Vegetables, fruit and flowers with geothermal energy

Most people know HVC as a waste-to-energy plant or waste company. However, the fact that HVC is also active in generating renewable energy from green gas, solar parks and geothermal energy is much less known. HVC asked KH Engineering to provide the basic engineering of the process installation of their 'geothermal plants'. In the Westland region, several geothermal projects are in operation or under development, mainly intended for greenhouse horticulture.

In the Westland region, the soil is extremely suitable for utilising geothermal energy, or geothermal heat. HVC is now working on its third geothermal installation in this region. Senior Project Manager Olaf Bresser says: 'Geothermal energy can technically be divided into three pillars: drilling, the actual drilling of a kilometre-deep pit; the process installation, which is the 'heat factory' where the hot water is converted into usable heat; and the heat network, that allows you to transport the generated heat via pipelines to where you need it.'

From the Triassic to the Cretaceous
'The first installation we built,' Olaf continues, 'is in Naaldwijk. It is called Trias Westland and has now been operational for three years. Trias Westland is an initiative of HVC, Capturam, Royal FloraHolland and a large group of greenhouse horticulture entrepreneurs. Five years of preparation preceded its realisation. At the time, we had planned to drill to the Trias layer in the soil, about four kilometres deep. We would then extract hot water from there at 120 degrees Celsius. However, the rock turned out not to be suitable enough to extract enough hot water from it. We then went back up and drilled a pit in the Cretaceous layer at a depth of 2,500 metres, from which we can now extract water of 87 degrees Celsius.'

Two pits form a doublet
For geothermal heat, you actually have to make two pits: one production pit from which you pump the water up and one injection pit through which you put it back into the ground. Together, this is called a 'doublet'. In the above-ground process installation, you lead the pumped-up water from the production pit past heat exchangers, that 'extract' the heat. It then goes to the injection pit. A special feature here is the natural gas that is released when pumping the water. This is collected and put into a gas engine, which in turn supplies the process installation with electricity. Thus, the process plant meets its own electricity needs.

Greenhouse horticulture Westland
Meanwhile, a second doublet has been made at the Trias site and HVC has started a geothermal heat project in Maasdijk. Olaf: 'We are planning to make three doublets there. We are currently drilling and the first doublet is ready. At this site, we are also going between 2,700 and 2,900 metres deep and we are expecting to pump up water of 90 degrees Celsius.' Why is the Westland ideally suited for geothermal heat? Olaf: 'It has to do with the soil: you can get to the right layer of earth here relatively easily. I emphasise 'relatively', because such drilling is expensive and is only possible with an SDE subsidy from the state. It also has to do with the demand: because of the many greenhouse horticulture in the area, there is a great demand for heat. Especially now that gas prices are so high, geothermal heat becomes even more interesting.'

Professionalisation
About the reason that HVC chose KH Engineering as a partner in this project, Olaf says: 'Geothermal energy is still a young technology in the Netherlands. It was pioneered in the first years by the growers themselves, with the help of horticultural affiliates. However, now we are in a new and more professional phase of the technology, which is under enforcement by SSM: State Supervision of Mines. They pay close attention to ensuring that this new branch is handled in a professional manner, including all safety aspects that apply. KH Engineering has solid experience in the base industry, where the strictest rules apply, and can, for instance, carry out HAZOPs and take into account ATEX zoning standards. And what I find very important: the engineering processes must be done with the right documentation. This is also an expertise of KH Engineering. That is why I asked if KH Engineering would do the basic engineering of the process installation.'

High standards
What appeals to Olaf at KH Engineering is the thoughtful and pragmatic approach, he says. 'They work very professionally, and even so professionally that we occasionally have to slow them down in deploying industrial standards. We work very professionally, but we are not a refinery. So we have to reconcile standards. This is a nice process, in which KH Engineering's industrial knowledge is very valuable. They can not only make a safe and good design, but also give useful advice on the materials to choose, for example in the pipes and gaskets. After all, the pumped-up water is extremely salty and therefore traditional materials would be eaten away in no time.'

Flexibility is important
The knowledge of industrial installations combined with the excellent documentation of all design steps in the engineering process makes KH Engineering the right partner in the geothermal project, Olaf believes. 'We obviously want to do it safely and according to the rules, and SSM also requires us to document the project perfectly. I also find flexibility a positive feature of KH Engineering. After all, that is very important in a geothermal project. Only after drilling and testing, you know what the actual situation is. Is the flow rate as high as I expected? Is the temperature as estimated beforehand? Can I pump it back as assumed and how much pumping capacity does that require? This all has implications for the design of the installation. You always have to bear in mind that the installation will look slightly different than previously thought. As soon as I have the results of such a test, I immediately consult KH Engineering about the consequences for the design. That is how we arrive at a safe and good design as quickly as possible.' 

Meanwhile, construction has started in Maasdijk and KH Engineering has started the basic engineering of a third project for HVC, in the Westland area of Polanen.

For more information about HVC, please visit: www.hvcgroep.nl.