Excellent Article. I congratulate the authors. Biochar is a name for charcoal when it is used for particular purposes, especially as a soil amendment. Like most charcoal, biochar is created by pyrolysis of biomass. Biochar is under investigation as an approach to carbon sequestration to produce negative carbon dioxide emissions. Biochar thus has the potential to help mitigate climate change, via carbon sequestration. Independently, biochar can increase soil fertility of acidic soils (low pH soils), increase agricultural productivity, and provide protection against some foliar and soil-borne diseases.[4] Furthermore, biochar reduces pressure on forests. Biochar is a stable solid, rich in carbon and can endure in soil for thousands of years. History Pre-Columbian Amazonians are believed to have used biochar to enhance soil productivity. They produced it by smolderingagricultural waste (i.e., covering burning biomass with soil) in pits or trenches. European settlers called it terra preta de Indio. Following observations and experiments, a research team working in French Guiana hypothesized that the Amazonian earthworm Pontoscolex corethrurus was the main agent of fine powdering and incorporation of charcoal debris to the mineral soil.[9] The term “biochar” was coined by Peter Read to describe charcoal used as a soil improvement.[10] Production Pyrolysis produces biochar, liquids, and gases from biomass by heating the biomass in a low/no oxygen environment. The absence of oxygen prevents combustion. The relative yield of products from pyrolysis varies with temperature. Temperatures of 400–500 °C (752–932 °F) produce more char, while temperatures above 700 °C (1,292 °F) favor the yield of liquid and gas fuel components. Pyrolysis occurs more quickly at the higher temperatures, typically requiring seconds instead of hours. High temperature pyrolysis is also known as gasification, and produces primarily syngas. Typical yields are 60% bio-oil, 20% biochar, and 20% syngas. By comparison, slow pyrolysis can produce substantially more char (~50%). Once initialized, both processes produce net energy. For typical inputs, the energy required to run a “fast” pyrolyzer is approximately 15% of the energy that it outputs. Modern pyrolysis plants can use the syngas created by the pyrolysis process and output 3–9 times the amount of energy required to run. The Amazonian pit/trench method harvests neither bio-oil nor syngas, and releases a large amount of CO 2, black carbon, and other greenhouse gases (GHG)s (and potentially, toxins) into the air. Commercial-scale systems process agricultural waste, paper byproducts, and even municipal waste and typically eliminate these side effects by capturing and using the liquid and gas products. Centralized, decentralized, and mobile systems In a centralized system, all biomass in a region is brought to a central plant for processing. Alternatively, each farmer or group of farmers can operate a lower-tech kiln. Finally, a truck equipped with a pyrolyzer can move from place to place to pyrolyze biomass. Vehicle power comes from the syngas stream, while the biochar remains on the farm. The biofuel is sent to a refinery or storage site. Factors that influence the choice of system type include the cost of transportation of the liquid and solid byproducts, the amount of material to be processed, and the ability to feed directly into the power grid. For crops that are not exclusively for biochar production, the residue-to-product ratio (RPR) and the collection factor (CF) the percent of the residue not used for other things, measure the approximate amount of feedstock that can be obtained for pyrolysis after harvesting the primary product. For instance, Brazil harvests approximately 460 million tons (MT) of sugarcane annually, with an RPR of 0.30, and a CF of 0.70 for the sugarcane tops, which normally are burned in the field. This translates into approximately 100 MT of residue annually which could be pyrolyzed to create energy and soil additives. Adding in the bagasse (sugarcane waste) (RPR=0.29 CF=1.0) which is otherwise burned (inefficiently) in boilers, raises the total to 230 MT of pyrolysis feedstock. Some plant residue, however, must remain on the soil to avoid increased costs and emissions from nitrogen fertilizers. Pyrolysis technologies for processing loose and leafy biomass produce both biochar and syngas. Uses Carbon sink The burning and natural decomposition of biomass and in particular agricultural waste adds large amounts of CO2 to the atmosphere. Biochar that