“You wouldn't believe how often wind turbines around Berlin had to be shut down in 2017,” says Frank Mattat while opening one of the high glass doors to the energy hub of the European Energy Forum in Berlin. Towering above him is the old gasometer of Schöneberg, a symbol of the energy supply in the 19th century. “If the wind turbines had been left on, Berlin could have been supplied with power for ten days,” continues the CEO of GASAG Solution Plus.

The GASAG Solution Plus installation in the hall behind the glass door should help put excess electricity in the grid to good use. It is the first and currently only installation of its kind in Germany. It transforms surplus electricity into hot and cold water, a perfect representation of the energy supply of the 21st century: the shutdown of wind turbines should soon be a thing of the past.

From the upper ring of the old gasometer, you can see the entire city: blue solar panels glint on the rooftops of the housing blocks and company buildings; where the metropolis fades into the Brandenburg countryside, dozens of windmills dot the landscape. Nowhere is the share of renewables in the power mix as high as in the north-east of Germany: over 53 per cent and rising. For this reason, over 70 partners are involved in the WindNODE project, mainly so that energy consumers can align their electricity demand with the fluctuating offer of wind turbines and solar plants, and in doing so make the operation of the power grids in the north-eastern grid area fit for the energy transition. WindNODE is part of the ‘Smart Energy Showcase’ (SINTEG) support programme and is sponsored by the Federal Ministry for Economic Affairs and Energy (BMWi) until 2020.

The EUREF campus is an important piece of the WindNODE puzzle, right at the heart of Berlin: at the foot of the gasometer, the S-train runs past the former industrial site; the campus was opened only ten years ago. Institutes of Berlin’s universities have settled here, as well as energy start-ups and renowned companies, creating a think tank for the energy transition. By now, some 3,500 people work here, and new offices and research facilities continue to rise up from the ground.

The size of a machine hall, the GASAG Solution Plus energy hub is located at the centre of the campus. From here, a 2.5 kilometre long pipeline system supplies heating and cooling to the office buildings and provides cooling for the computer and server rooms.

At the same time, the energy hub is an experimental set-up for the energy transition: “Here, we want to show how sector coupling works,” Mattat says about the project at EUREF, which is also part of WindNODE, ‘showcasing smart energy systems from north-eastern Germany’.

Mattat stops in front of two large silver cylinders, rising six metres high above the roof of the energy hub: “These water tanks contain 22 cubic metres, forming the heart of the Power-to-Heat/Power-to-Cold installation,” he explains loud enough to be heard over the constant roar of the ventilation system and the high-pitched whirr of the pumps starting up. The water in these storage tanks is heated by the large electrical flow heater located in front of the reservoirs and that resembles a gas- or oil-fired boiler, such as can be found in millions of households. The heater inside is invisible behind the red and grey metal panelling and has an output of 500 kilowatts; it can therefore consume as much electricity as produced by a small wind turbine or a medium-sized solar plant.

The cooling unit is even more impressive: to Mattat’s right, two compressors have been constructed with pressurizers of almost two metres long, resembling miniature submarines. The dimensions are formidable, but the principle is the same as that of any household refrigerator: cold is generated through compression and release. Here, it is merely bigger. Much bigger.

What happens here is what experts call “Power-to-Heat” (PtH) and “Power-to-Cold” (PtC): the use of electricity to heat up or cool down water. Until now, the heating of the EUREF campus of GASAG Solution Plus is mainly supplied by a biomethane combined heat and power (CHP) unit (400 kW_el, 460 kW_th), an own CHP unit (50 kW_el, 100 kW_th) running on natural gas as well as two natural-gas peak-load boilers with a capacity of 2,100 kilowatt each. The cooling units run on green electricity. All in all, this is already leading to a CO₂-neutral supply of the campus. The aim is to mainly operate the large water reservoirs when there is a particularly high supply of electricity from solar plants or wind power in north-eastern Germany. “This is how we help avoid that renewable energy generating units have to be shut down,” explains Mattat.

The result of the simulations surprised GASAG Solution Plus: “For the most profitable operation, we have to use the cooling units much more intensively than the electric heaters,” says Mattat, as the cheap electricity available on the energy exchange for the compressors then replaces the comparably expensive electricity that is otherwise used to operate the cooling units. However, when the electric heater is activated, it competes with the water heating by the biomethane cogeneration unit. Even before the official opening of the installations in September 2017, GASAG Solution Plus also learned many other things.

Inside the energy hub, Frank Mattat walks along green paths; literally: after the official opening, a veritable rush of visitors is expected and GASAG Solution Plus had the paths for the visitors marked in bright green. Eight stops lie between the heating and cooling units and the point of the installation where the heating and cooling lines from the energy hub connect to the campus pipeline system. Tablet in hand, Mattat shows the videos that GASAG Solution Plus will use to explain the details of the installation to future visitors: depending on their prior knowledge, there are three different levels of detail for their visit to the energy hub at EUREF.

GASAG Solution Plus  considers the project at EUREF as a ‘test run’: “We’ve arrived at the point where we are also integrating Power-to-Heat in other projects within the city as well,” says Mattat. In a neighbourhood with about 1,000 living units in Mariendorf, Mattat’s employees are combining a CHP unit with a Power-to-Heat installation that is operated with the self-produced electricity from the thermal power station. In Mariendorf, solar panels are also being installed on the façades to generate power, as well as batteries to store electricity. For the tenants, this means permanently cheap heating but also an electricity supply that is not subject to price fluctuations.

The decisive factor is that the interplay between small power stations, solar installations and the production of heat and cold is controlled. The objective of GASAG Solution Plus: “With this in mind, we want to equip neighbourhoods throughout Germany with a climate-friendly energy supply that also makes it possible to switch from coal-fired power plants to wind turbines and solar plants,” says a thoroughly convinced Mattat. At EUREF in Berlin-Schöneberg, the future has already begun.