The subsidiary is to start building a £6.5m aerobic digestion plant in Northern Ireland next year. Alkane said that a similar plant in North Wales was also expected to be ready by 2006. Anaerobic digestion plants are paid to take agricultural and good waste, which are broken down by bacteria to produce biogas, or methane, that is then burnt to generate electricity. Fertiliser is a by-product of the process. Alkane is paying £150,000 cash for its majority holding in Farmatic and lending a further £100,000. It expects to invest a further £700,000 in the Northern Irish project, which has been awarded a £3.1m government grant. PIN//FT