Abstract
China is under pressure to improve its agricultural productivity to keep up with the demands of a growing population
with increasingly resource-intensive diets. This productivity improvement must occur against a backdrop
of carbon intensity reduction targets, and a highly fragmented, nutrient-inefficient farming system.
Moreover, the Chinese government increasingly recognizes the need to rationalize the management of the 800
million tonnes of agricultural crop straw that China produces each year, up to 40% of which is burned in-field
as a waste. Biochar produced from these residues and applied to land could contribute to China’s agricultural
productivity, resource use efficiency and carbon reduction goals. However competing uses for China’s straw residues
are rapidly emerging, particularly from bioenergy generation. Therefore it is important to understand the
relative economic viability and carbon abatement potential of directing agricultural residues to biochar rather
than bioenergy. Using cost-benefit analysis (CBA) and life-cycle analysis (LCA), this paper therefore compares
the economic viability and carbon abatement potential of biochar production via pyrolysis, with that of bioenergy
production via briquetting and gasification. Straw reincorporation and in-field straw burning are used as
baseline scenarios. We find that briquetting straw for heat energy is the most cost-effective carbon abatement
technology, requiring a subsidy of $7 MgCO2e
1 abated. However China’s current bioelectricity subsidy scheme
makes gasification (NPV $12.6 million) more financially attractive for investors than both briquetting (NPV $7.34
million), and pyrolysis ($ 1.84 million). The direct carbon abatement potential of pyrolysis (1.06 MgCO2e per
odt straw) is also lower than that of briquetting (1.35 MgCO2e per odt straw) and gasification (1.16 MgCO2e per
odt straw). However indirect carbon abatement processes arising from biochar application could significantly
improve the carbon abatement potential of the pyrolysis scenario. Likewise, increasing the agronomic value of
biochar is essential for the pyrolysis scenario to compete as an economically viable, cost-effective mitigation
technology.
Original language | English |
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Pages (from-to) | 1272 - 1282 |
Number of pages | 11 |
Journal | GCB Bioenergy |
Volume | 7 |
Issue number | 6 |
Early online date | 14 Aug 2014 |
DOIs | |
Publication status | Print publication - 2015 |
Keywords
- Biochar
- Bioenergy
- Biomass
- Briquetting
- China
- Gasification
- Pyrolysis