Supporting Information
This SI document includes text, tables and figures that provide further detail on the parameter
values used to construct the CBA and LCA presented in this paper. The first half of the
supplementary information refers to the CBA, and the second half refers to the LCA.
Technology Readiness Levels
S1 Technology Readiness Level table
Cost-Benefit Analysis SI
S2 Project Lifetime
S3 Project Finance
S4 Straw Collection Cost
S5 Capital and Operation Costs
S6 Pricing Outputs
Life-Cycle Analysis SI
S7 LCA functional unit of analysis
S8 Global warming period
S9 Straw cultivation and removal
S10 Crop residue collection
S11 Straw reincorporation
S12 Straw burning
S13 Briquetting
S14 Equipment, fuel and buildings
- Table S2: Comparison of tonnes of materials estimates
S15 Direct emissions
S16 Energy offsets
- Figure S1: Sankey diagram of the gasification conversion of straw to syngas
- Figure S2: Sankey diagram of the sloq pyrolytic conversion of straw to syngas and biochar
- Table S3: Median and 95% confidence intervals for MWh produced per tonne feedstock
processed for gasification and pyrolysis units
S17 Carbon sequestration
S18 Monte Carlo analysis
Sensitivity Analysis SI
S19 Parameter values for CBA sensitivity analysis
S20 Parameter values for LCA sensitivity analysis
S1 Descriptions of Technology Readiness Levels1
TRL 1
Basic principles observed and reported
TRL 2
Technology concept and/or application formulated
TRL 3
Analytical and experimental critical function and/or characteristic proof-of-concept.
TRL 4
Technology basic validation in a laboratory environment
TRL 5
Technology basic validation in a relevant environment
TRL 6
Technology model or prototype demonstration in a relevant environment
TRL 7
Technology prototype demonstration in an operational environment
TRL 8
Actual technology completed and qualified through test and demonstration
TRL 9
Actual technology qualified through successful mission operations
1
Data source: (UK Ministry of Defence, 2014)
Cost-Benefit Analysis Supporting Information
S2 Project Lifetime
The briquetting, gasification and pyrolysis scenarios are compared for their economic
viability by contrasting their project level net present value (NPV). Project lifetime is
assumed to be 20 years, in accordance with Chinese bioenergy project timelines (Zhang et
al., 2014).
S3 Project Finance
Loans are assumed to be taken out for 75% of the project cost (Zhang et al., 2014), and the
opportunity cost of the remaining 25% capital investment is accounted for. Loan repayments
are spread over 20 years. The discount and interest rates are set according to data on the
Chinese economy (Federal Reserve Bank of St Louis, 2014; Trading Economics, 2014). Tax
rates and tax breaks provided for bioelectricity projects are based on data from Chinese
national policy documents (Zhang et al. (2014)).
S4 Straw Collection Cost
Sanli New Energy Factory provides local straw collection agents with free access to baling
machines, to enable straw collection. These agents then use their own tractors and trailers to
transport the bailed straw to the straw collection depots. Thus, for Sanli the cost of straw
collection is in the purchase and maintenance of balers, and in the payment to agents for the
straw they deliver. Straw price data was combined from interviews at Sanli, in surrounding
Henan villages, and from published academic data on straw pries for bioenergy projects
(Zhang et al., 2014). The average value across these data sources was $45 Mg-1. However
due to the volatility of straw prices, a +/- 20% range was also included in the sensitivity
analyses.
The local government subsidy for straw collection ($28 Mg-1) was included on the basis of
interview data from Henan. However it is not clear that this subsidy is widely available across
all parts of China, and is likely to depend strongly on local government incentives for
curtailing in-field straw burning.
S5 Capital and Operational Costs
A variety of data sources were used to price the capital costs of briquette machines, the
gasification unit, the pyrolysis unit and the buildings to house them (Bridgwater et al., 2002;
Badger et al., 2011; Zhang et al., 2014). In each case where market data was collected online,
three or more quotes were obtained for similar products, and then averaged to derive a mean
value. Maintenance of these capital units, as with all machinery in all scenarios, is estimated
at 5% of the capital value. Salvage value at the end of the lifetime is also fixed at 5%.
