Report 5 (of 5): Fuel for the Future - China

Introduction

China’s society has seen dramatic changes over the last few years. Until recently, China was a largely agrarian society, but it is making a rapid transition into a more urbanized and developed one, with consumer goods, such as fast food and fast cars, becoming more readily available. With a fifth of the world’s population living in China, the amount of processed and packaged goods the country has the potential to consume is vast. As a result, waste, and specifically plastic waste, has become an enormous problem.

Beijing alone produces 120,000 tonnes of plastic waste each year. At the present time, the infrastructure for waste management is straining to keep up with the increase and land fill sites are at a premium. Recycling of the waste plastic is difficult to do once the various plastics materials have been mixed together because each plastic item needs to be identified before it can be sorted.

Seeking Solutions

A group of Chinese industrialists and entrepreneurs came to the conclusion that the best solution to this problem would be to use the plastic waste as a resource to make fuel. This would not only reduce the large amounts of rubbish being produced but could also be used to provide much needed diesel fuel and gasoline. The concept of obtaining liquid fuels from waste plastic was initiated in the early 1970s when oil prices suddenly increased dramatically. A great many countries, including Japan, Germany and the United Kingdom, conducted laboratory experiments and pilot schemes on liquid fuel production.

Experimental work into the conversion of plastic into fuel began in China and currently, there are a number of factories working to produce fuels using the techniques developed from these pilot schemes. Most of the manufacturing processes have been on a small scale and, in the past, they have been of a low technological standard with a bad smell and low stability. However, the process has been developed over the years and it is being refined continually to increase the general performance and process efficiency.

Recyclable Plastics

Any old plastic products (including tyres) are suitable to use in the conversion process, although PVC needs to be treated with special attention using modified catalysts etc. Typically, plastics are made from polymers such as polyethylene, polypropylene and polystyrene. These plastics are made from long hydrocarbon chains and have a very high energy content, therefore, they are ideal materials for fuel production.

The Manufacturing Process

The whole process takes about six hours but it is run on a continuous basis. All technological parameters, such as weight, temperature, pressure and flow rates are automatically monitored and controlled to ensure that the process runs smoothly.

Unwanted gaseous emissions are filtered and cooling water is circulated in a closed system so that pollutants are kept at an acceptable level. There is also a small amount of solid waste residue which needs to be disposed of at intervals during the process. The final products are stored in separate tanks where they are ready to be sold to transport companies who will use the fuel to power their fleets of trucks.

The Use of a Catalyst

Waste plastic is separated from the rest of the rubbish and bought from recycling centres and other local organisations. It is then taken to a conversion plant where the uncleaned waste plastic is crushed to between 3 and 6 centimetre pieces, before it is passed through a cyclone and a sieve to remove any dirt.

Once the dirt has been removed, the plastic is loaded, using a hydraulic feeder, into the cracking reactors where it is heated in the presence of a catalyst. The catalyst is important because it lowers the amount of energy that is required to break down the structure of the waste plastics.

As well as promoting the initial cracking of the polymers, the catalysts are used to promote the production of a heavier fuel suitable for the manufacture of diesel and gasoline. Only a small amount of catalyst material is lost during the conversion process.

The Collection of Liquid Fuel

The reaction chamber is specifically designed with a stirring device set at the bottom to prevent coking and to promote the removal of residue. From the initial cracking process, gases are driven off. As the plastics are reduced, the gases are collected and cooled, yielding liquid fuel. This liquid fuel or crude oil is a complex mixture that has to be separated in a fraction chamber to form gasoline and diesel. The remaining incondensable gases pass through the top of the fraction chamber and are either burnt off in a flare stack or fed back to the initial stage of the process where they are used as an additional fuel to heat the incoming plastic materials.

Heating Sources

In China, coal is in abundant supply and it is cheap to buy. It is used as the main fuel to heat the plastic and catalyst reaction. Any alternative heating source could be used, depending on local circumstances. Designs exist for using oil fired or gas fired systems, even the diesel produced by the process could be fed back to heat the waste plastic.

Cost

At the moment in Beijing there is no systematic rubbish separation and collection programme which could deliver large quantities of waste plastic for processing. As a result the waste is collected and sorted on a small scale in a number of different locations in the city. This has meant that transporting the waste is more expensive than is strictly necessary and the quality of the materials is extremely variable. The cost of producing one tonne of liquid fuel is around US$200, with the largest single cost being the purchase price of the waste plastic from the recycling companies which is between US$70 and US$85, depending on the quality of the plastic. The selling price of 1 tonne of liquid fuel is US$300.

The existing factories in Beijing are too small to deal with the amount of waste plastic currently being produced so investment has been made for the construction of a large capacity plant that will be able to cope with 60,000 tonnes of plastic annually.

"Best Practice"

The process has been praised as a ‘Best Practice’ by the Chinese State Environmental Protection Administration and has been profiled as a project with commercial potential by the National Science Foundation of China. There is a possibility that other chemical products could be obtained from this process. For example the industrial solvent, toluene, could be manufactured or xylene which is used in the production of polyester. Ethylene, used for ripening fruit, could also be produced.
 

For further information, please contact:

Intermediate Technology would like to thank the China Aerospace Great Wall Group, the Lan Ye Corporation and the Beijing Energy Efficiency Centre for providing the original materials on the conversion of waste plastics to liquid fuels.

Further reading from ITDG Development Bookshop

Don't Throw It All Away
This new edition of Friends of the Earth's popular recycling guide examines the 'throwaway society' and offers positive solutions to its waste problem. It explains what is thrown away, why so much of it is produced, and the environmental problems this causes. And it offers practical suggestions for how to help the planet by reducing the amount of waste you and your family produce.
£4.99 1998 46pp pb (Friends of the Earth) ISBN 1857502000

Green Home: How to make your world a better place
Karen Christensen
A comprehensive, accessible and lively introduction to all aspects of green home-making.
£9.99 1995 326pp (Piatkus Books) ISBN 0749914602

Plastic Waste: Options for small-scale resource recovery
Inge Lardinois
Plastic Waste documents recycling activities in cities in economically less developed countries. The publication describes how plastic waste is reprocessed in informal small-scale enterprises and turned into end products or semi-manufactured products ready for use by formal industries. Attention is paid to the various technologies used in plastic recycling. Financial aspects, marketability of products, environmental problems occupational health and government policies are also dealt with.
£11.50 1995 112pp (TOOL) ISBN 9070857340

Reuse, Repair, Recycle: A mine of creative ideas for thrifty living
Jan McHarry
An up-to-date source book on how to reduce and recycle, how to create new from old, and how to help fights the Great Waste Problem of the present age.
£7.99 1993 288pp (Gaia Books) ISBN 1856750450
 

TVE/ Practical Action gratefully acknowledge support for the HANDS ON programmes from the UK's Department for International Development (DFID), the European Commission (EC), the UN Foundation and UNDP/The Equator Initiative in collaboration with the Government of Canada, IDRC, IUCN, BrasilConnects and the Nature Conservancy.