bright spot however is that your analysis included nothing related to carbon dioxide removal (CDR) - and especially nothing on any biomass technology - and therefore also not my favorite CDR approach: Biochar.
2. Dr. Hansen seems to have used only new extensive plant growth to actually remove carbon necessary to move towards 350 ppm atmospheric CO2. I believe that when coupled with extensive field management for maximum photosynthesis, and the use of excess annual trimming growth for Biochar, with its own additional out-year productivity advantages, there is a much greater chance to achieve both carbon neutrality and carbon negativity - hopefully with a CO2 peak well before 2050. The situation can be improving each year as additional area is devoted to biomass energy and sequestratrion.. 3. So, I hope you can find a way to add biomass areas to the many RE technologies you have already included in this study (link given below). By way of emphasizing the necessity and importance of biomass in an all-RE future scenario, I recommend a Danish "Green Energy" study which found their year 2050 optimum with 40% biomass, only a little less than wind for that country. This also included both the biofuels and biopower possibilities (and especially a lot of combined heat and power (CHP), that was not in your study. That Danish study was performed by: a) www.klimakommissionen.dk where I was bounced today to b) http://www.ens.dk/en-US/policy/danish-climate-and-energy-policy/danishclimatecommission/greenenergy/Documents/green%20energy%20GB%20screen%201page%20v2.pdf On p9. there is this summary sentence on Biomass: " Biomass will play an important role in the coming energy system, not least of which in the transport sector and as a backup for wind turbines " Of course they identify that biomass is not as available as wind - but still it comes in as a major, not zero. contributor. I think it very important to consider this backup (ie biomass as energy storage) role for biomass (and hence for Biochar) c) Two other documents from different Danish sources, but similar 100% RE goals in 2050 for Denmark (with similar large amounts of biomass). http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCQQFjAA&url=http%3A%2F%2Fwww.danishenergyassociation.com%2F~%2Fmedia%2FPower_to_the_people%2FPowertothepeople_UK_low.pdf.ashx&ei=yK9CT6ucI-LkiALErNWkAQ&usg=AFQjCNGngiyr-mo1CzoW0ZYccQzZ7ZKt-w&sig2=XpKbWbd1ONZsFy7g43aheg and http://www.denmark.dk/NR/rdonlyres/2BD031EC-AD41-4564-B146-5549B273CC02/0/EnergyStrategy2050web.pdf 4. I believe (certainly can't yet prove) that if you include CDR from Biochar (but also as an energy technology) with terawatt, petajoule, and gigatonnne C per year potential, we will find that the timing situation is not as dire as your results presently indicate. Your analysis must of course include Biochar's needed much increased standing and annually increasing (not decreasing) both standing biomass and annual yields. IF we are serious about numbers like 350 ppm CO2. 5. I recognize that you have not claimed that this latest paper has covered ALL possible RE resources. Still, I fear that many readers will not recognize that the situation can be quite acceptable as we (necessarily) move to 100% RE AND achieve both carbon neutrality and negativity (with Biochar providing about equal amounts of each). 6. Slightly different final subject: I like that you have included the solar "Bootstrap" concept (section SD2). I first saw this in the 1970s with at least one US firm using the phrase "Solar Breeder". Many PV firms still display a lot of their own PV on their manufacturing facilities. Not as practical for wind, but not impossible by fiat. The new issue for me is whether we can say the same about a "Biochar-Breeder" or "Biochar-Bootstrap" process. I think we can, since in many cases we will be using the world's least productive land - made productive through Biochar. Ron ----- Original Message ----- From: "Ken Caldeira" <kcalde...@carnegie.stanford.edu> To: "geoengineering" <geoengineering@googlegroups.com> Sent: Friday, February 17, 2012 10:09:18 AM Subject: [geo] study on transitions from coal-based electricity production Folks, The attached paper is a little far afield for this group, but it indicates some of the challenges associated with reducing the amount of warming that might occur this century through transformation of our energy system. Particles in the stratosphere change planetary radiative forcing very rapidly, whereas changes in emissions change the rate of change of radiative forcing, but do not substantially change radiative forcing on a short time scales. Furthermore, in, for example, a 40 year linear transition from coal to, say, solar power, only about 1/4 of the avoided emissions come in the first 20 years while 3/4 of the avoided emissions occur in the second 20 years. If you combine this with lag times introduced by thermal inertia in the oceans, you can see that only rapid transitions to the lowest emitting technologies can have a substantial effect on climate later this century. The paper is "open access" and is also available here (along with supporting online material): http://iopscience.iop.org/1748-9326/7/1/014019 We have also made a little YouTube video: http://www.youtube.com/watch?v=a9LaYCbYCxo A journalistic account can be found here: http://environmentalresearchweb.org/cws/article/news/48649 Best, Ken _______________ Ken Caldeira Carnegie Institution Dept of Global Ecology 260 Panama Street, Stanford, CA 94305 USA +1 650 704 7212 kcalde...@carnegie.stanford.edu http://dge.stanford.edu/labs/caldeiralab @kencaldeira YouTube: Crop yields in a geoengineered climate Influence of sea cucumbers on a coral reef CaCO3 budget -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to geoengineering@googlegroups.com. To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com. 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