Should China support the development of biomass power generation?

Accepted Manuscript Should China support the development of biomass power generation?

Jiaxin He, Ying Liu, Boqiang Lin PII:

S0360-5442(18)31672-4

DOI:

10.1016/j.energy.2018.08.136

Reference:

EGY 13612

To appear in:

Energy

Received Date:

05 March 2018

Accepted Date:

19 August 2018

Please cite this article as: Jiaxin He, Ying Liu, Boqiang Lin, Should China support the development of biomass power generation?, Energy (2018), doi: 10.1016/j.energy.2018.08.136

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Should China support the development of biomass power generation?

4 5 6

Jiaxin He a

Ying Liu b

Boqiang Linc, *

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a School of Economics, China Center for Energy Economics Research, Xiamen

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University, Xiamen, Fujian, 361005, PR China.

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b Institute of Economic, Chinese Academy of Social Sciences, Beijing 100836, PR China

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c School of Management, China Institute for Studies in Energy Policy, Collaborative

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Innovation Center for Energy Economics and Energy Policy, Xiamen University,

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Xiamen, Fujian, 361005, PR China

14 15 16

*Corresponding author at: School of Management, China Institute for Studies in

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Energy Policy, Collaborative Innovation Center for Energy Economics and Energy

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Policy, Xiamen University, Xiamen, Fujian, 361005, PR China

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Tel.: t86 5922186076; fax: t86 5922186075.

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E-mail addresses: [email protected], [email protected] (B. Lin)

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Abstract: Compared with wind and solar power, biomass power has grown relatively slowly in

2

China. With abundant biomass resources, the development of biomass electric power in China has

3

potential advantages. This paper analyzed the environmental impact of biomass power in the

4

construction and operation stages in comparison with wind and solar power. The results showed

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that biomass power produced relatively less emissions in the system construction stage at around

6

1700 ton CO2-e/MW. In the operation stage, biomass power projects achieved an average of 131462

7

ton CO2-e per year, which is greater than wind and solar power of equal installed capacity. Biomass

8

power plants could achieve net emission reductions in a shorter time (0.39 year) after operation. The

9

life cycle GHG emissions of biomass power projects are between 42-85 g CO2-e/kWh. The evidence

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pointed out that biomass power is worth supporting in China, from the perspective of environmental

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performance. Local governments should promote the sustainable supply of biomass materials and

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the development of renewable energy industry should depend on local conditions.

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Key words:

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power;

15

1. Introduction

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Biomass power generation is an important source of renewable energy, due to its abundance and

17

environmental friendliness [1].After the enactment of renewable energy law in 2006, the biomass

18

power industry in China has experienced a moderate growth. However, in comparison with wind

19

and solar power, biomass power has grown relatively slowly and received less attention [2, 3].

Economic input-output LCA; environmental impact; emission reduction; biomass

160000 Wind power

140000

Solar power

Unit:MW

120000

Biomass power

100000 80000 60000 40000 20000

20 21

0 2007

2008

2009

2010

2011

2012

2013

2014

2015

Year

2016

Fig.1 The installed capacity of renewable energy in China

22

Over the last decade, wind and solar power installation (or development) have rapidly outpaced

23

biomass power (Fig.1). In recent years, wind and solar power have increased considerably over the 2

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last decade and played increasingly important roles in China’s power sector. However, increasing

2

the supply of intermittent energy resources (wind and solar power) to the electricity grid is also a

3

challenge [4]. Therefore, biomass power is the only source of continuous electricity supply among

4

the three main non-hydropower renewable sources (solar, wind and biomass). From the point of

5

view of biomass supply, there are abundant biomass materials available for electricity generation in

6

China. According to Qin et al.[5], it is estimated that about 280 million metric tons (Mt) of crop

7

residue-based biomass are available in China. The results of Chen [6] indicated that with various

8

exogenously-given biomass prices, China can potentially produce about 174–249 million dry metric

9

tons of crop residues. These estimates were only for crop residues. The total volume for agricultural

10

and forest residues will be higher. In 2016, all biomass power plants in China only consumed 45.7

11

million metric tons (Mt) of agricultural and forest residues. Given the potential of energy crops in

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the future, there is no material limitation to the development of biomass power in China.

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Being the largest greenhouse gas emitter in the world, China is facing increasing pressure and

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has strong determination on emission reductions[7]. Unlike intermittent renewable energy sources

15

such as wind power and solar power, biomass power can provide a continuous source of electricity

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and flexibly change their output as balancing capacity. As a large agricultural country, the

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development of biomass power in China has potential advantages. It can economically benefit

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agricultural communities and increase the income of farmers. Meanwhile, the effective utilization

19

of agricultural and forest residues lead to environmental improvement in rural areas. According to

20

the above analysis, we can conclude that the development of biomass power has many social

21

benefits and no material limitations. Being a large country, climate, land cover, geomorphology and

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other factors vary across regions in China and hence biomass materials vary from region to region.

