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| 1 |
ID:
149450
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| Summary/Abstract |
According to N Sai Bhaskar Reddy, natural farming mitigates the pace and effects of climate change and biochar has the potential to add value to soils and ecosystems. He reviews various types of biochar and its uses as an organic compost, pesticide, fertiliser, etc and the impact on the land, microorganisms, water tables and ecosystems.
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| 2 |
ID:
109673
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| Publication |
2011.
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| Summary/Abstract |
This paper estimates the economic value of biochar application on agricultural cropland for carbon sequestration and its soil amendment properties. In particular, we consider the carbon emissions avoided when biochar is applied to agricultural soil, instead of agricultural lime, the amount of carbon sequestered, and the value of carbon offsets, assuming there is an established carbon trading mechanism for biochar soil application. We use winter wheat production in Eastern Whitman County, Washington as a case study, and consider different carbon offset price scenarios and different prices of biochar to estimate a farm profit. Our findings suggest that it may be profitable to apply biochar as a soil amendment under some conditions if the biochar market price is low enough and/or a carbon offset market exists.
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| 3 |
ID:
104936
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| Publication |
2011.
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| Summary/Abstract |
Life cycle assessment (LCA) of slow pyrolysis biochar systems (PBS) in the UK for small, medium and large scale process chains and ten feedstocks was performed, assessing carbon abatement and electricity production. Pyrolysis biochar systems appear to offer greater carbon abatement than other bioenergy systems. Carbon abatement of 0.7-1.3 t CO2 equivalent per oven dry tonne of feedstock processed was found. In terms of delivered energy, medium to large scale PBS abates 1.4-1.9 t CO2e/MWh, which compares to average carbon emissions of 0.05-0.30 t CO2e/MWh for other bioenergy systems. The largest contribution to PBS carbon abatement is from the feedstock carbon stabilised in biochar (40-50%), followed by the less certain indirect effects of biochar in the soil (25-40%)-mainly due to increase in soil organic carbon levels. Change in soil organic carbon levels was found to be a key sensitivity. Electricity production off-setting emissions from fossil fuels accounted for 10-25% of carbon abatement. The LCA suggests that provided 43% of the carbon in the biochar remains stable, PBS will out-perform direct combustion of biomass at 33% efficiency in terms of carbon abatement, even if there is no beneficial effect upon soil organic carbon levels from biochar application.
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| 4 |
ID:
111399
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| Publication |
2012.
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| Summary/Abstract |
Biochar is a carbon- and energy-rich porous material produced through slow pyrolysis of biomass, which has been proposed as a way of storing carbon in soils for the long-term (centurial to millennial timescales) but its production incurs an energy penalty. Gasification of rice husks at paddy mills combines the benefits of reasonably efficient delivery of energy with a reasonably high carbon char and ash mixture. The ca. 35% carbon content of the rice husk char is possibly a consequence of the protective shield of silica, preventing full exposure of the biomass to oxidation in the gasifier. In this paper we undertake an evaluation of the sustainability of this 'gasification-biochar system' (GBS) in Cambodia, where a rapid deployment of gasifiers is underway. In Part I, we describe the context and analyse (some of) the physical and chemical properties of the biochar. While there are some potential health, safety and environmental issues that require further analysis, they are problems that could be readily addressed in further research and appear to be resolvable. In Part II, we present results from field trials, summarise the data on the carbon abatement of the gasification-biochar system and present some preliminary economic data.
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| 5 |
ID:
111366
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| Publication |
2012.
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| Summary/Abstract |
In part I we described the gasification technology and characterised the physio-chemical properties and environmental impacts of the rice husk char (RHC) by-product. In part II we present summary results from field trials using the RHC, and provide an estimate of the carbon abatement and economic evaluation of the system. Statistically significant yield increases are demonstrated for RHC addition in irrigated rice cultivation (33% increase in paddy rice yield for a 41.5 t (dry weight) RHC application per hectare). The carbon abatement from the RHC addition is approximately 0.42 t CO2 t-1 rice husk; including energy generation from gasification this increases to ca. 0.86 tCO2 t-1. Assuming a carbon value of $5 t CO2 t-1, and agronomic value of $3 t-1 RHC based on the field trials, the economic value of the RHC varies from $9 t-1 (including only recalcitrant carbon) to $15 t-1 (including avoided emissions from energy production). We summarise results from parts I and II, concluding that the gasification-biochar system meets many of the criteria of sustainability, but requires better waste water management and more field trials to demonstrate repeatable agronomic efficacy of RHC application.
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