The future of fuel

As the era of cheap fossil fuels comes to an end, do alternative energy sources offer a viable alternative for growers?

Pentland's 2MW Reka biomass boiler: was set up to replace two 1MW oil burners. Credit: Gavin McEwan
Pentland's 2MW Reka biomass boiler: was set up to replace two 1MW oil burners. Credit: Gavin McEwan

Alternative energy sources, particularly biomass boiler systems, have seen increased interest in recent years as the UK has faced periods of erratic fuel prices.

Looking to escape an uncertain future in terms of heating costs, a switch to alternative energy sources has worked well for those with the initial capital outlay to set up a new system. Biomass trials and case studies have generated some impressive headlines for the horticulture press but, as prices stabilise, are alternative energies still a viable substitute for traditional oil, coal and gas heating systems?

Energy minister Malcolm Wicks warned last winter that for the UK the era of cheap energy was over, due to depleted fuel reserves and a heavy reliance on gas imports. His comment followed a turbulent period of energy price hikes, where during the previous winter cold weather snaps forced prices up by as much as 300 per cent virtually overnight. The developments caused shockwaves in the horticulture sector, with some people speculating a bleak outlook for the industry if things continued at this pace.

In reaction to the problem, £6bn of investment was secured to double Britain's gas storage capacity by 2008, with the aim to disperse Britain's dependence on one country or area of the world for its supply. Shippers can now bring in oil and gas from the Middle East, Central Asia, Africa and South America.

Despite this commitment from the gas industry and the Government, many in the horticulture sector still feel they need to make changes to safeguard their future energy costs while also making environmental commitments to cut CO2 emissions.

The use of biomass boilers for glasshouse heating has perhaps caught the highest level of interest and imagination from glasshouse growers looking to reduce costs.

Suppliers and existing users report strong interest in the technology despite a calming of energy prices.They maintain that there are still savings to be made in the short term and that an energy source free from the need of fossil fuels removes any future threats to heating costs.

Dragon managing director Peter Mowbray says the wide variety of fuel options offered by the heaters the company supplies makes them an attractive alternative. The Lincolnshire-based supplier offers a range of heater models to cope with timber offcuts, forest waste, logs, pallets, straw bales and woodchip and pellets. He explains: "We still see a lot of interest from the horticulture sector. Our woodchip-burning option is proving popular as the cost of wood pellets is now reaching that of coal. Simple woodchip is much cheaper and will still produce around 400Kw of power for heating water to warm the glasshouses."

The lack of availability of fuel material has deterred some from switching over but Mowbray says most of his customers secure a supply of fuel before buying the boiler systems. He believes the use of the company's woodchip heater has made the sourcing of fuel much easier: "There are factories and forest departments across the country able to offer woodchip, and even a lot of local councils produce woodchip waste through their parks maintenance etc.

"The critical thing with wood or straw burners is that for every tonne burnt, you are going to save on 450 litres of oil. As long as you can get a tonne of fuel for less than the cost of 450 litres of oil, you are saving money. I know of one customer who takes woodchip from those who are just looking to get rid of it and pays only £12 a tonne. That sounds like a good deal to me."

Parkers Nurseries in Essex switched to biomass heating ahead of winter 2006/07, investing £250,000 in a 700kW, woodchip biomass boiler. Nursery owner Geoff Parker explains: "We opted for the boiler to reduce energy costs in the long run. In principle, I'm very happy with how it has performed. There were a few teething problems but when you balance that with the saving we're making on fuel it's definitely worth it."

He adds: "If people are serious about staying in the industry and about growing high-energy crops then they really need to consider how they are going to produce that energy in the future."

Other alternatives

Biomass boilers are not the only alternative in escaping gas bills. The Sunergiekas closed-climate glasshouse system from Dutch manufacturer PLJ Bom Groep has been attracting the attention of growers since it took the Innovation Award at Amsterdam's International Horti Fair in 2005.

