Farm Ireland

Saturday 20 January 2018

Lighting the spark to fire a future in energy production

Biomass crops offer a real alternative for farmers but more State support needed

Bruce Lett

While economic conditions in farming may be challenging at the moment, there may be some light at the end of the tunnel -- or rather a spark of energy.

At Teagasc's Oak Park research facility in Carlow, extensive trials have been carried out growing mostly willow and miscanthus in an attempt to assess the potential of these energy crops, and, more recently, Teagasc held a harvesting demonstration of the crops.

Teagasc's Barry Caslin is a tillage specialist and one of those involved in biomass energy crop research at Oak Park. Barry is enthusiastic about the potential of certain crops, especially willow and miscanthus, as biomass energy crops now and into the future.

"With climate change and the new reform of CAP in 2012, these crops are going to become more important," he said.

"The 2012 CAP reforms will address four main areas: climate change, biodiversity, energy and water.

"All of these we can address with bioenergy crops and methods," Barry said.

"Most of this change is being driven by the Renewable Energy Directive 2009/28 EC, which has set targets for renewable energy, heat and transport fuels from the bioenergy sector."

Barry maintains that extensive research is needed from both Teagasc and outside, as there are so many vibrant and viable ideas to be explored and considered.

Also Read

Miscanthus and willow

At Teagasc's Carlow facility there are standing crops of both willow and miscanthus. Some of the willow has been harvested at a recent Teagasc demonstration and, on the day I visited, more of the miscanthus was being harvested.

Both crops are exceptionally tall and present their own difficulties in terms of establishment and harvesting.

Planting both is, for the most part, done manually and as a result the establishment costs are quite high.

"In the case of miscanthus, you are looking at establishment costs of around €2,600 per hectare and around €2,900 for willow," Barry said.

"A 50pc establishment grant is available, but this year was the start of the next cycle of grants which were late and may have affected the amount sown."

Miscanthus is grown from rhizomes, which, when harvested, need to be maintained at 4°C within four hours of harvesting, up until planting. According to Barry, this is critically important and one of the factors in proper crop establishment.

Weed control is another. "In years one and two glyphosate (eg Roundup) is used to control grass in the crop when it is in its dormant phase," Barry said.

"Timing is crucial as miscanthus is a grass and it really needs to be applied at precisely the correct time when the miscanthus is dormant."

The crop is well established in year three, and leaf litter effectively controls weeds on the crop bed floor.

Willow is a bit more complex than miscanthus and requires a lot of moisture.

"Willow is an effective bio filter and can filter up to 10 million litres a hectare each year of dirty water, but there are environmental limits on how much dirty water you can irrigate willow with, but it does tick a box on the new CAP reforms," Barry claimed.

Harvesting both crops is likely to be all mechanised and the Teagasc expert explained that willow can be coppiced and left to dry on the headlands or directly harvested with an adapted silage harvester.

"Miscanthus is mown with a conventional mower conditioner and baled up with a large square baler into 8x4x4 bales at high a density as possible," he said. "Typically, these bales weigh around 750kg. Moisture content is typically 25pc at harvest time (April) and, even at this moisture, the bales show no signs of heating. Willow harvested and chipped by the silage harvester is usually in the region of 55pc moisture and requires drying in a clamp."

Anaerobic digestion

Barry feels that anaerobic digestion is an area where there is a lot of potential, particularly for pig producers and bigger dairy units where there is a large amount of slurry waste.

In anaerobic digestion the slurry is broken down by bacteria in an oxygen-free environment. As a by-product, the bacteria produce the methane gas from slurry. The methane gas is captured and burnt, producing heat and electricity (combined heat and power) in adapted engines that are driving electricity generators.

"There is the potential to sell electricity back to the grid," Barry claimed.

"One of the advantages of anaerobic digestion over wind, for example, is that gas production is quantifiable. That means that out the other end you can generate a steady and consistent amount of electricity.

"You could also add whole-crop wheat or maize into the anaerobic digestion process to boost output, again by a quantifiable amount. You also see a lot of grass being added to the digester as well to boost output, and that is one of our most abundant natural resources."

Barry cites the German example where there are 4,500 anaerobic digesters, many of which take food waste and add them to their digesters. A gate fee is charged for the disposal of the waste, while anaerobic digestion output is increased.

Anaerobic digestion is an area that still requires a lot of development here and he points out that, with current electricity prices at 12c/kWh, the price for selling electricity would need to increase to18c/kWh to make it viable.

There is also the possibility of creating a local electricity supply, which would perhaps use existing ESB distribution networks, instead of having to construct additional overhead transmission infrastructures.

Below is an extract from Irish Biofuel Policy and Resources by Barry, which will give you an idea of what has to be achieved and the potential for Irish farming to be involved in producing the island's energy requirements.

At the moment we are producing enough food to feed around 20m people and we import more than 90pc of our energy needs. Changing a portion of food production to energy production would help reduce our carbon footprint, allowing us to achieve our 2020 target of reducing greenhouse gas emissions by 20pc.


The energy white paper, Delivering a Sustainable Energy Future for Ireland, is the bible in terms of Ireland's current energy policy. The paper describes the actions and target for the energy policy framework to 2020, to support economic growth and to meet the needs of all consumers.

The paper sets a path for meeting Ireland's goals of ensuring safe and secure energy supplies, promoting a sustainable energy future, and supporting competitiveness.


Heat: Five percent of heat from renewables by 2010 and 12pc by 2020. While this does not directly identify biomass, it is likely that biomass will contribute more than 90pc of this target if it's to be realised.

Electricity generation: A co-firing target of 30pc displacement of peat, with biomass in our three peat burning stations by 2015.

Transport: 5.75pc of our liquid biofuels (ethanol and biodiesel/ pure plant oil) to replace petrol and diesel by 2010, while this target goes to 10pc by 2020.

Combined heat and power (CHP): 800MWe, with an emphasis on biomass-fuelled CHP.

While non-biomass renewable energy sources, such as wind and solar power, will go some way towards meeting targets, their variability means they will not produce energy when the sun isn't shining and the wind isn't blowing. Biomass, whether for anaerobic digestion to produce biogas for heat and electricity, or wood chip, from forestry or energy crops, are the only means of producing a consistent supply of energy to meet electricity or heat base loads on a required basis.

Note: Miscanthus harvesting development -- in association with energy company Wexgen, Teagasc and Kelly's of Co Wexford-based contractor Trevor James developed another method of processing miscanthus for baling.

Using his self propelled Claas Jaguar 900 harvester with Kemper header, the crop was cut and, instead of being blown up the chute, was deposited on the ground in a windrow under the machine for baling.

One of Kelly's technicians removed all the knives from the chopping cylinder, reduced the harvester's engine speed and removed the chopper box belly band to allow the crop to exit onto the ground.

Trevor said it was much easier than trying to cut the three-metre high crop with a trailed mower conditioner.

Irish Independent