Making more money from muck

By Peter Young

We have already looked at the options of solar and wind energy to harvest the elements on Irish farms. Anaerobic digestion is another way for farmers to harvest the elements, albeit indirectly. This potential is already in use in other countries such as Germany, where there over 3,500 plants on farms harvesting energy crops like maize, grass silage and even grass, to produce electricity. With new incentives announced recently, is Ireland now ready for the tried and tested process?

New incentives spark interest

New incentives to produce electricity through anaerobic digestion have sparked farmers' interest in recent months.

The incentives from the Department of Communication, Energy and Natural Resources provide up to 30% investment grants, and increase the guaranteed price for the electricity produced up to 12c/kWh.

The limit on the grants varies depending on the size of plant (see Table 1). The biggest interest has come from pig and poultry farmers, who already have to export manure, and have a high heat requirement.

Anaerobic digestion (AD) is, in some ways, like a big rumen, in that it uses bacteria to convert organic matter into methane and nitrous oxide in the absence of oxygen. The methane can be used for heat, power or even as a transport fuel.

The systems can be divided into wet or dry processes. The wet process takes straight pig and cattle manure, while material for the dry process has to be over 25% dry matter (DM) with any slurry put through a separator first.

While there are talks of centralised biomass plants, most farmers I talked to are interested in smaller scale plants working on the farm.

In brief

• New incentives for anaerobic digestion have stimulated interest.
• Pig and poultry farms that have a large requirement for heat most interested.
• Unlike wind, anaerobic digestion produces a constant supply of electricity.
• Potential to be economic without gate fees.
• Could pay attractive price for sugar beet.
• Needs higher electricity price to really thrive in Ireland.

Table 1: Maximum cost per installed electricity generating capacity

Plant size	Maximum cost
>50-100KW	€4,500/kW
>100-500kW	€4,000/kW
500-1MW	€3,500/kW
>1MW	€3,000/kW

German success proves that anaerobic digestion can work

Germany embraced anaerobic digestion as a route to making electricity, proving that the right incentives, in the form of higher electricity price, worked.

The basic tariff for electricity derived from biogas from manure in Germany is 12c/kWh. This rises to 15c/kWh when energy crops are used, with an extra 2c/kWh paid when the heat can be utilised.

Different energy crops are used in anaerobic digestors in Germany. The increasing costs of producing these crops, as well as the opportunity cost in selling them for animal feed, has eroded the profit in the last year. This will always be the deciding factor on the profitability of anaerobic digestion.

Gate fees have potential to increase profitability, but there are risks when building a business model around their costs and availability in the future.

There are many projects being looked at in Ireland. But unless the difficulties with planning and licences are resolved, the potential will be slow to materialise. Future incentives to ensure success could include a higher energy price, linked to what is being used as material. IFA are already looking for a higher price per kWh for small-scale projects that provide an alternative enterprise on-farm.

We just have to look at the success in Germany to realise that we don't have to reinvent the wheel on this one, anyway.

The longest-running AD system in Ireland

Paddy Berridge's on-farm anaerobic digestor is one of the longest-running operations in the country. Based on his farm in Adamstown, Co Wexford, it has now been running for 12 years.

It was initially designed by Paddy to take slurry from the dairy farm, waste from his cheese plant and pig slurry during the summer.

The mix is retained in the tank for 20 days. It is heated to 36úC and agitated to recirculate the gas through the tank. Slurry leaving the tank goes through a separator, and the liquid is pumped through a heat exchanger to preheat the cold slurry coming in.

Five years ago, Paddy increased the capacity from 200 to 300 cubic meter. The 300 cubic meter produced 450 cubic meter of biogas each day.

Biogas from the unit can be used to run a 60-year-old two-cylinder engine to generate electricity. The efficiency of the engine was 30%, with the heat generated in the process used in the cheese-making plant.

Paddy believes that the investment has repaid itself more than twice over during the years. More recently, he has joined with Celtic Composting, and plans to build a larger 4,000kW unit with the capacity to handle 12,000 tonnes of waste on the site.

