Abstract

Greenhouse gas emissions are the main cause of todays climate change. To address this problem, the world is in an era of new round energy transformation, and the existing energy structure is being reformed. In this paper, according to the Chinese governments action plan for coping with climate change, the Chinas wind energy sustainable development goals and development route are discussed, and the countermeasures and suggestions are put forward. Wind energy is currently a kind of important renewable energy with matured technology which can be scale-up developed and put into commercial application, and in this transformation, wind energy will play a key role with other non-fossil energy sources. The development and utilization of wind energy is a systematic project, which needs to be solved from the aspects of policy, technology and management. At present, China is in the stage of transferring from “large wind power country” to “strong wind power country”, opportunities and challenges coexist, and the advantages of Chinas socialist system could be fully used, which can concentrate power to do big things and make contribution in the process of realizing global energy transformation.

Keywords

Climate change ; Energy transformation ; Wind energy ; Sustainable development

1. Introduction

The Chinese government believes that combating climate change is a significant approach toward promoting national economic and social development and incorporating green and low-carbon development into ecological civilization building.

Greenhouse gas emissions from energy production and consumption are the main cause of climate change (IPCC, 2014 ). To address this problem, important energy transformations characterized by upgrading of the existing energy mix, improving energy efficiency, accelerating the development of non-fossil energy sources, and increasing the contributions of non-fossil energy in the energy mix are being implemented worldwide; these transformations aim to eliminate the current dependence on fossil fuels and achieve a clean, low-carbon, safe, and highly efficient modern energy system where non-fossil energy plays a dominant role. After more than 10 years development, in 2015, the non-fossil energy consumption occupies 11.8% of the primary energy consumption in China, which is 2.9% higher than 2010.

Wind energy is an important renewable energy that makes use of sophisticated technologies with the potential for large-scale development and commercialization. The sustainable development of wind and other non-fossil energies plays an essential role in ecological civilization building and energy mix transformation. Wind energy has witnessed rapid developments in recent years; however, several opportunities and challenges continue to co-exist in the process of sustainable development.

This paper mainly discusses the role of wind energy in the process of realizing the governments goals to cope with climate change, analyzing the main constraints of wind energy development, and proposing countermeasures to address identified issues.

2. Overview of wind energy development

2.1. Overview of global wind energy development

The oil crisis in the 1970s promoted global wind energy development. Governments worldwide have reached a consensus on the strategic status of wind power and identified wind power as a significant contributor to their future energy supply. At present, over 100 countries are developing and using wind energy. In 2015, the newly installed wind power capacity stood at 63 GW and the total installed wind power capacity exceeded 400 GW (GWEC, 2016 ). The EU leads the world in the large-scale development of wind power. In recent years, Asia has turned to the core of large-scale developments in wind power, benefits from the rapid growth of Chinas and Indias wind power sector. However, in terms of the shares of electricity generation from wind power and wind energy technologies, EU continues to rank first in the world.

In 2015, Germanys total installed wind power capacity amounted to 44.95 GW, contributing 10.4% of its total installed power capacity. The share of electricity generation from wind power in total power generation reached 35.2%. As the largest offshore wind power market, Britains total installed offshore wind power capacity exceeded 5.06 GW in 2015, thereby allowing the country to rank first in the world. Electricity generation from wind power contributed 42.1% of the total power generated in Denmark. Eight-megawatt wind turbines developed by Vestas, which is based in Denmark, have been put in trial operation. Since 2005, the wind power industry in the U.S. has experienced rapid development because of the continuous enforcement of the Wind Power Production Credit Tax (PTC). With an annual newly installed capacity of over 5 GW, the U.S.' total installed wind power capacity reached 74.47 GW in 2015 and its power generation increased to 186.3 TW h; these figures allowed U.S. to become one of the largest producers of wind energy across the world.

One reason for the success of these countries in developing wind power is their stable policies. The governments of these countries introduced a market-based operation mechanism and paid great attention to innovations in wind energy technologies, thereby providing technological guarantee for the sound and sustained development of the wind power market and industry.

