CO2
CO2-dosing brings huge energy savings with same quality
By dosing lilies with CO2 the light level can be reduced by one third while the quality remains the same. This conclusion was made by researchers who carried out trials with lighting in 2013 and 2014. However, growers wanted further confirmation because for years they have grown lilies under high light levels without any CO2-dosing. A trial carried out in June 2015 should remove any doubt. And the results bring further good news. Even more energy savings appear possible.
It is unusual. While CO2-dosing is the norm for most greenhouse crops in the Netherlands it is hardly used in the country’s 200 ha of artificially-lit lily production. In the past, research institute, PPO, showed that it had no effect on bloom weight, especially in the group of Orientals.
These findings appear to disagree with the results of photosynthesis measurements made by plant physiologists Sander Hogewoning and Govert Trouwborst of Plant Lighting and researchers at Plant Dynamics in 2012/2013. The Dutch specialists showed that photosynthesis significantly increased by dosing CO2 at 800 to 900 ppm. This insight was the reason for a greenhouse trial in 2013/2014. The trial showed that the duration of the lily crop, for both LAs and Orientals, was the same at 60 μmol SON-T lighting with CO2-dosing as with 90 μmol SON-T without CO2, which is the current practise in lily production.
Search for lower limit
To confirm these results and dig somewhat deeper, it was decided, together with the supervisory committee to carry out further research on two consecutive crops. “You have to bear in mind that for years growers have been told that CO2 on Orientals does not work. Therefore they want assurance. For us it was also important to know the lower limit for lighting with respect to quality and cropping duration,” says Hogewoning.
Trouwborst adds: “Growers wanted confirmation that lighting with 60 μmol leads to worse performance than lighting with 60 μmol and CO2. The first option was not taken into account during the previous trial. Only then can you be sure that the effect is due to the dosing.”
Trial design
The research took place between October 2014 and March 2015 at the Improvement Centre in Bleiswijk, the Netherlands. As well as the two plant physiologists a large number of other experts were involved.
The researchers ran seven treatments on two crops in three trial greenhouses of 144 m2. The varieties on trial were Brindisi (LA), Robina (OT), Santander (Oriental) and White Heaven (Longiflorum) with a crop change in mid December. In greenhouse 1 three light levels of 45, 60 and 90 μmol/m2/s SON-T were combined without CO2-dosing; greenhouse 2 maintained the same light levels with 800 ppm CO2. The temperature regime was the same as that used in practise: ventilate at 17ºC and heat from 15ºC.
Set up to save 50%
Greenhouse 3 tested the so-called total concept for energy savings, which aimed to save 50% on energy. Earlier results in the area of energy savings were incorporated in one crop. “If you add up how much these measures can contribute, it is substantial,” says Hogewoning.
The first measure was to compensate the lower light intensity with CO2-dosing. The second was switching off the lights earlier when there was sufficient natural radiation. The third measure was to permanently switch off 40% of the lamps for several weeks at the beginning and end of the cultivation period. Hogewoning explains why: “The plant’s requirement for assimilates follows an S-curve. There is a high requirement in the middle of the cultivation period. Then you have to give plenty of light. But the plant needs far fewer assimilates at the start and at the end so you can turn the lights off.”
The fourth measure is temperature integration: ventilate later when the radiation is high and maintain a lower heating temperature at lower radiation. In this way the temperature, depending on the light intensity, can rise to 23ºC, but at low radiation the heating only comes on at 13ºC. However, the minimum night temperature remains at 15ºC to prevent too much stretching.
Good all round
In all treatments the effects on flower bloom weight, dry weight, stem length, weight/cm, turgidity, bud quality, cropping duration, bulb weight and vase life of the four different varieties were measured. The results of the first crop – from begin October to the beginning of December – were good in all respects. Light and CO2 had a positive effect on bloom weight. Only when the lighting was 45 μmol without any CO2 the blooms lighter in weight.