is stable, fixed, and recalcitrant carbon can store large amounts of greenhouse gases in the ground for centuries, potentially reducing or stalling the growth in atmospheric greenhouse gas levels; at the same time its presence in the earth can improve water quality, increase soil fertility, raise agricultural productivity, and reduce pressure onold-growth forests. Biochar can sequester carbon in the soil for hundreds to thousands of years, like coal. Such a carbon-negative technology would lead to a net withdrawal of CO2 from the atmosphere, while producing and consuming energy.” This technique is advocated by prominent scientists such as James Hansen, head of the NASA Goddard Institute for Space Studies, and James Lovelock, creator of the Gaia hypothesis, for mitigation of global warming by greenhouse gas remediation. Researchers have estimated that sustainable use of biocharring could reduce the global net emissions of carbon dioxide (CO2), methane, and nitrous oxide by up to 1.8 Pg CO 2-C equivalent (CO2-Ce) per year (12% of current anthropogenicCO 2-Ce emissions; 1 Pg=1 Gt), and total net emissions over the course of the next century by 130 Pg CO2-Ce, without endangering food security, habitat, or soil conservation. Biochar is a high-carbon, fine-grained residue which today is produced through modern pyrolysis processes. Pyrolysis is the direct thermal decomposition of biomass in the absence of oxygen to obtain an array of solid (biochar), liquid (bio-oil), and gas (syngas) products. The specific yield from the pyrolysis is dependent on process conditions, and can be optimized to produce either energy or biochar. Water retention Biochar is a desirable soil material in many locations due to its ability to attract and retain water. This is possible because of its porous structure and high surface area. As a result, nutrients, phosphorus, and agrochemicals are retained for the plants benefit. Plants therefore, are healthier and fertilizers leach less into surface or groundwater. Direct and indirect benefits • The pyrolysis of forest- or agriculture-derived biomass residue generates a biofuel without competition with crop production. • Biochar is a pyrolysis byproduct that may be ploughed into soils in crop fields to enhance their fertility and stability, and for medium- to long-term carbon sequestration in these soils. • Biochar enhances the natural process: the biosphere captures CO 2, especially through plant production, but only a small portion is stably sequestered for a relatively long time (soil, wood, etc.). • Biomass production to obtain biofuels and biochar for carbon sequestration in the soil is a carbon-negative process, i.e. more CO2 is removed from the atmosphere than released, thus enabling long-term sequestration. Research Intensive research into manifold aspects involving the pyrolysis/biochar platform is underway around the world. From 2005-2012, there were 1,038 articles that included the word “biochar” or “bio-char” in the topic that had been indexed in the ISI Web of Science. Further research is in progress by such diverse institutions around the world as Cornell University, theUniversity of Edinburgh, which has a dedicated research unit., and the Agricultural Research Organization (ARO) of Israel, Volcani Center, where a network of researchers involved in biochar research (iBRN, Israel Biochar Researchers Network) was established as early as 2009. Students at Stevens Institute of Technology in New Jersey are developing super capacitors that use electrodes made of biochar. A process developed by University of Florida researchers that removes phosphate from water, also yieldsmethane gas usable as fuel and phosphate-laden carbon suitable for enriching soil. Emerging commercial sector Calculations suggest that emissions reductions can be 12–84% greater if biochar is put back into the soil instead of being burned to offset fossil-fuel use. Thus Biochar sequestration offers the chance to turn bioenergy into a carbon-negative industry. Johannes Lehmann, of Cornell University, estimates that pyrolysis can be cost-effective for a combination of sequestration and energy production when the cost of a CO2 ton reaches $37. As of mid-February 2010, CO2 is trading at $16.82/ton on the European Climate Exchange (ECX), so using pyrolysis for bioenergy production may be feasible even if it is more expensive than fossil fuel. Current biochar projects make no significant impact on the overall global carbon budget, although expansion of this technique has been advocated as a geoengineering