Zweifel saves CO2...

Zweifel saves CO2

...and reduces operating costs

Since 2016, a mini CHP plant has been producing valuable electricity from renewable energy for the Swiss chips producer Zweifel and reducing its CO2 footprint. The wastewater from production is treated in the company's own wastewater treatment plant and the biogas produced from fermentation in the anaerobic reactor is fed into the CHP unit as a high-quality fuel. The waste heat from the unit is integrated into the production heating process or used to heat the anaerobic reactor. In addition, part of the heat is used for heating the building. Thus, the energy of the anaerobic starch degradation process is used practically completely and Zweifel can saveCO2. The CHP plant essentially consists of a CHP module and a gas purification system.

Combined heat and power plant Smartblock BHKW

The module

The smartblock 33 CHP module from KW Energie, based in Freystadt (DE), consists of a Kubota gas engine with coupled asynchronous generator. The newly developed gas engine with GSC combustion technology (GSC = gas stream combustion) impresses with its robust design and high energy efficiency. Thanks to the existing exhaust gas condensation, a total efficiency of over 100%, based on the lower calorific value, can be generated. The downstream 3-way catalytic converter ensures low exhaust gas emissions that are significantly below the prescribed values. During the design and especially the standardization of the module, great attention was paid to the accessibility and serviceability of the individual components of the unit. A sound insulation hood ensures low-noise operation. An important part of the module is the control system which is carefully adapted to all functions of the CHP operation. Important for the operator are the easy operability and the optimal display of the operating levels on the operation panel. A BUS connection enables the integration of the electronic data into the plant's own control system.

Biogas processing sewage treatment plant

Description Biogas upgrading

A purification system for the biogas installed outdoors ensures trouble-free and low-maintenance operation of the CHP unit. Furthermore, the gas cleaning guarantees a long service life of the module. In a first stage, the gas is cooled in order to wash pollutants out of the gas with the condensate. After subsequent heating, the gas enters a container with activated carbon to filter out further trace elements such as siloxane or sulphur compounds from the gas.

Operating experience

Operating experience

The module runs to the full satisfaction of the customer. The service intervals are much longer than planned. No major maintenance work has had to be carried out yet. Particularly noteworthy is the extremely low susceptibility of the unit to malfunctions. However, should a malfunction occur, the competent service team at 42technology is on the spot immediately.

The responsible team leader of the wastewater treatment plant, Markus Mutter, can only recommend smartblock . He would immediately choose a module from KW Energie again.

Support and service

Support - Service -Technical data

Our experienced and technically skilled team supports and accompanies our customer in the economic efficiency analysis, the project-specific design and selection of the suitable smartblock. Furthermore, we offer support in all questions regarding technical integration and with the necessary registrations as well as the completion of formalities.

The commissioning of the CHP unit is carried out by our technicians. We check that the installation work has been carried out, set the desired operating mode and output control, carry out a test run and check the safety functions. Finally, the customer or operator receives detailed instructions on how to operate the smartblock.

Sales Switzerland/Service

CHP Make

CHP type


Electrical power

Thermal power

Fuel output

Gas consumption

Noise at 1m distance

Year of manufacture

Operating hours

42technology, Aarwangen

KW Energie, Freystadt (DE)

smartblock 33

Sewage gas

30 kW +

58.8 kw

94 kW

11 Nm3/h

48 dB(A)


19'400h (as of July 2021)

Zweifel Pomy-Chips AG

Zweifelstrasse 5

8957 Spreitenbach



42technology Ltd.

Buetzbergstrasse 2c

4912 Aarwangen