Nutrient balance is an important and interesting question, but not simple.
Imagine collecting straw or corn stover for power generation, vs. letting it rot on the field. If left, then of the three major nutrients, K, P and N: phosphorus can be expected to stay in place. However, many soils have an excess of phosphate, enough in some areas to pose a health issue if it impacts drinking water supply. Potassium may return to the soil, but might be transported in runoff, depending on local precipitation patterns and very local topography. Nitrates are subject to runoff, and can be reduced back to nitrogen by bacterial action on surface biomass, notably in the spring (which is why in some agricultural areas grass seed is aerially sprayed in the fall, to move the nitrate in the grass, above the soil level, until spring plowing buries the grass). Hence the loss of nutrients from biomass collection is subject to local analysis. Biomass processing moves the nutrients away from the field. Ash can be recycled, at a cost, although not if char is buried (assuming the ash remains in the char). Nitrogen would have to be made up. If a dollar value is placed on carbon emission avoidance or negative carbon, it will overwhelm the cost of the incremental nitrogen requirement, since for agricultural crops there is already a fertilizer application, only the dosage is increased: the sole cost is the nitrogen itself. Peter Flynn Peter Flynn, P. Eng., Ph. D. Emeritus Professor and Poole Chair in Management for Engineers Department of Mechanical Engineering University of Alberta [email protected] cell: 928 451 4455 *From:* [email protected] [mailto: [email protected]] *On Behalf Of *Greg Rau *Sent:* Sunday, January 17, 2016 12:11 PM *To:* [email protected]; geoengineering < [email protected]> *Subject:* Re: [geo] Re: Carbon negative energy More specifically, from the website: "While today’s APL Power Pallets produce a relatively small amount of biochar byproduct (around 5% of input mass), it is still enough for modest carbon negativity in the fuel cycle. The round rule of thumb numbers are as follows: 1 tonne of dry biomass in produces about 1Mw/hr of electricity and 50kg of carbon byproduct. 50kg of raw carbon once recombined with O2 is the equivalent of 185kg of CO2 in the atmosphere. (mass C x 3.67 = mass CO2) 1 tonne of biomass input to the gasifier can soil-sequester the equivalent of 0.185 CO2 tonnes in the atmosphere. Avoided CO2 emissions from not burning fossil fuel in the process are added to the wins above." Question: How much of the nutrients in the biomass are returned to the soil and how much are sequestered/volatilized/lost, i.e is this sustainable? Greg ------------------------------ *From:* Brian Cady <[email protected]> *To:* geoengineering <[email protected]> *Sent:* Sunday, January 17, 2016 4:34 AM *Subject:* [geo] Re: Carbon negative energy An example of carbon-negative energy sources becoming available: http://www.allpowerlabs.com/products/20kw-power-pallets Brian -- 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]. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout. -- 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]. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout. -- 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]. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
