The potential for biogas in Sweden
by L Thyselius, et al, Swedish Institute of Agricultural Engineering

The Swedish government has stimulated considerable interest in anaerobic digestion of various types of solid organic wastes. The possibility of using upgraded biogas as a vehicle fuel has increased this interest further.

The biogas plant in Uppsala

Introduction

The implementation of biogas technology has increased in Sweden over the last 4-5 years. The main reason for this is an effort to replace landfilling of nutrient-rich, wet organic wastes with a more sustainable technology. The Swedish government has issued priorities for waste management options, re-use being the highest, followed by recycling and energy production. The government has allocated SEK 6.8 billion (where SEK is the Swedish krona) for sustainable development in Swedish municipalities, to be allocated during 1998Đ2001.

The inauguration of a new biogas plant at Linkšping

Existing and future plants

In Sweden, there are about 220 biogas plants in operation. The majority (134) are sewage sludge treatment facilities. At a further 60 sites, biogas is generated from landfills or cell digesters at landfills. Over the last seven years, eight centralised, full-scale plants for treating solid wastes have been constructed; these are currently in operation or in the start-up phase. During 1998, about 10 municipalities were granted support for constructing biogas plants under the programme for sustainable development. In 1999, 17 municipalities received support which totalled SEK 138 million.

In VŠxjš, plans are now being evaluated for a full-scale biogas project, which will be partly financed by the EU. It is expected that the plant will produce biogas equivalent to about 15 GWh/year for use

as vehicle fuel. The city of VŠsterŚs is also planning a biogas plant that will treat about 17,000 tonnes/

year of food waste from households and restaurants, and about 13,000 tonnes/year of energy crops. Biogas production will be equivalent to around 20 GWh/year, which will be used for heat, electricity and as vehicle fuel.

The municipality of Lund, together with the regional waste treatment company, has plans for a biogas plant treating about 50,000 tonnes/year of waste and manure. When running at full capacity, biogas production is expected to be equivalent to about 22 GWh/year. In Kil, a plant with the capacity to treat 4,500 tonnes/year of food waste has been constructed and is now in the start-up phase. Initially, the biogas will be used only for district heating, but other uses, such as electricity production and upgrading the gas for vehicle fuel, will be evaluated. The plant will produce the equivalent of about 4 GWh/year in a thermophilic process. There are also plans in the city of Jšnkšping to use an existing digester at its sewage plant for biogas production. The plant will have the capacity to handle 15,000 tonnes/year of food waste, and the biogas produced, equivalent to 10 GWh/year, will be used as vehicle fuel.

In Stockholm, there are plans for a full-scale solid waste digestion plant, which will treat 30,000 tonnes/year of food waste, producing biogas equivalent to more than 30 GWh/year for use as vehicle fuel, and generating about 50,000 tonnes of residue. Also in Stockholm, at the Bromma sewage plant where only excess biogas is currently upgraded and used as vehicle fuel (enough for 300 cars), future plans are to use all the biogas in this way; the same plans apply to the Henriksdal sewage plant. The total amount of gas produced from these three plants will then be equivalent to around 60 GWh/year, enough energy to run about 6,000 cars/year.

Vehicle fuel potential

500 vehicles are running on biogas in Sweden

During recent years, interest in using biogas as a vehicle fuel has increased considerably. Today, eight units for upgrading biogas and for vehicle filling are in operation and more are planned. In Stockholm, there are three public biogas stations and one non-public station, subsidised by the Swedish Transport and Communications

The major incentive for using biogas in this way is that it is one of very few renewable vehicle fuels. In addition, the emission of nitrogen dioxide is much lower from engines running on biogas than from those using diesel oil. Moreover, the sales value of the biogas is higher as a vehicle fuel ($0.26/m3 methane for diesel oil and $0.48/m3 methane for petrol, where $ is the US dollar), than as fuel for co-generation ($0.19/m3 methane). The investment cost for gas upgrading equipment is about 10Đ30% of the total investment cost.

In 1996, the amount of biogas produced in Sweden corresponded to an energy content of 1.35 TWh; about 0.8 TWh of this originated from sewage plants and 0.4 TWh from landfills. The rest came from co-digestion of solid waste and from industrial sewage plants. Now, the total biogas potential in the 55 largest municipalities has been calculated at 7.2 TWh/year Đ the energy required to fuel about 700,000 cars/year.

For more information contact the Swedish Institute of Agricultural Engineering Tel: +46 18 30 33 00; Fax: +46 18 30 09 56; or the CADDET Swedish National Team in Stockholm.

The CADDET Renewable Energy Newsletter is a quarterly magazine published by the CADDET Centre for Renewable Energy at ETSU, UK.

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