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There are abundant straw resources in some provinces with large crop planting areas, whereas

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forestry residues are a major source of raw biomass materials in mountainous provinces. However,

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due to long-standing prevalence and the political and economic power of the fossil-fuel industry,

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explicit policies are needed for renewable energy sources to substantially displace fossil energy

27

sources [8]. The supply of biomass material also needs to be supported to develop biomass power

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generation. If biomass power has relatively less environmental impacts and more emission

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reductions compared with other renewable energy sources, then the government should pay more

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attention to and support the improvement of the competitiveness of biomass power enterprises. In 3

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other words, biomass power is worth supporting in China. Thus, this paper aims to assess the

2

environmental impacts and emission reductions potentials of biomass power compared with wind

3

and solar power in order to answer the question of whether biomass power is a good choice for

4

China from the perspective of environmental impacts.

5

The rest of the paper consists of the following: Section 2 is literature review. Section 3 describes

6

the data and methodology. Section 4 presents the results and discussion. Finally, Section 5 concludes

7

the study with some policy implications.

8

2. Literature review

9

With the development of biomass industry in China, many scholars have studied it from different

10

perspective. The techno-economic feasibility, such as energy production and the levelized cost of

11

electricity is the most studied aspect of biomass power [10]. Ouyang and Lin[11] estimated the

12

levelized cost of biomass electricity in China and found that the high cost could be addressed by

13

providing subsidies in the short term. Except for economic cost, the resources, scale, market

14

operation, profitability and policies for China’s biomass power were also analyzed and investment

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risks in the current situation discussed[12]. Raw material supply, low feed-in tariff, and the poor

16

ability of technical research are obstacles that impede the development of biomass power in

17

China[13]. Meanwhile, there are also problems of supporting policies, such as over-ambitious

18

development goal, and difficulty in implementing tax policies[14]. To assess the impact of policies

19

on biomass power in China, Zhang et al.[15] established system dynamics models and the results

20

showed that the implementation of renewable portfolio standard promotes long-term and rapid

21

development of China's biomass power industry. Unlike other renewable energy sources, the

22

operation of biomass power requires the supply of biomass materials. The lack of biomass materials

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has hindered the development of biomass power. Based on investigation in northeast China, Wang

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and Watanabe [16] pointed out that most farmers are more concerned with personal risks on straw

25

supply activities and should be motivated to cooperate with straw procurers. Some optimization

26

models have also been proposed to handle issues of operational design of biomass power. Using a

27

nonlinear multi-objective optimization model, Tan et al.[17] estimated the optimal quantity of

28

electricity generation, the ideal blending ratio, acquisition quantity and price of each kind of fuel to

29

maximize the profit margins of biomass power plants. Similarly, integrating the economic and

30

environmental dimensions, Zhao and Li [18] developed an integer programming model for optimal 4

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locations and corresponding feedstock supply chain designs of biomass power plants. Gosens [2]

2

calculated the Net Present Value of new investments and the appropriate level of Feed-in-Tariff to

3

promote the development of biomass power.

4

The utilization of biomass in power plant can reduce uncontrolled open burning and reduce GHG

5

emissions. Shafie et al.[19] found that that rice straw power generation reduces about 1.79 kg CO2-

6

e/kWh of GHG emissions compared to coal. Life cycle assessment (LCA) is a common way to

7

evaluate the environmental impacts of biomass power. Life cycle assessment (LCA) is a systematic

8

tool, which is widely recognized as a useful framework that can be used to analyze and assess

9

environmental impacts over the entire life cycle of a product [20]. There are basically two categories

10

of life cycle assessment methodologies: the conventional process-based LCA and the input-output

11

based LCA. The former stresses energy and material flow in a manufacturing process, and the latter

12

links environmental data to the manufacturing process[21]. Process-based LCA can provide

13

relatively highly accurate inventory estimates for more recent data and definite system

14

boundaries[22]. Therefore, Process-Based LCA results are detailed and convenient for comparison

15

of specific products [23]. However, Process-Based LCA requires a great deal of primary data

16

collection and step-by-step tracking of each process, which tends to be time intensive and costly[24].

17

The unavailability of detailed data is a common problem for the analysis of renewable energy in

18

developing countries. Meanwhile, process-based LCA is difficult to define the system boundary

19

which may lead to a situation where upstream emissions are not captured [25]. In comparison with

20

process-based LCA, economic input-output LCA (EIO-LCA) model is a top down approach, which

21

relies on national input–output tables that present monetary values transactions among different

22

sectors of the whole economy [26]. Therefore, it makes upstream processes almost complete for the

23

nation or region, while reducing the problem of subjective boundary definition[27]. The EIO-LCA

24

method was theorized and developed by Wassily Leontief, and has been further enriched by

25

Carnegie Mellon University[28]. The results of EIO-LCA method are economy-wide,

26

comprehensive assessments and allowed for systems-level comparisons[23]. Although, the system

27

boundary of EIO-LCA is theoretically complete, it still has several inevitable drawbacks. One of

28

them is that it only provides Life Cycle Inventory(LCI) for pre-consumption stages of the product’s

29

life cycle [29]. For example, Zhang et al. [30] used Economic Input-Output Life Cycle Assessment

30

(EIO-LCA) model to calculate the energy consumption of several wind power plants in China 5

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during the construction stage. Considering the strengths of both methods, linking process-based and

2

IO-based analysis is introduced as hybrid method in some studies. A typical example is the tiered

3

hybrid analysis, which can be performed by adding IO-based LCIs to the process-based LCI

4

result[29]. Different methods of LCA have different advantages depending on what the process is.

