CHP
Houweling's smart solutions to save energy and water
Houweling's Tomatoes in Camarillo, California has been showered with awards for its sustainable approach. Many of the techniques for saving water and energy are new to the American horticulture industry and a source of inspiration for fellow companies.
"Going green" can be a successful economic strategy that leads to sustainable growth, the jury said at the presentation of one of those awards. That accurately sums up the vision of Casey Houweling, owner of Houweling's Tomatoes. "What sustainability is to us is a combination of caring for our planet - which we will leave to our children - and commercially viable solutions for growing healthy, delicious tomatoes," says the grower.
In this family, the innovative entrepreneurial spirit is passed from generation to generation. His father, a Dutch immigrant, built a horticultural company in British Columbia with years of hard work. Son Casey continued where his father left off and now has locations in Canada and the USA. While the company may now be significantly larger, one thing has not changed: the ambition to be in the vanguard of sustainability and produce top quality tomatoes.
Semi-closed Ultra Clima greenhouse
The location in Camarillo has 125 acres of greenhouses, with around 40 acres' worth of the semi-closed type that have few windows that open and instead have air handling units to regulate the greenhouse climate. "This type of system makes use of many fans which requires considerable additional electricity," says Richard Vanderburg, energy and water conservation manager. "That is why we installed five acres of solar panels over the water basins in 2008. This was attractive because the State of California provides a 50% subsidy."
"What sustainability is to us is a combination of caring for our planet - which we will leave to our children - and commercially viable solutions for growing healthy, delicious tomatoes."
Until then, the heat required for the greenhouses had been provided by gas boilers, but that is not the most efficient use of energy. "With a combined heat and power (CHP) system, because it simultaneously produces heat, electricity and CO2, you can utilize practically 100% of the energy. There is no longer any waste. We have Casey Houweling's enthusiasm to thank for the fact that we now have three 4.4 MW CHP units."
The cogeneration technique is still not all that common in the USA. The technique has been used for the combustion of gas extracted from garbage dumps and waste-water treatment, but it is virtually unheard of in horticulture.
Selling back to the grid
Purchasing the CHP system was the easy part. "Much harder were the negotiations to sell the generated electricity back to the grid. The regulatory environment was difficult. It took us three years to win that battle," says Vanderburg.
Another challenge was the interplay of boiler, combined heat and power units, solar panels, heat storage and assimilation lighting. "At certain times, exporting to the grid has a strong commercial position - in the summer the peak rate period is between noon and six in the evening - so we run the CHPs at their maximum and we can make good use of the produced CO2 at that time. Export is therefore given priority over our own use, for lighting as an example. The heat is stored in the buffer. The buffer charging must be done in such a way that the CHPs can run at full capacity during the lucrative hours. If, on the other hand, the heat demand cannot be met entirely with the CHPs, the boiler has to kick in," he says.
"We harvest rainwater from the roof, and we collect the condensation water from the CHPs. We don't waste a drop here."
Designing a system to control all this is very complicated, and therefore Houweling's called in world-class specialist Priva. The choice was made for a very user-friendly solution. Everything is presented graphically on the computer screen; this insulates the operator from most of the complex process coordination taking place in the background. "There is very little that has to be done manually," the manager realizes. "And the system stores all the data, which is useful because we not only need it for our own analyses but also for the energy subsidy. Working with Priva has been a pleasure. Project engineer Richard Zeeuw found smart solutions to meet all of our needs and made it very easy to operate." To integrate all the new technologies, John van der Wilk of Priva Business Solutions was closely involved in discussions with the local power company and the contractor.
Water scarcity
Houweling's is not only very progressive in its approach to energy but also in how it handles water. "Water scarcity is a major and ever-growing problem in California. We do have our own well, but we are only allowed to extract a limited amount of groundwater," says the manager. "Therefore we capture as much water as possible. We harvest rainwater from the roof, and we collect the condensation water from the CHPs. We don't waste a drop here."
The plants get the water they need: with the Priva computer we can dose the water based on the measured evaporation, enabling us to provide the exact amount of water needed. The evaporation is measured through continuous monitoring of the weight of the substrate mats. The drain water is recirculated to the extent possible, and potential contamination issues are ruled out by disinfecting the return water before reuse.
