- Substrate fed into the plant leaves it as a valuable fermentation product.
- Fermentation products in pellet form
Valuable Fermentation Products
It is widely known that biogas can be used to generate electricity, heat, and fuel. The energy yielded by biogas generation is closely linked to its material cycle: the manure, energy crop or organic waste which is brought into the fermentation plant as biomass will leave the production process as fermented substrate. This fermentation residue is a valuable product which can be used on fields, gardens and other land used for agricultural, horticultural and landscaping purposes – a product which is increasingly appreciated.
In general, fermentation products are spread in liquid form close to the farm. For many plant operators, this constitutes the simplest and cheapest method of closing the material cycle and returning the nutrients to the fields. Many years of experience have taught farmers the advantages of livestock manure, which is rich in nutrients and forms humus. Fermentation makes these nutrients more readily available for the plants, thus replacing traditional mineral fertiliser, the production of which requires a great deal of energy.
But that is not all: new processing methods and technologies can be used to create even more valuable goods from the liquid fermentation product. If the liquid and solid parts are separated, the solid fraction can be composted or dried further and processed into easily transportable pellets; or the liquid fraction can be refined using reverse osmosis and ultrafiltration technology to yield concentrated liquid manure. Another option is to enhance the fermented product with other substances – such as charcoal – to create valuable soil products.
New perspectives – new value added
The production of valuable fermentation products offers the biogas industry as a whole new perspectives and new options for value creation. This could particularly offer interesting alternatives to biogas producers in locations with high cattle density and bottlenecks resulting from fertiliser legislation. Though much remains to be done in terms of logistics, technology and economics, at least in Germany the EEG’s CHP bonus is creating a great deal of optimism in the biogas industry. The bonus applies when the heat generated by a biogas plant is used to dry fermentation residue. There is no doubt that the market for processed and dried fermentation products will continue to grow, as they are easily on a par with traditional fertilisers.
Meeting requirements for fields, plant beds and balconies
In order to find new sales markets for processed fermentation products, the product characteristics must be adapted to the needs of each particular group of users. There is real potential for producing specially processed liquid fertiliser from fermentation products, and for selling these as rival products to the mineral fertiliser solutions used in agriculture today. However, there are as yet only a few such processing plants, and these are still extremely expensive. Nevertheless, in due time the various fermentation products will find buyers – in horticulture, in agriculture, as a replacement for peat in soil production facilities, or in pellet form for private gardens and balconies.
However, legally sound marketability of the fermentation products is an essential requirement for this. Currently, this is guaranteed through the quality label “Gärprodukt” (fermentation product) or “NawaRo-Gärprodukt” issued by the German Federal Association for Compost Quality (BGK). To make greater headway in a legally complex environment, the German Biogas Association, together with the BGK, has founded the Association for Fermentation Product Quality. In addition to general quality assurance, the association will be responsible for developing new marketing strategies through the creation of harmonised standards.