SlimPark on campus: demo-site for energy transition

| Hans Wolkers

By better matching the consumer demand with energy supply from solar and wind, Johann Hurink, Professor of Applied Mathematics, develops smart solutions for an optimal use of these forms of energy. The first demo-site, SlimPark on campus, shows how solar energy can be utilized most efficiently.

SlimPark at the UT is a modest building, looking like a good mix of Scandinavian design and modern art: a construction of steel and wood that contrasts nicely with a futuristic roof made out of solar panels. It is a living laboratory as well as a demonstration site to study the optimal use of solar energy to charge electrical cars. Nine electrical cars can be parked and plugged into the charging stations. ‘SlimPark demonstrates the essence of a microgrid,’ Hurink says. ‘In this demo-study, important aspects of energy management are integrated: we generate solar electricity, use this energy locally for charging and store the excess in a battery.’

Smart energy use

Hurink and his colleagues have transformed the concept of smart energy use, where demand and supply are balanced, into reality. At SlimPark, software and algorithms plan the charging of electrical cars to maximize the use of available solar energy. For example, when there is no sun in the morning, and the weather forecast predicts sun in the afternoon, the system delays charging until the sun shines. This prevents peak loads on the electrical grid and allows for a very efficient use of solar energy. User flexibility is key to the success of SlimPark, and charging a car can be done during the whole day. Users fill in an app, indicating at what time they will depart and how many kWh they need to charge the car battery. The system plans the charging in such a way that the user always has a filled battery when leaving.

Professor Johann Hurink and PhD researcher Bart Nijenhuis

Uncontrolled energy supply

Due to policies to replace fossil fuels, energy generation is moving from fossil-based energy to new energy, like sun and wind. Currently, about four percent of our total energy supply is generated by solar and wind, and it is expected to grow in the future. However, one of the problems with these new energy sources, is their uncontrolled energy supply. During windy or sunny days, an enormous surplus of energy is generated, while an absence of these natural forces results in an energy shortage, that usually is compensated for by traditional fossil fuel plants. These can easily be scaled up or down to match energy supply and demand, but new energy sources can’t.

‘Production of wind and solar energy are highly unpredictable’

‘Production of wind and solar energy are highly unpredictable due to the dependance on the weather,’ Hurink says. ‘During peak generation, the local supply is higher than the demand and surplus energy is transferred to the grid. When there is not enough sun or wind, consumer demand exceeds the available energy.’

This imbalance between electricity supply and demand results in huge problems for the electrical grid and may in the future lead to power black-outs. This is a costly and often life-threatening situation, since consumers, industries, and hospitals require a steady supply of energy. With the increasing electrification of society, this black-out problem will only get bigger. ‘As mathematicians and computer scientists, we can come up with nice systems and ideas to better match supply and demand, but we also need cooperation with other scientists’, Hurink says. ‘This makes it a very multidisciplinary field.’  


According to Hurink, part of the solution to better match new energy supply with demand, is to decentralize energy production and combine it with local storage and demand in one integrated system: a microgrid. This involves local energy production by a small neighborhood or even a single building, by, for example, solar panels on roof tops or a few windmills. During peak production, energy can be shared with other households, avoiding a massive energy return and a consequent overload of the power grid.

‘This decentral energy management is our main expertise,’ Hurink says. ‘Using models, algorithms, technology and case-studies, like SlimPark, companies and scientists from the departments of Electrical Engineering, Computer Science, Applied Mathematics, Behavioral Management, and Social Sciences work together to develop solutions to better balance power supply and demand.’

Consumer behavior

For an optimal performance of such a microgrid, consumers also need to be flexible in their energy use. ‘We can’t control sun or wind, but to some extend we can control the energy demand at different times of the day: consumer behavior may help to match supply and demand’, Hurink says. ‘We need to help users to be more flexible in their energy use and change their behaviour to avoid peak loads on the energy system and make it more attractive to avoid using energy during periods of high demand.’

This can for example be achieved by giving energy a different price during the day: relatively cheap during peak production hours, and more expensive when energy is scarce or demand exceeds production, for example, during the evening. ‘Charging an electrical car is usually done when people come home from work. This is exactly the moment when energy demand peaks,’ Hurink illustrates. ‘But charging the car battery can also be done during the night, when demand is much lower, or, if possible, during the afternoon, when demand is low and supply by solar panels is high.’

Demo site

The so-called ‘smart’ devices are a next step in flattening peaks in energy supply and demand. These are programmed to automatically use energy when it is plentiful. For example, a smart fridge could be programmed in such a way that the temperature is always kept between four and eight degrees. During periods of energy shortage, the temperature will be close to eight degrees, while temperatures will be lower when there is sufficient energy, for example, during mid-day.

‘The UT should serve as an experimental set-up and demo site’

SlimPark can also be considered a ‘smart’ device: it matches supply and demand and even the expected energy generated by the solar panels is taken in the equation by including the weather forecast. But for Hurink, this is just the beginning: ‘To solve the challenges of the energy transition, the UT should serve as an experimental set-up and demo site, where case studies with new technologies are tested, but also demonstrated to the public,’ Hurink says. ‘Here we have the right academic climate, the infrastructure and scientific ecosystem.’   

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