2.2. Overview of Chinas wind energy development

Since the implementation of the Renewable Energy Law in 2006 (PRC, 2006 ), there has been rapid growth in the wind power industry in China. In 2015, Chinas newly installed wind power capacity exceeded 30 GW, and its total installed wind power capacity was 145 GW or 8.6% of the national total power capacity (Fig. 1 ). Power generation in the whole year climbed to 186.3 TW h or 3.3% of the total energy produced. Wind energy has become an important part of Chinas energy portfolio. In 2015, Chinas newly installed wind power capacity made up 48% of the global wind power market, and China became a large user of wind energy.


Chinas newly installed wind power capacity and total installed capacity (CWEA, ...


Fig. 1.

Chinas newly installed wind power capacity and total installed capacity (CWEA, 2016 ).

As the scale development of the wind power market continues, China has established a wind power industry system and implemented the manufacturing technology of megawatt-grade wind turbines. Today, 1.5–2.0 MW wind turbines are major products in Chinas market, among which products manufactured by Chinese wind turbine manufacturers account for 80%.

As the wind power industry is developed, wind energy technologies have also seen increased activity. National achievements have been made in wind resource projection and assessment, wind farm location selection and construction, serialization design of low-speed wind turbines, construction of Ultra High Voltage alternating current (UHV AC) and direct current (DC) transmission lines, application of multi-energy complementation, and improvement of the quality of electricity generated from wind power and the security of grid operations. Great progress has also been achieved in wind energy research through key technology breakthroughs and capacity building with the support of the Major State Basic Research Development Program (973 Program), National High-tech R&D Program of China (863 Program), National Key Technology R&D Program, and National Natural Science Foundation; Chinas active engagement in international technological and scientific exchange and cooperation projects has also supported the growth of this industry. Six-megawatt wind turbines are at the R&D and demonstration stage. Offshore wind energy development and construction are accelerating. China has even embarked on an Internet Plus Wind Power Program, established a group of national key laboratories and engineering development centers, and set up domestic wind power standards, as well as testing and certification systems. Moreover, major fields of study related to wind power have been implemented in Chinese colleges and universities. These initiatives have cultivated a number of wind power professionals and a mindset where the advancement of wind power technology is believed to lay a good foundation for Chinas sustainable wind energy development.

3. Constraints in Chinas wind energy development

3.1. Wind power curtailment

In 2015, Chinas total installed wind power capacity accounted for 33.5% of the worlds total; thus, the country was ranked first in the world in terms of wind power capacity. However, in the same year, electricity generation from grids connected to wind power was only 186.3 TW h, which is about 3.7 TW h less than that produced by the U.S. One of the most important reasons for the gap is wind power curtailment. Fig. 2 shows wind power curtailments in China from 2011 to 2015. Over the five years, the national average curtailment rate was 13.4%, leading to electricity losses of 95.8 TW h, which could provide 1728 average availability hours, and rendering the capacity factor of wind farms to less than 20%. Wind curtailments mainly took place in Chinas northern regions, namely, Gansu province, Jilin province, Xinjiang, and Inner Mongolia, among others. Of these regions, the first three provinces showed curtailment rates of over 30%.


Annual wind power loss and curtailment rates in China (2010–2015) (CWEA, 2016).


Fig. 2.

Annual wind power loss and curtailment rates in China (2010–2015) (CWEA, 2016 ).

Reasons for wind power curtailments vary among the different provinces and regions, but four major reasons are often cited: 1) electricity demands are low and wind power consumption is insufficient; 2) wind energy development and the construction of supporting grids do not match well; 3) thermal power projects are expanding, thereby exacerbating the conflict between thermal power and wind power; and 4) the scheduling capability of grid systems remains weak.

To solve the problem of wind power curtailments, the National Energy Administration has dispatched documents on work related to wind power integration and consumption every year and set out the necessary requirements; local governments and power companies have implemented the corresponding measures, and positive results have been attained. For example, in terms of wind power transmission, the 750 kV transmission and transformation project in Gansu and the southern Hami–Zhengzhou ±800 kV UHV DC Transmission Project have been implemented, thus relieving the curtailments to some extent. The eastern Jiangsu and southern Anhui ±1100 kV UHV DC Transmission Project, which is about to begin construction, will provide further support for the development and utilization of renewable energy in northwestern areas. To address the issue of wind power consumption, demonstration projects have also been launched to achieve hydrogen production through wind power, wind-powered seawater desalination, wind-driven heat and wind-solar-battery hybrid power supplies, and explorations of smart grid.

