I thank the committee members for the invitation to address the sub-committee on the subject of the possible use of anaerobic digestion for the provision of heat and power and the job creation possibilities these new technologies could bring to an area. This presentation will have three parts. Mr. Patrick Berridge, Dr. Andrew Walsh and I will contribute to it. In my part of the presentation, I will elaborate on some of the areas of which I have knowledge. I will refer in particular to the findings of a feasibility study, carried out in County Cavan in the early 1990s, on the possibility of using an anaerobic digester to treat pig slurry. I will comment on the environmental considerations that need to be taken into account when a decision is being made on the location of an anaerobic digester. I will point out some important factors that affect the economics of running such a facility.
I will be followed by Mr. Patrick Berridge of Ballyshannon Recycling Limited, County Wexford, who will make a presentation from the perspective of an operator of an anaerobic digester. Members of the committee may be aware that Mr. Berridge, who is the driving force behind the Carrickbyrne Farmhouse Cheese company, works as a dairy farmer in County Wexford. He has been operating an anaerobic digester on his dairy farm since 2001, thereby facilitating both heat and energy recovery. Mr. Berridge will be followed by Dr. Andrew Walsh, who is the managing director of the Celtic BioEnergy company, which provides expertise in anaerobic digestion technologies and other renewable energy areas. Mr. Berridge and Dr. Walsh have developed a joint venture to demonstrate the capabilities of anaerobic digestion technologies in the processing of a wide range of organic matter.
When I worked for Cavan County Council, I had some experience of the pitfalls which can be encountered when assessing the suitability of anaerobic digestion as a method of waste management. While it is not all negative, it is important to point out some of the problems. I will speak about my first experience of anaerobic digestion of animal slurries. The committee is probably aware that before the late 1960s, Lough Sheelin was a brown trout fishery of considerable repute. By 1970, however, algal blooms were becoming evident on the surface of the lake and beginning to proliferate. In 1972, An Foras Talúntais — the predecessor of Teagasc — carried out a research project on agriculture within the lake's catchment area. The results of the project indicated that the spreading of pig slurry at inappropriate times and in inappropriate quantities was responsible for the deterioration of water quality at the lake. A Government-funded pig slurry export scheme was established and run by an interdepartmental committee between 1981 and 1984. It was eventually taken over by Cavan County Council. This led to an improvement in lake water quality. The scheme eventually closed as a result of the considerable transport costs that were associated with it.
Research was carried out in the early 1990s on behalf of a number of the larger pig producers, in conjunction with Cavan County Council, in an effort to establish the feasibility of using anaerobic digestion to treat animal slurries — specifically pig slurry — in the Cavan-Monaghan area. To that end, an in-depth feasibility study on the technologies available, as well as the economics of using anaerobic digestion to treat pig slurry, was researched. The study found that if an anaerobic digester is to operate properly, it cannot operate solely on pig slurry. It also needs additional organic matter with a higher fat content, such as that originating from hotels, restaurants, poultry litter and milk processing waste. Pig slurry simply does not have enough energy content per tonne to enable an anaerobic digester to work properly. To put it simply, there is too much water in pig slurry. The feasibility study indicated that the Cavan-Monaghan area could support a system capable of taking approximately 400 tonnes of material a day, five days a week. The optimal material would consist of pig slurry, milk processing waste and poultry litter, which could be sourced in the immediate hinterland of the proposed digester.
A number of insurmountable problems continued to exist after the feasibility study had been completed. The overall operating costs were high, compared to the alternative method of disposal of pig slurry. It was simply cheaper to spread slurry on nearby fields, even if they were already saturated with nutrients. At the time, the relevant technologies in this area were immature. Anaerobic digestion technology and the combined heat and power plants were in their infancy. There was no outlet for the heat that was being generated. Little incentive was given for the sale of the electricity that was generated. The concept of micro-generation was just beginning to gain credence. The system ended up with a liquid slurry — the digestate — that had to be disposed of. The cost of transporting the digestate to those farms using it as a fertiliser replacement was very high.
As I have already mentioned, animal slurry is naturally high in water content. The last of the problems to which I referred — transport costs — proved to be the most intractable and is often forgotten. One needs to decide what to do with the digestate that is produced at the end of the anaerobic digestion process. While the content of the organic matter may be reduced as it is broken down to methane, that process has little impact on the water content of the slurry and virtually no impact on the nutrient value of the slurry, which needs to be disposed of in an environmentally sustainable manner. It cannot simply be dumped on the nearest fields.
A necessary component of the Cavan project was that the sludge be removed from the Lough Sheelin catchment, which already had high nutrient status, and be brought to those areas that needed it most, particularly the tillage counties of Meath, Carlow and Kilkenny. However, animal slurry, even that which has been treated by anaerobic digestion, is low in nutrient value, especially when compared to artificial fertilisers. This is due to its very high water content. The additional cost of separating the solids from the water fraction was proving expensive. Thus, the project failed due to the high cost of transporting the digestate, the lack of gate fees charged to other operators for the disposal of their organic waste and the large distance from the end user of the product of the anaerobic digestion, particularly the slurry.
