Technical director Tim Pratt of FEC Services, a Coventry-based energy consultancy, believes that progressive growers who have consistently invested in equipment have now, technologically, reached the point of no easy “big wins”.
He says: “Thermal screens have given a good, solid payback in energy saving. More growers are expected to put screens in this year. But, for those already using screens, it’s difficult to see where the next big saving can be made.”
For some growers, however, the high-energy prices will have turned the sums upside down. Four or five years ago investments in energy-saving technology may have been shelved because of slow payback. But it could now work. If you run a system 24 hours a day, seven days a week, small savings made each day can mean a huge saving over the season.
What fuel is best?
The price of fuel depends on the amount you use, when you are likely to use it and your location. It is important to investigate the various tariffs and discounts thoroughly and, if you are thinking of switching fuels or supplier, look into any penalties or extra charges that may be incurred. Don’t forget to factor in the cost of labour required to keep the system running. In the long term you could save money by seeking the advice of an energy consultant.
Not surprisingly, there is a great deal of interest in alternative fuels, such as woodchip and straw, as well as heavy fuel-oil. Alternatives can work well, but only if you have a local, guaranteed source and the price is right.
In the next few months FEC Services expects to start work on an HDC project looking at biomass fuels to gain an understanding of the costs involved and implications/limitations of transport. It is hoped that information will be available after next spring to help with decisions for the 2007/08 winter. HOK Engineering of Hull is one company offering biomass-burning equipment as an option for glasshouse heating.
What are the key points to consider when looking at a new heating system?
There are three parts to a heating system: the boiler or firing equipment, the mains and distribution system, and the control system. All parts must be capable of meeting the maximum heat demand expected and the system must be amenable to close control with a rapid response to changes in weather. Above all, it must be efficient.
The choice of distribution system will depend on the type and condition of the glasshouse and on the crop grown, but must be capable of maintaining accurate and uniform temperatures throughout each zone. It should not interfere with the production of the crop, and heat input into the house should be planned so that the higher heat input is received at the sides and ends of the house.
All parts of the system must be reliable and must be of sound quality and well-constructed. Equipment should be tested, comply with relevant standards and meet health and safety requirements. It is important that any installation work is carried out by qualified engineers and that a quick-response back-up service is provided to assist in the event of breakdown. Alarms should be fitted to the system to warn of failure. Find out about servicing and maintenance requirements.
What features are important when buying a new boiler?
It is important that a new boiler can match the maximum demand required but it’s not just this “headline rate” that needs consideration. A boiler will rarely be run flat out; so it is important to know the efficiency at part load.
Boiler selection and fuel type go hand in hand. However, with energy prices so volatile, it is worthwhile investigating the possibility of multiple-fuel burning equipment and, for example, switching between gas and gas-oil or gas and heavy fuel-oil as prices and conditions dictate. Flexibility could be key to making small savings without major changes, but remember oils require special storage tanks with bunding and the facility must meet the requirements of the Environment Agency.
What are the latest developments in lighting?
In terms of commercially available products to make a plant photosynthesise, high-pressure sodium lighting is still the main option. Improvements in technology see the new energy-efficient lamps having a five to eight per cent improvement in efficiency over older types. They are also lighter in weight.
Light-emitting diodes — LEDs — are believed to be the next major step forward. Hotbox Heaters is currently offering experimental red lights and blue lights to initiate different plant responses.
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