This efficient use of water has also played a role in the sustainability awards the company has received. "We do everything possible in the current situation," tells Vanderburg. "But we are already pursuing a new initiative: obtaining purple water from the treatment plant three miles away. That water is currently being discharged to the ocean after treatment, but we could put it to good use. With reverse osmosis we can make it suitable for cultivation. In time, this could completely offset the water we currently extract from the well."
Source/photo: Priva.
‘We want to be entirely fossil fuel-neutral; and that extends to our electricity consumption as well.’
In part 2 of this interview, tomato grower Ted Duijvestijn speaks about how he aims to operate his business without any need for fossil fuels, reduce environmental pollution caused by packaging waste and grow even healthier tomatoes using LED lighting.
Would combining a CHP unit with geothermal heat be viable?
‘We only use them as a back-up for geothermal heat. Our tomatoes aren’t grown with assimilation lighting, so we don’t need the CHP units for that. We do have one CHP unit that’s constantly in operation. It runs on gas from the heat well. The water from the geothermal well apparently contained methane gas. An old 0.9 kWh CHP unit was used to assess the possibility of using this by-product. As soon as it became apparent that we could, we bought a new CHP unit with a little more capacity that could be run at full capacity on the by-product. With this CHP unit in addition to the geothermal heat we have exactly as much energy as we need. We can independently provide in 100% of our energy need.’
Do you really need that back-up?
‘The geothermal heat well initially met all our expectations, but we experienced a problem in March 2015 when the pump got disconnected. It was anticipated that this pump was located 400 meters below the surface and we had to “fishing” for it. We were able to retrieve the motor, but the pump had sunk to a depth of 2,400 metres. We tried to get it our using a cable with a grapnel. After fourteen attempts we decided to give it one last try and were successful.
‘That’s the problem with new technology; you simply don’t have everything fully under control. Initially everything was running smoothly, with a flow rate of 90 up to 185m3/hr. After some time, the return water was no longer absorbed as easily into the ground; the rate dropped to 60m3/hr. We then discovered that it contained gas. The deeper you get, the warmer the gas becomes and it expands, which makes pumping more and more difficult. We then halted operations. Some relief was brought by a separator, which is now being used to retrieve the gas from the supply pipe that fuels the CHP unit. All of this caused us quite a headache. We had to adjust the process three times before it finally worked properly.’
Were you taking too big a risk when you switched to geothermal energy?
‘Innovation is always paired with risks. You could just as easily say: “I prefer not to take that risk”, but that only leads to stagnation. Fortunately, the government can lend a helping hand by supporting, stimulating and acting as a safety net. Ultimately, all the risks such a business case entails are covered sufficiently. It is very important that innovative projects are backed by the government, because they serve a higher purpose, after all. The entire sector can benefit from the know-how thus gained. Besides that, you can use geothermal energy for a multitude of purposes. Look at our oven-dried tomatoes, for example.’
What else can you do with geothermal energy?
‘Numerous conventional uses come to mind: supplying energy to third parties, such as nearby residences. What will the distribution of geothermal energy be like five, or even ten years from now? The real estate market is continually evolving. It is becoming energy neutral, and as a result discussions are taking a completely new turn. If you enter the market for residential energy supply, you may notice that the situation has changed entirely within the space of five or ten years. You have to calculate that into your plan, too.’
Your geothermal energy project got a lot of attention.
‘That was unprecedented. The first year alone drew over 4,000 visitors from all wakes of life: from ministers to students and from colleagues to interested parties from numerous branches of industry, all with a common interest: sustainable cultivation. From this, you notice that sustainability is becoming increasingly important. These visitors are very important to our firm. The discussions you have with them often lead to unexpected and new insights. They ask smart questions, which forces you to come up with smart answers!’
You are participating in a project for wind turbines. Why? You’re already growing tomatoes on an energy-neutral basis.
‘We aim to become even more sustainable. We want to be entirely fossil fuel-neutral; and that extends to our electricity consumption. We brainstormed on this topic, too: how can this be achieved? We came to the conclusion that you should investigate wind energy, specifically. We learned about a wind turbine initiative in the direct vicinity and decided to participate. This project met with some resistance, so the outcome is still rather uncertain.’