approach. In May 2009, the Biochar Fund received a grant from the Congo Basin Forest Fund for a project in Central Africa to simultaneously slow down deforestation, increase the food security of rural communities, provide renewable energy and sequester carbon. Application rates of 2.5–20 tonnes per hectare (1.0–8.1 t/acre) appear to be required to produce significant improvements in plant yields. Biochar costs in developed countries vary from $300–7000/tonne, generally too high for the farmer/horticulturalist and prohibitive for low-input field crops. In developing countries, constraints on agricultural biochar relate more to biomass availability and production time. An alternative is to use small amounts of biochar in lower cost biochar-fertilizer complexes. Various companies in North America, Australia, and England sell biochar or biochar production units At the 2009 International Biochar Conference a mobile pyrolysis unit with a specified intake of 1,000 pounds (450 kg) was introduced for agricultural applications. The unit had a length of 12 feet and height of 7 feet (3.6 m by 2.1m). A production unit in Dunlap, Tennessee by Mantria Corporation opened in August 2009 after testing and an initial run, was later shut down as part of a Ponzi scheme investigation(Source: Wikipedia). Action Plan for Biofuel/Biochar/Biogas for India: Biofuel/Biogas power from Agave and Opuntia: Another area which yields immediate results and gainful employment is to grow care-free growth plants like Agave and Opuntia in waste lands. There are millions of hectares of waste lands. In the debate Food Vs Fuel the alternative is to grow plants with multiple uses which have care-free growth. Yet another option is Biofuel from Agave and Biogas from Opuntia and power generation. Agave is a care – free growth plant which can be grown in millions of hectares of waste land and which produces Biofuel. Already Mexico is using it. Another Care free growth plant is Opuntia which generates Biogas. Biogas can be input to generate power through Biogas Generators. Biogas generators of MW size are available from China. Yet another option is Water Hyacinth for biogas. Water Hyacinth along with animal dung can produce biogas on a large scale and then power. In Kolleru lake in Godavari and Krishna Delta in Andhra Pradesh in India it is available in 308 Sq. Km for nearly 8 months in a year. Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions In a plant using full CAM, the stomata in the leaves remain shut during the day to reduce evapotranspiration, but open at night to collect carbon dioxide (CO2). The CO2 is stored as the four-carbon acidmalate, and then used during photosynthesis during the day. The pre-collected CO2 is concentrated around the enzyme RuBisCO, increasing photosynthetic efficiency. Agave and Opuntia are the best CAM Plants. Researchers find that the agave plant will serve as a biofuel crop to produce ethanol. Agave has a huge advantage, as it can grow in marginal or desert land, not on arable land, and therefore would not displace food crops, says Oliver Inderwildi, at the University of Oxford.The majority of ethanol produced in the world is still derived from food crops such as corn and sugarcane. Speculators have argued for years now that using such crops for fuel can drive up the price of food. Agave, however, can grow on hot dry land with a high-yield and low environmental impact. The researchers proposing the plant’s use have modeled a facility in Jalisco, Mexico, which converts the high sugar content of the plant into ethanol. Another plant of great use is OPUNTIA for biogas production. The cultivation of nopal((OPUNTIA FICUS-INDICA), a type of cactus, is one of the most important in Mexico. According to Rodrigo Morales, Chilean engineer, Wayland biomass, installed on Mexican soil, “allows you to generate inexhaustible clean energy.” Through the production of biogas, it can serve as a raw material more efficiently, by example and by comparison with jatropha. Wayland Morales, head of Elqui Global Energy argues that “an acre of cactus produces 43 200 m3 of biogas or the equivalent in energy terms to 25,000 liters of diesel.” With the same land planted with jatropha, he says, it will produce 3,000 liters of biodiesel. Another of the peculiarities of the nopal is biogas which is the same molecule of natural gas, but its production does not require machines or devices of high complexity. Also, unlike natural gas, contains primarily methane (75%), carbon dioxide (24%) and other minor gases (1%), “so it has