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Benefits for Biogas Plants
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AD-WISE will save over €20,000 per year for Biogas Plant Operators. AD-WISE is a system for AD monitoring and control that will help biogas plant operators to improve the efficiency of the process.
Biogas plant operators have two ways of operating a biogas plant:
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CONSERVATIVE – run the plant with a “safe” organic loading rate, so that acidification and process stop is avoided. This mode of operation forces the operators to give up efficiency (more biogas production per m3 digester) because of stability assurance.
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OPTIMISED – run the plant with a limit organic loading rate, where biogas production is maximum but stability has to be tightly controlled. In this mode, frequent single VFA (VFA profile) analysis should be carried out and the results should be immediately available, which is not possible nowadays. |
AD-WISE system will allow having real-time single VFA measurements. Moreover, the system will suggest to the operator the actions to carry out in the plant in order to efficiently control the process as follow:
Economic impact of AD process stops
A standard 500 kW anaerobic digestion plant produces 4GWh in a year.
Plants like those treating varying organic waste, sewage sludge digesters performing co-digestion, etc. are likely to suffer process stops, especially if plant operators try to optimise the plant by increasing the feed rate, which is the only way to do it in existing plants. If process is stopped, it takes 2-3 months to recover steady state conditions.
A reasonable hypothesis is to consider that the electric energy production of one month would be lost (0.33 GWh). The cost of the process stop will be different depending on the price of the renewable energy of different Member States. In the following table, the prices of the kWh of electricity produced from biogas are given, and the corresponding losses due to process stop of a 500 kW biogas plant are shown.
Table: Savings derived from the installation of AD-WISE system in biogas plants
Country |
Energy price (feed-in tariff)*, €ct/kWh |
Savings thanks to AD-WISE, €/year |
Austria |
18.5 |
61,667 |
Belgium |
19.8 |
66,000 |
France |
12.5 |
41,667 |
Germany |
21.2 |
70,667 |
Italy |
28 |
93,333 |
Poland |
11.4 |
38,000 |
Spain |
13.8 |
46,000 |
Slovenia |
17.25 |
57,500 |
United Kingdom |
15.5 |
51,667 |
Energy market price (pessimistic case) |
6 |
20,000 |
Worst scenario |
3 |
10,000 |
*Data from Biogas Regions 2010. In countries where the tariff is variable, a mean value has been taken.
According to the table, even if we consider that the plant does not take the feed-in tariff but sells the electricity in the market, the cost of the equipment would be recovered during the first year of operation if we consider the risk of one process stop a year.
Even considering one process stop every 2 or more years, the payback period would be below 3-4 years, which is usually considered as economically feasible for industrial investments. Additional savings can be considered due to the fact that external analysis of SVFA is not needed anymore.
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