The experiences of foreign countries and domestic practices have shown that wind power curtailment is not a technological issue; instead, it is an issue that could be solved by coordinating the interests of different parties. Thus, China must take measures to solve this problem from the perspectives of policy, technology, and management.

3.2. Weak independent innovative ability

In China, development of wind energy technologies, from small off-grid wind turbines (<100 W) to megawatt-class grid connected wind turbines, began in the 1970s. The R&D of large grid connected wind turbines was initiated in the middle of the 1980s, and the concept design of 100 kW-class wind turbines was completed with the support of the scientific and technological programs offered by the former State Scientific and Technological Commission (now known as the Ministry of Science and Technology). In the middle of the 1990s, 200 and 250 kW wind turbines were successfully developed but could not be transformed into products. At the end of the 1990s, as China realized the introduction and nationalization of 100 kW-class wind turbine technologies through the Ride the Wind Program and national R&D programs, 600 and 750 kW turbines were successfully developed and the countrys large-scale production capacity in China was gradually enhanced. At the turn of the century, megawatt-class wind turbines were introduced from Germany and China began to develop its own turbines with the support of national R&D programs. During this process, the countrys researchers performed technological introductory studies, analyses, joint design, and independent R&D. Large wind turbines are multi-body systems combining rigidity and flexibility; they are able to operate securely for 20 years with fluctuating aerodynamic loads even in adverse weather conditions. Considering the characteristics of these large turbines, their development is a complicated systematic project.

Although China has developed different models of megawatt-class turbines, generally speaking, its independent innovative ability remains weak from the following aspects. 1) The foundation of basic research remains weak with few original innovations. China continues to rely on foreign countries to optimize and design wind turbines and core technologies. 2) The material and technological bases for enhancing innovative ability are not strong enough. Given scattered and overlapping resources, China has not established an internationally acknowledged state-level wind energy research base that can coordinate nationwide innovations on national wind energy missions and international frontiers in this industry. 3) Science and technology are not closely linked to economic and social development. The development of the wind energy industry must rely on the advancement of science and technology. Without the support of innovations, scientific and technological results cannot be put into real applications. 4) An innovation system where enterprises play a leading role and enterprises, universities, and research institutes work together has yet to be implemented. Scientific and technological systems and mechanisms that promote innovation-driven development have not been established.

In the field of wind power, China is considered a companion instead of a follower. Considering its goal to become a strong wind power country, China must seize opportunities to strengthen its innovative ability by taking full advantage of the strong leadership and resource integration of the government.

3.3. Obstacles posed by irrational market systems and mechanisms

Obstacles posed by irrational systems and mechanisms in the wind power market hinder the sound development of this industry. At the initial stage of wind energy development, adopting supportive policies to nurture the industry is a common measure in the international community. Since the adoption of the Renewable Energy Law in 2006, China has set up a relatively complete policy system for wind energy development, including policies on on-grid power tariff, wind power concession project tendering, feed-in tariff, and delegating approval powers to lower levels; these activities have played a positive role in Chinas wind energy development. However, during implementation, some measures, such as subsidy allocation to renewable energy projects, energy-saving dispatching, and peaking regulation compensation, have not been carried out properly. In addition, when the industry enters into the scale development stage, it becomes more important to have an efficient market mechanism. A large amount of work remains before this goal can be achieved. In March 2015, the introduction of a new electricity system reform plan and its supporting policies laid a solid foundation with which to improve the wind energy market.

4. Forecasts of wind energy development

4.1. Strategic goals

To combat climate change, the Paris Climate Change Conference proposed that all countries should work together to achieve net-zero emissions of CO2 as early as possible, limit warming to no more than 2 °C above pre-industrial levels, and maintain global warming to below 1.5 °C (UNFCCC, 2015 ). Estimates indicate that renewable energy will completely replace fossil energy by around 2050 at the earliest. At the conference, the Chinese government pledged to abide by its international obligations in line with its national reality, development stage, and actual capability. Specifically, China intends to raise the share of non-fossil fuels in primary energy to 15% by 2020, cut CO2 emissions per unit of GDP by 40%–45% from 2005 to 2020, achieve peak CO2 emissions at around 2030, increase the proportion of non-fossil energy consumption in primary energy to 20% by 2030, and reduce CO2 emissions per unit of GDP by 60%–65% from 2005 to 2030.