The researchers saw hardly any softening of flower stems; the only exception was the variety Brindisi at 45 μmol without CO2. “Also in greenhouse 3, which saved a lot of energy, good results were achieved across the board,” explains Hogewoning about the figures. “Certainly the good autumn meant there was a lot of natural light. Due to the high level of radiation we could allow the temperature in greenhouse 3 to be higher,” adds Trouwborst.
60 μmol with CO2 in winter
There was some concern about the second crop, from mid December to the beginning of March. How would the varieties cope with a lower level of natural light?
The results were similar to the first crop. But whereas during the first crop 45 μmol with CO2 was sufficient (except for Brindisi), in the second crop 60 μmol with CO2 was the lower limit for good quality. Without additional CO2, 60 μmol was too little to achieve top quality. “Then we saw too many soft flower stems. If you want to grow top quality for the entire year then you need to supplement 60 μmol with CO2 in the darker periods.” It is also important to confirm the conclusions drawn from the research in 2012/2013: when dosing with CO2 there is no additional benefit from dosing with 90 μmol compared with 60 μmol.
The results from the total energy savings concept showed that it came out on top, even in the darker period. “In the beginning the growers were most interested in greenhouses 1 and 2. Greenhouse 3 went a bit too far for them. They thought this was taking too big a risk. They were very surprised by the positive results. However, attention does need to be drawn to the number of softer flower stems and slightly too much stretch during the darker period.”
Application in practise
What do the conclusions mean for application in practise? Hogewoning: “For growers who strive for top quality, artificial lighting at 60 μmol with CO2-dosing is certainly possible. During open days I’ve heard growers say that they found the quality of flowers grown with artificial lighting of 45 μmol and CO2 quite spectacular. For DIY retailers the lilies don’t need to be so heavy.”
How growers respond to this research differs depending on the market segment. Certainly as a result of this research some growers have started to dose with CO2. Across the board this appears to be a good strategy, which saves energy and it has a positive effect on the strength of the crop.
The total concept approach seems to have a good chance of success. Calculations with models show that its application in a commercial greenhouse leads to a 45% saving on electricity. A crop does then use 1.5 m3 extra gas to compensate for the heat from the lights. The type of cogenerator and availability of CO2 will determine the economic return. In the end every grower will have to calculate for himself which strategy is most suitable.
Summary
If CO2 dosing is used in lily production the light level can be reduced by one third. A recently completed trial confirms the results. More energy savings are possible by using temperature integration and by adjusting the lighting further to suit the growth phase.
Text: Karin van Hoogstraten. Photos: Studio G.J. Vlekke
Greenhouse horticulturists in Bergerden to buy sustainable CO2 from biogas plant
A fermentation plant on a greenhouse horticulture site in Bergerden will be fermenting biomass in a controlled manner as from 2017, in which biogas will be released. A follow-up procedure will upgrade the biogas into green gas, with CO2 and minerals such as nitrogen and phosphates as its by-products. The horticulturists plan to purchase the CO2.
The raw materials to be processed by the fermentation plant will consist primarily of grass and animal fertiliser obtained from intensive livestock farming. This will also enable the plant to contribute to reducing the Netherlands’ surplus of manure. Besides grass obtained from road maintenance and the region’s natural surroundings, the plant will also process green waste from horticulture and arable farming. The initiative takers expect to produce up to 7.2 million m3 green gas per year as from the beginning of 2017. This is comparable to the amount of gas consumed by a city of 10,000 inhabitants.
Circular economy
The green gas thus generated will be transported to the Liander natural gas network in Huissen. The green certificate that this will yield will become available for regional bus transport, for example. The liquid CO2 will be sold to the greenhouse horticulturists in Bergerden, who will be using it for their crops, through a regular supplier. The regained phosphate will be exported abroad. As a result, multiple circuit chains will be closed: reuse of regional biomass, reuse of CO2 and reuse of fertilisers.
