Cleaner Technology Projects in Denmark 1996
Environmentally Sound Stoves and Ovens
Miljøvenlige komfurer og ovne
Miljørapport nr. 338, 1996, Miljøstyrelsen
The report examines the life cycle of a stove and analyses and evaluates the most important health- and environmental issues. Several choices of technology have been tested but the report cannot point out one of them as being the best solution. The conclusion is that the future development should be concentrated on the energy consumption when using stoves and ovens since this is the main problem when it comes to environmental strain.
More than 150.000 Danish families buy a new stove every year. At the same time the old stove must be disposed of, and this generates about 7.500 tonnes of waste of which most is recycled. The greatest environmental impacts come from the use of the stoves as the average Danish family annually consumes 400-600 kWh for cooking. The consumption of energy is based on fossil fuels, and the conversion causes a significant contribution to global, regional and local health and environmental impacts.
The report analyses different technologies for cooking. The conclusions are expressed as advice to product developers, producers and consumers on how to reduce the overall impact on health and environment. The methodology used is based on the life cycle concept, i.e. that all major impacts from acquisition of raw materials to final disposal have been taken into account. It should be stressed that many of the results and conclusions apply only to Danish conditions as these have been the basis for most of the analysis.
The target group for the investigation is product developers, stove manufacturers and public and private consumers. Together, these actors are responsible for the overall impacts throughout the lifetime of the stove.
The impacts from a stove were analysed considering the following elements: Consumption of raw materials, consumption of energy, environmental impacts (global, regional and local), health and risk of accidents.
The analysis of the raw material consumption show that the essential materials (iron, steel and other metals) generally stays in circulation (i.e. they are recycled), while plastics and mineral-based materials as glass, ceramics and enamel are landfilled and must be considered as lost for future consumption. The present way of disposal, shredding, is considered as relatively satisfying with respect to the materials presently used in stoves.
The major part of the energy consumption takes place in the use phase. Irrespective of technology there is a large consumption of fossil fuels with a limited supply adequacy, and future developments in stove technology should focus on reduction of the energy consumption, e.g. by increasing the efficiency of energy conversion. Gas technology uses less primary energy, but new ways of energy conversion, e.g. induction technology, also holds some promise with respect to efficiency.
The major global and regional impacts are caused by the conversion of fossil fuels to energy. An increase in conversion efficiency will therefore decrease these impacts. With respect to local environmental impacts the report points to raw materials acquisition as having the greatest contribution.
Two specific technologies were investigated with respect to their potential health impacts. Use of gas technology causes emission of NO2 in the kitchen, and a toxicological assessment shows that with the present emissions from gas stoves an increased incidence of airway diseases in susceptible groups (children in densely trafficked areas, asthmatics) must be anticipated. Induction technology was assessed with respect to the potential impacts from electromagnetic radiation. No conclusion was reached because of the lack of information on both exposure and effect. Therefore, the development in this area should be followed closely by both stove producer and toxicologists.
Analysis of the risk of accidents had a low priority as it was shown early in the study period that legal demands and technological development has eliminated the risk of gas explosions when using modern technology. Assessment of the risk of large accidents, e.g. shipwrecking of tankers, was not included in the study.
The general conclusions are summarised below:
 | It is impossible to point out one cooking technology as being the best. Instead, product developers must continue their efforts in both development of new technologies and improvement of existing technologies in order to make cooking more energy efficient. In so doing, resource consumption as well as global and regional environmental impacts will decrease. |
| Promotion of more energy-efficient technologies must not take place at the expense of an increased impact on human health. It is therefore important to continue the efforts to decrease the emission of NO2 from gas stoves and reduce the exposure to electromagnetic radiation from induction technology. |
| The choice - and amount - of materials for stoves is of relatively small importance as most materials are recycled today. If new materials are developed and used in stoves, it should be taken into consideration whether these are suited to enter the same waste streams as today’s technology, or if special arrangements are necessary in order to recycle the materials. |
| The consumer can often save the same amount of energy by changing his cooking habits as he can by changing to a more energy efficient technology. The stove manufacturers can help the consumers by developing solutions that are easily implemented in everyday cooking - also for people without a technical background. |
Author/ institution
Anders Schmidt, Birgitte Holm Christensen and Allan Astrup Jensen, dk-TEKNIK.
This report is subsidised by the National Council for Recycling and Cleaner Technology.
ISSN no. 0105-3094
ISBN no. 87-78-659-1