Heating and Lighting

As the cost of oil, gas and electricity continues to rise, many growers are seeking alternatives that will allow at least the maintenance of profit margins in future, if not produce actual savings. Additionally, pressures relating to climate change and concerns over fuel security -- whether it will be available at the right time and in the quantity required -- make it even more essential that growers keep an open mind about what they use to produce heat and power in their glasshouse facilities. The range of alternative fuel sources, particularly natural and renewable, is wide -- from straw and wood to solar and wind power. Even anaerobic digestion has its place. Which fuel is best for any given horticultural site will largely depend on the location of the enterprise as well as requirements in terms of when and how much heat and power is needed. In the right place, heat may be available as a by-product from industrial processes.

B Series LEDs 2 - image: Valoya
B Series LEDs 2 - image: Valoya

Surplus energy

At John Baarda, based in Teesside and one of the UK’s largest tomato producers, surplus energy and carbon dioxide are used from nearby factories to provide the right conditions for growing all year round.

In Norfolk, British Sugar’s award-winning horticulture business produces around 140 million tomatoes at Cornerways Nursery, thanks to its location close to the Wissington sugar factory. More than 240 miles of piping carries hot water — otherwise destined for cooling towers — from the factory’s combined heat and power plant around Cornerways’ glasshouses.

For many growers, surplus or waste heat from neighbouring industries is a pipe dream. A more likely option will be the installation of -biomass boilers. That might mean wood, straw or perhaps Miscanthus. East Yorkshire-based Manco Energy specialises in the supply and installation of Danish biomass boilers ranging from 60kW up to 8MW in size.

Sales manager Dick Palmer advises on fuel types. "Fuel type is determined by a number of factors including cost per kilowatt availability in the local area and transport. By their very nature, biomass fuels tend to be bulky, with the exception of wood pellets," he notes.

In the arable-dominant east of England, he might suggest straw or Miscanthus as a likely source. "Our Link-ka automatic-feed straw boilers are proving popular, especially at 995kW output, to maximise financial returns from the Renewable Heat Incentive. On a smaller scale, our CN Maskinfabrik boiler, rated at 195kW output, could maximise returns on a smaller unit.

"Where straw is less readily -available but there is ample managed woodland, we would probably suggest woodchip, either from virgin timber or possibly recycled sources. On other sites, we might suggest wood pellets, again from virgin timber or recycled for ease of management where space might be an issue."

Pellets have the advantage of being free-flowing, clean, dust-free and provide highly efficient combustion. They are also cost-efficient to transport and store. In addition, Manco Energy acts as biomass broker, matching supply and demand from a number of suppliers around the UK, and it can also offer long-term contracts to users concerned about increasing oil and gas prices.

Providing a range of woodchip and pellet boilers as well as fuel-handling equipment, Mercia Energy of Rugby will carry out site assessments, design systems and supply, install and commission biomass heating solutions for greenhouses. The -company will also customise energy service contracts covering fuel supply and maintenance.

Also offering bioenergy solutions — heat, steam and power — Imperative Energy can provide a full turnkey service that covers feasibility study, design, equipment supply, installation, operation and maintenance. The company also sources and supplies fuel.
Business opportunity

With continuing interest in natural power, Hallmark Power of Leicestershire focuses on the supply and maintenance of wind turbines, anaerobic digestion plants and solar panels. The company works with nurseries and landowners of any size, providing a business opportunity while reducing the costs of power consumption and CO2 emissions.

Finding the right fuel is only part of the equation. Having generated the heat and power, the most efficient equipment must be used to get the best results. Specifying the most appropriate heating system, fans, screens, lights and controllers is part of ensuring minimum waste.

Artificial lighting, either for growing or as a supplement, has been used in horticulture for the past 30-40 years. High-pressure sodium, fluorescent tubes, metal halide and incandescent lights have all been used on nurseries. Only recently have LED solutions become available for growers. One company specialising in the technology for use in horticulture is Valoya, based in Helsinki, Finland.

The benefit of Valoya LEDs is the continuous spectrum of light distributed in different intensities over the wide wavelength range to provide desired results. The light spectrum is developed for plant growth and made with Valoya proprietary LEDs and hence is not limited to what can be achieved with off-the-shelf red and blue LEDs. The company’s technology is used by growers, plant breeders and researchers on plants ranging from flowers and vegetables to ornamental trees and algae.

Within its product ranges, Valoya offers R- and B-Series products. The R-Series are high-power lights with minimal shadow footprint. They are suited to large-scale installations in traditional greenhouses and are designed for a long lifespan. B-Series products are bar shaped and more suited for multi-layer, interlighting and greenhouse installations at lower height. No heat radiation is emitted towards the plants so the fixtures can be close to the crop.
Growth chambers

A third range, the L-Series, is suitable for growth chambers and high--density multi-layer growth systems where it can be positioned as close as 10cm from plants without sacrificing light uniformity or damaging the plants with heat radiation from the fixture.

Valoya offers four main spectrum types in the R- and B-Series products. AP67 is a general growth spectrum for vegetative and generative growth. It reportedly performs well with a large variety of plants, from cucumbers and tomatoes to lemon trees, flowers and tree seedlings. At the end of the scale, NS2 accentuates plant compactness and is used to control elongation and to stress plants’ protective substances that enhance taste or colour. It provides light output that is balanced across the full visible spectrum, without suppression of the green-light area.

The firm also offers AP67S Arch — an architectural spectrum for use in spaces where humans coexist with plants. But the firm’s most recent introduction is AP673, optimised for leafy green vegetables. Benefits over traditional luminaries include better growth, increased biomass and enhanced visual appearance.
Extensive research

"The new AP673 growth spectrum is based on extensive research that we have conducted in co-operation with research institutes and leading growers of lettuce and herbs," says Valoya sales and marketing officer Sanna Naveri.

 "By using the AP673 light spectrum, the plant gets the light energy and information that focuses it to grow leaf and biomass and to delay flowering. It drives the plant quickly to a state where it can be harvested with good weight, excellent texture and outstanding visual appearance. It also accentuates the aroma and taste of plants, even with no sunlight."

After extensive testing of the available lighting solutions, WS Bentley opted for Valoya LEDs for its new pea shoot growing facility in Snaith, Yorkshire. Managing director Jan Bentley says: "We wanted to have the right light spectrum for our plants, as well as high light intensity fixtures, that we could use as moving lights. With Valoya’s LEDs as artificial illumination, we got the best quality of pea shoots while achieving the significant energy savings that we were after. I would say we got the best of both worlds."

Faster growth, improved quality, better timing and energy savings are essential in today’s commercial market and they are achievable with the right products.

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