The expansion coincides with a move to take in other householders' wastes, charging gate fees to make the process profitable. It's a route that has made getting planning and licences much more difficult.

A separate entrance from the farm was installed, and a pasteruisation unit is to be included to treat the external waste as part of the process requirements. In all, Paddy will have spent €1.4m, excluding the cost of the land. Getting a grid connection to sell electricity proved to be one of the most difficult obstacles. With his experience, Paddy has set up a company with Celtic Composting to sell anaerobic digestion systems in Ireland. He also plans to look to China and India, the homes of anerobic digestion, to see if lower-cost systems can be set up.

Kedco offers farmers 50:50 partnership

Kedco Power is an Irish company that is selling high dry matter (DM) anerobic digestors. They say these systems are becoming more popular in Germany.

The system uses material that can be stacked into chambers. The material is normally over 25% moisture, but lower dry matter material can be mixed in.

They have a number of farmers on the verge of applying for planning permission for the systems. "Some have their own source of pig and cattle slurry, but will also be contracting farmers to produce crops to feed into the system,'' said Paul Kingston, Chief Technical Officer at Kedco Power.

According to Paul, this system could herald the revival of sugar beet in some areas. Sugar and fodder beet are a good source for biogas. A tonne of sugar beet produces 300 cubic meter of gas, compared to 200 cubic meter from fresh grass and 100 cubic meter from organic waste.

With 1 cubic meter of gas producing 2.2kW per hour, a tonne of sugar beet could produce 660kWh (300 x 2.2). At 12c/kWh, this would be equivalent to €79 of electricity produced per tonne of sugar beet, giving the potential for an attractive price to growers.

Pig and cattle slurry have to be first put through a separator to remove some of the high N liquid fraction. A 30,000t digestor that is currently being planned has ten 400t compartments that have to be filled by a loader every four to six weeks.

The system uses just 2.5% of its own electricity to run - an important measure. After composting, the material could be spread back on the land, or wind rowed to reduce the moisture further.

Paul put the cost of installing a system to deal with 30,000 tonnes a year at around €3.5m. Kedco Power are promoting their business model in which they set up a 50:50 partnership with the farmer. "The farmer provides the land and supplies the material, and we bring the technical efficiency,'' said Paul. "This way, we can ensure the system is working to its potential and the level of electricity produced in maximised.''

The returns are, of course, split between the farmers and Kedco. A 30,000 tonne system has the capacity to produce around 1.3mkWh (1.3GWh). At 12c/kWh, that's a potential output of €1.6m a year.

From this, the cost of the material as well as running costs and administration etc, have to be paid. The heat on many of the systems planned is being used for pig and poultry houses, but could also be used for small housing estates - a practice that is popular in Germany.

"Anaerobic digestion has many advantages, but unfortunately, many people automatically think about sludge or other materials that they feel are undesirable,'' Paul said. "We believe a model can be set up that does not rely on attracting gate fees to be profitable.''

Energy monitor giveaway

Surface Power, a company based in Tourmakeady, Co Mayo have given us five wireless energy monitors to give away to our readers.

The OWL wireless monitor makes it easy to check the cost of operating your electrical appliances on the farm or in the house.

You simple click a sensor onto the live wire of your electrical supply, and a wireless device beams the information to a remote monitor up to 30 metres away.

The remote monitor gives a reading as to how much energy you are using, and the cost in cents per hour.

You can quickly see how much each pump or cooler is costing to run by simply switching it on and seeing how much the electricity usage jumps.

It will quickly educate you about what is using the most electricity on your farm, as well as in the home. Armed with this knowledge, you can start to reduce your bills.

To be in with a chance to win one of the five monitors, send in the answer to the question below with your name and address to:

Free energy monitor,

Peter Young,

Irish Farmers Journal,

Irish Farm Centre

Bluebell,

Dublin 23.

The simple question is: what Co Mayo town is Surface Power based in?