Thanks to the heat and power generated by cogeneration, new builds and energy-renovated existing buildings can now be supplied with energy with a level of efficiency previously only possible in large or old buildings with a high heat demand. Until now, this high demand was the decisive factor for optimum and therefore economical operation of a cogeneration unit. But now innovative fuel cell technology provides the optimum solution for detached homes with low heat demand – like the low-energy wooden house owned by the Dilger family in Freiburg in Breisgau, Germany.

Since March 2016 the Dilgers’ family home, already an efficient low-energy house, has been saving even more energy, money and environmentally harmful CO₂ emissions thanks to a Dachs InnoGen unit with fuel cell technology. The innovative energy solution from SenerTec supplies the house (135 sqm of living space) with low-cost and eco-friendly heat and electricity. The chemical reaction of hydrogen and oxygen inside the fuel cell, known as ‘cold combustion’, produces both electrical energy and usable heat. The ‘exhaust gas’ produced is water.

“Energy-efficient and eco-friendly living has always been as important to us as modern living,” says Peter Dilger, who is the head of finance, IT and HR at a mid-sized German firm. As part of a series of modernisation measures, the existing gas-fired condensing boiler was replaced with a Dachs InnoGen with an additional 300 litre buffer vessel and hot water module.

The Dilger family was pleased that there was no need to upgrade or convert their existing heating system; nothing more than a simple replacement was needed. Like the old system, the Dachs was installed in the attic. Once a hydraulic check had been professionally carried out, it was possible to continue using all the same pipes and radiators, thus reliably providing the entire house with heat, hot water and now also with electricity. “The opportunity to be less dependent on rising energy costs and be among the first to demonstrate the possibilities of the new technology as part of the EU-funded project ene.field has confirmed our decision to opt for a high-efficiency micro-cogeneration unit like the Dachs,” says Dilger. He was also impressed by the ease of operation, especially the new ‘energy manager’ with touch screen, which provides constantly up-to-date information about the operating status and current technical data. The unit’s settings can also be adjusted quickly and conveniently to suit individual heating and power requirements.

The fuel cell heater, which has an overall efficiency of around 90%, operates all year round in the low-energy wooden house, amounting to around 8,000 operating hours. The Dachs covers nearly 100% of the heat demand of approximately 13,000 kWh per year. The Dilgers, who have an annual power requirement of around 5,000 kWh, use about 50% of the electricity they produce. In the past, the main energy cost drivers were the washing machine, dryer, dishwasher, router, computer and laptops. With the Dachs, these costs have been reduced. The Dachs also delivers impressive results in terms of climate protection, saving around 2 tonnes of CO₂ per year. “For us these are excellent results, because they help us contribute to a healthier environment for our children to grow up in.”

Beyond the environmental aspect, the family is also delighted with their ene.field unit because it saves them around €700 annually on their electricity bills. In addition, the fuel used by the system (natural gas) is exempt from energy tax, saving them even more money. The subsidies available from the German Federal Office for Economic Affairs and Export Control (BAFA) further increases the cost-effectiveness of the Dachs InnoGen. Even more, the InnoGen’s three-year maintenance interval is another reason why the Dilgers are so satisfied with their choice.