Sustainable thermal energy to be pumped up

Geothermal energy to heat your greenhouses: eight growers from Vierpolders in the Dutch province of Zuid-Holland are seizing this opportunity with sixteen hands. From the beginning of 2016, 70 percent of their energy requirements will be met from under the ground. Rabobank is a co-financer of the project.

Greenhouse horticulturalists in Voorne-Putten join hands to capture geothermal energy

For years, Paul Grootscholten of Globe Plant had been looking for an alternative source of energy to heat his greenhouses. This is finally set to become a reality at the start of 2016. If everything goes to plan, growers from the area will then be using geothermal energy to grow their pot plants, aubergines, tomatoes and other vegetables. That geothermal energy comes from a well near Vierpolders that is more than two kilometres deep. Paul: 'There are liquid rocks beneath the earth’s crust. Their temperature fluctuates between 650 and 1,200 degrees Celsius. This magma also heats the underground water supply that is available there, to around 85 degrees Celsius. We will pump up that water and use it to supply energy to the nine participants in the Aardwarmte Vierpolders-project (Vierpolders Geothermal Energy project).'

Sustainable alternative to natural gas

Initiator Paul Grootscholten was looking for a sustainable alternative to natural gas, which he found in geothermal energy. 'Greenhouse horticulture accounts for around ten percent of total natural gas consumption in the Netherlands. Using geothermal energy will enable us to save fourteen million cubic metres of gas. That is enough to heat 9,000 households every year. In addition, we will be cutting our CO2 emissions by 25,000 tonnes.' But sustainability is not the only reason for switching to the new energy source. Reducing dependence on the fluctuating gas market is also an important aim. 'Thanks to geothermal energy, the bulk of our energy costs will be fixed for an extended period.'

Heat transfer

When the warm water comes out of the ground at the beginning of 2016, it will not be routed directly to the greenhouses. 'The warm ground water will first flow along another, clean water stream with which it will exchange its heat. The water that has been pumped up will be returned to the ground, where it will be heated again. A seven-kilometre distribution network will be built to pump the warmed-up water to the participating growers, where a second heat exchanger will transfer the heat to a third water stream that will actually heat the greenhouses. Meanwhile, the other water will be returned to the pumping station. There are therefore three different, fully separated water circuits. The water streams are separated in order to prevent pollution.'

No soil movements

From the start of the project, the participating parties devoted a great deal of attention to communications concerning the Vierpolders geothermal project. Grootscholten: 'At first, the neighbouring residents were quite suspicious. But after we demonstrated again and again what we intend to do and how we intend to do it, responses are now basically all positive. For instance, we explained carefully that pumping up the water does not involve any risk. We only collect the heat and the water goes back down again immediately. In the end, we are extracting nothing, so no one needs to fear the kind of soil movements that natural gas production can cause.'

Securing financing

The project has been financed with the assistance of four parties. Besides the participating growers, the government and Rabobank, Meewind contributed as well. This is an investment fund that invests in sustainable energy production. While both Rabobank and Meewind very much welcomed the initiative, they both asked critical questions as well. What were the risks? Which parties were participating? Grootscholten: 'Ultimately we benefited from this scrutiny. It makes you think again very carefully about the choices you are making and ensures that you set clear limits for yourself. All in all, the financing was basically in place within a year. The mutual cooperation was very important in that respect. We all worked extremely hard on this, united by a common goal: the project had to go ahead!'

Greenhouse horticulturalists want to increase sustainability

It was an intensive process for the bank. A thorough risk analysis for the project was followed by a process of adapting a wide range of research reports and contracts for financing, construction and heat offtake to make them suitable for all parties. 'At present, Rabobank is the only bank that finances this in the Netherlands,' says Ivan Das of Rabobank Project Finance, who helped to put the financing in place. 'Geothermal energy is still fairly rare. At present there are only twelve projects of this kind in the Netherlands. Rabobank is a leader in this area. We are meeting the needs of a large group of greenhouse horticulturalists who have been customers of ours for a long time. They are eager to make their businesses more sustainable by using geothermal energy. This is renewable energy that does not deplete the soil. Moreover, the market appreciates the importance you attach to sustainability.'

The proof is in the drilling

The benefits are counterbalanced by substantial risks. Das: 'Seismic surveys enable you to map the soil, but you can never be sure that you will immediately find a viable source when you start drilling. This also depends on other matters, for instance soil subsidence and how easily the water-containing layer is accessible as a result. In fact, you can only be sure when you have drilled a hole – by which stage, you will have spent several millions of euros. And you also always need two boreholes because the water that is pumped up has to be returned to the same stratum. Fortunately, we drilled two right wells in the right places. In my view, that is the reward for the risk that all the parties were prepared to take.'

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