5

Meanwhile, the availability of data sources is also involved in the evaluation of the choice of method.

6

Using Life cycle assessment method, Dias et al.[31] showed that direct combustion of short-

7

rotation willow in Canada reduced global warming potential (GWP) by almost 85% relative to the

8

fossil fuels. Similarly, Wang et al. [32] used a tiered hybrid life cycle assessment(LCA) model to

9

calculate the energy consumption, greenhouse gas emissions, and economic cost and profit of the

10

Salix direct-fired power generation system in Inner Mongolia, and found that the GHG emissions

11

of Salix is 114gCO2-eq/kWh. Biomass power has the potential to significantly reduce GHG

12

emissions but different biomass-to-energy conversion technologies may have environmental

13

impacts. Costa et al.[33] studied two biomass power technologies - Grate furnace vs. fluidised bed

14

furnace - from the combustion of residual forest biomass in Portugal using life cycle assessment.

15

The GHG emissions of biomass power are sensitive to moisture content and plant lifetime. The

16

results of the life-cycle assessment of Thakur et al. [34] showed that the GHG emissions of power

17

generation from forest biomass are 19.5~22.2 gCO2-eq/kWh. Compared with biomass power using

18

agricultural and forestry residues, life cycle GHG emissions from municipal solid waste (MSW)

19

incineration are generally high. Song et al.[35] indicated that the mean GHG emissions of electricity

20

production from MSW incineration in Macau is 950 g CO2-eq per kWh. More specifically, Kadiyala

21

et al.[36] reviewed few studies on the statistical evaluation of the life cycle GHG emissions

22

(expressed in grams of carbon dioxide equivalent per kilowatt-hour, gCO2e/kWh) of biomass

23

electricity generation systems. The results showed that the mean life cycle GHG emissions resulting

24

from the use of agriculture residues, dedicated energy crops, forestry, industry, and wastes in

25

biomass-only electricity generation systems are 291.3 gCO2e/kWh, 208.4 gCO2e/kWh, 43

26

gCO2e/kWh, 45.9 gCO2e/kWh, and 1731.3 gCO2e/kWh, respectively.

27

Based on the previous studies on biomass power in China, we found that most studies are focus

28

on the resources, cost control, market operation, development obstacles, related supporting policies

29

and decision optimization. The study of life cycle assessment of biomass power in China is not

30

broadly established. There are significant differences in the GHG emissions of biomass power 6

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systems according to biomass combustion technology and materials. Few studies have analyzed

2

whether biomass power is an effective way to mitigate emissions from the perspective of the net

3

emission reductions effect, compared with other renewable energy sources. Currently, government

4

supports are required for most renewable energy sources. As a developing country, subsidies may

5

pose a financial burden with more renewable energy generation. The main objective of developing

6

renewable energy is to reduce emissions. However, the development of renewable energy may also

7

lead to negative environmental impacts, such as the greenhouse gas emissions resulting from the

8

construction stages. It is meaningful to determine which renewable energy can provide more energy

9

supply while having less environmental impacts. Considering the development of biomass power is

10

far behind wind and solar power. Therefore, it is important to answer the question of whether

11

biomass power is a cost-effective way to mitigate emissions and merits more support. Meanwhile,

12

biomass power is also an effective way of using agricultural and forest residues. If these residues

13

are not treated properly, negative environmental impacts, such as uncontrolled straw burning, may

14

result. Hence, the study of biomass power in China is also significant in other domains, such as

15

waste management and rural environment.

16

3. Data and methodology

17

The main objective of this paper is to investigate the environmental impacts of biomass power,

18

wind power and solar power. As China is a very large country, there are big differences across

19

regions. For biomass power, the type of biomass materials used in power plants differs across

20

regions. For solar power, solar energy intensity varies geographically within China. Wind energy

21

intensity is also different across the country. Meanwhile, it is very hard to obtain data of all biomass

22

power plants in China. Therefore, representative biomass power plants were selected to analyze the

23

environmental impacts and emission reduction effects, rather than the whole industry. Then several

24

nearby wind and solar power plants were chosen as comparison power plants.

25

In China, there are four wind resource zones divided according to wind energy intensity. Wind

26

resource zone Ⅰ has the most abundant wind resources within China. On the contrary, wind

27

resources in zone Ⅳ are poor compared to other zones. Government’s subsidy for different zones

28

is not the same. Similarly, there are three solar resource zones in China. Different from wind and

29

solar resource zones, the support of the central government for biomass power is basically the same

30

across the country. 7

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In order to compare the cost-effectiveness of the three renewable energy sources, several

2

renewable power projects from different regions were selected to assess the environmental impacts

3

and emission reductions effects. The information on renewable power projects is given in Table 1

4

and 2. The location of each power project and the distribution of Wind and Solar resource zones are

5

presented in Fig 2 and Fig 3. Data on biomass power projects in Wind resource zone Ⅰ and Solar

6

resource zone were not available, because these regions are mostly desert and grassland. They do

7

not have adequate biomass fuels for biomass power projects. The data of all power projects were

8

obtained from the database of United Nations Framework Convention on Climate Change

9

(UNFCCC).

