This advanced technology has the potential to be implemented on a mass scale, but achieving such a transformation in how power is supplied is no easy feat. We caught up with BTU professor, Dr. Harald Schwarz, who has been spearheading this research since its inception over a decade ago, to chat about the benefits of smart-grid technology, the potential of using it to power cities, and the challenges that still lie ahead.
A mission to reduce emissions
Professor Schwarz has been in the field of electricity for decades. He studied electrical engineering at the Technical University of Berlin and completed his PhD before entering the workforce. In 1995, he joined BTU, working in the field of high-voltage engineering and grid planning.
At that time, the idea of switching to renewable energy sources was in its infancy. And with funding hard to come by, most research in the area was abandoned. ‘We’re only now returning to these ideas,’ says Professor Schwarz. ‘And we’ve missed out on all those years of development. This makes the matter all the more urgent, especially in light of the German government’s commitment to switching off coal and nuclear power in the near future.’
Professor Schwarz has spent close to 15 years researching technical solutions that enable a sustainable power supply. It’s not as straightforward as simply generating more renewable energy and switching off coal and nuclear power plants. Supplying electricity is a delicate balancing act. To completely move to sustainable power sources, the system needs to manage power in a smarter and more efficient way.
Balancing supply and demand
‘Grid planning is all about optimising the power system,’ explains Professor Schwarz. ‘The output of a power station needs to be adjusted continuously in order to meet the demand. With combustible sources like coal and nuclear power, we are able to balance power generation with load forecasts. However, as we turn to renewables, generating power on demand becomes much more difficult.
‘The main renewable power sources available in Germany are photovoltaic (solar power) and wind energy. These natural forces are outside of our control. You can’t simply adjust the sun exposure or increase the wind speed to meet an increasing demand for electricity. And storing electricity for later presents a whole range of challenges.
‘To give you an idea, the current storage available in all of Germany today is 40 GWh (gigawatt hours), which could power the country for about 30–60 minutes. That’s all. We’d need 1000s of GWh in storage, enough to power the country for weeks, to make switching off coal and nuclear power feasible. It would require millions of batteries, which would in turn have a socioeconomic impact. Then there’s the question of where do we house all these batteries? We need innovative ways of balancing the supply and demand on a mass scale. One option we are exploring here is using the car batteries as part of the power storage system, making the electric vehicles themselves part of the solution. Enabling this kind of integration is one of the reasons why smart-grid technology is so important.’
One option we are exploring here is using the car batteries as part of the power storage system, making the electric vehicles themselves part of the solution. Enabling this kind of integration is one of the reasons why smart-grid technology is so important.
Prof. Dr.-Ing. Harald Schwarz, Brandenburg University of Technology Cottbus–Senftenberg
Changing how we charge
‘The standard charging process is to simply charge batteries as quickly as possible,’ explains Professor Schwarz. ‘When you plug in your electric vehicle, a lot of power is used at once to charge the battery in a couple of hours, and then the car sits there doing nothing until you return. Now imagine that everybody in your neighbourhood is driving EVs. They all knock off work at the end of the day, make their way through the traffic to get home, and plug in around the same time. For the next few hours, the drain on the power-supply system is huge, followed by a long period with little demand for power. It’s not very efficient.’
BTU’s smart grid manages power input and output differently. It draws on renewable resources—120 kW of solar power is fed into the grid from one of BTU’s own research facilities. To compensate for the unreliable nature of solar-power generation, the grid is supported by a gas-powered reactive mini-CHP (combined heat and power unit) from which 40 kW of electricity and 80 kW of thermal energy can be extracted. On top of this, 15 grid-serving EV charging stations help to keep the supply and demand in balance.
‘We have the solar power and the mini-CHP, and then we have the electric cars. They use controlled charging, meaning the charging is adjusted to the availability of green energy,’ explains Professor Schwarz. ‘The electric vehicles are actually part of the storage capacity. There is a central control system and a user app. The driver tells the system what they need, based on when and how they plan to use the car. For example, you’d tell it how much power you need and when you’ll be leaving. This user input enables the supply of power to be optimised.’
The smart technology behind the smart grid
BTU’s smart grid is run using a commercial control system that was specially built for the project—a process that took years. The customisation included opening up all of its functionalities so it can be adapted to function in different research scenarios. It’s now powerful enough to continue operating at the core of the control centre as the smart grid is expanded.
The grid’s EV-charging system includes six Delta 150 kW Ultra Fast Chargers and three Delta V2G bi-directional EV chargers. With 150 kW of output power, Delta’s Ultra Fast Chargers offer a powerful and modular, future-proofed design that is easy to upgrade, which is an important feature. To take smart-grid technology to the next level, BTU needs to upscale.
V2G (vehicle-to-grid) chargers allow electricity to flow both ways between the supply and EV battery. This is made possible using the bi-directional charging technology known as CHAdeMO. Delta’s partnership with Nissan, a Japanese car company at the forefront of EV optimisation, was also beneficial in this area. Nissan cars with CHAdeMO charging have played a valuable role in facilitating Professor Schwarz’s research.
The next step for smart grids
Professor Schwarz now plans to take his learnings from the development of BTU’s microgrid and expand the technology to create a smart campus. ‘Upscaling is a slow process,’ he explains. ‘We can’t simply roll out the current technologies across the entire campus, we need to take it step by step.
‘The microgrid is in the range of 50–100 kW. It took five years to iron out all the kinks and get the grid working properly. Each scale-up presents new challenges, which is why we can only scale up by a factor of 30–50 at a time. Our next goal is to transform BTU into a smart campus. And we’ll certainly encounter new problems and system-integration issues that we need to solve before we can upscale again after that.’
Whilst there are many challenges ahead, including securing the funding needed for further research, BTU’s successful smart grid is a big step forward for sustainable electromobility. And Professor Schwarz is thinking outside the box when it comes to getting the powers that be to sit up and take notice: ‘To get people’s attention, you really need a flagship vehicle—people see the car, see the advertising and are convinced about the technology. For sustainable electromobility, this could well be the recently released Mercedes EQS. This is something we’ll be considering as we look to the future and the possibilities for implementing smart-grid technology on a much larger scale.’
