#BiogasCanDo: Generation of electricity for 800 households in Exeter, Maine/USA

Exeter Agri-Eergy

Diary farm, Exeter, Maine/USA

Technical Details: The anaerobic digester system that was introduced at Stoneyvale Farm in 2011 is the first of its kind in New England. The manure of the farms animals is mixed with organic food waste. After fermentation the biogas consists of sixty percent methane and forty percent carbon dioxide. The biogas fuels three sixteen-cylinder 1500 horsepower engines that produce 24,00 kilowatt hours per day – enough electricity to provide power for 800 homes on a continual basis. The electricity is sold to local utility company, responsible for the power generation and transmission system in New England.

Type of engine: 3 x Guascor SFGLD 560 engines
Oil volume: 3 x 208 liters
Type of gas: Biogas
Applied oil: ADDINOL Gas engine oil MG-40 Extra Plus
Application since: April 2021

Challenge

Safe control of the acidic components due to the biogas quality in order to permanently protect the engine components. On top of that extension of the oil change intervals based on regular oil analyses with maximum safety for engine and operation.

Oil operating time extended by 300 percent

Experiences in use so far:
Exeter Agri-Energy began to work with ADDINOL in April 2021 and converted the first GEN 1 engine to ADDINOL Gas engine oil MG-40 Extra Plus. The engine was operating with a major competitor’s product, another high ash gas engine oil. Oil changes were performed every 500 operating hours.

Safe control of acidic components:
Operation with special gas is usually characterised by exposure to highly acid-forming substances. To ensure safe lubrication at the highest level, the gas engine oil used must reliably neutralize the resulting acids. The three special gas engines manufactured by Guascor operate safely and trouble-free with ADDINOL Gas engine oil MG-40 Extra Plus. The high alkaline reserve is especially tailored to these difficult conditions and reliably protects against corrosion and abrasive wear.

Extending the oil change interval threefold:
After the product was changed to ADDINOL Gas engine oil MG-40 Extra Plus, immediately the oil operating time could be increased up to 1100 oh. There was no loss in product quality or performance, although residual quantities of the previously used engine oil always remain in the system after the changeover. The next oil change was performed after 1500 oh. With this the oil change interval was tripled compared to the competitive product. After the excellent performance of ADDINOL Gas engine oil MG-40 Extra Plus, the second and third gas engines were also changed over to ADDINOL.

“We connected with a consultant from Italy and started working together. His focus is on the biological health of our system but he is also very well versed in all things related to anaerobic digestion. He quite strongly recommended we start using an oil called ADDINOL in our engines. He said they use it extensively in Europe and have great success. Generally speaking, we test every 500 hrs, even if we don’t change oil. ADDINOL uses Jet-Care International for independent oil testing. So I take a sample, send it to Jet-Care and Jet-Care sends the results to myself and to ADDINOL. ADDINOL then reviews the results and recommends a new oil change interval. By doing this, we have extended our oil change interval from about 500 hrs to 1500 hrs (and at 1500 hrs, ADDINOL is still not recommending we change oil – I am just changing it out of an abundance of caution). It’s taken some time to get comfortable with their recommendations, but I think it’s their long-term experience in Europe, where anaerobic digestion technology is MUCH more mature than here in the US, that gives me comfort”

John Wintle,
Project and Facilities Manager Exeter Agri-Energy