Prior to the Climate Conference in Paris in September 2015, the General Secretary Xi Jinping declared that China will follow the path of low-carbon development, raise its share of non-fossil energy to 20% by 2030, and substitute non-fossil energy for fossil fuels. Many countries across the world have begun to create their own renewable energy development plan. Denmark plans to generate 50% of its electricity from renewable energy by 2020 and completely eliminate its dependence on fossil fuels by 2050. The U.S. and Germany aim to generate 80% of their electricity from renewable sources by 2050.

Since 2006, the Energy Research Institute of National Development and Reform Commission, Chinese Academy of Engineering, Chinese Academy of Sciences, and China National Renewable Energy Center have performed research on middle and long-term development plans of renewable energy sources (ERINDRC, 2015 ). These institutions have proposed development targets for wind, solar, and other non-fossil energies by 2020, 2030, and 2050.

Here are some research achievements by Chinese Academy of Sciences (CAS, 2015 ). First, based on Chinas future economic and social development, Chinas overall energy consumption was estimated to stand at 5.6 Gtce; this per capita electricity consumption is expected to reach 8000 kW h by 2050. Second, the Energy Development Strategy Action Plan (2014–2020) issued by the State Council in 2014 identified various energy development targets by 2020, including raising non-fossil fuel energy consumption to 15% and 20% in primary energy by 2020 and 2030, respectively (SC, 2014 ). Based on this document and taking into consideration future energy demands and the fact that China is striving to achieve a clean, low-carbon, safe and efficient modern energy system, the following wind targets were set: the installed wind power capacity will amount to 200 GW, 400 GW, and 1000 GW and power generation will reach 400 TW h, 800 TW h and 2000 TW h by 2020, 2030, and 2050, respectively (Table 1 ). By then, wind power is expected to be as important as hydropower and nuclear power as a non-fossil energy source.

Table 1. Chinas wind power development targets in 2020, 2030, 2050.
Wind power development targets 2020 2030 2050
The cumulative installed capacity (GW) 200 400 1000
The annual electricity generated by wind (trillion kW h) 0.4 0.8 2.0
The proportion of electricity generated by wind to the total electricity (%) 5.0 8.5 15.9
The proportion of wind to primary energy consumption (%) 2.6 4.7 10.7
The proportion of wind to electricity consumption (%) 7.0 9.5 17.8
The proportion of wind to non-fossil energy (%) 17.7 22.2 27.8

Source: CAS (2015) .

By 2020, 2030, and 2050, the proportion of electricity generated by wind to the total electricity will reach 5.0%, 8.5% and 15.9%, respectively. And the proportion of wind to primary energy consumption will reach 2.6%, 4.7% and 10.7%. In addition, the proportion of wind to electricity consumption will increase to 7.0%, 9.5% and 17.8% while the proportion of wind to non-fossil energy will increase to 17.7%, 22.2% and 27.8% by 2020, 2030, and 2050, respectively.

4.2. Development path

To achieve Chinas wind energy development strategic goals, the following development path are recommended.

From the perspective of the wind energy market:

  • Combine concentrated and dispersed development. In regions rich in wind energy in northern China, the government must promote the construction of a large wind power base, expand the scale of wind power integration, and improve wind power consumption capability. The government must also promote the construction of dispersed wind farms in the middle-eastern and southern regions of China.
  • Combine on-shore and off-shore wind power. On-shore wind farms will play the key role and off-shore wind farms are stably developing to realize the scale development. The development of on-shore and off-shore wind power will enjoy equal importance gradually.
  • Optimize the allocation of various non-fossil energies and realize multi-energy complementation and its coordinated development. China should give full play to the application of middle and small-sized wind power and wind–solar-battery hybrid power systems in distributed energy resources and micro-grid systems.

From the perspective of wind energy technological routes:

  • Intensify efforts in research on basic theories and cutting-edge wind power technologies and improve the countrys independent innovative capability. Great efforts must be made to develop Chinas large wind turbine optimization design technique, large-scale energy storage technology, direct wind energy application technology, intelligent wind power equipment manufacturing and quality control technologies, wind farm operation reliability technique, and digitalization and internet technology of wind power system to allow China to match international advanced levels.
  • Enhance wind energy technology capacity building. Setting up standard and testing and certification systems for the wind energy industry is necessary to integrate resources and achieve an overall plan for constructing a state-level physical and digital experiment platform as well as a state-level big data wind power platform. Initiatives in this area are also necessary to establish a wind energy technology consulting and operation and maintenance service systems.
  • Strengthen international exchange and cooperation and enhancing international competitiveness. China should take full advantage of the opportunities provided by the One Belt and One Road building initiatives and help Chinese wind power companies participate in global wind energy technology cooperation programs organized by international renewable energy organizations to improve Chinas discourse power in wind energy technologies.

