Home Posts Tagged "sustainable energy" (Page 2)

sustainable energy

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Plant-e was commissioned this autumn by the Province of Zuid-Holland and the Delfland Water Board to conduct a pilot in which green electricity is generated by plants growing on the wet grasslands near the N470 provincial motorway in the Netherlands. This is the first time the Dutch startup has tested this method of generating power outside of a laboratory.

Plant-e was acclaimed one the world’s most promising Technology Pioneers by the World Economic Forum last summer, which puts the company in the same league as Google, AirBnB and Twitter. Plant-e director Marjolein Helder: ‘We are very proud of the recognition we received from the World Economic Forum. Of course we already won the confidence of the Province of Zuid-Holland and the Water Board before receiving this international acclaim. The test set-up in Zuid-Holland was a big step for us to ensure that this system will become a full-fledged alternative for generating sustainable energy.’

Plant energy

The technology works as follows: pipes are laid on a plot of grassland, between the roots and the grass. Grass excretes organic material through its roots, which is broken down by micro-organisms in the soil. In this process, electrons are released as a waste product which are then captured in the pipes and harvested as electricity. Following the further development of this technology the energy can be used to power lights incorporated into crash barriers, or other traffic lighting. The pilot was developed to discover how much electricity plants can yield.


The startup has taken this technology to a higher level than anywhere else in the world. ‘I dare say that we are the only ones in the world to conduct practical tests at this level,’ says Pim de Jager of Plant-e. A big advantage to generating electricity from plant growth is that it all takes place underground and is therefore not visible. The pipes used in the test set-up protruded slightly above the ground, but this will soon no longer be necessary,’ explains De Jager. ‘You can keep using your land as you would normally. Nothing changes, except that it will be producing electricity.’

Currently, electricity derived from plants is not yet able to compete with other methods of sustainable energy generation. Plant-e intends to further develop this pipe system and hopes that the price per kilowatt hour will be comparable to that of solar and wind energy in the next few years to come - and ultimately with that of our current ‘grey’ electricity (electricity from non-renewable sources).

Source: NOS/Province of Zuid-Holland. Photo: Mario Bentvelsen.

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Tomato grower Frank van Kleef of Royal Pride believes a lot can still be done regarding cooperation between the horticultural and industrial sectors in the field of energy management. 'There are a lot of opportunities, particularly in places where the sectors are located close to each other, such as Westland and the Rotterdam harbour.'

According to the entrepreneur, the same is also true for the development of geothermal energy. 'It is still in its infancy. However, for the greenhouse horticultural sector, it is essential to be economical with the available energy and to make optimal use of the alternatives to fossil fuels.'

'In my opinion, the best way to help each other is to return energy to the grid at exactly the right time.'

Van Kleef is critical of developments such as heating residential areas with waste heat from greenhouse horticulture. 'It is expensive to move heat from one place to another and I am, therefore, not in favour of it.' He also does not think that bringing both segments physically closer is a viable option. 'In other areas, horticulture and home owners get in each other's way. In my opinion, the best way to help each other is to return energy to the grid at exactly the right time.'

Microsoft data centre

Royal Pride is located at Agriport A7, where the entrepreneurs cooperate as much as possible where energy is concerned. Microsoft recently built a large data centre there and, according to Frank van Kleef, that offers excellent opportunities for sustainable, mutual cooperation.

He is convinced that a lot can be gained by working together, particularly in the field of energy management. 'The greenhouse horticultural sector should stop putting itself first all the time. The interests of the whole should be given priority over the interests of the individual.'

'In order to achieve the international environmental and energy objectives, the greenhouse horticultural sector must look for worldwide solutions.'

During the journeys that he regularly makes, Van Kleef has noticed that foreign countries do not take advantage of the lessons that have been learnt in the Netherlands. 'Abroad, horticultural companies too often choose to be located far away from their fellow horticultural companies. I would rather have my competitors as my neighbours than have no neighbours at all.'

In his opinion, in order to achieve the international environmental and energy objectives, the greenhouse horticultural sector must look for worldwide solutions. 'With the same investment, greater advances can be made abroad than in the Netherlands, where great progress has already been made over the last couple of years.'

Watch the video with Frank van Kleef about energy management.

Source/photo: Priva/The Grower Files.

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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.

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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.