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On a sandy soil 10 different energy plant species were cultivated under practical conditions for a period of 6 years while determining yield, energy profit and environmentally relevant substances in soil and plants. Each species was fertilised in 4 different ways from 0 to 150kg N/ha and with wood and straw ashes. No pesticides were applied. The results show. That with the exception of stems of Jerusalem artichoke and of short rotation coppice without under seed the yields range between 8.5 and 11.8. tDM/ha and that a reduction of nitrogen application from 150 to 75kg N/ha merely results in a small yield depression. In case of non-fertilisation, the yields fall by nearly 20 to 40% after 6 years, except poplar (without under seed), which renders similar yields as with fertilisation (8.9 tDM/ha). The content of emission and combustion relevant plant nutrients. Such as nitrogen, potassium, sulphur and chlorine, is significantly lower in poplar and willow than in cocksfoot gras, rye, triticale and hemp. An application rate of 150kg N/ha results in an absolute increase of the nitrogen content of plants by 0.1 to 0.3%. Heavy metals accumulated from fertilisers and energetical generated pollutants. Such as cadmium, lead, copper and zinc, are absorbed to a different degree. Trees preferably assimilate the cadmium and cereals the copper. High energy yields are obtained from hemp, poplar and winter rye. A reduced nitrogen fertilisation -- and in case of poplar even non-fertilisation -- results in an energy profit of more than 3200 litres oil equivalent per hectare and year. [ABSTRACT FROM AUTHOR]