5. Countermeasures and suggestions for wind energy development

5.1. Establishment of an overall plan for energy development

An energy plan is an authoritative document covering the guiding principles, strategic policies, goals and missions, layouts and procedures, and policies and measures on energy development that can play a significant role in the sound and sustainable development of the industry. As we continue to achieve the targets set out in the Energy Development Strategy Action Plan (2014–2020), establishing an overall plan for energy development in the next three decades during the 13th Five-Year Plan period is important; the objectives of this plan may include limiting the share of fossil energy in the energy mix, raising the contribution of wind, solar, and other renewable energies, incorporating plans of generating electricity from renewable energy into the overall plan of electric power development, balancing power source planning and grid planning, planning supportive transmission and distribution and energy storage systems and local consumption measures, encouraging each province to create scientific plans for renewable energy development based on their local conditions and the principle of multi-energy complementation and keeping in line with the national development plan, and enhancing regional cooperation to achieve optimized allocation of resources, coordinated development, and win–win cooperation on a wider scale.

5.2. Strengthening independent innovative capacity

Implementing innovation-driven development and promoting comprehensive innovation centered on technological innovation are strategic measures to improve Chinas national power and international competence. Thus, enhancing independent innovative capacity is an important endeavor. In the recent technological and industrial revolution, the global wind energy industry has seen new developmental stages where novel technologies and business opportunities are emerging. Thus, China must seize the opportunity to enhance its independent innovative capacity.

First, challenges to wind energy development must be identified by performing thorough research on top-down designs and trends in global wind energy development to achieve clear and realistic directions, goals, and key tasks in this field. China must increase its capital input in wind energy basic research and core technology R&D, such as setting up of wind energy laboratories that can compete in the international arena, laboratory-led wind energy innovation platforms, and a multi-disciplinary research base. China should establish a wind energy technology innovation system where wind power enterprises are leading players and enterprises, universities, and research institutes work together. With the support of important national R&D programs and major engineering projects, researchers can focus on key technologies in the digital design and green manufacturing of wind energy equipment, large off-shore wind farm construction, wind power system reliability, distributed power sources and large-scale energy storage, and Internet Plus Wind Power. Commercialization of these technological achievements can be promoted to maintain the healthy and sustainable development of the wind energy industry.

Second, China should accelerate the building of wind energy talent teams, including wind energy champions, technological talents, managers, technicians, and high-quality workers. On the basis of two-way opening and mutually beneficial principles, cooperation agreements between governments and exchange platforms between communities may be taken advantage of to enhance international exchange and cooperation. Under the opportunities provided by The Belt and Road Initiatives, the country can combine the concepts of “bringing in” and “going abroad” to strike a balance between domestic and international markets, thereby forming a renewable energy industry system with international competitiveness.

5.3. Improvement of wind energy development systems and mechanisms

Systems and mechanisms are important guarantees for the sound and sustainable development of the renewable energy industry. As the Renewable Energy Law is being implemented, supporting laws should be introduced to state the relationship between governments, development enterprises, equipment manufacturers and grid companies clearly. China can adopt the mechanisms of Guidance on the Establishing Target Guidance System of Renewable Energy Development and Utilization and Acquisition Management Approach for Renewable Energy Electricity with Full Purchase Protection (NDRC, 2016 ), as well as set up green certificate trading systems and examine their implementation regularly. The renewable energy subsidy delivery mechanism may be improved and sources of renewable energy funds may be expanded by imposing resource taxes, environmental tariffs, and carbon taxes with the aim of ensuring the delivery of renewable energy subsidies. Research on renewable energy investment, financing, and new business models may be performed and demonstration projects may be promoted. As technological advancements and cost reduction of large-scale development and construction are achieved, complete market-oriented developments in renewable power will be gradually realized.