Decommissioning costs were estimated at 2%.
Electricity requirements for the balers are derived from the supplier website (9.9 kWh odt-1),
and the cost of purchasing electricity from China’s central grid is estimated as $0.02 kWh-1,
as obtained from interviews at Sanli and around Henan villages. Start-up fuel requirements
for gasification and pyrolysis are taken from Roberts et al., (2010) and costed according to
fuel cost data from the World Bank, (2014).
Staffing requirements for all scenarios also estimated from Sanli interviews, and priced
according to labour market information (Clare et al., 2014).
The CBA is calculated from the perspective of a potential investor, therefore the costs to a
farmer of straw reincorporation and/or straw burning are not considered as part of the
economic analysis.
S6 Pricing Outputs
Briquettes were valued according to their energy density (16MJ kg-1; Roberts et al., 2010)
and the market value of an equivalent energy delivery from coal (Zhao & Che, 2012;
Bloomberg, 2014), which is the fossil fuel material that they would be offsetting.
Electricity outputs were valued using data on the base price for electricity from coal-fired
power plants and the data on the subsidised prices provided for bioelectricity generated from
agricultural wastes (Zhang et al., 2014).
Biochar outputs were valued according to the latest meta-analytical data on biochar’s
agronomic impact for a given application rate (Crane-Droesch et al., 2013) and interview
data on the agricultural market prices and cropping systems in Henan (Clare et al., 2014).
Life Cycle Analysis Supporting Information
S7 LCA Functional Unit of Analysis
The functional unit of analysis for each LCA is one oven dry tonne (odt) of straw, assumed to
be 40% maize and 60% wheat, to reflect the reported proportions of straw that Sanli New
Energy Factory uses annually in its operations, and the cropping system of Henan province
more generally.
S8 Global Warming Period (GWP)
The LCA considers the global warming potential of each scenario on a 100 year basis,
according to calculated emissions of CO2, CH4 and N2O. Carbon monoxide (CO) emissions
were treated as equivalent to CO2, as CO quickly oxidises to CO2 once released to the
atmosphere (Woolf et al., 2010). Due to uncertainties of global warming potentials for NOx,
SOx, and particulate emissions, we are unable to include them in the 100year GWP estimate.
S9 Straw Cultivation and Removal
Emissions from agricultural inputs and activities involved in generating the grain-crops from
which the straw is taken are not included in the LCA scenarios. This is because straw is a
waste product that is generated as a by-product of food cultivation, which would exist in the
absence of the SBriq, SGas, or SPyr scenarios. At present, farmers do not receive payment for
their straw, because it is seen as a nuisance by-product of little value. However it is worth
noting that demand for biomass can change rapidly, therefore sensitivity analysis is used to
model the effects of price changes (i.e., as a result of increased demand for a straw).
S10 Crop Residue Collection
One tonne of straw containing 40% maize and 60% wheat is assumed to contain 433160
grams of carbon (Li et al., 2007). All subsequent calculations of emissions per tonne of
feedstock are normalised, assuming this starting carbon content of 433160 grams per tonne.
Carbon and energy contents of maize and wheat straw are taken from (McKendry, 2002; Li et
al., 2007; Roberts et al., 2010). Straw availability is calculated according to surveyed grain
yields (Clare et al., 2014) and grain:straw conversion ratios (Jiang et al., 2012), accounting
for 40% of wheat straw and 50% of maize straw to be left as crop cover (Scarlat et al., 2010)
in order to avoid negative impacts on soil organic carbon (SOC). The straw is collected and
baled mechanically, and transported using a tractor and trailer (fuel requirements calculated
using data from Dalgaard et al., (2001)). Distance for straw transportation from field to plant
is calculated according to a methodology developed by French, (1960) and subsequently
modified by McCarl et al., (2009) and Roberts et al., (2010).