Initiative takers
The biomass fermentation plant will be built by Groen Gas Gelderland (GGG) in collaboration with Biogas Plus. GGG is an initiative launched by Bio Energie Bergerden. Eneco provided assistance in the development phase and will buy the green gas. GGG has concluded a contract for optimising the economic value of the by-products, which contain mineral fertilisers such as phosphates. The biogas fermentation plant was funded both by GDF Suez and with venture capital provided by PPM Oost through the Innovation and Energy Fund for the Province of Gelderland (IEG). The preparations alone took thirteen years to complete.
Sources: http://degroenehub.nl/www.bergerden.nu/www.gelderlander.nl. Infographic: Eneco.
EnergiekEvent 2016 looks back and forward
'We should not depreciate the closed greenhouse', 'Greenhouse growers should rely less on feelings and more on knowledge' and 'In the greenhouse sector of 2050 gas is no longer relevant'. These were some of the remarkable statements that were made at the well-attended EnergiekEvent 2016 in Bleiswijk, where the 10th anniversary of Kas als Energiebron was also celebrated.
Looking back, Kas als Energiebron (Greenhouse as a Source of Energy), the innovation and action programme for energy efficiency and sustainability in the greenhouse horticulture sector, was found to be successful. The energy efficiency of the Dutch greenhouse growers has increased significantly, while the energy sources are becoming more sustainable. Especially thanks to geothermal and residual heat, wind energy, (semi-)closed greenhouses, diffuse glass, LED lighting and - the manual is in need of a reprint - Next Generation Cultivation.
Micro-controller
The best news of the EnergiekEvent was that the increased energy efficiency does not affect the quality or production. But it does require more data, knowledge and insight of the growers. "Before, there used to be one measuring unit on each hectare. In the future we want to change this to smaller units. Maybe even to micro-controllers for every plant, not only for the production, but also for the quality. For example, think of LED lighting to enhance certain plant components," says Sjaak Bakker, manager of Wageningen UR Greenhouse Horticulture.
Bakker outlined a future in which electricity will play a leading role. "We are rapidly moving towards an all-electric situation. Just look at electric cars, batteries and what's happening in LED lighting. They are already thinking about lighting through foils or glass cells."
Our CO2 supply should also be different in 2030 or 2050, Bakker said. "If we no longer burn gas in the future, where would we get our CO2 from? An example might be extracting CO2 from the air."
Closed greenhouses
Next Generation Cultivation is being succesfully applied in various crops, including tomato and gerbera. An estimated 15 to 20% of the Dutch growers is using this method. A lot of knowledge has been gained in closed greenhouses and during previous research, Bakker said. "In Next Generation Cultivation many things that were already developed have been put together: think of temperature integration, research on screens, air movement, etc."
The closed greenhouse is disappearing, it seems. But Wilco Wisse, chairman of Kas als Energiebron and staffmember of Lans Tomaten, thinks that closed greenhouses should not be depreciated. "We ourselves also have an Optima greenhouse of 1.5 hectares and we know better than anyone how difficult it is to make profits with it. It is actually a huge solar collector though, it stores excess heat of the summer and supplies it in the winter. Therefore, we should not depreciate the closed greenhouse.”
Sustainable future
Leo Oprel, currently working as a policy advisor at the Ministry of Economic Affairs - who is considered as the founder of Next Generation Cultivation at Wageningen UR - outlined a sustainable vision of Dutch horticulture, in which:
- new greenhouses will look very similar to existing greenhouses
- gas has been replaced by sustainable electricity and heat
- virtually no chemical pesticides are used
- the use of CO2 for growth is limited
- knowledge is crucial
- climate control will include energy and ventilation management
- heat exchangers will become commonplace to transfer energy from the moist greenhouse air to the incoming drier air
- cultivation is done with more humidity, with a very homogenuous greenhouse climate
- light is the key for temperature control
- the diffuse greenhouse roof transmits more light and there are more screens hanging above each other
- super translucent greenhouses will determine the production - and the existence - in the winter
- light will be flexibly captured above a certain level in the summer and will be available for energy storage
- excess radiation is immediately absorbed without the greenhouse air heating up too much
- assimilation lighting is used on the basis of the requirements of the plant
- the artificial light is also dimmable because it works with direct current
- the heat requirement is reduced to 10 cubic meters of gas per m2
- geothermal energy and heat pumps with heat/cold storage supply the residual heat
- the backup will consist of batteries
- offices and industrial buildings supply additional electricity with roof-integrated solar panels
- windmills are a regular appearance in horticultural areas
- proud entrepreneurs have created a sustainable future!
