RENEWABLE ENERGY RESOURCES AND TECHNOLOGIES 1. Wind energy

As estimated by the National Meteorological Bureau and the Meteorology Institute, the capacity of wind energy in China is about 1.6 TW, and the existing installed capacity of wind power generators is about 30 MW. The criteria for qualita-tive determination of the potential of wind energy are divided into high, moderate, marginal and poor (see Table I).

Most of the high potential wind energy generators are located in areas that are far away from industrialized regions. However, in most of these areas, other energy resources are scarce. Wind power generation could be used in remote rural areas, such as Inner Mongolia, and on islands in the eastern coastal regions.

China has a long history of wind turbine and wind power development, which started in the early 1950s with the development of small turbines for application in remote areas. By the end of 1994, there were about 140 000 household size wind turbines which supplied electricity to the population in remote rural areas, especially

TABLE I. CRITERIA FOR QUALITATIVE DETERMINATION OF THE POTENTIAL OF WIND ENERGY

Criteria High Moderate Marginal Poor

Hours/year with wind velocities of > 3 m/s

> 5 0 0 0 4 0 0 0 - 5 0 0 0 2 0 0 0 - 4 0 0 0 < 2 0 0 0

Hours/year with wind velocities of > 6 m/s

> 2 0 0 0 1500-2000 5 0 0 - 1 5 0 0 < 5 0 0

Wind energy density > 2 0 0 150-200 5 0 - 1 5 0 < 5 0

TABLE П. COST COMPARISON OF WIND/DIESEL HYBRID SYSTEMS AND CONVENTIONAL DIESEL SYSTEMS (yuan/kW-h)

Cost elements Hybrid system Diesel system

Investment 0 . 3 3 0.14

Operation and maintenance 0 . 0 6 0.15

Fuel 0 . 4 0 0.75

Total 0 . 7 9 1.04

husbandry farmers of Inner Mongolia; the costs of these wind turbines were comparable with those of diesel generators.

In recent years, China has also developed some grid connècted wind farms, which use mainly imported equipment and technologies. By the end of 1994, about 14 sites of wind farms had been set up, with a total capacity of about 30 MW.

Currently, most of the grid connected wind farms are located in rural areas and supply electricity to the rural economy.

China has also developed technologies for so-called hybrid systems. A number of wind/diesel/battery systems in the range of 30-130 kW are being tested in China.

These systems are mainly located in Inner Mongolia and on islands in the coastal region.

The most popular wind turbine in China is of a size suitable for house-holds in remote rural areas. A typical small wind energy system consists of a

100 W generator and two batteries of 60 A-h each. This system is able to supply energy for two or three fluorescent lights, a black and white television set and a radio, depending on the wind resource and the battery charging capacity. In 1993, the total cost of the system was about 1060 yuan, and the levelized power generation cost was about 0.85 yuan per kilowatt-hour, which was lower than the cost of diesel power generation in some regions.

The cost of power generation by a hybrid system is lower than that by a conventional wind power system. Table П presents a cost comparison of hybrid and conventional diesel systems.

2.2. Solar energy

Solar energy is abundant in China, especially in the north-eastern parts and in Tibet and the Yunnan province. The solar radiation intensity is about 0.6 MJ per square metre. The most popular way of using solar energy is through heating panels that are applied mostly on the roofs of houses. Solar heating panels of an area of about 3.3 million m2 have been installed previously in China, and about 0.8 million m2 of such heating panels are produced annually. These solar heating panels can supply hot water to both rural and urban areas for residential use. Another utilization of solar energy is the provision of solar housing systems. By the end of 1994, housing systems with about 150 000 m2 of heating panels had been provided.

These houses were located mainly in the north-eastern and north-western parts of China. Both solar heating panels and solar housing systems mainly provide energy for the needs of households. However, some of these panels are used also in agri-culture, e.g. for drying tea, tobacco and bricks. According to calculations by the Ministry of Agriculture (MOA), solar heating panels can provide about 1 million toe for energy production for rural and urban households.

In China, the solar photovoltaic (PV) technology is used mainly for solar power generation. The annual capacity of solar PV power production is about 3-5 MWpeakj most of it is sold to companies using signalling systems for communi-cation and transportation; some of it is sold to to rural households. Because of the high cost of solar PV energy, it is hardly suitable for poor people in rural households.

Currently, one W ^ of PV energy from a battery system costs about 100 yuan, i.e.

a 50 Wpeak system costs about 5000 yuan. The per capita income of most of the poor people in rural areas is less than 200 yuan per year. A household of five people would need the total income of five years to buy one solar PV system. Therefore, the development of solar PV systems in China is based mainly on three strategies:

(1) PV energy is sold to relatively rich husbandry farmers who can pay the total cost of the system, with different payment options, e.g. high or low down-payment;

(2) PV energy is sold to households with moderate incomes, with Government subsi-dies; and (3) PV energy is provided to poor people who do not have enough money to buy a solar PV system. The money for dissemination of solar PV energy comes

mainly from the Government fund for the elimination of poverty, from bilateral or multilateral assistance funds and from international assistance funds.

Technologies for solar power generation connected to the grid and for solar thermal power generation have not been developed and utilized in China. However, it has been proposed to use these kinds of technology for overcoming power shortages in Tibet, since this option seems to be the cheapest one for that region.