Embedded emissions of straw balers are included in this analysis, as Sanli purchases these to
loan to straw collection agents. However embedded emissions within tractors and trailers are
excluded, as these are already owned by the straw collection agents. It is assumed that 50
balers are required for the twenty year lifetime of the project, based on estimates of maximum
machine lifetime, measured in hours of operation (Edwards, 2009). An average baler weight
is calculated from Chinese agricultural equipment sales websites, and assumed to be
predominantly constructed from steel. All steel accounted for in these calculations is assumed
to be 70% recycled and 30% virgin (Wang, 2008; Roberts et al., 2010).
Emissions embedded within storage buildings are also included. Building size is calculated
according to the expected peak volume of straw that will be stored at any one time during the
year (~17,500 tonnes). Building construction materials are assumed to be concrete and steel.
Finally, embedded emissions for four straw chopping machines are included. Machine weight
is taken from a Chinese equipment website and assumed to be predominantly constructed
from steel.
Emissions factors for virgin, recycled and stainless steel; concrete; virgin and recycled cast
aluminium; and cast iron are taken from the GREET 1.8b spreadsheet (Wang, 2008).
S11 Straw Reincorporation (SRein)
We assume that all carbon contained within the feedstock is released as CO2 over the 100
year time period (Knoblauch et al., 2011). In agricultural soils, where straw is reincorporated
and then turned twice a year for planting, it is extremely unlikely that any carbon in this
feedstock would remain stabilised in soil after 100 years (Lehmann et al., 2006).
S12 Straw Burning (SBurn)
Data on CO2, CH4 and N2O emissions from open field straw burning is taken from Li et al.,
(2007). Monte Carlo methods were used to generate distributions using mean and standard
deviation emissions values for maize and wheat straw. These distributions were plotted,
normalised, and combined in a 4:6 ratio according to the reported maize:wheat straw
processed at Sanli.
S13 Briquetting (SBriq)
The briquette machines process 2.75 tonnes of straw per hour, using 9.9kWh odt-1 feedstock.
Electricity emissions are estimated according to a grid emissions factor for the north regional
grid, which includes Henan within its service area (World Resources Institute, 2014). It is
assumed that the 20 year project lifetime will require 100 briquette machines, each processing
5,600 tonnes of straw during its working lifetime. Each machine weighs 1.6 tonnes and is
made primarily from steel. The briquette machines also require a shelter, which is estimated
to require 1 tonne of steel and 2.5 tonnes of concrete.
Mean and standard deviation values for emissions of CO2 and CH4 from burning straw
briquettes and coal in domestic stoves is taken from Zhang et al., (2000) and Wang et al.,
(2013). Monte Carlo method was used to generate distributions according to these reported
mean and standard deviation values. These distributions were plotted, normalised, and
combined in a 4:6 ratio according to the reported maize:wheat straw ratio. The coal emissions
distribution was then combined with an estimate for emissions required to source coal (Hill et
al., 2013), which accounted for 15% of the total coal emissions. In the absence of available
data on emissions related to sourcing coal in China, the coal sourcing emissions estimate is
based on UK data.
S14 Equipment, Fuel and Buildings
For SGas and SPyr, the emissions associated with equipment (i.e., construction of gasification
and pyrolysis units), start-up fuel, and buildings are assumed to be the same. This is because
each unit processes the same quantity of straw, and there is little data available to justify
distinctions in estimates in construction materials needed for each unit. Data from Mann &
Spath, (1997) is used to calculate the volumes of materials needed, and we find that our
materials estimates are similar to those reported by Roberts et al., (2010) (See Table S1).
Emissions from plant decommissioning and the transport and recycling of materials have
previously been found to be negligible (Lombardi, 2003) and are therefore not included in the
analysis.
