Biobusters – China

June 2004

The Nature Conservancy has been working with people in southern China to introduce wood-saving technologies, especially fuel-efficient stoves, biogas and solar water heating. From a modest start new businesses are now ensuring that fuelwood saving and replacement technologies are really taking off.

The mountainous northwest of Yunnan Province in Southern China is an ecologically and ethnically diverse area where the environment and the livelihoods of the people are under threat from continued deforestation. It is bordered by the Tibetan Autonomous Region, northern Myanmar (Burma) and the Chinese province of Sichuan. The project is based in the most ecologically sensitive and diverse part of the province that by itself covers an area of 69,000 square kilometres, or equivalent in size to the island of Ireland. The area is characterised by high mountains and deep gorges covered, in part, by indigenous forest containing some of the world’s most ecologically diverse and threatened plants and animals. It is a very important source of medicinal plants.

The area also contains the upper reaches of some important rivers including the Yangtse, Mekong, Salween and Irrawaddy on which the livelihoods of many millions of people further downstream depend.

About 3.2 million people live in the project area. They are from 15 distinct ethnic groups, each with its own unique culture, traditions and relationship with the environment. Poverty is a great problem for many of the inhabitants and 13 of the 15 counties in the project area have been classified by the Chinese government as below the poverty line.

Responding to Environmental Threats

The main threats to the ecology and environment in the project area come from tree cutting, mostly for fuelwood, insensitive tourist activities, unmanaged collection and use of plants and animals and over-grazing of animals on grasslands. The Chinese branch of the international conservation organisation The Nature Conservancy, the main project-implementing organisation, has given priority to addressing the fuelwood issue.

This project currently constitutes the CREED (China Rural Energy Enterprise Development) programme. The Nature Conservancy is the local partner, working with local entrepreneurs to develop businesses making, selling and installing fuel-efficient cooking stoves, fuel briquettes made from crop wastes, ‘four in one’ biogas digesters, solar water heaters, solar cookers and micro-hydropower plants. By early 2004 more than 4200 of these products had been supplied in the area.

Most impressively, businesses that The Nature Conservancy has assisted have supplied communities with more than 3100 household scale biodigesters and nearly 540 fuel-efficient cooking stoves. Biogas can replace much of the need for a household to use wood for cooking and the fuel-efficient stoves can consume significantly less wood than traditional cooking stoves. These stoves also produce less smoke and so reduce the risk of respiratory diseases of users. These developments are already likely to be saving thousands of trees and other woody plants per year.

The CREED Programme and Its Partnership with The Nature Conservancy

The CREED programme is the newest of the three REED programmes and currently The Nature Conservancy (TNC) is the only country enterprise development partner in China. The partnership between TNC, UNEP and E+Co is still relatively recent but the work TNC is doing under this partnership is building on its earlier experiences of introducing cleaner and renewable energy options to villages in the region. TNC has been doing this since 2001.

TNC is primarily a wildlife and ecology conservation organisation, but it is also interested in supporting communities in ecologically diverse environments to improve local people’s lives in harmony with their natural environment. Its headquarters is in the United States and it undertakes conservation projects in nearly 30 countries in the Americas and Caribbean and in Asia, in most of which it has local offices.

The China office, based in Yunnan Province where most of its work takes place, has been particularly active in engaging local people in nature conservation. TNC has been working in northwest Yunnan since 1998. It has prepared a plan for the Chinese government to create 3.4 million acres of nature reserves to protect important animals and plants such as the Yunnan golden snub-nosed monkey, the Asian black bear, the snow leopard, the red (lesser) panda, the black-necked crane, the mottled bamboo and the Yunnan pine.

TNC has organised numerous training workshops in villages and with organisations working in the area. These workshops covered conserving natural resources and diversity, marketing, business development and assisting tourists. TNC has given a high profile to addressing the deforestation problem through reducing fuelwood use and promoting alternatives. However it has also been active in addressing other environmental problems in northwest Yunnan as part of a comprehensive conservation and sustainable development strategy. Its other projects have included facilitating and managing ecotourism, sustainable fisheries development and improving nutrition.

Up to now funding for the sustainable energy project has come from The Nature Conservancy itself, the Dequin County government and from villagers themselves, in some cases through obtaining a bank loan. Most of the villages where TNC has introduced more sustainable energy technologies are located between the Lashihai and Wenhai lakes or around the Meili Snow Mountain (Meilixueshan).

‘Four in One’ Biogas Production

The ‘four in one’ process incorporates an underground biogas digester, a greenhouse for growing vegetables, a pigpen and a latrine. The opening cover for the digester is located close to the pigpen and latrine. The greenhouse also covers this area, so that it gets heated and this accelerates the fermentation process in the digester. Human excreta falls directly into the digester from the latrine and a shovel is used to put the pig waste into the digester through the top cover. Other organic household or farming residues can also be put into the digester. However, the digester works best with a significant amount of excreta in the feed. Using only plant and domestic wastes gives a slow gas yield. Note that the chutes which take the waste into the digester have to be covered by the accumulating slurry in the digester. Until the level of the slurry is built up sufficiently most of the gas generated escapes through the openings for the chutes. Once the slurry level is sufficient the gas accumulates in the top of the digester above the slurry.


