We can work without a grid as well
As part of the publicly funded “FlexECO2” research project, a highly flexible dual-fuel CHP engine has been developed in cooperation with the Amberg-Weiden University of Applied Sciences. It can be used as a sole power generator in isolated networks – without the need for auxiliary equipment. Isolated networks are electrical networks of generators and consumers or entire locations (“islands”) that are not connected to the public power grid. These are sometimes technically necessary because the power required is not available at the location. Or it makes more economic sense because high connected loads also lead to higher costs. Usually, only diesel generators are available for isolated operation, which entail high fuel costs and emissions. The control behaviour of pure gas engines isn’t yet state-of-the-art enough to allow them to be used in isolated systems without the support of diesel engines or electricity storage systems.
This newly developed engine is operated using gaseous and liquid fuels in variable mix ratios. The original aim was to use methane / natural gas alone. However, due to the upheavals caused by the war in Ukraine, a quick switch was made to using wood gas in order to offer potential customers a crisis-resistant and sustainable solution. On average, gas accounts for around 70% of the power supplied. In addition to diesel oil, biodiesel, vegetable oils and synthetic fuels such as HVO can also be used as liquid fuels.
The dual-fuel engine is able to exploit the advantages of both fuel systems: the good control behaviour and load spectrum of a diesel engine and good environmental balance and cost effectiveness of a gas engine.
For this purpose, a power controller was developed as part of the project that can regulate the constantly fluctuating load in isolated networks using two fuels simultaneously.
The CHP unit offers greater security of supply than conventional diesel units: even if the gas supply fails, the engine is able to continue generating electricity using liquid fuel without interruption. It is also possible to connect a consumer at 50% of the nominal load, which corresponds to an output of 120 kW (164 hp). In dual-fuel operation, the engine can be briefly overloaded up to 315 kW (430 hp), which corresponds to around 130% of the nominal load.
An additional aim was to fulfil the emission requirements of 44. BImSchV [German Federal Immission Protection Ordinance], in particular the NOx limit value. This is 100 mg NOx/Nm³ when natural gas is being used. This has been realised using a highly potent and dynamic SCR system, the potential of which far exceeds the requirements of this application.
The CHP unit is also H2-ready, i.e. prepared for future increases in the proportion of hydrogen in the fuel gas.
The CHP system can help to massively reduce energy costs for electricity and heat in the wood-processing industry, for instance, and reduce dependence on fossil fuels and utilities. In addition, an uninterrupted supply can be guaranteed, even in the event of a power failure.
Key technical data:
Nominal output: 240 kWel
Specific output: 25.4 kWmax/l displacement
Publicly founded research project "FlexECO2"
