Watch: Harvesting willow for warmth at Gurteen School

Just a few years in the past there was a lot speak in agricultural circles of rising different crops, akin to willow, to provide power from the land along with its position of offering meals.

Nonetheless, there have been solely a handful of farmers who put the concepts into apply because it all appeared a bit too radical for a lot of, and a diversion from the intense enterprise of manufacturing for a recognized and established market.

Investing in willow

One farm that took the plunge again in 2010 was that belonging to Gurteen School in Co. Offaly which planted 80ac of willow in complete, with the primary harvest occurring 4 years later.

The faculty had a prepared use for the willow and that was to supply heating and sizzling water to the farm, pupil lodging and all the opposite customers of sizzling water within the institution.

The funding, round €750,000 on the time, is now paying off handsomely with the all-in prices of manufacturing and drying the willow, and shopping for in additional wooden for chipping, being round €40,000 each year, as in comparison with the estimated value of €200,000 of constant with oil.

Willow is a low enter crop, it’s lower each three years and receives a dose of slurry after every lower, in any other case it’s left to its personal units though, come harvest time, there’s a particular header required for the entrance of the harvester.

Devoted harvesting header

Harvesting is a job for a contractor and this yr Farrelly Brothers from Kells, Co. Meath took the job on with a John Deere 8400, which is rated at 540hp when leaving the manufacturing unit.

The harvester itself is saved as commonplace, however the header is a particular unit purchased in from the UK which is the third, and thus far probably the most profitable, mannequin utilized by the agency.

The willow crops are set in rows of two with house between every line for the harvester wheels. The pinnacle is subsequently coping with a twin row of saplings on every move.

Slicing peak is about at round 9″ and two serrated round blades draw within the saplings, lower them from their stumps after which feed them into the cylinder consumption.

The slicing motion is created by having the blades set at barely completely different heights, enabling them to overlap and so produce a shearing motion.

As soon as free from the stumps, the sticks are fed into the chopper decrease finish first, the place they’re lower and blown into the trailer within the regular method.

Oil cooling important

The harvester is run with the same old 40 blades on the cylinder and it’s only a matter of minutes to revert again from the willow harvester to the usual forager header and be prepared for silage.

The 2 harvesting blades are pushed by hydraulic motors that are, in flip, pushed by a pump hooked up to the enter PTO shaft.

The most important method through which this specific header scores is that the oil circuit is plumbed into the harvester’s personal oil cooling circuit, holding its temperature down and so avoiding the overheating issues related to the earlier items.

Harvesting velocity will clearly rely on crop situations; in a thick standing it may be as little as 3km/h, nevertheless it was quite a bit faster at Gurteen because of the thinner crops produced on the drier soils of the location.

Moist floor vs power yield

Kenneth Flynn is the farm supervisor and he defined to Agriland that though willow will yield extra on moist floor, the issue then turns into considered one of harvesting it on the proper time.

Ideally, it needs to be lower in late winter reasonably than early spring as that’s the time when the plant is getting ready to bud and accommodates probably the most power.

When leaves first begin to seem, the power content material drops and the leaves themselves can kind a mud throughout drying which reduces the effectivity of the boilers.

This season, the harvest was later than optimum for numerous unexpected causes, however as soon as began, it might holding going with out the delays related to engaged on waterlogged soils.

Round 25ac are harvested annually and the operation usually takes one or two days.

Underfloor drying

As soon as harvested the chips are taken to a retailer with underfloor drying. 20% is the goal moisture content material with it normally coming in at round 50% or extra.

Drying is in two levels – first cool air is blown by way of to take away any pure heating after which heat air is launched to carry the moisture content material right down to the specified degree.

Having a number of hundred tonnes of moist willow chips to dry takes a great deal of warmth, and could be costly if counting on purchased in fuels.

To beat this, sizzling water is drawn off from the recent tank and is used to warmth the drying air, in impact, the willow is used to dry itself.

As soon as dry, the chips are loaded into considered one of two hoppers and are then routinely fed into the boilers at a fee decided by the temperature of the water in the principle reserve tank.

This sizzling water is then distributed all through the faculty buildings in accordance with want.

Wooden chip complement

Altogether this sounds the perfect answer, but there may be not sufficient willow grown to provide all the faculty’s wants, so it must be supplemented by wooden chips, the break up being 60/40% in favour of the willow, though it does range from yr to yr.

The wooden is introduced as recent logs that are then left to dry naturally earlier than being chipped by a forestry contractor.

The boilers will work equally nicely off both materials and there’s no want for any adjustment when switching between the 2.

Given the associated fee saving, the faculty is delighted with how the system is working in its favour. There’ll although, be a must replant the willow sooner or later, however not for at the least a decade.

There’s little administration concerned within the crop; brambles are the largest weed downside and illness is saved in test by there being seven completely different types of willow within the discipline.

It’s, general, a system which works nicely and with the faculty being a registered charity reasonably than state-funded institution, it must take specific care of its funds, and the willow crop is an enormous a part of that.