Papers Delivered at International Conference on Cleaner Production
Beijing, China -- September 2001 -- Paper 27 of 30

Prospect of Cleaner Energy Development in China

Du Minghua
Beijing Research Institute of Coal Chemistry, China Coal Research Institute
No.5 Qingniangoulu, Hepingli, Beijing, 100013 P. R. China

1. To Develop Cleaner Energy is an Important Content of Cleaner Production in China

The total primary energy consumption in China is high, ranking the second in the world. Coal in the consumption mix of the Chinese energy end-use accounts for 45%. The issues related to low efficiency and environmental pollution in energy development and utilization, energy processing and transportation are serious. There is great development potential in renewable energy, such as hydropower, biomass energy, wind energy sources, solar energy, etc.

The energy construction guideline in China is “energy construction should give full play to resources advantage, optimize energy structure, improve utilization efficiency and intensify environmental protection”. To develop cleaner energy is an important content of cleaner production in China.

2. Direction of Cleaner Energy Development

Development of cleaner energy is an important content of implementing the energy construction guideline in China. It aims to solve the energy-related environment issues and convert energy cleanly in order to promote the development and utilization of advanced energy technologies and provide reliable guarantee for economic and social development.

The development of cleaner energy is closely related to the future energy production and supply as well as energy end-use consumption demand. The trend of the future primary energy development in China should be of plural pattern with coal as main energy source. The trend of energy end-use consumption demand is to optimize energy mix, increase the proportion of power generation and develop and utilize natural gas, new energy and renewable energy.

The predicted energy end-use consumption of China in 2010 is shown as Table 1. Compared with the present energy end-use consumption, the proportion of coal consumption will be reduced by about 13%; natural gas and electric power will be increased by about 8% and 5% respectively; oil rises slightly. The energy end-use consumption mix and quality of energy will be obviously improved. The proportion of cleaner energy will rise.

Notes:

1. Data of Table 1 is from reference 2-6.
2. Coal includes feed coal for synthetic ammonia in chemical industry, a small quantity of coal for gasification in other sectors, and fuel coal and household coal in non-power generation sectors, excluding coking coal.
3. Electricity generation in 2010 will be 2070 TWh, of which 1760 TWh will be used for end-use consumption.
4. Oil consumption means the energy end-use consumption.
5. In 1998, the consumption of biomass, methane and bagasse was about 223Mtce. It is predicted that this value will not change in 2010. The heat power will only be provided by coal-fired power plants.

The predicted primary energy supply of China in 2010 is shown as Table 2, including commercial energy resource and non-commercial energy resource. The proportion of natural gas supply increases greatly, about 2.3 times of that in 1999. The proportion of oil supply decreases; coal drops slightly; hydropower rises a little. The primary energy supply mix will not change substantially restricted by resources and development in the coming decade.

Note:

1. Oil output refers to raw oil, 1 ton of raw oil = 1.52 tce
2. The predicted total installed capacity of hydropower is 120 GW; nuclear power 8.7GW, based on 340 gce/kWh of coal equivalent consumption for electricity generation.
3. The shortage between production and demand of primary energy is 130Mt of oil and 20 Gm3 of natural gas, totally 224Mtce. The total demand of primary energy is about 1988 Mtce, excluding 1774Mtce of commercial energy from non-hydropower renewable energy.
4. The predicted coal production excludes 80Mt of exported coal.

Comparing the data of Table 1 and Table 2, conclusions are given as follows.

• It is predicted that coal in primary energy supply mix in China in 2010 will still occupy a dominant position, accounting for 65% of commercial energy sources.
• In electricity end-use consumption demand, hydropower and nuclear power account for 26.1%; the rest is mainly coal-fired power generation. Coal-fired electricity generation still plays an important role in power supply.
• Based on raw oil, the shortage between oil demand and supply is about 130Mt, which is one of the main problems of energy development.
• Coal in energy end-use consumption mix accounts for about 28%. The problems about environment and efficiency should not be neglected.
• Non-hydropower renewable energy in primary energy and energy end-use mix takes certain proportion.