Duijvestijn Tomaten also collaborated on a project that makes cardboard packaging from waste foliage, joining forces with other growers as well as the Smurfit Kappa cardboard factory and the Van Vliet waste treatment company.
Why make packaging from your own waste foliage?
‘It creates residual value. We recently designed packaging to our innovative “Silky Pink” cocktail tomatoes, in collaboration with Rijk Zwaan and The Greenery. I always consider waste a thorn in my side. I like to prevent waste, and so we hit upon the idea of a box made from waste foliage. Nevertheless, the challenges you meet with are becoming more and more complex. You need a different perspective and a different approach. And you need to look at things from a different angle: not from an economical point of view, but by thinking about sustainability. You are doing something society believes in: the bio-based economy, sustainability. These are demands you can respond to wholeheartedly.’
To you, sustainability is not simply a catchword.
‘Absolutely not. There is nothing I hate more than wasting food. You have put everything you have into your product: time, energy, labour, nutrients, attention, love - and that’s being thrown away as if it were nothing! I therefore wholeheartedly support the “Kromkommer” Project (ed. Kromkommer is a contraction of ‘crooked’ and ‘cucumber’), in which odd-looking vegetables and fruit are put to use instead of thrown away. Why throw them away? There’s nothing wrong with them. Supermarkets only want perfect products, and that’s only becoming worse. Many products are therefore not suited for sale to supermarkets, while consumers actually couldn’t care less how straight or crooked their cucumbers actually are.
Do you derive inspiration from this for your own firm?
‘Kromkommer is endeavouring to create a more honest chain to alleviate strain on the environment. From the same perspective we also develop products, test them and assess their market potential. Consider our oven-dried tomatoes. You could fill a container of these only halfway, fill the rest with oil, and offer it at a cheaper price. That puts you in a more competitive position, but we’re convinced that this approach is not viable in the long run. Our preferred target audience is composed of conscious consumers. This group may not be large now, but it is growing. Even senior citizens are becoming more quality-conscious and can afford luxury products. And health freaks may be willing to pay a good price for a good product, but the information you present alongside your products has to appeal to them.’
Is this why you produce extra healthy tomatoes?
‘We are investigating this. Wageningen University Research Centre discovered that LED lighting on sprouting tomato bunches produces fruit with a higher vitamin content. We are now trying this out in the ID Greenhouse®. We are testing the effect of LED lighting on the fruit and expect this to bring us even farther in the future. We have also launched a photosynthesis study among LEDs with a view to further optimising our production. However, if all you are taking into consideration is the cost price, this won’t bring you a step further.’
You regularly mention Wageningen University Research Centre.
‘We have a joint venture with the research centre and with various schools. Many of our visitors are students. I like that fact that they don’t pass instantaneous judgement; they never say: “that’s impossible”. An attitude like that allows you to transcend borders. If you promote that, you will go far. You can build on that. And it’s good training for them. Training and education are becoming increasingly important.’
Can you, as a business, keep abreast of all the new developments?
‘Developments come and go at a rapid pace. This puts a lot of pressure on you. However, you can never keep up with all the developments. You simply have to let go. You shouldn’t let this take the upper hand. You may think you can take control of all the developments, but if you’re not careful they will be taking control of you. The dividing line is very thin: innovation is fun, but it brings a lot of risks with it. On the other hand: if you don’t jump aboard the bandwagon, you won’t be able to travel far.’
Duijvestijn Tomaten in Pijnacker was elected ‘the world’s best tomato grower’ in the Crop & Process Technology category in 2015 by a jury who also presented the accompanying Tomato Inspiration Award. The jury was composed of experts Gene Giacomelli (University of Arizona, USA), Ep Heuvelink (Wageningen University, the Netherlands), Stefanie de Pascale (University of Naples, Italy) and Tadahisa Higashide (NARO Institute, Japan). Duijvestijn Tomaten grows 14.5 hectares of primarily round and plum tomatoes. Besides these tomatoes, they also grow Silky Pink, an exclusive new variety of pink tomato with an exceptionally fruity flavour.