10

Table.1 Biomass and wind power projects analyzed in the analysis wind power plant wind zone I

HelinShimenzi

-

wind zone II

FengningWanshengyong

Pingquan

wind zone III

wind zone IV Offshore wind power

11 12

Lingwu

Tianshui Kaidi

Raohe Dadingzi

Youyi

Longyuan Dagang

Pizhou

SuizhouSister Mountain

ShishouYueneng

Rudong Chaojiandai

Date sources: the database of United Nations Framework Convention on Climate Change (UNFCCC); the database of National Renewable Energy Information Management Centre in China.

13

Table.2 Biomass and solar power projects analyzed in the analysis

solar zone I

solar zone II

solar zone III

14 15

biomass power plant

solar power plant

biomass power plant

Jinta

Pingquan

Jingneng Beijing Badaling

TianshuiKaidi

Gonghe

Youyi

Huadian Shangde Dongtai

Pizhou

Wuhan

ShishouYueneng

Date sources: the database of United Nations Framework Convention on Climate Change (UNFCCC); the database of National Renewable Energy Information Management Centre in China.

8

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1 2 3 4

5 6 7 8 9 10 11 12 13 14 15

Figure.2 The distribution of wind power resources in China

Figure.3 The distribution of solar power resources in China

9

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Table 3. Basic information on renewable energy power projects

Projects

Installed

Static

capacity(MW)

investment (million RMB )

2 3

Annual operation

Operational

hours

lifetime years

Annual power supply (MWh)

Pingquan

30

266.07

6,000

20

158,400

TianshuiKaidi

30

311.08

6,500

20

171,600

Biomass

Youyi

30

350.35

6,462

20

150,150

Power

Pizhou

30

298.39

7,000

20

185,850

ShishouYueneng

30

289.41

6,500

20

167,700

HelinShimenzi

49.5

488.18

2,438

20

120,680

FengningWanshengyong

150

1423.09

2,218

20

332,758

Wind

Lingwu

49.5

435.58

1,954

20

96,723

power

RaoheDadingzi

49.5

498.14

2,257

20

111,726

LongyuanDagang

49.5

448.10

1,940

20

96,050

SuizhouSister Mountain

49.8

526.86

1,868

20

93,026

Rudong Chaojiandai

49.5

761.19

2,635

20

130,440

Jinta

40

761.80

1,423

25

62,302

Solar

Jingneng Beijing

31.08

698.17

1,146

25

35,620

Power

Gonghe

30

429.38

1,647

25

49,346

HuadianShangdeDongtai

20

382.85

1,111

25

22,219

Wuhan

2.2

69.10

913

25

2,012

Date sources: the database of United Nations Framework Convention on Climate Change (UNFCCC); the database of National Renewable Energy Information Management Centre in China.

4 5

The installed capacity of all biomass power projects is 30MW, which is also the most common

6

capacity of biomass power in China (Tab.3). The basic information of each renewable power project

7

used in this analysis is provided. Although the installed capacity of each project is the same, the

8

total static investments are different. For instance, the investment on Pingquan project is 266.07

9

million RMB, whereas that of Youyi project is 350.35 million RMB. The reasons for the difference

10

in the investment cost may be equipment or land acquisition. There are also differences in the annual

11

power supply, which is more likely dependent on the annual operation hours. Pizhou project, with

12

the most annual operation hours, has the maximum annual power supply among the five projects.

13

Compared with biomass power projects, the installed capacity of wind power projects are relatively

14

large, and have more investment that is static. However, the annual power supply of biomass power

15

projects are larger than wind power projects given the same installed capacity. This is because the

16

average annual operation hours of biomass power projects are higher than wind power. This

17

phenomenon was also observed when compared with solar power. Generally, the land requirement 10

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of a solar power system is larger. Due to its strong influence on the choice of the site and the scale,

2

the installed capacities of solar power plants differ from others.

3

The biomass power industry is still in its infancy stage, compared to other traditional power

4

technologies. Some power technologies associated with biomass are still being developed in co-

5

fired and direct-fired combustion for electricity generation[37]. In China, biomass gasification

6

power generation and co-fired with conventional fuels are less used in practice. Most biomass power

7

projects in China are biomass direct-fired combustion systems. Therefore, all the five biomass

8

power projects in this paper are biomass direct-fired combustion systems with the similar

9

technology and equal installed capacity. The main equipment of these projects are high-temperature

10

boilers, high-pressure steam turbines and associated generators. In this power system, the heat is

11

generated in the boiler and transferred to the steam turbine.

12

the generator to generate electricity, which is finally connected to the local grid1.

After, the steam will be inputted to

13

Although the installed capacity and technology of these biomass power projects are similar, the

14

type and manufacturers of key equipment are different, as well as the annual biomass consumption

15

and gross electricity generation (Tab.4).