advantages from the technical point of view since it has the same capacity heat but is cleaner, “he says, and as sum datum its calorific value is 7,000 kcal/m3. In the fields where Jatropha is being grown,Agave and Opuntia can be grown as Inter cropping. In their research paper SARAH C. DAVIS et al conclude: Large areas of the tropics and subtropics are too arid or degraded to support food crops, but Agave species may be suitable for biofuel production in these regions. We review the potential of Agave species as biofuel feed stocks in the context of eco physiology, agronomy, and land availability for this genus globally. Reported dry biomass yields of Agave spp., when annualized, range from 1 to 34Mg /ha/yr without irrigation, depending on species and location. Some of the most productive species have not yet been evaluated at a commercial scale. Approximately 0.6Mha of land previously used to grow Agave for coarse fibers have fallen out of production, largely as a result of competition with synthetic fibers. Theoretically, this crop area alone could provide 6.1 billion L of ethanol if Agave were reestablished as a bioenergy feedstock without causing indirect land use change. Almost one-fifth of the global land surface is semiarid, suggesting there may be large opportunities for expansion of Agave crops for feedstock, but more field trials are needed to determine tolerance boundaries for different Agave species(The global potential for Agave as a biofuel feedstock, GCB Bioenergy (2011) 3, 68–78, doi: 10.1111/j.1757-1707.2010.01077.x). Agave and Opuntia are the best choice to grow in waste and vacant lands in Asia,Africa and Latin America.The advantage with the plants is both are regenerative and thrive under harsh conditions. There is huge waste land in India. Government can start Agricultural Economic Zones(AEZ) on the lines of SEZ and unemployed youth (after short training in Farm practices) each can be allotted 10 acres. 10 such people can form a co-operative and start production leke Agave and Opuntia. Biogas/biofuel plants can be set up in rural areas with this input. Biogas can be supplied by pipes in villages for cooking through pipes just as in China. Also power generation from biogas in villages. This way waste land can be converted into usable land besides providing employment and livelihood to millions. These plants will act as Carbon Sink for Climate stabilization. The ideal choices for Biochar are CAM plants like Agave and Opuntia. According to Dr. Promode Kant(Could Agave be the Species of Choice for Climate Change Mitigation? IGREC WORKING PAPER IGREC-11:2010 ) “Agave is to the drier parts of the world what bamboo is to its wetter zones. Capturing atmospheric CO2 in vegetation is severely limited by the availability of land and water. The best choice would be species that can utilize lands unfit for food production and yet make the dynamics of carbon sequestration faster. As much as 40 % land on earth is arid and semi arid and on almost half of these lands, with a minimum annual rainfall of about 250 mm, many species of agave grow reasonably well since its Crassulacean Acid Metabolism photosynthetic pathway permits it higher productivity on lands with severely restricted water availability and prolonged droughts. Agave sugar is a rich source of bioethanol for renewable energy. And agave can also be used for carbon sequestration projects under CDM even though by itself it does not constitute a tree crop and can not provide the minimum required tree crown cover to create a forest as required under CDM rules. But if the minimum required crown cover is created by planting an adequate number of suitable tree species in agave plantations then the carbon sequestered in the agave plants will also be eligible for measurement as above ground dry biomass and provide handsome carbon credits. This makes agave an excellent CDM crop for bioethanol as well as for afforestation over poor quality arid lands giving both permanent carbon credits for bioenergy and temporary credits of forestry for carbon sequestration. It causes no threat to food security and places no demand for the scarce water and since it can be harvested annually after a short initial gestation period of establishment, and yields many products that have existing markets, it is also well suited for eradication of poverty. “ igrec.in/could_agave_be_the_species_of_choice_for_climate_change_mitigation.pdf Dr.A.Jagadeesh Nellore(AP),.India
Posted on: Thu, 15 Jan 2015 09:33:54 +0000
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