Visit the website of Duijvestijn Tomaten-Nursery.
Download the complete interview with Ted Duijvestijn on innovative projects such as geothermal energy, the ID Greenhouse®, CHP units, LEDs, geothermal energy-dried tomatoes and packaging made from waste foliage (login required).
Copy/photo: Tuinbouwteksten.nl/Theo Brakeboer.
‘The focus points of our brainstorming sessions are sustainability, sustainability and sustainability.’
Duijvestijn Tomaten in Pijnacker was elected ‘world’s best tomato grower’ in the Crop & Process Technology category in 2015. Ted Duijvestijn explains the innovative projects his firm is currently working on and what prompted their development. An interview with a passionate entrepreneur.
We are speaking to Ted Duijvestijn in his company’s Innovation Center.
Why do you have an Innovation Center?
‘When we switched from natural gas to geothermal heat we got a lot of interested visitors. And when we built the ID Greenhouse® in 2013, we realised that we needed a solution to be able to continue receiving visitors on this scale. This gave birth to the idea of the Innovation Center, with a big reception area and a balcony with a view over the entire ID Greenhouse®.
‘We attach great value to hygiene and safety. We can now receive visitors and show them what we do without any concessions to either hygiene or safety. Apart from that, we can now receive our customers in a pleasant environment while our day-to-day operations can be carried out without any disturbance.’
What prompted you to choose that name?
‘Our firm has grown step-by-step to 14.5 hectares. After the last expansion we asked ourselves: “How shall we continue: will we try to cut as many costs as possible or are there other opportunities for growth?” We decided that our greatest affinity lay in the field of innovation and that this is precisely where new opportunities can be found. This is our Innovation Center. We regularly hold brainstorming sessions here. This is where we discuss how to respond to changes and what is really important to us. These discussions have generated several innovative projects, such as the ID Greenhouse®. The focus points of our brainstorming sessions are sustainability, sustainability and sustainability. And of course, we always ask ourselves when we come up with a new idea: is it commercially viable, what will it bring us?’
Did you decide to switch to geothermal heat because it is sustainable?
‘Sustainability was a key issue when we made this choice, but our investment had to be profitable, too. We made the switch in 2011. This summer we even had a heat surplus on account of the warm weather. Due to the EHEC crisis we also had a tomatoes surplus, so we came up with the idea of producing oven-dried tomatoes. This is responding to long-term developments and seeing if you obtain a position in a new market. Of course, there is also the financial aspect to consider: can you get funding and develop more know-how? What happens is that you learn new things that take you another step further. We designed a machine dries tomatoes using geothermal heat. We conducted tests on content, taste, temperature, time, varieties - we tested everything we could possibly think of.’
Duijvestijn shows the result with due pride: wedges of dried tomato, in small round containers and in different flavours. The tomatoes were grown on the Duijvestijn premises and are marketed as “Frezta, oven-dried Dutch tomatoes”.’
Isn’t ‘oven-dried’ misleading? They aren’t dried through and through. like most dried tomatoes.
‘They are semi-dried and we add seasoning plus a little oil. You do have to store them in the refrigerator.’
Was it difficult to find distributors?
‘We are still working on it. It is a question of getting distributors interested and gradually building up a market. We can now count several supermarkets, restaurants and delicatessen shops among our customers. In addition to the tomatoes, we also developed a tapenade that market under the name “Tomade”.’
The next innovative product you came up with was the ID Greenhouse®.
‘Looking at new greenhouse systems, we didn’t see many developments that would actually take you a lot further. The frames became higher, that was all. What’s really important is light. Another key topic is energy consumption, even if you have geothermal heat. We wondered how you can combine the two and further optimize your use of energy and hit upon the idea of double glazing. The K factor (thermal conductivity coefficient) of double glazing is twice that of regular single glazing. So we launched a pilot, in collaboration with the Wageningen University Research Centre, based on the VenlowEnergy Greenhouse study that was being conducted at that time. This resulted in the ID Greenhouse®, with a surface area of one hectare. This lets you perform tests on a substantial scale, without being too small to get genuine results.’