Material
Concrete
Steel
Aluminium
Iron
Our Estimate
(tonnes per pyrolysis
unit)
1748.2
653.9
5.1
7.6
Roberts et al. estimate
(tonnes per pyrolysis
unit)
1759.5
558.5
7.3
3.7
Table S2: Comparison of tonnes of materials estimates with Roberts et al. (2010)
Estimated start-up fuel for each scenario is based on Saft, (2007), with associated emissions
for natural gas calculated from the a report by the Biomass Energy Centre, (2014). Finally we
assume that four tonnes of steel and ten tonnes of concrete are used to build a shelter that
houses the gasification/pyrolysis unit. Again, emissions associated with each material are
based on estimates from the GREET 1.8b spreadsheet (Wang, 2008).
S15 Direct Emissions
Guidance for estimating emissions from gasification and pyrolysis of straw is taken from Lu
& Zhang, (2010), who report emissions from the combustion of syngas created from biomass
gasification. The latter was used as an estimate of direct emissions for syngas generated from
both gasification and pyrolysis, in the absence of data specific to the combustion of pyrolysisderived syngas. It should be noted that other pyrolysis LCA papers have assumed complete
combustion of syngas to carbon dioxide and water (Roberts et al., 2010; Hammond et al.,
2011).
Lu & Zhang (2010) provide mean values, with no measure of variance. Therefore variance
was estimated by calculating the percentage of initial feedstock carbon released to
atmosphere during combustion of syngas derived from biomass (~80%) and then using the
reported ratio of CO2:CH4 (assuming that this is a guideline to the efficiency and/or
cleanliness of the burn process) within a Monte Carlo generated distribution whose variance
was determined by varying this ratio by 50% in each direction.
S16 Energy Offsets
In order to calculate energy offsets for each LCA scenario, the efficiency of each system must
be calculated. These calculations are based on a variety of high quality published articles,
government agency reports and contact with commercial companies (Quaak et al., 1999;
Bridgwater et al., 2002; EPA, 2008; Lu & Zhang, 2010a; Roberts et al., 2010; Clarke Energy,
2014; Weifang Naipute Gas Genset Co. Ltd., 2014).
Figures S1 and S2 provide Sankey diagrams for the conversion of straw to cleaned syngas for
gasification and pyrolysis systems, respectively. The cleaned syngas is then converted to
electricity via combustion in a gas engine, at 32.5% efficiency (Clarke Energy, 2014;
Weifang Naipute Gas Genset Co. Ltd., 2014).
Figure S1 – Sankey diagram of the gasification conversion of straw to syngas
Figure S2 – Sankey diagram of the slow pyrolytic conversion of straw to syngas and biochar
Table S2 outlines the median and quartile ranges of estimates for MWh produced per tonne
of feedstock, using the efficiency estimates that are displayed in the Sankey diagrams above.
Median
95% confidence interval
Gasification
(MWh odt-1)
0.95
(0.73, 1.18)
Pyrolysis
(MWh odt-1)
0.38
(0.31, 0.47)
Table S3: Median and 95% confidence intervals for MWh produced per tonne of feedstock
processed for gasification and pyrolysis units
Offsets are then calculated by estimating the equivalent emissions that would be generated
had the same number of MWh been provided by the Chinese northern grid, with an estimated
emissions factor of 1.13Mg CO2e MWh-1 (World Resources Institute, 2014).
S17 Carbon sequestration
In SGas it is assumed that 80% of feedstock carbon is emitted as CO2 or CH4 during
gasification (Lu & Zhang, 2010b), leaving 20% of feedstock carbon remaining in the ashy
char by-product. This char is assumed to be 90% stable (Singh et al., 2012). In SPyr it is
assumed that 29.6% of feedstock weight is converted to biochar (Roberts et al., 2010), which
contains 71% carbon (Thomsen et al., 2011), 80% of which remains in the soil after 100
years (Singh, Abiven, Torn, & Schmidt, 2012). The higher stability of SGas char is based on
the positive relationship between high temperatures with long-term carbon stability (Crombie
et al., 2013).
