In order to maximise the value of the thermal system overall, a fundamental understanding of each component is essential. This is EnergyVille’s strength: determining the state of renewable sources of generation, storage systems and buildings and quantifying residual heat - it’s all part of the larger puzzle. The thermal energy systems that we study include heat pumps, new concepts for energy storage (phase-change materials, thermochemical materials, etc.) and
bidirectional substations for the connection to the thermal network.
In order to exploit the untapped renewable source of geothermal, EnergyVille includes the activation of this form of energy in its expert assessments. In doing so we combine our unique knowledge of the ground underneath Flanders with technological developments for coupling and converting this type of geothermal heat.
1. Thermal energy conversion
The extensive development of renewable energy sources will lead to major changes in the energy networks. Trends include a higher level of interaction between different energy carrier systems like electricity, chemical and thermal systems. Often one source of energy is abundantly available while another source is needed, thus requiring a conversion of energy. In the case of thermal energy conversion, waste heat, heat from a geothermal power plant or heat from other sources are converted to a different energy carrier (like electricity, heat on a different temperature level, cold).
In this research, EnergyVille focuses on three subjects. The first are the so-called Organic Rankine Cycles or ORC’s that convert heat from various low temperature sources into electricity. A second research branch in this activity are heat pumps: devices that pump heat from a source and realize a temperature lift using only a small amount of electricity. Air conditioning systems and freezers are very well known applications, but more recently heat pump systems for households have gained a lot of attention as well. A third branch of research is heat exchangers, components that transfer heat from one medium to another. EnergyVille focuses on the development, implementation, demonstration and efficiency improvement of these conversion systems and the increase of flexibility in systems used as a link between the different energy carriers.
2. District heating and cooling networks
The heating and cooling of our buildings accounts for more than 50% of the total EU energy demand. Today this demand is mainly filled in by burning fossil fuels, but the pressure on the energy supply and the climate compels us to focus on renewable energy and sustainable sources like waste heat. One of the areas EnergyVille is working on to unlock the potential of waste heat is district heating and cooling networks (DHC). Heating networks can match the demand and supply of heat and can function as infrastructure for all sorts of sustainable heat. The coupling of heating networks and electrical networks by means of, for instance, heat pumps or ORCs remains an important topic of research. One of the research domains in this regard is sustainable district heating and cooling networks or DHC-networks. Intelligently controlled DHC-networks are vital in the transition to carbon free solutions. Therefore, the focus lies on fourth generation networks and on the challenges posed by the third generation networks all over Europe.
3. Thermal storage
EnergyVille also conducts research on thermal energy storage technologies. With these technologies you can store excess heat or cold to be used when needed. In other words, the delivery of heat or cold is made independent of demand. This provides a solution to the daily mismatch between heat demand on a domestic level and supply from renewable sources (such as solar collectors or PV coupled heat pumps. ). A lot of different techniques can be used to store heat or cold, ranging from water tanks to the more exotic PCM (Phase Change Material) or thermochemical energy storage. The increased use of renewable energy sources and the increased self-consumption and self-production of energy are driving forces for the use of energy storage. Storage can also add operational flexibility to energy systems and helps drive waste heat recovery in both industrial processes and buildings. Overall, it also improves the resource use efficiency of the energy system.
Thermal energy storage systems are especially used in buildings and industrial processes. In these applications about half of the energy used is in the form of thermal energy. Thermal energy storage systems can help balance energy demand and supply in different timeframes. For instance, a water buffer for sanitary hot water in a household stores heat for a few hours, while a large underground borehole storage stores up to a whole season.
Thermal storage can play an important role in both electrical and thermal grids. In order to couple thermal energy storage to an electrical grid, conversion systems like heat pumps or ORC’s are necessary connection systems. In thermal networks storage can play a balancing role between renewable heat production, connected conversion systems and heat consumers both on a short term (day-night) but also on a long term period (summer-winter). EnergyVille focuses on the development, demonstration and implementation of intelligent control of energy storage systems, on the state of charge, on storage integrated concepts and on compact thermal energy storage.
Lieve Helsen, Professor Applied Mechanics and Energy Conversion
'Today we face absolutely fascinating challenges: we are allowed to think across different boxes and combine efficient technologies untill 1 + 1 becomes more than 2. Thermal systems, such as GEOTABS and thermal networks only reach their full potential when all components work together. Just like in a successful marriage, it is only the insights in the system that can translate to optimal components in view of and as a crucial part of the system. That is system integration in a multidisciplinary and sustainable context!'