The biogas digester in this programme is built of concrete. It has a capacity of six to eight cubic metres. This is sufficient to meet most of the cooking and, if suitable lamps are available, lighting needs of households. Nevertheless, little or no gas is produced during cold and overcast weather, or when the digester is being emptied or in the early stages of filling up and then a backup biomass stove is required. The cost of the ‘four in one’ system varies from US$250 to 800, depending on the size of greenhouse.

Biogas is generated by the anaerobic (without air) decomposition of organic matter in the digester. The decomposition is caused mainly by the action of bacteria in the waste. Biogas is usually 50 to 70 per cent methane with carbon dioxide as the other main constituent together with small amounts of hydrogen sulphide and other flammable gases. Biogas is produced most efficiently at temperatures between 30 and 40°C or between 50 and 60°C. Although the greenhouse unit contributes heat to the digestion process and heat is produced in the process itself, a combination of low temperatures and reduced atmospheric pressure make biogas not viable at altitudes above about 2900 metres (9000 feet) in northwest Yunnan province.

When the digester is filled to its capacity it will still continue to produce gas for a few more weeks. After that the solid residue is removed and used as fertiliser in the greenhouse or on fields. It normally has little odour and is free from bacteria that cause diseases.

Cooking with Biogas

A biogas cooker Photo - The Nature Conservancy
A biogas cooker Photo – The Nature Conservancy

Biogas can be used in most commercially available cookers that use bottled gas or gas from the mains. If the cooker has been designed for bottled gas then the jets on the burners on the cooker have to be removed as biogas is supplied at a much lower pressure than the gas held in bottles. Hydrogen sulphide damage, especially of brass fittings, is sometimes a problem with cookers that run on biogas. This usually occurs if a lot of chicken droppings are put in the biogas digester as then sizeable amounts of hydrogen sulphide are produced. Using excreta from other animals or plant and vegetable matter in the digester does not usually cause a problem when cooking with the gas.



Fuel-Efficient Stoves

Stoves types that have been installed include an improved traditional type that incorporates prefabricated parts, a water jacket stove, a biogas cooker and a biogas rice cooker. The fuel-efficient stoves that burn wood need significantly less woodfuel than the traditional stoves.

In a water jacket stove some water is poured into the bottom of a metal stove just above a combustion chamber and the cooking vessels stacked in the stove one above the other. When the water is heated steam is produced and this heats the food in the vessels. An outer metal jacket constrains the flames so that they surround the inner container where the vessels with the food have been placed. Food still continues to cook well after the fuel has burnt up and the stove is efficient in the use of fuel.

Improved stove designs are adapted to the needs of particular ethnic communities in northwestern Yunnan. An example of an improved combined stove and fireplace for the Yi community is illustrated.

Improved cooking stove and fireplace for the Yi community. Many of their villages are at high altitude, so space heating is often required. A traditional Yi cookstove is shown on the right. Photo - The Nature Conservancy
Improved cooking stove and fireplace for the Yi community. Many of their villages are at high altitude, so space heating is often required. A traditional Yi cookstove is shown on the right. Photo – The Nature Conservancy
Improved wood burning stove in Haixi village where the ethnic community is Naxi Photo - The Nature Conservancy
Improved wood burning stove in Haixi village where the ethnic community is Naxi Photo – The Nature Conservancy
The combustion chamber of the improved stove Photo - The Nature Conservancy
The combustion chamber of the improved stove Photo – The Nature Conservancy

Scaling Up

The work on renewable and cleaner energy of The Nature Conservancy in northwest Yunnan Province in China has up to now been largely a pilot project that has tested prototypes and different ways of promoting and disseminating renewable and wood-saving energy technologies. In the CREED partnership together with other organisations The Nature Conservancy now wants to scale up its programme and facilitate the delivery of more sustainable energy usage to half a million households within the conservation zones.

There is clear evidence that many households are interested to use renewable and cleaner energy and some have taken out bank loans to pay for the installation. In a given area a high proportion of the population are also interested to take up these options. This is exemplified in Haixi village, one of the villages where the approach is being piloted. Here 71 of 122 households have installed biogas digesters and many have new stoves.


ITDG would like to thank Mr Xia Zuzhang of The Nature Conservancy for help and advice in putting together this case study.

Further Information

Relevant Organisations

The Nature Conservancy



Fuel Saving Cookstoves, Aprovecho Institute, 1984
Solar Water Heater with Thermosyphon Circulation, Bernd Sitzmann, 2003

A Chinese Biogas Manual, Ariane Van Buren, 1979
Biogas Promotion in Kenya, Stephen Gitonga, 1997
Running a Biogas Programme, David Fulford, 1988
Solar Heating in Cold Regions, Jean-Francois Rozis & Alain Guinebault, 1996
Stoves for People, Roberto Caceres, 1989
The Kenya Ceramic Jiko (stove), Hugh Allen, 1991
The Stove Project Manual, S.D. Joseph, Y.M. Shanahan & W. Stewart, 1985

ITDG Publishing


Using Integrated Biogas Technology to Help Poor Communities in Baima Snow Mountain Nature Reserve, Yunnan Province, China, Yin Chuntao, Boiling Point No. 47, Autumn 2001, pp. 13 – 15


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