16

Table 4. The additional information of biomass power projects Biomass power

Biomass residue type

plant

maize stalks, waste tree

Gross electricity generation （MWh）

Self-consumption rate (%)

68.49

180,000

12

225,410

74.2

195,000

12

maize stalks, rice straw

151,600

62.79

168,200

11.7

wood residues, wheat straw and

260,000

79.91

210,000

11.5

262,276

74.2

195,000

14

wheat Straws, corn Straws, forestry Residues

Youyi

maize stalks rice straw, rape residues, cotton

g

17

factor (%)

branches

TianshuiKaidi

ShishouYuenen

consumption(ton/year)

Load

210,000

Pingquan

Pizhou

Annual biomass

residues, wood residues

Date sources: the database of United Nations Framework Convention on Climate Change (UNFCCC);

18 19

Currently, renewable energy generations such as biomass, wind, and solar power are all at their

20

initial stages in China. Most renewable energy projects in China have not reached decommission

21

stage. Therefore, only system construction and operation stages were considered in this paper. The

1 Date sources: the database of United Nations Framework Convention on Climate Change (UNFCCC); PROJECT DESIGN DOCUMENT

OF BIOMASS POWER

11

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emissions in the operation stage of each renewable energy project was obtained from in the database

2

of the United Nations Framework Convention on Climate Change (UNFCCC). For biomass power,

3

emissions in the operation stage include emissions due to fossil fuel consumption, emissions from

4

the combustion of biomass residues, emissions due to transport of the biomass residues to the project

5

plant, emissions from wastewater generated from the treatment of biomass residues and etc. Based

6

on the previous literature review, we found that different methods have potential advantages and

7

disadvantages. Considering the data limitation and the advantages of Economic Input-Output Life

8

Cycle Assessment (EIO-LCA) in the construction stage, EIO-LCA method was chosen to estimate

9

the emissions of renewable energy projects in the construction stage.

10 11

To derive the EIO-LCA method, we first consider the standard input–output model proposed by

12

Leontief [38].

13 14

(1)

X = AX + Y Where X is the vector of total outputs of the sectors, Y is the final demand vector,

15

A is the direct input coefficients matrix and each element aij is the amount of input required from

16

sector i(i=1,2,…n) to produce per unit output of sector j(j=1,2,…n). Equation (1) can be transformed

17

into equation (2).

18 19

X = (I ‒ A)

-1

Where I is the identity matrix and (I ‒ A)

(2)

Y -1

is the Leontief inverse matrix.

20 21

The input-output technique can be extended for environmental analysis by assuming that the

22

environmental impacts generated by an industry is proportional to its output level, and the identity

23

of the environmental impacts and the ratio between them are fixed[20, 29].

24 25 26

Then according to the EIO-LCA model proposed by Hendrickson et al [23], the total (direct and indirect) environmental burden associated with an exogenous demand vector is as follows: e = R [I – A]

-1

(3)

f

27

Where R is a k × n matrix of environmental intervention coefficient showing the amount of

28

emissions or natural resources consumed when producing unit output of each sector. For example,

29

element Rkj of matrix R represents environmental burden k (such as carbon monoxide emissions)

30

per unit output of sector j. The environmental intervention coefficient matrix can include coefficient 12

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vectors for any environmental impact of interest, such as energy consumption, carbon dioxide

2

emissions, etc [20]. The f is a vector that shows the industry output of the system investigated. e is

3

a k × 1 vector that shows the total direct and indirect environmental impact vector of the system

4

investigated. In this paper, we considered three kinds of emissions, which are carbon dioxide (CO2),

5

methane (CH4), and nitrogen monoxide (N2O). This is to achieve comparability of environmental

6

impacts estimated in this stage with that of the operation stage. The project emissions in the

7

operation stage include CO2, CH4, and N2O emissions. In this case, k equals to 3.

8

The Leontief inverse matrix [I – A]

-1

was computed from China’s input–output tables. The

9

vector f for each renewable project system was obtained from the database of the UNFCCC. The

10

complicated part is to calculate the matrix of environmental intervention coefficient R. In other

11

words, we need to estimate CO2, CH4, and N2O emissions per unit output of all sectors in the

12

economy. Therefore, for each sector, we calculated all kind of energy consumption such as coal,

13

oil, etc. The total emissions of each sector was estimated by multiplying energy consumption with

14

the emission factors.

15

The detailed data of energy consumption and production of energy sectors was obtained from

16

China’s Energy Statistical Yearbooks. Data of intermediate energy inputs and outputs for other non-

17

energy sectors is calculated using the method of weighted average energy prices. The weighted

18

average energy prices for non-energy sectors are calculated as follows [39, 40]:

19 20

Pej =

Xj - EXj + IMj - Yj - ∑Xm,j Ejs - EjY - ∑Em,j

(4)

21 22

The Xj from equation 4 is the total output of the energy sector j. The EXj and IMj are the exports

23

and imports of sector j. The Yj is the final demand of sector j whereas ∑Xm,j is the intermediate

24

inputs from sector j to other energy sectors. In addition, Ejs is the total consumption of energy

25

product from sector j, EjY is the energy consumption for final consumption, ∑Em,j refers to

26

intermediate energy inputs from sector j to other energy sectors and Pej is the weighted price of

27

energy sector j for non-energy sectors. For example, when energy sector j refers to oil product sector,

28

Pej is the average price of oil products provided to other non-energy sectors.