S18 Monte Carlo Analysis
Monte Carlo analysis was used to generate distributions and estimates of uncertainty around
each parameter used in the LCA scenarios. Some data sources provided measures of variance
around their point estimates, in which case these were used to generate distributions (as in the
case of emissions of in-field straw burning, briquette burning, and various estimates of
process efficiency for the combustion, gasification and pyrolysis processes).
Where no variance points were given, distributions were created around the mean point
estimates provided, using a standard deviation based on a 95% confidence interval +/- 50%.
In the absence of a pre-existing estimate of variance, it is appropriate to use a broad range of
possibilities to test the sensitivity of the analysis to such parameter variability.
All distributions were then reported according to their median value, rather than the mean.
This is because some distributions were skewed, making it more appropriate to use the
median as comparative measure of location, rather than the mean.
S19 Parameter values for CBA sensitivity analysis
SBriq
Straw price
($ Mg-1)
Local subsidy
($ Mg-1 straw burn
avoided)
Capital cost
(m$ total)
Labour cost
($ hour-1)
Briquette sale
price
($ Mg-1)
SGas
Straw price
($ Mg-1)
Local subsidy
($ Mg-1 straw burn
avoided)
Capital cost
(m$ total)
Labour cost
($ hour-1)
Bioelectricity
price
($ kWh-1
bioelectricity)
SPyr
Straw price
($ Mg-1)
Local subsidy
($ Mg-1 straw burn
avoided)
Capital cost
(m$ total)
Labour cost
($ hour-1)
Bioelectricity
price
($ kWh-1
bioelectricity)
Biochar price
($ Mg-1)
Baseline
parameter value
Parameter Value
and Range
49
39 - 59
28
22 - 34
0.32
0.26 – 0.38
3
2.4 – 3.6
57
46 - 67
49
39 - 59
28
22 - 34
6.34
5.07 – 7.60
3
2.4 – 3.6
0.12
0.10 – 0.14
49
39 - 59
28
22 - 34
7.6
6.10 – 9,16
3
2.4 – 3.6
0.12
0.10 – 0.14
110
88 - 132
S20 Parameter values for LCA sensitivity analysis
SBriq
SGas
SPyr
Straw collection
(MgCO2e odt-1
feedstock)
Machinery
(MgCO2e odt-1
feedstock)
Briquette
combustion
(MgCO2e odt-1
feedstock)
Coal briquette
offsets
(MgCO2e odt-1
feedstock)
Straw collection
(MgCO2e odt-1
feedstock)
Machinery
(MgCO2e odt-1
feedstock)
Straw gasification
(MgCO2e odt-1
feedstock)
Electricity offsets
(MgCO2e odt-1
feedstock)
Straw collection
(MgCO2e odt-1
feedstock)
Machinery
(MgCO2e odt-1
feedstock)
Straw pyrolysis
(MgCO2e odt-1
feedstock)
Electricity offsets
(MgCO2e odt-1
feedstock)
Fertiliser
avoidance offsets
(MgCO2e odt-1
feedstock)
Biochar stability
(% over 100 years)
Baseline
parameter value
Parameter value
and range
0.05
0.04 – 0.05
0.01
0.01-0.01
1.67
1.33 – 2.0
-1.44
-1.16 - -1.73
0.05
0.04 – 0.05
0.01
0.01-0.01
1.28
1.2 – 1.53
-0.91
-0.73 - -1.09
0.05
0.04 – 0.05
0.01
0.01-0.01
0.66
0.53 – 0.79
-0.34
-0.27 - -0.41
-0.39
-0.31 - -0.47
80
64 - 96
References
Badger P, Badger S, Puettman M, Steele P, Cooper J (2011) Techno-economic analysis:
preliminary assessment of pyrolysis oil production osts and material energy balance
associated with a transportable fast pyrolysis system. bioResources, 6, 34–47.
