Turning waste into green electricity

The city of Shenzen is also called the Silicon Valley of China. From 30,000 inhabitants in the early 1970s, the southern Chinese city has grown to more than ten million, with glittering skyscrapers, a modern transportation system and world-class shops. New factories and start-ups open almost daily, driving the boom. But this growth also brings  problems with it : energy demand is rising and the environment is being polluted. Power generators from Rolls-Royce now help to solve these problems. Landfill gas is produced at the many waste disposal sites and thus gensets produce electricity.

The challenge of landfill gas
The big challenge: Landfill gas is a waste product that is relatively easy to obtain. Bacteria decompose the organic part of the waste and thereby produce landfill gas. It contains the flammable methane that gas engines run on. However, depending on the type of waste that decomposes, the composition of landfill gas is different and so is the methane content. On average, between 35 and 60 percent of landfill gas consists of methane, the rest is carbon dioxide. And the amount of methane has a great influence on the performance of the engine. If the methane number of the gas is too low, the engines begin to knock: then parts of the compressed gas-air mixture explode even before it has been fully ignited by the spark of the spark plug and the engine's performance drops.  

"So far, our gensets have been running very stably at a methane content of about 50 to 55 percent," explains Darren Ding, who supports mtu gas customers in China.