29

Therefore, the energy consumption of non-energy sectors is calculated as follows: 13

ACCEPTED MANUSCRIPT Xji

1

(5)

Eji = P

ej

2

Where Xji is the monetary input from energy sector j to non-energy sector i, Pej the weighted price

3

of energy sector j for non-energy sectors, Eji is energy consumption from energy sector j to non-

4

energy sector i.

5

According to this method, all kind of energy consumption of each non-energy sector can be

6

estimated. With the help of emission factors, the total emission of all sectors were calculated. The

7

emission factors are obtained from [41]. In the results, the emissions of CH4 and N2O were converted

8

into CO2 equivalents. The China’s input-output table is published every five year. Therefore, the

9

input-output table used in this paper was the 2012 input–output tables published by China’s National

10 11 12 13 14

Bureau of Statistics.

4. Results and discussions Table.5 Emissions in construction stage of power projects

Projects

Biomass power

Wind power

Solar power

15 16

Installed capacity (MW)

Total emissions(direct and indirect) (ton CO2e)

Emissions per installed capacity (ton CO2-e /MW)

Pingquan

30

49,697

1,657

TianshuiKaidi

30

53,075

1,769

Youyi

30

52,518

1,751

Pizhou

30

53,320

1,777

ShishouYueneng

30

50,926

1,698

HelinShimenzi

49.5

110,714

FengningWanshengyong

150

309,277

2,062

Lingwu

49.5

100,858

2,038

2,237

RaoheDadingzi

49.5

110,204

2,226

LongyuanDagang

49.5

93,212

1,883

SuizhouSister Mountain

49.8

109,780

2,204

Rudong Chaojiandai

49.5

119,077

Jinta

40

177,204

4,430

Jingneng Beijing

31.08

130,848

4,210

Gonghe

30

102,838

3,428

HuadianShangdeDongtai

20

82,689

4,134

Wuhan

2.2

10,177

4,626

2,406

Date sources: the database of United Nations Framework Convention on Climate Change (UNFCCC); the database of National Renewable Energy Information Management Centre in China.

17

The emissions of each renewable power project during the construction stage were estimated

18

according to the methodology mentioned above. For these biomass power projects, we found that 14

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although the installed capacity of each project is the same, the total emissions in the construction

2

stage were different(Tab.5). Pingquan project, with the smallest investments, had the lowest

3

emissions of all five projects. This may be due to the less equipment and other inputs required

4

for the project. The last column of table 5 gives the emissions per installed capacity, which were

5

around 1700 ton CO2/MW for biomass power. The unit emissions of biomass power projects

6

during the construction stage were not significantly different. This indicated that the construction

7

of biomass power projects in different regions may have similar environmental impacts. The total

8

emissions of the five biomass projects were around 50000 ton CO2. It seems that the

9

environmental impacts of biomass power in the construction stage were not significant. A

10

comparison of biomass with wind and solar power was provided to give more insights.

11

The total emissions of wind power plants in the construction stage are provided in the middle

12

of table 5. The biggest project, Fengning Wanshengyong, generated the most emissions. Rudong

13

Chaojiandai, the offshore project, had more investments than other onshore projects with the same

14

installed capacity. Its total emissions were also greater than other onshore wind power projects.

15

This may be because offshore wind power generally requires more equipment inputs. The

16

emissions per installed capacity of Rudong Chaojiandai are 2406 ton/MW, which is greater than

17

that of all other wind power projects. By comparing biomass and wind power, we found that the

18

emissions per installed capacity of wind projects were greater than all the biomass power projects.

19

In other words, the construction of wind power project will generate more emissions than biomass

20

projects.

21

The bottom part of the table presents the total emissions of solar power projects in the

22

construction stage. Unlike biomass power projects, the installed capacity of the solar power

23

projects differs much from one another. Therefore, there are significant differences in the total

24

emissions of the five solar power projects. Similar to wind power, the total emissions during the

25

construction stage of solar power are greater than biomass power given the same installed

26

capacity. The comparison of the emissions in the construction stage of biomass, wind and solar

27

power is provided in the last column of table 5. We found that the emissions per installed capacity

28

of solar projects were greater than that of wind projects, and that of wind projects were greater

29

than that of biomass projects. For example, the emissions per installed capacity of Pizhou biomass

30

project were 1777 ton CO2, and is the largest among the five biomass projects. However, it is still 15

ACCEPTED MANUSCRIPT 1

less than the emissions per installed capacity of Longyuan Dagang wind project, which is the

2

smallest among the wind projects. Similarly, the emissions per installed capacity of Rudong

3

Chaojiandai wind project, which was the largest among the wind projects (2406MW/ton CO2),

4

were still lower than the smallest of the solar projects, Gonghe(3428MW/ton CO2). According to

5

the analysis above, we can conclude that the environmental impacts of solar power in the

6

construction stage are largest, followed by wind power while the environmental impact of

7

biomass power is the smallest. This is only in the construction stage and more information about

8

the operation stage should be taken into consideration to provide a comprehensive assessment.