How does the ID Greenhouse® distinguish itself from other greenhouses?
‘The ID Greenhouse® has diffuse double glazing with panes measuring 3x2 metres; twice as big as conventional panes. The greenhouse is tilted, so that the rows are at right angles to the cover. We chose this construction because it lets you get as much light as possible to the crop. This construction consolidates the power where it needs to be in the greenhouse. As the screen runs from gutter to gutter, the screen package closes beneath the gutter and barely takes any light away. A tiny grille at the top edge of the ridge vent prevents rain from coming in when the ventilation grid is left slightly open. The exterior has a sloped wall to reinforce the frame. Besides that, you can mount equipment onto it, such as air handling units.’
Does the greenhouse meet your expectations?
‘We chose this greenhouse to grow tomatoes with smallest energy input possible. The first year we used it we received some guidance from Wageningen University Research Centre and were able to achieve energy savings of 60 per cent, by using only low-quality heat. The water from the geothermal well is 75°C. In the standard greenhouse this is cooled to 45°C - depending on the return flow rate - and is then transported to the ID Greenhouse®. The challenge is to cool the water in the ID Greenhouse® down to 25°C, which means that you’re making optimum use of the geothermal energy. After using it in the standard greenhouse you get your heating water practically for free, but in the first year we unfortunately had to make some concessions to quality.’
So the greenhouse isn’t performing satisfactorily?
‘The level of quality rises every year, as is already apparent in the second year. During the first year it is particularly important to ensure that all your equipment is functioning properly. At this stage, it doesn’t pay to spend a lot of time making all sorts minute adjustments to your climate settings in an attempt to take things to the next level. Now that we’re in the second year we aim to achieve savings of 50 per cent, in combination with a higher production at the right level of quality. In first year we achieved our goal of 50 per cent, but not the production level we were after. The biggest problem was related to light loss on account of condensed moisture on the glass. Both the interior and exterior glazing had been provided with an HR coating to prevent light reflection, because you want to get the same amount of light inside the greenhouse that you would with conventional glazing. This coating creates tiny pyramids on the glass, as it were, onto which droplets of condensed moisture cling. We have since removed the coating on the inside. Now the moisture can flow away more easily. A small percentage of light is still lost in comparison to single glazing, but compared to last year we have gained 5 per cent more light.’
So the greenhouse is performing satisfactorily after all?
‘It’s too early to really say anything about it. We aim to compensate for the loss of light through the frame. You can come up with the best ideas on the drawing board, but you never know how well something is going to work until you’ve put it into practice. Only then can a product be truly tested and will you learn more. The CO2 supply - from Ocap - was adjusted in this second year, for example. It failed to produce the correct values from time to time. Instead of the extension of the CO2 supply in the other greenhouses we managed to put together provisionally there is now a direct supply.
‘We achieved the envisioned energy savings, and now we’re working on raising our production level, step by step. After only one year you can’t rightly draw any conclusions; only after about three years can you truly say anything. In the meantime you identify the challenges, look for improvements and learn from your experiences.’
Is such a small ridge vent enough to meet for ventilation needs?
‘The air vents in the greenhouse had been fitted with mesh. As a result, insects could not enter the greenhouse, which means that we can achieve an even lower maximum residue level in our tomatoes. You could then get even more out of using natural enemies. However, the fine mesh obstructed the flow of air; particularly on days with little wind and warm, humid air. Weather conditions like that put a lot of stress on the plants. We therefore abandoned that idea, since stress has a negative impact on quality and production. Now that the mesh has been removed we are able to control the climate, in combination with the AHUs, more accurately.’
Do you expect more greenhouses to be built with double-glazing on the roof?
‘Taking into account the energy savings, our expectations are high. Economically speaking, however, there is still a way to go. Double glazing is still rather expensive.’
Duijvestijn Tomaten in Pijnacker was elected ‘the world’s best tomato grower’ in the Crop & Process Technology category in 2015 by a jury who also presented the accompanying Tomato Inspiration Award. The jury was composed of experts Gene Giacomelli (University of Arizona, USA), Ep Heuvelink (Wageningen University, the Netherlands), Stefanie de Pascale (University of Naples, Italy) and Tadahisa Higashide (NARO Institute, Japan). Duijvestijn Tomaten grows 14.5 hectares of primarily round and plum tomatoes. Besides these tomatoes, they also grow Silky Pink, an exclusive new variety of pink tomato with an exceptionally fruity flavour.
