New biogas unit processes organic waste into free energy
Food service businesses accumulate large amounts of organic waste. Often, this ends up in landfill, bringing costs for the enterprise and negative environmental effects. Businesses have an incentive to find alternative ways of dealing with the waste. Biogas offers that alternative. It is a by-product of the anaerobic digestion of organic waste, consisting of about 60 % methane and 40 % carbon dioxide. The methane can be captured and used for cooking and water heating, since urban natural gas supplies are mostly methane anyway. For some years, HOMEBIOGAS Ltd. has been manufacturing a small biogas production unit for the household market. Householders place organic waste in the unit, which collects and stores the biogas, leaving a bio-slurry that makes good garden fertiliser.
Numerous food businesses – including restaurants, hotels and supermarkets – requested that the company produce a larger version. The company is now the only partner in the EU-funded HOMEBIOGAS project of the same name. The project developed an affordable biogas system, targeted at food businesses, able to convert up to 250 kg per day of organic food waste into clean gas that can be used for cooking or heating. Apart from the higher capacity, the new HBG 20 unit also introduces automation. “Instead of throwing organic waste into garbage bins,” explains Alon Civier, project coordinator, “the user puts it into the automatic crushing unit. The waste is crushed and automatically transferred to the anaerobic digester, where it is converted to biogas.” The project also developed a special anaerobic bacterial mix not derived from animal manure. It is administered in tablet form. The HBG 20 unit can be activated using the bacterial mix to create the anaerobic bacterial slurry. The HBG 20 filters off dangerous hydrogen sulfide gas and stores the biogas in a low-pressure container. An industrial computer system monitors the unit and employs dedicated sensors to control temperature, gas pressure and gas level. The computer is connected to the internet and can be accessed remotely. A gas blower pumps the stored biogas at higher pressure for cooking, or for heating water.
The project tested and verified the device via two trials. One was a boarding school dining room, the other a vegetable packing facility. Results indicate that approximately 100 kg of organic waste yields around 10 m3 of biogas, enough to heat 1 m3 of water to about 50 °C, or to provide about 10 hours of commercial stove cooking. In both cases, trials reduced costs for the host organisation. The company will be launching HBG 20 during 2021. Before then, the HomeBiogas team will be further demonstrating the system at 10 additional locations in the EU and United States. Soon, the team will begin working on an improved model able to accommodate up to 1 t per day. “This development will allow small to medium food businesses to handle their waste on-site instead of paying for its collection,” reports Civier. “The businesses will also benefit from the generated biogas, that will lower their energy bills and add self-sufficiency.”
HOMEBIOGAS, biogas, gas, organic waste, cooking, food business, HBG 20