Tractor heritage, news and features

Unleashing the power of grape prunings

A New Holland TN 75 tractor at Grove Mill Winery in New Zealand was converted to run on gas produced from canes pruned from vines. It was then used successfully for mowing between the rows of grapes. The tractor ran on a mixture of 75 per cent gas and 25 per cent diesel. A petrol engine could run entirely on gas.

Designer of the prototype, Kevin Parker, believes that wineries are ideally placed to become fossil fuel free by using what is currently a waste product to produce energy.

“Vineyards already grow and harvest all the fuel needed to be entirely self-sufficient in energy. The physical properties of the prunings make them simple to collect, store and prepare as fuel. Gasification of prunings can produce the equivalent motive power of up to 2000 litres of petrol per hectare of cultivated vines. Additionally, gasification produces ‘Black Ash’ or biochar, which is high in carbon and is an invaluable soil conditioner. It provides a permanent carbon sink to help offset any fossil fuels used in the distribution of finished wine to the marketplace.”

The process of extracting gas from the prunings is accomplished using a process called pyrolysis. This is a form of incineration in, as far as possible, an oxygen free environment. The organic materials are transformed into gases, small quantities of liquid and a solid residue containing carbon and ash.

Biochar is a fine-grained charcoal, high in organic carbon and largely resistant to decomposition. The net result is that biochar is a soil carbon pool that is carbon negative and serves as a net withdrawer of atmospheric Co2. The enhanced nutrient retention of biochar-amended soil not only reduces fertiliser requirements but also the climate and environmental impact of cropping land. Biochar-amended soils have shown 50-80 per cent reductions in nitrous oxide emissions and reduced runoff of phosphorus into waterways and the leaching of nitrogen into groundwater. The need for chemical fertilisers is reduced and crop yields are enhanced.

The technology is not new but has been largely forgotten due to the ready availability of fossil fuels. In 1699, Dean Clayton produced coal gas from a pyrolytic experiment. In 1901, JW Parker ran the first passenger car on producer gas. During 1939, over one million vehicles worldwide were converted to run on gas.

The current increases in the price of fuel makes one wonder whether in years to come, the by-product of vineyards could be worth more than the end product? For more information on Biochar visit the Vinegas website at  www.vinegas.com

Andrew Ritchie
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