Kas als Energiebron, the innovation and action plan for energy efficiency and sustainability in greenhouse horticulture of LTO Glaskracht Nederland and the Ministry of Economic Affairs, will continue until the end of next year. Both the greenhouse horticulture industry and the government want to continue with the program. The ministry of Economic Affairs wants to maintain the 50/50 cost sharing – but is still negotiating with LTO.
At the end, the participants visited the workshops and greenhouses at Wageningen UR/Delphy Improvement Centre, where they were informed of the latest research.
Text/photos: Mario Bentvelsen.
Understanding photosynthesis important for CO2 dosing and lighting
It used to be rare to come across plants that bind CO2 mainly at night: CAM plants. But it’s no longer an exception in the horticultural sector. Nowadays the best-selling pot plant in the Netherlands – phalaenopsis – belongs to this group. This then raises questions such as: When do CAM-plants behave according to the book and when don’t they? And when does it make sense to dose with CO2 and provide lighting?
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Steering with high EC improves taste and quality of fruits
With a little more effort you can improve even more. This is the approach behind new trials aimed at optimizing water and fertiliser use with the specific aim of reducing fertiliser emission to the environment. It sounds rather demanding until you realise that the quality of the end product can also improve, while maintaining or even increasing yield. Excess drain as an insurance policy for the cultivation is an out-dated idea.
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Contributing to the region’s self-sufficiency in vegetable production
Agro-Invest’s new 20 ha greenhouse, located in the Kaluga region of Russia, has successfully completed its first growing season. This is the first stage in a project which will ultimately comprise a total of 100 hectares of greenhouse on 238 hectares of land. The Kaluga region is a special economic zone, located around 300 km from Moscow. The local government is committed to improving the diversification of the region’s economy with the cultivation of tomatoes, cucumbers and leafy vegetables. This greenhouse complex will make a tangible contribution to the region’s goal of becoming self-sufficient in the production of vegetables in the longer term.
Mr. Evgeniy Gorlach joined Agro-Invest in July 2014 to coordinate the greenhouse construction project in the Kaluga region. At first there was nothing but an empty field. Now, less than 18 months later, the company has completed its first growing season and started the second season of cucumbers and tomatoes in the new greenhouse complex, which was built in record time: just one construction season.
The greenhouse comprises 10 ha for the production of tomatoes (four varieties: one beef tomato variety, one truss tomato variety and two varieties of cherry tomatoes), 8 ha of cucumbers and a 2 ha propagation area for young plants and seedlings, plus a packing area/irrigation room and an energy building.
Specific expertise
Headquartered in Moscow, Agro-Invest operates numerous farms in Russia and its business activities include land, crops, livestock farming, equipment, technology and logistics. In his role as Technical Director, Gorlach was tasked with coordinating the project together with Dutch company Dalsem – a company specialised in the development and realisation of complete high-tech greenhouse projects – and the Russian sub-contractors.
The first point of contact for him and everyone else on the project site was Dalsem’s Maurits Zomer as Project Supervisor. “He virtually moved to Russia to work on the project – I think he spent just three weeks back in the Netherlands during the whole year,” recalls the Technical Director. “Although I’d worked on many similar projects in the past, I had no specific experience in greenhouse construction. We benefited tremendously from the expertise of Zomer and his colleagues in terms of greenhouse building and quality control of sub-contractors.”
