Energy Crops and AD Plants
Anaerobic Digestion, often referred to by the abbreviation AD, is the controlled breakdown of organic matter in the absence of air to produce a combustible biogas. The bi-product of the process is a nutrient-rich organic fertilizer.
The AD Process
The process takes place in the digester, an enclosed airless silo-like container. The feedstock, which can comprise agricultural waste such as cow and pig slurry, amenity and household biodegradable waste, maize, grass and wholecrop cereal silage and root crops such as fodder beet, is broken down by bacteria to create biogas. The biogas is combusted to generate heat and/or electricity (CHP) or, in some cases cleaned and fed directly into the gas supply grid (Gas to Grid). What remains after the biogas has been extracted is the digestate, which can be returned to the land as a soil conditioner and fertiliser with much greater nitrogen content that raw manure.
The process is dependent on maintaining stable conditions within the digester in which the bacteria thrive, so it is vital that none of the feedstock compromises these conditions.
In the case of energy crops such as maize silage, it is vital that the crop is stored in stable, airtight conditions until it is required, to prevent energy and dry matter (DM) losses. High levels of yeasts, moulds and undesirable bacteria are naturally present in such crops and, when exposed to air (or more precisely oxygen) can result in the premature release of valuable energy content that should be claimed by the digester.
With both on-farm and centralised AD plants recognising the potential of energy crops, the effective treatment and ensiling of wholecrop feedstock is a vital stage in the process. Now, Kelvin Cave Ltd, with nearly 40 years of expertise in the processing and preservation of home-grown livestock feeds, is delivering a range of proven products and solutions to minimise risk, protect investment and improve performance and profitability for the emerging AD market.
Recent trial work conducted by Harper Adams University concluded that applying Safesil Pro to forage maize at harvest reduced dry matter loss, increased methane production and provided a significant financial return when compared to a widely used biological inoculant and an untreated control. You can use our calculator to select your plant type (CHP or Gas to Grid), input variables such as plant efficiencies, crop area and growing costs, to calculate the benefit to your business based on the trial results.