Drilling a two-kilometre-deep geothermal well is basically done with similar equipment as drilling conventional geothermal wells – the equipment is only slightly more robust. The picture is from QHeat’s earlier site at the end of last year.

Quantitative Heat Oy, or QHeat, is a company founded in 2018 that develops the use of thermal energy in the earths crust. A medium-deep geothermal well means a borehole about two kilometres deep with a temperature of about 40°C at the bottom. With high-temperature heat pumps, the temperature is further raised so it is hot enough to be fed into the district heating network.

Vantaan Energia has ordered a plant from QHeat, which will be built on the site of the Varisto heating centre. With the help of the plant, Vantaan Energia will be able to produce district heating in a completely new way. The clean and almost emission-free renewable heat produced by the plant is intended for the Vantaa district heating network. The plant is also suitable as an energy store and makes it possible to compensate for seasonal fluctuations in energy production.

High temperature with good efficiency

“The geothermal plant to be built in Vantaa is the first to produce district heat with heat pumps directly from the heat produced by a medium-deep geothermal well,” says Jussi Alpua, sales manager of Oilon industrial heat pumps and chillers. “Oilon’s heat pump system consists of two Oilon ChillHeat high-temperature heat pumps connected in series and controlled by inverters. The solution achieves very good efficiency, flexible adjustability and excellent functionality even with partial loads. Low GWP (Global Warming Potential) safe refrigerants are used in the heat pumps.”

“QHeat’s solution is very interesting and we are glad that they have ended up with Oilon high-temperature heat pumps in implementation,” says Martti Kukkola, chief business officer for industrial heat pumps and chillers at Oilon. “Oilon manufactures both heat pumps and complete, conceptualised heat pump plants. We have implemented many plants producing district heat, but this is the first implementation to utilise a medium-deep geothermal well as the heat source. It is interesting to be able to follow the dynamics of the operation of the plant in different conditions.”

“The thermal power of the plant at the design point is more than 700 kilowatts and the temperature of the water supplied to the district heating network is 80°C. About 1,400 megawatt hours of heat are produced per year. The plant will help Vantaan Energia reduce its carbon footprint when electricity is needed for only a third of the amount of heat produced. What makes the whole implementation model interesting is that no high-temperature heat source like a data centre or other waste heat source is needed – just a hole in the ground is enough.”

The heat pump plant built in a container will be delivered to Vantaa pre-assembled and tested to its place of use. The advantage of container delivery is that the plant can be built in the factory and the delivery time is fast, typically four months from the order.

Delivery of a pre-built and tested heat pump plant in a container makes installation quick. The container is simply lifted to its installation location and connected to the electrical and pipe connections.

Deep enough relatively easily

Rami Niemi, QHeat’s chief technology officer, one of the company’s founders, became acquainted with drilling energy wells when he worked as a VTT researcher 7–8 years ago. This sparked a strong enthusiasm for utilising geo-energy and later he worked for almost three years as the technology manager of St1 Deep Heat Oy.

“Along the way, my own vision turned to the development of a clearly lower energy well than six kilometres,” says Niemi. “With the depth of two kilometres, many things are much easier and for many uses it will suffice. Really deep drilling requires several tens of times the capacity and the costs become very high.”

“The surface temperature of the earth’s crust is about 4-6°C in Finland, and when going down, the temperature initially rises about 1.4°C per hundred meters and somewhat more deeply. At two kilometres, the temperature is around 38–40°C. In Finland, the temperature of the stone is very predictable, because here the stone has had time to cool for 1.9 billion years and the stone is very even. We can drill a medium-deep well basically anywhere and it always works just as well.”

One well can fit anywhere

“Drilling a medium-deep well is very similar to drilling a conventional, 200–300 meter deep geothermal well – the equipment needs only to be a little more robust,” continues Mikael Maksimow, chief operating officer of QHeat. “However, we put several hundred meters of steel pipe in the hole, fasten it with concrete, and drill deeper through it.”