Thus, it can be seen that the leading development direction of cleaner energy in China is high-efficiency and clean utilization of coal, including clean conversion and end-use utilization technologies of coal. At the same time, the processing, conversion and utilization technologies of the non-hydropower renewable energy, such as solar energy, wind energy sources, geothermal energy, especially biomass energy, should be improved.

3. Main Technologies of Cleaner Energy Development

3.1 Fields of the clean and high-efficiency utilization of coal

Coal will be dominant energy in energy production and supply mix in future decades. Therefore, the clean and high-efficiency utilization of coal is the most important content of cleaner energy development in China.

The predicted coal consumption in different industries of China in 2010 is shown in Table 3. It follows that coal consumption for power generation accounts for 46% of total, and the rest were distributed over various industries and sectors. Coal consumption as fuels accounts for about 84% of total. Coal consumption as fuel for non-power generation accounts for about 37% of total.

Notes:

1. Coal consumption for mining industry includes the loss in coal washing.
2. Coal consumption for coal chemical processing means feed coal for coal liquefaction, synthesization of liquid fuels or substitute of liquid fuels from coals.
3. Coal consumption for others means that for light industry, mechanical industry, commerce, etc.

Coal as fuel in non-electric power industry is used in boilers, kilns (such as building materials) and resident cooking, etc, of which coal consumption for medium and small-sizedd coal-fired boilers is more than 300Mt/a.

Based on the coal consumption and present technical level, the clean and efficient utilization technologies of coal are as follows.

• Clean coal-fired power generation technologies
• High-efficiency and clean coal combustion technologies for medium and small-sizedd coal-fired boilers
• High-efficiency and clean coal combustion technologies for industrial kilns
• Coal liquefaction (direct coal liquefaction, indirect coal liquefaction) technologies

3.2 Clean Coal-fired Power Generation Technologies

The development of thermal power units with large capacity and high parameter as main development direction will be speeded up in power industry in China. Most of sub-critical units and super high-pressure units which are operating now will be remolded. The condensing steam units of 50MW and less than 50MW will be shut down. The advanced circulating fluidized bed boilers will be applied and popularized. The advanced IGCC and PFBC demonstration projects will be set up. The coal-fired power generation technologies will be improved by a big margin in China in 2010.

The coal-fired power generation is the main way to convert coal into cleaner energy. The control technology of SO₂ caused by coal burning is an important technology to realize this conversion.

At present, limestone/gypsum wet scrubbing process for desulfurization, in-bed desulfurization by calcium injection, electron beam for desulfurization, rotary spaying process, CFB for flue gas desulfurization, etc. have been demonstrated and tested. The domestic manufacturing engineering of desulfurization technique and equipment is under way. By the end of the year 2000, the capacity of desulfurization units which are under construction and put into operation had exceeded 10000MW. During Tenth Five-year Plan period, the conventional thermal power unit capacity of 15000MW will be innovated for desulfurization.

The flue gas desulfurization and de-NOx technologies by dry adsorption have be industrialized abroad and are researched and tested in China’s research institutes in power industry and coal industry. The achievements have been made in bench scale tests. It is expected that during Tenth Five-year Plan period, the demonstration projects by adopting these technologies will be put in practice.

3.3 High-efficiency and Clean Coal Combustion Technologies for Medium and Small-sized Coal-fired Boilers

China has about 500,000 medium and small-sized coal-fired boilers with average single unit capacity of 2.4 t/h in various industries and social sectors. Above 80% of the boilers are layer-combustion boilers with low efficiency and high pollutant emission. The realization of high-efficiency and clean coal combustion for medium and small-sized coal-fired boilers is the emphasis of cleaner energy technologies in China. The energy conservation and pollution control have great potentials in China.

In recent years, coal-fired boilers are retrofitted into oil-fired boilers for meeting the requirement of environmental protection in some regions. Obviously the retrofit does not accord with China’s resources condition and market development because of the shortage of liquid fuel and the increase of oil price.

The central heating is a good way for the retrofit of medium and small-sized boilers. However, according to the analysis of the coal-fired boiler distribution and number, a large quantity of boilers with capacity of less than 30t/h will still be operated in a considerable long time to come.