9

The next part will focus on the operation stage of each renewable power project.

10 11

Table.6 Annual project emissions and emission reductions of power plants in operation stage Baseline emissions

Emission reductions (ton CO2-e)

134,605

13,501

121,104

TianshuiKaidi

153,688

12,605

141,083

Youyi

145,420

6,271

139,149

Pizhou

147,891

8,647

139,244

ShishouYueneng

130,919

14,188

116,731

HelinShimenzi

108,105

5,536

102,569

FengningWanshengyong

298,117

15,464

282,653

Lingwu

75,856

5,043

70,813

Pingquan

Biomass power

wind power

Solar power

12 13 14

Project emissions (ton CO2-e)

Projects

(ton CO2-e)

RaoheDadingzi

107,648

5,510

102,138

LongyuanDagang

76,167

4,661

71,506

SuizhouSister Mountain

81,588

5,489

76,099

RudongChaojiandai

103,438

5,954

97,484

Jinta

55,844

7,088

48,756

Jingneng Beijing

31,911

5,234

26,677

Gonghe

47,311

4,114

43,197

HuadianShangdeDongtai

18,762

3,308

15,454

Wuhan

1,990

407

1,583

Date sources: the database of United Nations Framework Convention on Climate Change (UNFCCC); the database of National Renewable Energy Information Management Centre in China.

15

In the operation stage of each project, we mainly focused on the annual project emissions,

16

including the annual baseline emissions, the project emissions and the emissions reductions (Tab.6).

17

Renewable energy projects reduce emissions through substitution of fossil fuels power generation

18

by renewable energy generation. The baseline emissions refer to the emissions in the baseline 16

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scenario of the proposed project. In other words, it is the emissions in the absence of the proposed

2

project activity. For biomass power projects, this consists of two kinds of emissions. The first is the

3

emissions from grid-connected fossil fuel power plants. The second is the emissions from dumping

4

and decay of biomass residues on fields or burnt in an uncontrolled manner. For wind and solar

5

power projects, the baseline emissions only include the first source of emissions. Detailed

6

information can be found on the website of UNFCCC2. There are two sources of emissions in the

7

project operation stage. The first is the embodied CO2 emission from the construction stage, which

8

amortised over the lifetime of each project. The second is the emissions generated in electricity

9

production. Then the emission reduction of each renewable project equal to the baseline emissions

10

minus the project emissions.

11

For biomass power, although installed capacity is the same, the project emissions differed. For

12

example, the project emissions of Youyi project were much less than that of Shishou Yueneng

13

project. One reason may be the lower annual operation hour of the former. A second reason may be

14

due to transport of the biomass residues to the project plant. The annual emissions of Youyi project

15

caused by biomass transportation to the power plant was only 500 ton CO2, whereas that of Shishou

16

Yueneng was 6426 ton CO2. The last column presents the annual emission reduction of each

17

biomass power project. It can be seen that all biomass projects had a relatively high emission

18

reductions potential, which were more than 110000 ton CO2 per year.

19

Except for Fengning Wanshengyong project, the installed capacities of other wind projects are

20

about 50MW. However, the annual emission reductions of these projects were much less than the

21

five biomass projects, with installed capacity of 30MW. The main reason may be that the annual

22

operating hour of biomass power is greater than that of wind power. Similarly, the emission

23

reductions of solar power projects are also smaller than biomass power projects. From the

24

perspective of annual emission reductions, biomass power can achieve more emission reductions

25

compared with wind and solar power. This indicates that the current biomass power industry in

26

China has relatively high operating efficiency.

27

2

http://cdm.UNFCCCc.int/ 17

ACCEPTED MANUSCRIPT

1 2

Fig 4. The time of achieving net emission reductions of each project after operation

3

Next, we combined the construction and operation stage to investigate how long it will take for

4

each project to achieve net emission reduction. To do this, we divided the total emissions in the

5

construction stage of each project by the respective annual emission reductions. Note that in this

6

case, the emissions from construction were not amortised over the lifetime, and the emissions in

7

construction stage and operation stage were separately considered. The result of biomass projects

8

were all less than 0.5 (average value is 0.39 year), which means that the biomass projects can achieve

9

net emission reductions after half year of operation(Fig.4). In other words, the annual emission

10

reductions of all biomass projects were two times more than the total emissions in the construction

11

stage. This shows that although the construction of biomass power leads to emissions, it is much

12

less than the annual emission reductions. As shown in Fig. 4, the time to achieve net emissions for

13

wind projects are more than one year, which means the annual emission reductions of all wind

14

projects were less than the total emissions in the construction stage. This indicated that it would take

15

more than one year for wind projects to achieve net emission reductions after operation. Unlike

16

biomass power, the total emissions in the construction stage of solar power projects were much

17

greater than the annual emission reductions. For solar projects, the average time is 3.79 years. This

18

result indicated that averagely it would take more than three years to achieve net emission reductions

19

for solar power. According to the comparison outcome, it was found that biomass not only yield

20

more annual emission reductions, but could also achieve net emission reductions in a short time

21

after operation. In biomass power plants, agricultural and forestry residues, such as crop straws and

22

wood residues, are main fuels. This biomass are by-products of agricultural and forestry processes.

