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Practical fuel option moves a step closer New Holland has confirmed that it will offer gas-powered tractors as early as 2021.

For most farms, generating tractor power to prepare the ground, look after, harvest and transport crops is an expensive investment, requiring large quantities of diesel which continues to rise in price. But if some of the fuel could be supplied from farm waste, it would not only benefit the farmer’s pocket, but also the environment. David Williams reports. Anaerobic digesters have become a familiar sight on UK farms, fuelled by maize or other specially grown crops while others are fed by-products from animal slurry, sub-standard produce or waste from food processing. But whatever the supply route the principle is similar in that crops grown on the land are converted to gas which can be burned to produce electrical power or heat. Most of the gas is methane and New Holland parent company FPT Industrial has been busy developing and adapting engines capable of running on this alternative fuel for its commercial vehicle and agricultural line-ups.

Why not a battery? When alternative fuels are considered, electrical power is often seen as the inevitable solution but New Holland argues that for a typical 180hp mixed farm tractor, a 130kW battery would be needed weighing 3t, taking 8hrs to charge and providing just 1hr’s operation. It would also increase the unladen weight above the legal maximum so it couldn’t be used on public roads. However, advantages

would include simpler drive with no conventional transmission needed and only wheel motors generating the torque. A compromise could be diesel or methane-fuelled engines driving generators to produce electrical power for an implement, with advantages including simpler drive systems and improved control. New Holland’s recent acquisition of Kongskilde suggests one route the company could use to progress this potential development. Commercial vehicles have been available with gas-fuelled engines for many years but an issue for tractors is storage space for gas at very high pressures. Accepting lower pressures simplifies the process, but restricts operating time between fills and at least 5-6hrs working at high engine loads is needed for machines to be viable. New Holland’s early prototypes had gas reservoirs filling every available space including forming over-sized cab pillars but development work has continued and gas storage is improved including tanks with a composite layered tubular structure providing capacity for a full day’s work.

if a fuel leak occurs gas is released into the atmosphere and disperses, whereas a diesel leak could leave areas of crop and soils unusable. A reservation from some potential gas tractor users has been reduced working time in colder weather due to inability to extract all the gas from the cylinders but these fears are groundless, explained the company. Unlike propane and butane, which become less volatile in the cold, methane retains a constant pressure, so all the fuel is available. At a February press launch New Holland displayed a concept gas-fuelled tractor loaded with new technology to test market response, but there was also an opportunity to test-drive a gas-fuelled preproduction example and compare it with a similar diesel-powered model. Electronic engine management means designers have been able to replicate running speed and torque curves to precisely match the equivalent diesel so in theory the gas tractor can take on any task currently carried out by conventional tractors.

Affordable installation Transferring gas from the AD plant to the tractor tanks is relatively simple. A gas refining system cleans the gas ready for use and a high pressure pump fills the tanks, all through one filling point. Apart from investment in the fuelling station there is little additional cost and New Holland claims 30 per cent reduced running costs compared with diesel, including the value of gas which could otherwise be sold to the grid or used to generate electricity. Diesel price fluctuations are a headache for many farmers making it difficult to judge the ideal time to buy and running tractors on home-produced gas removes this

Pre-production models have the gas tanks around the cab but the concept tractor has them under the cab (above), and with capacity for a full day in the field.

uncertainty. However, for many the biggest advantage is the greener footprint, essential for those supplying vegetables or salad to supermarkets. CO2 emissions are reduced by 10 per cent and overall emissions are down 80 per cent. Particulate matter is just one per cent of an equivalent diesel. New Holland’s team has designed the new tractors to have almost identical service requirements to conventional models and farmers carrying out basic services themselves could continue to do so. The only additional maintenance for gas models is an occasional gas tank inspection, the frequency of which depends on local regulations. Although the high-pressure gas cylinders are heavier than liquid fuel tanks the gas itself is lighter than diesel, so average operating weight is similar.

Green revenue streams “Where crop residues are used to produce the gas, these tractors offer virtually carbon-free fuel,” explained continued over...

Ideal for all roles

Pre-production examples will be working on UK farms this year.

Natural-gas-powered engines have much lower emissions than diesel and an advantage is that they run hotter, allowing emissions control systems to run efficiently even at low speeds where diesel emissions controls struggle. This makes them ideal for slow speed applications requiring low power, such as vegetable and salad production. An added benefit is that

Refuelling with gas produced on-farm will reduce running costs by 30 per cent, predicts the company.

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