Since the project began, however, a number of developments have taken place that may negate many of the problems encountered in the early 1980s. These include more advanced technology, particularly combined heat and power plants; higher prices being paid for electricity generated; the advent of district heating; more stringent environmental legislation pertaining to the regulation of the disposal of waste; the cessation of the disposal of organic matter to landfill; and the nitrates directive, which prohibits excessive nutrient application to farmland. New uses for digestate, particularly the liquid fraction, are being examined, including its use as a fertiliser for willow and miscanthus. These crops are growing in importance as there is a growing market for woodchip and wood pellets for home heating.
The changes to the regulatory framework concerning how we deal with waste and the increasing costs of importing fossil fuels are resulting in an environment in which anaerobic digestion, if correctly planned and executed, is becoming economically viable. For example, to comply with the landfill directive's target of removing all organic matter from landfill by 2016, this country would be required to develop additional capacity to manage upwards of 1 million tonnes of organic matter. Much, if not all, of this could be utilised in anaerobic digestion to generate bio-gas heat and power. The resulting digestate, after further treatment, could be utilised as a soil conditioner or, after further drying through the CHP system, could be used as a biofuel itself.
There are a number of issues pertaining to economic support, including gate fees and prices for electricity, that need to be addressed to support the start-up enterprises. These will be highlighted by Mr. Berridge and Dr. Walsh.
Job opportunities will arise. Experts will be needed for the design and installation of the anaerobic digester plants and agronomists will be needed to produce biannual reports on the nutrient needs of the energy crops. This area will grow in importance as environmental matters come to the fore. People will be needed to operate the plants. Farmers will be required to continue farming to generate animal slurry and accept the digestate for application to tillage crops, be they food or energy crops.
InterTradeIreland, a North-South intergovernmental business development body, recently published the results of research it carried on the composting and anaerobic digestion sector. Its report, Market Report on the Composting and Anaerobic Digestion Sectors, suggests that if every household and business on the island were provided with a brown bin, between 1.5 million to 2 million tonnes of organic waste could be diverted from landfill, thus meeting our obligations under the landfill directive while at the same time generating approximately 1,500 jobs directly and nearly 10,000 indirectly. Even if only 6,000 jobs were generated, the number would be substantial.
The facility at Mr. Berridge's farm was originally developed in 2001 to process the manure, animal slurry and cheese waste generated on his dairy farm and cheese manufacturing site. It is currently being upgraded through the inclusion of a pasteurisation unit, reception hall and storage tanks. To that end, Mr. Berridge has recently applied for and was granted planning permission by Wexford County Council to upgrade his anaerobic digestion facility, which, by using modern technology, will make more efficient use of the energy generated. The digestate will be used as a fertiliser replacement on his agricultural lands.
As well as dealing with the development by Mr. Berridge, Wexford County Council has had, over the past six months, pre-planning discussions with a large established enterprise based in County Wexford with a view to opening another anaerobic digester in the county. This proposal is substantially larger that the former one and the documentation received to date suggests a site is being considered that would utilise approximately 99,000 tonnes of organic matter per annum from a variety of sources. Initially it will be able to generate up to 5 MW of electricity. Put another way, it will be able to supply enough green electricity to power approximately 2,500 homes. This ambitious project, which is at an advanced stage of planning, also proposes that the digestate emanating from the digester be split into two waste streams. A solid fraction will be used as a fertiliser and soil conditioner on nearby tillage lands and a liquid fraction will be utilised on an on-site willow plantation, the aim being that the willow itself will eventually be utilised as an energy crop in the project. There will be a variety of jobs required using varying skills to plan, construct and run these plants. They will vary from the collection of waste to the design and planning of the projects, from evaluating environmental impacts and the preparation of NMPs, nutrient management plans, to the running of the plants. The jobs will range from engineers, agricultural scientists and steel installers to general operatives, as well as specialist electricians, structural engineers and farmers. They will also benefit the country in replacing imported fossil fuels.
From a local authority perspective, it is imperative that careful consideration be given to the selection of the sites for anaerobic digesters so as to minimise the distance for transporting raw material to them. They should be situated close to a site where the liquid fraction can be cheaply transported and utilised and areas where heat and power can be utilised. It is imperative that every aspect of the site is thought through with consideration given to all of the end products. The Gussing project and other similar successful projects in Europe were sourced locally with all final products – electricity, recovered heat and digestate – locally utilised. This aspect will be need to be incorporated into Irish proposals for such projects to be environmentally and economically unique and sustainable.