New CHP system from mtu
Seven years later, stricter values for emissions and the need for reliable, powerful units and higher efficiency led to the operators of the plant rethinking their approach. They reshuffled their cards and chose Otto cycle engines. Three combined heat and power modules from mtu using 400-Series engines, each producing 350 kilowatts (kW) replaced the dual-fuel engines. The reliability of these modules from the 400 Series was the deciding factor. Thus, when the opportunity arose to try a pre-production model of the large 4000-Series biogas engines, the team in Löningen did not hesitate long. Twelve cylinders, 1,166 kW of electrical output and more than 1,300 kW of thermal output were attractive characteristics, and the compact dimensions in relation to the power produced were also very practical to make best use of the available biogas.
The low maintenance costs are also one of the major benefits of these large engines. For a large machine it is only necessary to do one oil change or replace one set of spark plugs, for example. Three of the machines from the 400 Series are required to produce the same power, and the time required for maintenance and inspection is correspondingly higher.
Biogas version of Series 4000 engine impresses
Although the biogas variant of the engine from the 4000 Series was a pre-production model, the decision-makers did not doubt its quality. After all, the unit is based on a diesel engine that has proven itself over many years, from which mtu has already derived a reliable natural-gas engine. Some design changes were necessary, however, for use with biogas. The biogas engine differs from its naturalgas cousin with tough new steel pistons and a different combustion geometry, along with a plumper cam shape in favour of a larger valve opening, to name but a few alterations.
The trial users also benefited from the engine management that modifies the combustion for the amount of methane contained in the fuel and avoids knocking, which can result in excessive wear. Above all else, the developers at mtu concentrated on maximising the reliability of the new engine. Despite its conservative design, the engine shows an excellent electrical efficiency of 42.5 percent.
Permanently placed after trial period
The 4000-Series engine has proven itself at GF-Bio-Energie Hasetal and has also shown its quality in the laboratory. After six months of operation, the engine was dismantled at mtu’s Friedrichshafen facility and measurements were taken. The result was that even the newly designed components performed well, showing extremely low wear. Now reassembled, this engine is once again operating in Münsterland. In its twelve months of trial operation, it has already run for over 7,500 hours, and it is still humming powerfully away in the machine shed in Löningen.
The Groß brothers have already planned on the 4000-Series engine for their base load. The smaller 400-Series modules are to be distributed as satellite combined heat and power modules. These satellites will produce electricity and heat close to the consumers and will be supplied with biogas via pipelines. In this way, the operators hope to optimise the use of heat. Satellite operation increases their profit as it prevents loss of heat during transport, and it protects our climate. After all, bioenergy replaces heating energy, which would otherwise be produced using fossil fuels.
The environment also benefits from the latest investment made by GF-Bio-Energie Hasetal. They have now added on a catalytic convertor to their 4000-Series engine. This reduces the formaldehyde emissions, and alongside the profits from electricity, the brothers are now also paid an additional formaldehyde bonus.