Biogas is a mixture of various types of gas (mostly methane,with a variable percentage of 50-80%) produced in oxygen absence by a bacterial fermentation of organic waste (slurry, decaying plant etc..). With dedicated technologies (biodigester) it is possible to extract large amounts of biogas from utilized substances and turn them into electricity and heat through cogeneration plants.

Biogas plants offered by Restag are made in cooperation with primary manufacturers having operational references and many years of experience. The minimum size of plants starts from small 25 kWe units, having high efficiency co-generation units (electricity and heat). The technology is the same as large biogas plants (of several MW), but their small size makes them suitable for our territory, in particular for :

- Small farms (for example : 200 buffalos or cows + 10 ha of land for biomass cultivation may sustain a plant of 100 kW);

- Dairy Industries;

- Agricoltural farms;

The overall dimensions of such system are extremely small (about 200 square meters of total space requirement) and there are no emissions, smells and / or odors. Authorization procedures are simplified and, in any case, absolved by Restag:

- For plants up to 50 kW it’s sufficient a simple communication to the Municipal Administration;

- For plants from 50 kW to 1 MW: it is required a PAS (Procedura Abilitativa Semplificata) a simplified procedure for Municipal Administration evaluation.

Incentives can be obtained directly (DM 06/07/2012) without being enrolled in the authority register, with a € 0.236 / kWh rate for a period of 20 years. Considering an 8000 h / year operational time for a 100 kW plant, it is possible to reach an annual income of € 188,000 , only for the electricity produced. The thermal energy (heat) can be used instead to heat homes, sanitary water, stables, swimming pools, dryers, etc.., thus generating additional savings for heating costs. This, together with the reduced requirements in terms of maintenance (1-2 intervention per year), means a ROI (return of investment) of approx. 5 years.

These small plants can be easily financed by economic entities (banks, cooperative credit institutions, cooperative unions, financing firms, etc..). These plants are achievable and affordable to all those who have availability of manure and / or land suitable for biomass cultivation. Moreover, this type of system is able to recycle almost all waste food and animal residual waste produced, transforming them in a resource and an interesting income source. At the end of the generation process for biogas production, the digestate is separated into solid and liquid. The liquid part can be reused for irrigation, while the solid part becomes an excellent fertilizer with nitrogen in ammonium form (therefore with a very low level of nitrate) that does not generate unpleasant smell or odors, unlike the traditional fertilizer, and that may form another source of economic income, as well as savings on traditional fertilizer purchase.