GHG reduction by rewetted arable land : a study on cultivated peatland for biogas production in temperate climate in Sweden

Abstract: Hydrophytes can be cultivated on rewetted drained peatland and used as substrate to produce biogas which can be utilized as vehicle fuel. This results in less GHG from rewetted peat soils and at the same time leads to renewable energy that substitutes fossil fuels. A literature research was conducted to study the impact of different species (Phragmites australis = Pa and Typha latifolia=Tl) and soil nutrient status on GHG emissions of rewetted fens in N Europe. In addition, biogas production and the exposure to different N-load were investigated for these species. Pa has a methane yield of 235 ml CH4 g-1 VS-1 regardless the input of N whereas Tl needs to be fertilized in order to produce high methane yield (204 ml CH4 g-1 VS-1).  Pa sequesters more CO2 and converts it into biomass which makes it a C-sink but by using the GWP factor to convert CH4 into CO2-equivalents, Pa becomes as Tl a GHG-source. Still Pa’s GHG emissions are lower than Tl’s if water depth is maximum 20 cm. Pa also contributes to peat formation and can cope with water fluctuations.