To improve the techniques of medium and small-sized boilers has been giving attention. The measures such as retrofit of boilers, combustion of coal briquette, stratified feeding of coal, flue gas clean up, etc. have been made. Although the operation situation has been improved to a certain extent, as a whole, technical level is still low.

In the 1990s, low nitrogen burning, in-boiler desulfurization, efficient dust removing, automatic control systems had been used in medium and small-sized coal-fired boilers in the world. The boiler efficiency of over 86% and desulfurization efficiency of more than 50% are future development models of medium and small-sized coal-fired boilers in China.

3.4 High-efficiency and Clean Coal-fired Technologies for Industrial Kilns

Most industrial kilns take coal as fuel which are used in metallurgy, building materials, chemical industries, etc. There are various types of industrial kilns in China. Main problems of the kilns are backward in coal-fired technique, low thermal efficiency, serious pollutant emission such as kilns for producing ceramics and glass in building material industry.

In recent years, many industrial kilns have been retrofitted out of environmental protection requirements, such as adopting combustion mode with secondary air, change of fuels, etc.

The way of realizing clean coal combustion for industrial kilns is to supply heat for industrial kilns through producing gas from coal and then burning coal gas. It has widely been applied in the advanced enterprises for building materials. The simple coal gasification and combustion techniques are being developed in the light of existing industrial kilns which are small-scale and scattered.

One of the key points of cleaner energy technologies is to realize high-efficiency and clean combustion technologies for industrial kilns. Based on different kinds of kilns used in various sectors, the practical technical development and technical popularization will be conducted accordingly.

3.5 Coal Liquefaction Technology

Coal liquefaction refers to the process in which coal is converted into liquid fuels such as gasoline and diesel oil under certain conditions. Coal liquefaction is usually classified into direct coal liquefaction and indirect coal liquefaction.

Coal liquefaction technology can convert coal into liquid fuels in shortage, is the leading technology for high coal conversion technology and the development of cleaner energy in the future, and is of strategic significance in the development of energy technology in China.

The shortage of oil (crude oil) will be 130 Mt in 2010. 60Mt/a of liquefied oil will be demanded even though coal liquefaction can make up about half of the shortage of oil.

At present, the demonstration project of direct coal liquefaction is underway in China. The first-phase research for indirect coal liquefaction is conducted in some areas. If the industrialization of coal liquefaction is realized during Tenth Five-year Plan period, a batch of industrial units for coal liquefaction will be set up after the period. And then, the new industry of coal conversion in China will be formed in the next 20-30 years.

If the coal liquefaction plant capacity of 10Mt/a is built up in 2010, about 40Mt/a of feed coal is needed.

The total energy consumption of non-hydropower renewable energy in China in 1998 was about 227Mtce/a, of which biomass fuel consumption was 22Mtce/a, accounting for 97.6%. The total energy consumption for residents in rural area was 3.65Mtce/a, 57% of which is from straw and firewood. Depended on present biomass energy, the research and development of new technology and equipment for reducing pollutant emission, protecting environment and improving people’s living standard in rural areas are both market demand and focal point of the cleaner energy technology development.

The utilization technologies of biomass energy have existed for many years and have made achievements, such as producing methane by organic waste and gasifying, pyrolyzing and compact briquetting of straw. Some techniques have found application and popularization, others have made the phased fruits.

The status of biomass energy utilization in China has the following characteristics: large quantity, broad distribution, big difference in natural conditions and kinds of biomass, scattered raw material. A large number of biomass is burned in farmland and has caused serious pollution. The biomass resource is seasonal heavily and closely related with living energy of farmer. Based on these characteristics, the research and application for the clean biomass energy technology in China should be focused on the following aspects in order to adapt the features of countryside and the consumption convention.