5.4. Provision of better regulatory services for wind energy development

The main responsibility of governments is to provide regulatory services. Under the leadership of the National Energy Administration and relevant authorities, the regulatory service system for wind energy in China may be improved. A wind energy standard system and state-level wind energy testing center will be set up in line with national goals to enhance Chinas comprehensive testing ability and improve its wind energy equipment testing and certification systems. Wind energy market access standards could be established and certificates of competency could be issued for exported wind energy products to ensure their quality. It should be supported to establish third-party service institutions and give full play to wind energy societies and associations. These organizations, working together with energy authorities, can play an important role in creating sound wind energy plans, performing research on wind energy policies, providing regulatory services, realizing technological breakthroughs, evaluating wind energy equipment, and offering consulting services and technological support to promote and apply new technologies. By implementing these changes, China may be able to ensure wind power product quality, improve product efficiency, shorten production cycles, and reduce costs.

6. Conclusions

  • To combat climate change and reduce greenhouse gas emissions, China must contribute to transform primary energy, improve energy efficiency, increase the share of non-fossil energy in the total primary energy resource, and set up a clean, low-carbon, safe and efficient modern energy system.
  • Wind energy is an important renewable energy that makes use of sophisticated technologies with the potential for large-scale development and commercialization. The sustainable development of wind and other non-fossil energies plays an essential role in ecological civilization building and energy transformation.
  • The main constraints of sustainable wind energy development include wind power curtailment, weak independent innovative ability, and obstacles brought about by irrational market systems and mechanisms. These problems must be addressed from the policy, technological, and management perspectives.
  • To address climate change, China must increase its installed wind power capacity to 200, 400, and 1000 GW by 2020, 2030, and 2050, respectively.
  • With the largest market in the world, China has taken great strides to become a leading country of wind power. Countries are united in their common aspiration to develop green energy and protect the ecological environment. China needs the world and the world needs China as well. China should enhance its international exchange and cooperation with other countries to achieve mutual benefits and win–win outcomes.

Acknowledgments

During the writing process, we quoted the research results from Chinese Academy of Sciences Consulting Project “Countermeasures and suggestions on strongly promoting Chinas sustainable development of wind energy” chaired by the academician Mr. Li Jiachun, here we would like to express our heartfelt thanks to this contribution.

References

  1. CAS (China Academy of Sciences), 2015 CAS (China Academy of Sciences); Countermeasures and Suggestions on Strongly Promoting Chinas Sustainable Development of Wind Energy; (in Chinese)  (2015)
  2. CWEA, 2016 CWEA (China Wind Energy Association), 2015. China installed wind power capacity. Wind Energy 2016 (3), 48.
  3. ERINDRC (Energy Research Institute of National Development and Reform Commission), 2015 ERINDRC (Energy Research Institute of National Development and Reform Commission); China 2050 High Renewable Energy Penetration Scenario and Roadmap Study; China Science Press, Beijing (2015) (in Chinese)
  4. GWEC (Global Wind Energy Council), 2016 GWEC (Global Wind Energy Council); Global Wind Report 2015; (2016) http://www.gwec.net/publications/global-wind-report-2/
  5. IPCC, 2014 IPCC; Climate Change 2014: Synthesis Report; Geneva  (2014) http://www.ipcc.ch/report/ar5/syr/
  6. NDRC (National Development and Reform Commission), 2016 NDRC (National Development and Reform Commission); Guidance on the Establishing Target Guidance System of Renewable Energy Development and Utilization and Acquisition Management Approach for Renewable Energy Electricity with Full Purchase Protection; (2016) http://www.sdpc.gov.cn/zcfb/zcfbtz/201603/t20160328_796404.html
  7. PRC (Peoples Republic of China), 2006 PRC (Peoples Republic of China); Renewable Energy Law; Law Press China (2006) (in Chinese)
  8. SC, 2014 SC (State Council); Strategic Action Plan for Energy Development in China (2014–2020); (in Chinese)  (2014)
  9. UNFCCC (The United Nations Framework Convention on Climate Change), 2015 UNFCCC (The United Nations Framework Convention on Climate Change); Paris Agreement; (2015) http://unfccc.int/meetings/paris_nov_2015/items/9445.php
Back to Top

Document information

Published on 07/10/16

Licence: Other

Document Score

0

Views 0
Recommendations 0

Share this document

claim authorship

Are you one of the authors of this document?