Visit the website Duijvestijn Tomaten.
Would you like to know more? Download the complete interview with Ted Duijvestijn on innovative projects such as geothermal energy, the ID Greenhouse®, CHP units, LEDs, geothermal energy-dried tomatoes and packaging made from waste foliage (login required).
Copy/photo: Tuinbouwteksten.nl/Theo Brakeboer.
Mobilising all efforts on the imbalance market
Now that the rates for the return of electricity have dropped lower than ever before, growers will have to make all possible efforts to achieve a profit on the imbalance market from their CHP. AgroEnergy is launching a new service that will allow growers to place bids directly on the control power market, which will enable them to trade actively through TenneT. This initiative would also allow growers to collectively offer emergency power.
Cogen Nederland, the Dutch association for the promotion of CHP, anticipates that the current capacity generated by CHP units will be reduced by fifty per cent in the next decade to come. With a rate of 3.6 cents per kWh and a peak rate of 4.8 cents for the next three years to come, the energy market is suffering tremendously. The peak price will barely cover the variable costs of a CHP unit. Nevertheless, Arjan van der Spek of Enova is convinced that the fifty per cent referred to above will probably not be achieved, taking into account that half of all growers deploy their CHP units for assimilation lighting for their own crops anyway. CHP is here to stay. With regard to the fifty per cent that would remain unused, growers will have to rely on returning electricity to the grid at the right moment. ‘They will have to actively make use of this option.’ There is, however ray of hope as opportunities on the imbalance market are likely to improve. The increasing number of wind turbines and solar panels has heightened the risk of imbalance problems in the supply of electricity. After all, no electricity will be generated when the sun doesn’t shine or there is no wind.
Power control under contract
‘Based on the by-the-minute forecast price, growers can adjust their CHP production upwards or downwards through the imbalance control platform’, explains Willem Bijlsma of Tenergy Services. ‘This will allow them to benefit from the higher rates arising from a shortage in electricity at a particular point in time. TenneT, however, determines its quarterly rates in retrospect; you can never forecast precisely how much you will earn. This is a drawback in passive participation on the imbalance market. Additionally, this supply option is gradually phasing out because TenneT prefers to regulate the supply of energy through contracts.’
TenneT contracts extra control power capacity for a sufficient supply of energy on the imbalance market. As TenneT concludes these contracts with large energy companies, and not with greenhouse growers (these parties being simply too small), AgroEnergy is developing a service that will let growers offer their CHP as control power capacity. This service will be launched on 1 October 2015. The collective power will than be offered to TenneT by means of a bid, provided that the capacity will amount to at least 5 MW. ‘Every grower can subscribe and decide for himself whether or not to participate’, explains Fieke Rijkers of AgroEnergy. ‘In the event that we are unable to supply the required 5 MW, Eneco will make up for the deficit. The biggest advantage for growers is that they will get the rate that has been fixed at that particular moment.’
Rijkers believes that growers will benefit in terms of security by collectively offering control power capacity rather than responding to the imbalance market without a contract. ‘This will provide growers a realistic alternative to earn some extra money on top of the long-term spark spread and trading on the Amsterdam Power Exchange (APX). As soon as TenneT gives the sign for delivery, participants will have thirty seconds to respond with an upwards or downwards revision. This will require some adjustments with regard to the necessary software.’
Making use of all the available options
Robert Willemsen of Powerhouse – a subsidiary of RWE – is wondering why a grower would allow his CHP unit to contribute to a pool, ‘particularly if a fine applies when you fail to respond in time.’ This is, however, not the case with regard to the product offered by AgroEnergy, taking into account that this concerns voluntarily offered control power capacity instead of a fixed contract with TenneT. His solution: ‘Make sure that you get the most out of your CHP unit and that you are using good software. For an optimum yield you have to make use of all the available options: the imbalance market, the APX and keeping a vigilant eye on the highs and lows: selling when the price is up and buying when the price is down. Not everyone will be able to do this equally well; it requires a lot of time and attention.’