• Researching methane technique with dry fermentation and commercial construction technique of methane tank and promoting its application in the southern China
   
• Researching co-pyrolysis and co-gasification of biomass and coal, developing small equipment and simple technique suitable for town and village and solving the problems about seasonal change of energy types and load change of energy consumption in the northern China
   
• Developing compact biomass fuel technique (or briquetting mixed with coal) and high-efficiency boiler through adopting the separate cooking and heating suitable for the large energy consumption and strong seasonality in winter in northeast China, northwest China and northern China
   
• Making various technologies mature, successfully demonstrated and popularized in some areas in 2010, increasing the utilization efficiency of biomass energy, reducing environment pollution caused by direct combustion of biomass and promoting the modernization development in rural areas

4. Environmental Prediction for the Development of Coal-fired Cleaner Energy Technology

4.1 Reducing SO₂ Emission in Coal-fired Power Generation

Up to the year 2010, the fuel coal consumption for the newly built capacity of coal-fired power generation will be 90Mt/a. 140Mt/a of coal will be consumed by the retrofitted units with desulfurization installation which have put into operation and will be built during Tenth Five-year Plan period and Eleventh Five-year Plan period. The capacity of retrofitted unit during Eleventh Five-year Plan period is supposed two times of that during Tenth Five-year Plan period. On the basis of fuel coal with 1% of average sulfur content, 0.9 of emission coefficient and 90% of desulfurization efficiency, SO₂ emission will be reduced by 3.7Mt/a.

4.2 Prediction for Coal Saving and Pollutant Emission Reduction in Medium and Small-sized Coal-fired Boilers

Comparing with present layer-combustion boiler, the efficiency of advanced medium and small-sized coal-fired boilers increases by more than 25%, desulfurization efficiency can be over 50%. If 50% of boilers are retrofitted before 2010, coal will be saved by about 45Mt/a and SO₂ emission, dust emission and ash discharge will be reduced by more than 1.75Mt/a, about 6Mt/a and about 45Mt/a respectively, and 15Mt/a of fly ash will be provided for raw material of building.

The expense of boiler renovation can be compensated by that of energy saving and pollutant emission reduction in 4-5 years.

4.3 Effect of Energy Saving and Pollutant Emission Reduction for Efficient and Clean Coal-fired Technology on Industrial Kilns

Due to diversity and complexity of industrial kilns, we only take the existing kilns with ceramics, fire-resistant material and glass for example. It is estimated that coal consumption of these kilns in 2010 will be about 25-30Mt/a. If 50% of them are retrofitted, the coal will be saved by about 8Mt/a and SO₂ and dust emission will be reduced by about 130,000t/a and 400,000t/a respectively.

4.4 The Effect of Pollutant Emission Reduction for Coal Liquefaction

At the same time of chemical conversion, coal liquefaction technology recovers sulfur from coal and controls the dust emission. By 2010, conversion and processing of 40 Mt/a of coal can reduce 0.65 Mt/a and 0.8 Mt/a of SO₂ and dust respectively as compared with combusiton of the quantity of coal.

4.5 Summary of Prediction for Environmental Results

It is shown that the cleaner energy technology taking clean combustion as main technology is very effective in energy saving and pollutant reduction. The development of FGD possibly reduce about 60% of SO₂, and the adoption of advanced medium and small-sized coal-fired boilers possibly reduce about 28% of SO₂ and more than 80% of dust (excluding the power station with high-efficiency dedusting units). The coal saving effect of 45Mt/a for the advanced medium and small-sized boiler is remarkable

5. Conclusions

• The development of cleaner energy technology is an important content of cleaner production.
• The leading ways for cleaner energy development in China are efficient and clean utilization of coal and the development of hydropower and renewable energy.
• The main technologies for cleaner energy development are FGD, advanced medium and small-sized coal-fired boilers, high-efficiency and clean coal combustion technologies for industrial kilns, coal liquefaction and utilization technologies for biomass energy.
• FGD technology for coal-fired power stations plays an important role in control of SO₂ emission, and will be developed further.
• The environment benefit and energy saving benefit of the advanced technologies for medium and small-sized coal-fired boiler are remarkable. However, the technologies have not been developed substantially. It is suggested that departments concerned coordinate and fund the related projects to speed up the development and demonstration of the advanced technologies.
• Coal liquefaction has vast market. It not only mitigates the conflict between oil demand and supply but also has good environment benefit. The technical development and research of coal liquefaction should be strengthened greatly. At the same time, the advanced technology should be introduced from abroad and the commercial demonstration should be set up.
• The development of cleaner energy technology involves many factors such as capital, technology, policy, etc. It is suggested that the departments concerned organize the scientific research to encourage the development of advanced technology for promoting actively the economic and social development.

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