Biomass Energy Centre (2014) Carbon Emissions of Different Fuels. Web page http://www.biomassenergycentre.org.uk/portal/page?_pageid=75,163182&_dad=portal
&_schema=PORTAL.
Bloomberg (2014) China Benchmark Spot Coal Price Drops First Time in Three Months.
http://www.bloomberg.com/news/2014-01-06/china-benchmark-spot-coal-price-dropsfirst-time-in-three-months.html.
Bridgwater a. V, Toft AJ, Brammer JG (2002) A techno-economic comparison of power
production by biomass fast pyrolysis with gasification and combustion. Renewable and
Sustainable Energy Reviews, 6, 181–246.
Clare AJ, Barnes AP, McDonagh J, Shackley SJ (2014) From rhetoric to reality: farmer
perspectives on the economic potential of biochar in China. International Journal of
Agricultural Sustainability.
Clarke Energy (2014) GE Jenbacher Type-6 Engine. Clarke Energy website http://www.clarke-energy.com/gas-engines/type-6-gas-engines/;%20http://www.clarkeenergy.com/gas-type/synthesis-gas-syngas/.
Crane-Droesch A, Abiven S, Jeffery S, Torn MS (2013) Heterogeneous global crop yield
response to biochar: a meta-regression analysis. Environmental Research Letters, 8, 44–
49.
Crombie K, Mašek O, Sohi SP, Brownsort P, Cross A (2013) The effect of pyrolysis
conditions on biochar stability as determined by three methods. Global Change Biology
Bioenergy, 5, 122–131.
Dalgaard T, Halberg N, Porter JR (2001) A model for fossil energy use in Danish agriculture
used to compare organic and conventional farming. Agriculture, Ecosystems &
Environment, 87, 51–65.
Edwards W (2009) Estimating Farm Machinery Costs. IA State website http://www.extension.iastate.edu/agdm/crops/html/a3-29.html.
EPA (2008) Direct Emissions from Stationary Combustion Sources. Climate Leaders GHG
Inventory Protocol, EPA, USA.
Federal Reserve Bank of St Louis (2014) Discount rate for China.
http://research.stlouisfed.org/fred2/series/INTDSRCNM193N.
French BC (1960) Some considerations in estimating assembly cost functions for agricultural
processing operations. Journal of Farm Economics, 62, 767–778.
Hammond J, Shackley S, Sohi S, Brownsort P (2011) Prospective life cycle carbon abatement
for pyrolysis biochar systems in the UK. Energy Policy, 39, 2646–2655.
Hill N, Venfield H, Dun C, James K (2013) Government GHG Conversion Factors for
Company Reporting : Methodology Paper for Emission Factors. London, UK.
Jiang D, Zhuang D, Fu J, Huang Y, Wen K (2012) Bioenergy potential from crop residues in
China: Availability and distribution. Renewable and Sustainable Energy Reviews, 16,
1377–1382.
Knoblauch C, Maarifat A-A, Pfeiffer E-M, Haefele SM (2011) Degradability of black carbon
and its impact on trace gas fluxes and carbon turnover in paddy soils. Soil Biology and
Biochemistry, 43, 1768–1778.
Lehmann J, Gaunt J, Rondon M (2006) Bio-char Sequestration in Terrestrial Ecosystems – A
Review. Mitigation and Adaptation Strategies for Global Change, 11, 395–419.
Li X, Wang S, Duan L, Hao J, Li C, Chen Y, Yang L (2007) Particulate and trace gas
emissions from open burning of wheat straw and corn stover in China. Environmental
science & technology, 41, 6052–8.
Lombardi L (2003) Life cycle assessment comparison of technical solutions for CO2
emissions reduction in power generation. Energy Conversion and Management, 44, 93–
108.
Lu W, Zhang T (2010a) Life-cycle implications of using crop residues for various energy
demands in China. Environmental science & technology, 44, 4026–32.