“A standard heat well has a plastic pipe collector, a U-pipe, in which the antifreeze flows up and down. We have a coaxial flow where plain water passes down the drilled hole and returns up in the insulated pipe. We can also change the direction of the flow. This is essential because then we can use the hole as a heat storage. When extra heat is available, we convey hot water to the bottom of the hole and the stone begins to heat from the bottom.”

According to the men, the two kilometre-deep hole brings many advantages over conventional heat wells. There are many more meters and the stone is warm at the bottom, so one hole is equivalent to 40 ordinary geothermal wells. The water coming to the heat pump is warmer, so it is possible to produce hotter output heat with better efficiency. In addition, it is possible to place one hole on almost any property, even in the city centre. Forty holes would require nearly five acres of space.

Climate change requires strong solutions

In Finland, heating of buildings consumes a quarter of the total end use of energy. District heating accounts for almost half of this, in 2018 about 37 terawatt hours (TWh). More than half of district heating, about 51 per cent, was produced with fossil fuels and peat. About 80 per cent of the electricity was generated from zero-emission energy sources, while nuclear power accounted for about a third of total production.

District heat produced by QHeat geothermal wells and Oilon high-temperature heat pumps reduces emissions from real estate heating by up to 95 per cent compared to fossil district heat, according to QHeat. This is extremely important for climate goals, as heating currently causes about one-fifth of Finland’s carbon dioxide emissions.

There are many dozens of small district heating plants in Finland, whose main fuel is woodchips, but which also have to resort to fossil fuels in various situations. A geothermal plant is the perfect solution for such heating plants. The extra, affordable heat of summer can be stored in the bedrock and used in winter. On the other hand, it is possible to close the woodchip boiler for the summer season, when its service life will increase significantly.

Thermal power plants of all sizes benefit significantly from heat storage, which can be used to balance fluctuations in production and consumption in the long or short term.

Dynamic production

All of Oilon’s ChillHeat industrial heat pumps are dynamically tested with actual load before delivery.

The geothermal plant to be built in Varisto will be commissioned at the beginning of 2021. The plant is used both for heat production and for storing excess heat in the bedrock. The price of electricity varies a lot and quickly. In one morning for example, the price rose to almost 150 euros per megawatt hour and fell below 20 euros in the evening. However, this change was probably due to the maintenance of the Loviisa nuclear power plant.

The increase in wind power will even cause negative prices in the future, and the completion of Olkiluoto 3 nuclear power plant in due course will bring a significant amount of inflexible production to the Finnish electricity grid. The heat load is most affected by the outdoor temperature and then the time of day. Few take a shower at night, but many in the morning. There are big spikes in both production and consumption, and rapid energy storage helps to hunt them down.

“QHeat’s solution offers our customers the benefits of geothermal energy without their own investment as a carefree service and at a stable price,” says Ilkka Reko, director of Vantaan Energia’s Heat Business. “Geothermal heat is an excellent addition to our other renewable heat products and an innovative way to produce renewable heat.”

“Vantaan Energia is a brave change driver in the energy sector that is actively seeking new solutions to achieve its climate goals,” says Miska Eriksson, CEO of QHeat. “It is great to start a cooperation that can replace fossil fuels in district heating production and thus make urban heating more carbon-neutral and low-emission. QHeat’s mission is to be involved in accelerating society’s transition to clean energy.”

Vantaan Energia has announced that it will accelerate the abandonment of coal and plans to phase it out in energy production in 2022.

Oilon has experience in district heating

“Oilon was active and was able to convince us of the superiority of its solution,” Maksimow answers the question about choosing Oilon as a heat pump supplier. “They have experience operating in district heating environments and temperatures. The whole band is very professional and the product is good. One more advantage is their highly developed remote monitoring, so we always know what is happening at the plant. The container solution is delivered to us complete and tested, which we just lift onto the well and connect.”