23

Therefore, in the LCA, the greenhouse emissions due to fertilizer or irrigation used for agricultural 18

ACCEPTED MANUSCRIPT 1

products are not included in biomass power production.

2

Table 7

Emissions results comparison with other studies of biomass power

This study

Wang et al.[32]

Dias et al[31].

Thakur

et

Costa et al.[33]

al.[34] Country

China

Biomass fuel

Agricultural and

(Review article)

China

Canada

Canada

Portugal

Various countries

Salix

willow

forest biomass

forest biomass

agriculture

forest

cycle

GHG

42~85

residues，

dedicated energy crops，

residues Life

Kadiyala et al.[36]

forestry 114

51.5

19.51 ~22.24

161

43 ~291

emissions(g CO2e/kWh)

3 4

In order to have a better understanding of environmental impacts of biomass power projects, a

5

comparison with other studies of biomass power was made (Tab.7). Considering the environmental

6

impacts of municipal solid waste incineration power are greater than agricultural and forestry

7

residues power, only agricultural and forestry biomass-based power were investigated. The

8

estimated life cycle GHG emissions of the five biomass power projects in this paper are between

9

42~85 g CO2e/kWh. The result of Wang et al.[32] in China is 114 g CO2e/kWh. In their study, the

10

biomass project used salix, a typical local plant, which is much different from other biomass power

11

projects in China. Therefore, the value is significantly different from what was obtained in this paper.

12

Currently, the component of biomass feedstock of most biomass projects in China are similar (see

13

table 4). By comparing with the results of other studies, we found that the life cycle GHG emissions

14

in this work are relatively within the range of other studies. Because of the differences in biomass

15

feedstock, transportation distance and technologies, it is difficult to simply compare the results of

16

each study. However, to some extent, this would show that the environmental impacts of biomass

17

power in China are relatively limited. The development of biomass power may be a good choice.

18 19

5. Conclusions

20

This paper assessed the environmental impacts and emission reductions potential of biomass

21

power in China. The unit emissions from the construction stage of biomass power is about 1700 ton

22

CO2-e /MW, which is smaller than that of wind and solar power. In the operation stage, biomass

23

power projects achieved more annual emission reduction (121,104~141,083 ton CO2-e) compared

24

to wind and solar power, due to the higher annual operating hours.

25

construction stage and the operation stage, we found that the biomass power projects can achieve 19

Considering both the

ACCEPTED MANUSCRIPT 1

net emission reductions in half year after operation. However, the average time to achieve net

2

emission reduction for wind power and solar power were 1.16 and 3.79 years respectively. The life

3

cycle GHG emissions of the biomass projects are between 42~85 g CO2-e/kWh, which is not high

4

compared with other studies.

5

China has abundant biomass resources, such as crop straws and forestry residues, which are

6

generated from the agricultural and forest sectors. However, the development of biomass power

7

industry in China is relatively slow compared to wind and solar power industries. The main

8

objective of developing renewable energy is to achieve emission reductions. Whether a renewable

9

energy source should be given more attention and fiscal support depends largely on the performance

10

in emission reductions. Based on the analysis of environmental impacts and emission reductions

11

potential, this paper showed that biomass power generated provides relatively less emissions in the

12

construction process compared to wind and solar power. Meanwhile, biomass power has much more

13

emission reduction potential and can achieve net emission reductions in the shortest time (less than

14

half year). These results provide a quantitative point of reference for the environmental performance

15

of biomass power in China.

16

According to the analysis of emission reduction potentials, biomass power was found to be the

17

more attractive among the three renewable energy sources. At the end of year 2017, there was

18

decentralization of biomass power industry, shifting its management from the national government

19

to provincial government authorities. Based on the estimated results in this paper of different regions,

20

it would be reasonable for local governments to support the biomass power industry in the future

21

since they have more autonomy after the decentralization policy. Some central and eastern provinces

22

in China are relatively abundant in agricultural and forestry residues. However, some of these

23

provinces place more focus on wind or solar power and provides more fiscal support even if the

24

wind and solar resources are not particularly robust. For these provinces, governments should give

25

more subsidies to biomass power rather than solar and wind power. There are also large desert and

26

semiarid desert areas in the northwest provinces of China, which have abundant wind and solar

27

resources but lack agricultural and forestry activities. Therefore, renewable resources should be

28

prioritized based on local resource endowments. Agricultural and forestry residues are mainly in the

29

vast rural areas and the cost of transportation is relatively high. Considering the high cost of biomass

30

materials, the collection and transportation of biomass fuels should be given subsidies and other 20

ACCEPTED MANUSCRIPT 1

financial support. For local governments, it is necessary to set a reasonable and adjustable Feed-in-

2

tariff for biomass power to reflect its cost and environment benefits.

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

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ACCEPTED MANUSCRIPT Highlights

The unit emissions of biomass power from construction is around 1700 ton CO2-e/MW

Biomass power projects achieved net emission reductions less than half year

The life cycle GHG emission of biomass power projects are between 42-85 g CO2-e/kWh