The system utilises the fact that glasshouses receive more energy than they need each year from the sun. During summer months the system collects this extra energy in the form of evaporated water, given off by crops. The water vapour is passed through condensing chambers and stored as warm water in underground aquifers. In winter the process is reversed and the stored water is used to warm the glasshouse. As a closed system, no roof vents are installed but if temperatures become too high, outside air can be brought in as necessary via an inlet system placed in the front gables of the glasshouse structure.

Further improving efficiency, the Sunergiekas system features glass panels with incorporated anti-reflection technology to increase light transmission from the usual 90 per cent to as much as 97 per cent.

FEC Services is one of the UK's leading sources of information and consultancy on the application of energy-based techniques in business. The Warwickshire-based company has particular specialist knowledge in the farming and horticulture sectors, and has seen impressive results in closed-system trials.

Technical product manager Tim Pratt says: "The closed-greenhouse system has created some impressive headlines and there have been some good results in trials - a 20 per cent increase in yield and 35 per cent in energy saving."

But while the results are there, Pratt notes uptake has been slow and questions the system's suitability in the UK.

He believes the next step is to look at a semi-closed glasshouse set-up more suited to the UK. The principles are fundamentally the same, he says; the semi-closed system accepts the fact that a 100 per cent closed environment needs a lot of expensive cooling equipment to satisfy just a few growing days each year when temperatures reach the extreme. "The semi-closed system says when it's cheaper and cleaner to let in some fresh air."

Despite its potential, there are still barriers to its adoption in the UK. According to Pratt, the closed system's use of aquifers makes it not feasible in the UK and alternative heat storage methods need to be identified. "Aquifer thermal energy storage is not viable in the UK," he says. "Aquifers are very rare and there is currently no other commercially viable option for heat storage.

"However, air handling with the use of fans and ducts could offer a lot of opportunities and benefits to growers. Improved air movement provides more uniform temperatures across the glasshouse as well as better humidity and CO2 conditions. It also allows for heating with lower-temperature water and increases alternative heat supply opportunities, particularly when starting out from scratch."

Pratt looks forward to the results of a "truly cutting edge" HDC project that is investigating the potential uses and development of fan and duct technology for glasshouse heating.

How the gas market works

Wholesale gas is traded like any other commodity. Suppliers buy from shippers - companies that contract offshore producers to bring gas onshore or receive gas via interconnector pipelines or liquid natural gas terminals - in order to meet needs of homes and businesses.

To ensure they can provide suppliers with enough volume, shippers buy capacity on the high-pressure gas pipeline system owned and run by the National Grid. This is bought at auction, with the option of buying capacity up to 15 years in advance. The National Grid is responsible for ensuring the system remains in balance, and buys and sells gas to ensure supply meets demand.

Britain's gas supply chain

1. Producers and importers

  • Companies that bring gas onshore from North Sea gas fields, interconnector pipelines via Norway and Belgium, liquid natural gas terminals or offshore gas storage facilities.

2. Shippers

  • Companies that bring onshore gas to pipeline system.
  • They trade gas and capacity.

3. The National Grid

  • The UK's monopoly transporter of gas on the National Transmission System.
  • Transportation within local distribution zones is done by the National Grid and four other distribution companies.

4. Suppliers

  • These are companies like Npower and British Gas, which sell to and bill the end user. This supply chain has come under scrutiny in the past few years, sparked by allegations of price fixing. Following both industry and domestic concerns, the House of Commons' Business, Enterprise and Regulatory Reform Select Committee has called for an inquiry into Britain's energy market. Independent industry watchdog Energywatch has welcomed the move. Campaign director Adam Scorer says: "Energywatch has long voiced concerns that there are serious problems in the way the energy market works, or rather doesn't work. Consumers need this inquiry to provide some clear thinking about how this market lets consumers down and what needs to be done to fix it. This is a sensible step and we hope that it will convince the Government to make a referral to the Competition Commission."

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