2.3. Biomass energy

China has a wide range of biomass resources that can be used for energy generation; these resources include firewood, straw and stalks, agriculture and forestry residues and organic wastes. The annual production of biomass resources in China is shown in Table Ш. The annual biomass production is about 5000 million tonnes, of which about 600 million tonnes can be used for energy production.

TABLE Ш. BIOMASS ENERGY RESOURCES IN CHINA (1993)

Biomass resources Annual production

(million tonnes)

Crop straw 450

Forestry residue 15

Garbage 73

Municipal sewage 146

Rice husks 15

Sugar cane 67

Waste water 18 2 5 0

Biomass is the major energy resource that can be used as fuel for households.

Biomass provides about 70% of the energy for households in rural areas; in some remote areas, biomass provides about 100% of the energy for households. In recent years, following the economic development in rural areas, people used commercial energy instead of energy from biomass. In 1993 the amount of coal used in rural areas was twice that in 1980 and reached about 100 million tonnes. However, because of increased environmental pressure, utilization of biomass energy has become an important issue in China. If rural households would rely too much on biomass energy, then the impact on forestry and land use would become more

serious. On the other hand, the use of large amounts of coal in rural areas would cause more pollutants; the current environmental situation in China is already very serious, especially regarding emissions of total suspended particles and S02.

The strategy of biomass energy utilization in China can be described as follows: (1) increasing the efficiency of biomass energy, for example by promotion of the programme for providing improved stoves in rural areas; and (2) promoting the commercial utilization of biomass energy, such as biomass gasification (e.g.

biogas). In the past 20 years, the programme for providing improved stoves was successful; by the end of 1994, more than 70% of rural households had improved stoves. However, commercialization of biomass energy is progressing very slowly because of high costs and decentralization problems.

Firewood is one of the major biomass resources for energy use in rural areas;

it provides about 70% of the total biomass energy for households. However, fire-wood resources are scarce, since the land that can be used for firefire-wood plantations is limited. Currently, most of the firewood (more than 70%) comes from timber and other forestry plantations, which results in a lower productivity of these plantations.

By 1993, about 5.5 million hectares of firewood plantations supplied about 30 million tonnes of firewood. Thus, increasing the area of firewood plantations will be one of the options for supplying enough energy to the rural population, without negative impacts on both the local and the global environment.

Biogas production used to be one of the measures for commercial utilization of biomass resources. However, because of problems in connection with the main-tenance of the equipment used, the speed of biogas development slowed down in the late 1980s compared with that in the 1970s. One target of the biogas development programme was the development of technologies that can be used in rural households by people to perform certain activities that will provide a source of income. For example, in the north-east of China, biogas digesters did not work well because of the cold weather in this part of the country. However, recently, farmers have combined solar greenhouse systems with biogas digesters. The solar greenhouse system supplies heat for both the house and the biogas digester, and the biogas supplies energy for the household. Biogas residues can be used as fertilizer for the vegetables grown in the greenhouse. Therefore, biogas plays a key role in activities aimed at combining energy supply, environmental protection and economic develop-ment of rural households. It has been calculated that for rural households the income from one greenhouse with a biogas digester can be increased by about 6000 yuan.

Therefore, a biogas programme was developed for the north-east of China. In 1994, 10 000 biogas digesters were installed in the province of Liaoning alone. By the end of 1994, about 5.3 million households in rural areas used biogas digesters to produce biogas for cooking and lighting purposes.

Another target of the biogas programme is to develop large scale biogas digesters and to use them for supplying clean energy to rural and urban households;

biogas could even be used for power generation for economic development of rural

areas. One important component of the plan for the development of new and renew-able energy sources is large scale development of biogas. The development of large scale biogas digesters depends upon the growth of the rural economy. In recent years, there was a very large increase in large scale animal husbandry farms to meet the meat demand of people in both rural and urban households. Since a large amount of animal residues accumulates in such farms, the biogas digester technology is used as a means of both energy production and environmental protection. In the rural areas of Beijing, ten husbandry farms have been selected to demonstrate biogas production and power generation in a pilot project in which both energy and power are supplied to the farms.

Biomass gasification and briquetting technologies are other options for the commercial utilization of biomass. In recent years, China has developed several biomass gasification and briquetting technologies. However, the cost of these technologies is high and their reliability is low. Thus, biomass gasification and briquetting technologies are still in the research and development stage and far from commercial utilization.

2.4. Geothermal energy

The total resources of geothermal energy in China represent about 3000 million tee, of which about 0.3 million tee have been utilized. Geothermal energy resources can be divided into two types: high temperature (>150°C) resources, which are located mainly in the Yunnan province-Tibet geothermal zone and in the eastern Taiwan geothermal zone; and low temperature resources.

However, it is difficult to use high temperature resources for rural economic development. For rural areas, mainly the low temperature geothermal resources are utilized; these are located in the northern part of China (Hebei and Beijing areas).

Geothermal energy is used mainly for heating of houses and greenhouses. The utili-zation potential of geothermal energy depends on the availability of resources and on the cost of drilling.

3. GOVERNMENT PROGRAMMES FOR DEVELOPMENT