Stijn Schlattman of Energy Matters argues for adequate compensation for flexible power supply to compensate for the fluctuations in the supply of wind and solar energy. ‘It is important that gas-fuelled engines are able to contribute to this. This will improve the case for gas engines and people may even begin to invest in new gas engines. Following on another two meagre years with a weak market and a low spark spread new opportunities are arising fro flexible CPHs. Until then owners of CHP units will simply have to muddle through.’
Contract for emergency power supply
TenneT contracts emergency power supplies to compensate for possible failures at power plants. This counters the considerable imbalance on the electricity grid. Back-up generators or CHP units that would otherwise be on stand-by could be used for this. The power generated by these, which is used once a month on average, must be continually available. Companies can register on an annual basis for a scalable emergency power supply of 350 MW, to be made available within ten minutes. This could be financially worthwhile, says Hendrik Koetsier of Energie365. Energie356 collects flexible power from companies for emergency power supply for TenneT. This flexible power supply is provided by companies with back-up generators. Koetsier has noted interesting opportunities for CHP units in this. However, the power generated by multiple growers would have to be offered collectively, because TenneT applies a 20 MW minimum. This would enable infrequently deployed CHP units to nevertheless bring up some cash. TenneT pays an annual availability compensation of over ten thousand euros per MW, plus a variable compensation for the electricity actually supplied. ‘Supplying emergency power could be interesting particularly in cases where a CHP unit generally doesn’t produce anything normally, while entering the imbalance and control power markets is a more obvious alternative for CHP units that are deployed on a regular basis. Emergency power is a better option for CHP units that are not deployed as frequently.’ The drawback is that the emergency power reserved for TenneT has to be continually available; a grower will neither be able to offer it on the imbalance market or the APX nor make use it for his own crops in peak periods.
Supplying emergency power is not a viable alternative for growers who make use of assimilation lighting, says Remco Wiegmink of NIFE-energieadvies. Chances are high that the emergency power will be demanded from the grower when he needs the electricity for his own crop. Besides this, the power may need to be delivered at times when there is no demand for heat. It is doubtful whether the yield for emergency power contributed by a CHP unit that would otherwise not be producing will be sufficient to cover such fixed cost items as gas power and transport. Growers switching to geothermal heat hardly ever offer the power generated by their CHP units on the imbalance market for this reason alone. Robert Willemsen of Powerhouse even considers participating in pools like this a ‘very dangerous’ option. ‘It is better to participate in the control power or imbalance markets by gearing the sale of your power to the opportunities that come your way.’
Careful deployment
CHP yields only minimal returns in the horticulture industry. A new CHP unit is not profitable unless it is used for assimilation lighting for your own crops. Based on variable costs, if you already own a CHP unit selling power to the grid will barely be profitable. According to Schlattman of Energy Matters operating hours for CHP units are dropping as far as approximately 3200 hours a year. Fieke Rijkers of AgroEnergy understands the difficulties faced every day by growers placing a bid on the APX, in terms of calculation effort as well as time. ‘The automated BiedOptimaal system offered by AgroEnergy will take a load off their shoulders.’
Robert Willemsen of Powerhouse: ‘Growers who own a CHP unit that has not been written off yet will have to deploy their CHP unit very carefully in order for it to be profitable. If it does not operate for at least 4,000 to 4,500 hours it will be very difficult indeed to pay back your investment. On top of that, you can optimise short-term returns through the APX and the imbalance market. The price risk is, however, high. In fourteen years’ time I have never seen rates as low as they are now, with 3.6 cents per kWh and a peak of 4.8 cents for the next three years to come. The peak price is just enough to cover the variable costs of the CHP, so this will only be profitable with an old CHP unit. The problem is that you can’t simply shut down a CHP unit when you have taken out a 3,500-hour maintenance contract. In this case, your best bet is to deploy it as frequently as possible, if only to minimise your losses.’
Source: Tuinbouwteksten.nl/Theo Brakeboer. Photo: Mario Bentvelsen.