Lu W, Zhang T (2010b) Supporting Information: Life-cycle implications of using crop
residues for various energy demands in China. Environmental Science and Technology,
1–62.
Mann MK, Spath PL (1997) Life Cycle Assessment of a Biomass Gasification Combined
Cycle System. National Renewable Energy Laboratory, Task No. BP811030, Golden,
Colorado.
McCarl BA, Peacocke C, Chrisman R, Kung C-C, Sands R. (2009) Economics of biochar
production, utilization and greenhouse gas offsets. In: Biochar for Environmental
Management - Science and Technology, pp. 341–357.
McKendry P (2002) Energy production from biomass (Part 1): Overview of biomass.
Bioresource technology, 83, 37–46.
Quaak P, Knoef H, Stassen H (1999) Energy from biomass: A review of combustion and
gasification technologies. World Bank Technical Paper No. 422. The World Bank,
Washington D.C.
Roberts KG, Gloy B, Joseph S, Scott NR, Lehmann J (2010) Life cycle assessment of biochar
systems: estimating the energetic, economic, and climate change potential.
Environmental science & technology, 44, 827–33.
Saft RJ (2007) LCA Case Studies Life Cycle Assessment of a Pyrolysis / Gasification Plant
for Hazardous Paint Waste. Hazardous Paint Waste, 12, 230–238.
Scarlat N, Martinov M, Dallemand J-F (2010) Assessment of the availability of agricultural
crop residues in the European Union: potential and limitations for bioenergy use. Waste
management (New York, N.Y.), 30, 1889–97.
Singh N, Abiven S, Torn MS, Schmidt MWI (2012) Fire-derived organic carbon in soil turns
over on a centennial scale. Biogeosciences, 9, 2847–2857.
Thomsen T, Hauggaard-nielsen H, Bruun EW (2011) The potential of Pyrolysis Technology
in climate change mitigation Risø-R-Report, Vol. 1764. National Laboratory for
Sustainable Energy, Roskilde Denmark.
Trading Economics (2014) China Interest Rate.
http://www.tradingeconomics.com/china/interest-rate.
UK Ministry of Defence (2014) Technology Readiness Levels (TRLs) in the Project
Lifecycle.
http://www.publications.parliament.uk/pa/cm201011/cmselect/cmsctech/619/61913.htm
#note221.
Wang M (2008) Greenhouse gases, regulated emissions, and energy use in transportation
(GREET) model, 1.8b. UChicago Argonne, LLC: Chicago, IL.
Wang Q, Geng C, Lu S, Chen W, Shao M (2013) Emission factors of gaseous carbonaceous
species from residential combustion of coal and crop residue briquettes. Frontiers of
Environmental Science & Engineering, 7, 66–76.
Weifang Naipute Gas Genset Co. Ltd. (2014) 35kW DEUTZ syngas Generator Quotation.
Weifang Website - www.wfnpt.com.cn/www.wfnpt.com.
Woolf D, Amonette JE, Street-perrott FA, Lehmann J (2010) Sustainable biochar to mitigate
global climate change: Supplementary information. Nature communications, 1, 1–42.
World Bank (2014) Pump price for diesel fuel (China). Web page:
http://data.worldbank.org/indicator/EP.PMP.DESL.CD.
World Resources Institute (2014) Getting every ton of emissions right.
http://www.wri.org/sites/default/files/calculation_spreadsheet_of_china_regional_grid_
emission_factors.xlsx.
Zhang J, Smith K., Ma Y et al. (2000) Greenhouse gases and other airborne pollutants from
household stoves in China: a database for emission factors. Atmospheric Environment,
34, 4537–4549.
Zhang Q, Zhou D, Fang X (2014) Analysis on the policies of biomass power generation in
China. Renewable and Sustainable Energy Reviews, 32, 926–935.
Zhao G, Che K (2012) A Study on Predicting Coal Market Price in China Based on Time
Sequence Models. International Journal of Business and Social Science, 3, 31–36.