Complete solution
In addition to the greenhouse framework, the Dutch high-tech specialist provided Agro-Invest with a complete solution for the greenhouse facility, including all machinery and equipment for the installation of the cold storage and the loading and discharge section. The growing area is fully equipped with a heating/climate control system, high-pressure fogging, roof sprinkler system, substrate irrigation, substrate cultivation, CO2 dosing, overhead (1,000W) and intermediate (250W) lights and screens. The propagation areas are equipped with aluminium rolling benches and ebb and flood irrigation.
Power is generated by four Rolls Royce Gensets of 9,285 MW each, two of which are equipped with selective catalytic reactors for the production of CO2. Additionally there are four hot-water boilers with a capacity of 11.6 MW each. The water management system also includes rainwater collection, reuse of drainage water and purification of well water.
Tight coordination
“One of our biggest challenges on this project was to complete everything on time,” comments Gorlach. “We had a very tight schedule so we worked in parallel with the project institute, which meant we made a start on the construction work for greenhouse as soon as we obtained the drawings from Dalsem. This created quite a stressful situation because we ran into various problems, such as due to the soil and a lake which meant that we had to recalculate the foundations as we went along. Later on in the project, we were particularly under pressure to get the pipework for heating finished and the water circulation system in place so that the pipes wouldn’t freeze when the first snow arrived – which is usually late November – so work started on the boiler room before all the sandwich panels were finished. We wasted no time; for example, the small irrigation room was finished on a Monday, and the tomato seeds were planted in the cubes on Tuesday – the very next day,” he recalls.
“And we even conducted ‘real-life testing’. We were testing the systems when seeds were already on the table.” This tight coordination was the key to fast completion of the project, which took less than eight months for the construction part. “No one else in Russia has ever achieved that so quickly,” states Gorlach. “It’s thanks to such terrific collaboration between all of us, including our sub-contractors, that the preparation and building work ran relatively smoothly and was completed in time for the growing season as planned. I’m also grateful for the tremendous help we received from the people at our sister companies within the holding.”
Multiple language options
The climate management system plays an important role in the control of all processes in the facility. “From an efficiency perspective, it’s important for us that everything can be managed in one, single system,” says the Technical Director. Based on the flexibility, reliability and user-friendliness of the system, the project group made a conscious decision for the iSii climate computer from Hoogendoorn, an international developer and supplier of automated climate management, water management, energy management and data management solutions for horticultural businesses.
“The system controls literally everything in our greenhouse: climate, irrigation, CO2, ventilation windows, screening and energy consumption. Everything is connected to Hoogendoorn, without it, nothing will work.” he adds. All the settings of the new climate computer are flexibly configurable. Furthermore, thanks to the multiple language options, the Dutch crop advisor and the Russian managers can log into the system and adjust the settings in their own respective language.
First-season results
“We received a lot of help with the program settings as well as local training for our employees to help them select the right parameters. The contact was very intensive,” continues Gorlach. The system went live at the end of November 2014 so that the first plants could be irrigated. “Because the system is so comprehensive, the software is very complex so there were a few teething troubles. But we were helped remotely from the Netherlands, and if necessary we received on-site support. In one case, we needed a spare part and a specialist from Dalsem flew in to Moscow and delivered it to our greenhouse on the very same day. You can’t ask for better, quicker and more flexible service than that.”
Despite it being such a whirlwind project, Agro-Invest can look back on the first season with satisfaction. “Apart from the teething troubles, we had no major problems during our first year. A manager from Hoogendoorn recently visited us to answer all our practical questions based on the first-season results and to help us to further optimise the precise settings, so we’re now ready to achieve maximum results in our second season,” he concludes.
Summary
Agro-Invest’s new, high-tech 20 ha greenhouse in the Kaluga region of Russia was constructed in record time thanks to tight project management and excellent collaboration between all members of the project team. The climate management system controls everything in the greenhouse, from irrigation and CO2 to ventilation, screening and energy consumption. Following on from a successful first growing season of tomatoes and cucumbers, the second season is already underway.
Text: Lynn Radford