We interviewed PhD student Christoffer Alenius about his work as part of the sub-project “Energy-smart cultivation and waste heat recycling”. His research focuses on the utilisation of waste heat from server rooms to supply to greenhouses, which also serve as educational facilities and resources for local vegetable production. The aim of the project is to optimise energy consumption, explore synergies between different industries, integrate renewable energy sources and create economic business models for a sustainable food supply.

What is the sub-project about?
The project is about finding energy solutions and optimising the reuse of heat between industrial parties that do not otherwise work together. This is known as industrial energy symbiosis. The project focuses on the energy symbiosis between greenhouse cultivation and data centres in the north.

What synergies do you see between the different industries when it comes to energy-efficient cultivation and waste heat utilisation?
Waste heat can be reused in practically any industry where it is a by-product. However, the area of application depends on the temperature of the heat. Greenhouses generally require low temperatures. Warm air of around 30–40 °C would be sufficient. Data centres have a very high cooling requirement in order not to damage the IT equipment. They are therefore considered to be large producers of low-grade heat, which is usually simply released into the empty air. This is not very resource-efficient. Let us assume that a data centre and a greenhouse form a specific energy system. Using a greenhouse as a heat sink for the data centre extends the life cycle of each energy unit and reduces the total energy demand of the entire energy system.

What challenges do you think we face in implementing energy efficient cultivation and waste heat recycling and how can these challenges be overcome?
One of the biggest obstacles with energy symbioses is that very few people know how to set them up effectively. Good communication between stakeholders and an efficient energy transport infrastructure are required. When it comes to energy symbioses between data centres and greenhouses, it is important that the needs of both parties are met. Are the data centre and the greenhouse sized correctly for each other? Are there any problems that may arise and for which one of the parties must be prepared? Good planning is the basis for effective collaboration.

The use of free cooling for data centres is very common here in the north. Then you let the outside air flow over the processors. This is usually a simple way of cooling, and air is also an easy medium to transport to nearby buildings. However, data centres can also use a variety of other cooling methods. The energy symbiosis between greenhouses and liquid-cooled data centres has been little explored. More effort would therefore be required to find out how usable this residual heat is for this purpose.

What results do you hope to achieve?
  • We want to find out how to effectively set up an energy symbiosis.
  • What effects energy-saving measures in greenhouses and different electricity utilisation have on the energy symbiosis.
  • Which other cooling methods for data centres can be used as a heat source for greenhouses in addition to free cooling.