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Demand grows for green feedstock Farmers are being encouraged to grow alternative energy crops and help meet demand from anaerobic digestors. The International Energy... More renewable energy options to fuel supplies

Demand grows for green feedstock

Farmers are being encouraged to grow alternative energy crops and help meet demand from anaerobic digestors.

The International Energy Authority (IEA)  expects the global biogas sector is expected to grow by 8-22% annually over the coming years – a figure described as startling by Chris Huhne, chairman of the Anaerobic Digestion and Bioresources Association (ABDA).

At the lower projected growth rate, an extra 500 AD plants will be needed in the UK by 2030, says Mr Huhne. “If we grow at the higher rate, we’d be looking at an extra 2,000.”

 At the end of 2023, the UK had about 723 plants, adds Mr Huhne. “This is a substantive projected increase. Even at the lowest IEA forecast, the industry would overtake the nuclear sector during the 2030s.”

Wholecrop options

Future Biogas feedstock director Angela Battle believes biomethane produced via AD is a scalable solution to gas decarbonisation and growing crops for it can help farms achieve a neutral or even negative carbon footprint with rotational benefits.

“Gaps between energy and food crops can also be filled with cover crops capable of holding plant nutrients, water and helping to build soil organic matter.

“Introducing AD and sustainable farming practices into an arable production system, therefore, provides multiple opportunities to help build soil organic carbon and restore the soil carbon sink potential for generations.

“The growing of bioenergy crops provides significant diversification opportunities for growers, too, supporting them in making long-term changes.”

Rory Hannam, KWS UK technical manager for hybrid crops, says wholecrop cereals are a viable alternative option to maize for biogas production and can provide significant agronomic, environmental and economic benefits.

“Given hybrid rye’s benefits it’s no surprise that the UK area has increased from 25,000 – 35,000ha annually just four years ago to possibly just under 50,000ha today.”

About 50% of this is used for biomass to produce feedstock for AD plants, says Mr Hannam.

“It’s one of the most drought-tolerant crops available and is typically well suited to lighter, drier, drought-prone soils, particularly in areas of low rainfall, as well as being suited to heavier land with many farming businesses in that situation now considering the crop.”

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Energy balance

Rye fits well with energy beet or maize in the rotation and can be utilised in the biogas plant to balance the high productivity of energy beet or maize substrates, he adds.

“Used alongside maize, rye has a synergistic effect by improving the gas yield, as it increases the length of time for the maize to produce methane in the digester.

“By mixing 25% hybrid rye with 75% maize, plant managers can increase gas output by nearly 15% more than from maize used on its own.”

According to KWS UK hybrid crops product manager Kate Cobbold, hybrid barley grown as wholecrop offers a similar opportunity to rye.

“Hybrids generally have greater vigour than conventional varieties and this results in the highest biomass which then provides the best gas yields.

“If weed control is a higher priority, hybrid barley offers some specific advantages over hybrid rye. As farmers increasingly battle with blackgrass, hybrid barley can help reduce grassweed pressure considerably.”

Choose carefully

Variety choice is important and a series of UK field trials is showing some exciting benefits for the new KWS hybrid barley Inys, says Ms Cobbold.

“There is a definite yield advantage for Inys over the leading hybrids currently available in the UK with good yield stability plus we’re seeing thicker plant stands and deeper rooting.

“There are indications that Inys also has a much more vigorous growing habit in the early stages of development with up to 40% greater ground cover being seen in some trials conducted across the UK.”

Standout rye varieties include KWS Igor, KWS Serafino and KWS Tayo. In trials with Agrii, all three produced outstanding wholecrop yields with Igor and Serafino topping 50t/ha at 34% DM.

“Our breeders are also developing biomass only varieties that will be particularly suited to wholecrop markets and this in an exciting development that growers and end users should look out for in the next few years.”