A Working Lab - one of the largest direct current installations in the world

The office complex A Working Lab is a part of the Johanneberg Science Park at Chalmers in Gothenburg. It works as an innovation arena for community building and learning environments, and is a physical link between academia, business, and community. The building is certified for Environmental Building Gold and is today the most intelligent building in Akademiska Hus’ real estate portfolio.

Within the frame for the FED-project (the Fossil free Energy District), has Akademiska Hus tried new solutions that will create conditions for a completely fossil-free society. In other words, they take advantage of all excess energy through Micro-grids that transfer the energy between about 50 different buildings in the area, with distribution where it is needed.

There are multiple interesting examples among the innovation projects - one being an electricity grid for direct current (DC) from solar panels with battery storage, and another one being a property that has been built with minimal impact on the climate and without the need of a weather tent.

- An electricity grid for DC makes it possible to fully use the solar produced electricity from the roofs, since the power loss in the conversion process between direct current (DC) and alternating current (AC) basically goes away, says Jonas Hansson, innovation leader for the project in the innovation arena A Working Lab. We also want to take advantage of the solar electricity during all hours of the day, and this is possible through battery storage, where we save any excess from the sunny hours during the mid-day. These solutions result in a more even energy usage and eliminates any expensive power peaks, continues Jonas.

The project has faced a lot of challenges that the collaborating participants Akademiska Hus, RISE, Ramböll, and Afry have had to experience. One of the challenges was to find suppliers that could provide A Working Lab with products that are compatible and could be run directly with the DC from the solar cells and battery storage.

A number of products were identified as potential direct current electricity consumers - including fan units, pumps, water heaters, control and regulation systems, access control system, emergency and general lighting, IT switches, and vehicle charging.

Due to difficulties with matching against the right voltage level, the fan units and general lighting were successfully run by DC. There are also other examples of products that can be run by DC, for example mobile phones, computers, USB powered computer accessories, desk lamps, copiers, and coffee machines.

The solution eventually became a Swedish developed bidirectional inverter from the Swedish technology developer Ferroamp. The EnergyHub is an inverter that can both convert DC to AC and vice versa.

- This property built by Akademiska Hus is a good example of what we want to achieve with our system solutions. At the same time as the demand to use more clean electricity increases for, for example, electromobility, the cost of distributing electricity also increases, as well as the need for local solutions to manage the power peaks, says Björn Jersntröm, founder and CTO at Ferroamp.

- We know that sometimes it is not financially feasible to expand the grid connection, dig up streets, and pay for expensive power subscriptions. This is when solar cells on the roofs and the DC grids, as well as solutions for phase balancing and battery storage that we have developed, are a part of the solution. The power loss will be minimal and the real estate owner gets both the control and tools to act financially and environmentally sustainable. To our knowledge, this is the largest commercial building in the world that is built on direct current technology, continues Björn Jersntröm.

For the DC-driven electric system there were some additional challenges, such as finding lighting fixtures and fan motors that can handle 760 Volt DC - which is the voltage that the EnergyHub-system manages. Standard products were sought that could use that voltage level directly, without any conversion losses.

A standard fan to the ventilation unit that could handle 670 Volt was eventually found - however, not one that could handle 760 Volt. That is where an ESO-unit (Energy Storage Optimizer) from Ferroamp came to use - that normally is used for battery storage - and that after some adjustments could reduce the DC-voltage to 670 Volt.

For the lighting in the building, the DC system’s center of symmetric balance could be used - in other words, the 760 Volt was split up into two voltage components +380 Volt and -380 Volt - and where the market offers lighting fixture for LED luminaires that can handle the voltage range 380-400 Volt DC. This made it possible for all of the general lighting in the entire building being run by DC.

Now there are two parallel electricity grids and power stations in the building - partly for regular AC and partly for DC. The DC-grid has also been complemented by a 300 kWh battery storage delivered by Ferroamp, with its own ESO-units, and that is adapted to the property’s EnergyHub-system.

It is clear that A Working Lab in Johanneberg Science Park has the future ahead of itself, with the vision of being a leading long-term arena, where innovations are being tested within multiple areas. The building is certified according to Environmental Building level Gold, with energy usage < 35 kWh/sqm/year, excluding tenants’ energy usage, thanks to high ambitions in terms of climate adaptation, resource efficiency, and low CO2 footprint.