Waste not, want not – Ireland’s newest renewable-energy source
16 May 2013
John Ahern, managing director of Indaver, is speaking at Engineers Ireland’s 2013 Annual Conference, entitled ‘Building Ireland’s Business Networks’, on Thursday, 6 June at Dublin’s Ballsbridge Hotel
This year marks the second year of operation of Ireland’s first waste-to-energy (WTE) facility in Co Meath. The facility took over two-and-a-half years to complete, at a cost of €140 million – representing the largest ever single investment in solid waste management infrastructure in Ireland. This facility uses the most advanced technology available, processing over 200,000 tonnes of waste each year and generating enough energy to fuel 20,000 homes.
The Indaver group provides integrated solutions for sustainable waste management in throughout Europe. Indaver operates its Irish business from its head offices in Dun Laoghaire, a regional office in Cork and a hazardous waste facility in Dublin Port. In 2011, the Indaver group treated over 3.2 million tonnes of waste and had a turnover of €500 million.
Indaver Ireland Ltd has joined other electricity generators such as ESB and Bord Gais in the electricity market. Indaver’s waste-to-energy facility in Duleek, Co Meath, is converting waste into energy and exporting it in the form of electricity to the National Grid.
“The facility in Meath has been operating successfully as Ireland’s first large-scale WTE plant for 200,000 tonnes of residual municipal waste since 2011,” said John Ahern, managing director of Indaver. “An important element to the facility however, is the recovery of energy and its export from the site in the form of electricity.
“Beyond the extraction of energy from the boiler system, the infrastructure requirements for energy recovery involved the building of an electricity substation on the site, a connecting underground cable to the nearest substation – which was 4km away in Rathmullen, Co Meath – a steam turbine and a generator.”
Energy from a WTE facility is similar to a conventional coal/oil/peat power plant in that it gives a steady, constant and predictable supply of electricity. But it is also similar to green electricity producers such as wind/solar/wave, in that it produces renewable electricity.
Over 50% of the electricity is considered renewable electricity, which comes from the biomass fraction of waste. This contributes to Ireland’s security of energy supply and decreases the amount of fossil fuel needed in the country. “The Meath facility exports approximately 16MW of electricity, which is equivalent to 20,000 homes, or the population of Navan. This facility is also run by a majority [87%] of staff from the north-east region, which means Carranstown is a local facility run by local people,” said Ahern.
HOW IT ALL WORKS
• Reception area
On entering the facility, waste trucks make their way to the reception hall. Here the waste is offloaded into large bunkers for storage. The air in the reception area and in the bunkers is maintained at a lower pressure than outside (negative pressure) and this prevents odours escaping.
• Combustion chamber
The cranes transfer the mixed waste from the bunker to the furnace ‘hopper’. Combustion takes place at temperatures of 850-1100 degrees C, the temperature at which odourous gases and all dioxins will be destroyed.
• Flue gases
The combustion process produces flue gas containing water vapour, nitrogen, carbon dioxide, nitrogen oxides, oxygen and particulate matter. Some of these compounds are harmful to health and therefore the flue gas is thoroughly cleaned before it is discharged to the air. The flue gas cleaning equipment of a modern incineration plant is complex and can take up about half of the space within the plant.
• Electricity generation
A boiler converts the energy from the combustion into high pressure steam. The combustion chamber is surrounded by water tube walls, which are heated by radiation from the combustion. The hot flue gases release additional heat in additional tube panels in the boiler. The steam goes into a turbine, which drives an electric generator.
• Bottom ash
At the end of the incinerator, the solid waste has been completely burned out. The remaining residue is called bottom ash, which is ejected at the bottom of the combustion chamber. The ferrous metals in the ash will be extracted using large magnets and sent for recycling. The remaining bottom ash is non-hazardous and while it could be used in other applications such as an aggregate in concrete or for road building, it is currently sent to non-hazardous landfill in Ireland.
The north east is the first region in the country to have the full set of infrastructure in place to deal with household and commercial waste. This comprises bring banks, recycling centres, mechanical treatment facilities, compost facilities, landfills and now one WTE plant.
“This means that the region has taken a sustainable approach in dealing with its household waste by putting facilities in place to reduce dependence on landfill,” Ahern explained. “The benefit of this infrastructure is that the north east is helping Ireland meet its environmental targets and reduce its reliance on landfill, increasing the generation of renewable energy and the overall aim of reducing the effects of climate change from the waste sector.
‘This established and working waste-management solution is also an essential element in attracting corporate investment into the region,” he added.
Waste to energy delivers a number of real and immediate benefits, which have the capacity to assist Ireland meet its EU waste policy commitments. “While WTE is still somewhat new to Ireland, it is accepted throughout Europe as a highly effective and beneficial means of waste disposal and treatment,” Ahern continued.
“WTE actively diverts waste from landfills, helping Ireland meet its Landfill Directive diversion targets. It’s also regarded as a recovery operation under the Waste Framework Directive, as it actively recovers energy from waste. This energy recovery process assists Ireland in complying with this Directive.”
WTE contributes to reducing greenhouse gas emissions by diverting waste from landfills. It is also a source of renewable energy by producing renewable and sustainable electricity, replacing traditional fossil fuels and positively contributing to the security and supply of national energy. WTE is also recognised as the most energy-efficient way to treat residual municipal waste, according to Ahern.
BENEFITS TO THE ECONOMY
WTE energy can contribute hugely to economic development by providing a safe and cost-effective means of waste disposal, he continued.
“WTE energy can contribute hugely to economic development. It’s not an economic luxury; it’s an economic necessity. It’s also a fundamental part of a competitive, modern economy. Efficient and effective waste-disposal services are a key requirement for all Irish businesses. WTE offers the best solution to business to dispose of their waste in an efficient and convenient way.”
While WTE energy can contribute hugely to economic development by providing a safe energy source, and facilities can deal with both commercial and household waste, there are a number of specialised industries in Ireland which are particularly suited to WTE energy, such as the pharma-chemical sector. This sector is hugely important to the Irish economy. It employs over 50,000 people and exports over €50 billion in products annually.
“Take the example of the Cork region, where Indaver wishes to build a second WTE energy,” the Indaver MD continued. “Nineteen of the 20 largest global pharma-chem companies have a presence in the county. Waste disposal is hugely important issue for their business. Unfortunately, the waste facilities in Cork are much less than what they should be and have actually deteriorated in recent years, at a time when the pharma-chem sector is actively considering future global investment locations,” Ahern concluded.
John Ahern’s presentation at the Engineers Ireland 2013 Annual Conference is entitled ‘Waste not, want not – the role of waste to energy’. For more details or to book your place at the conference, which takes place on 6 June at Dublin’s Ballsbridge Hotel, see www.engineersirelandconference.ie. Other speakers at the conference include:
Michael Phillips, chartered engineer and president of Engineers Ireland
Dr John Tierney, managing director, Irish Water
Laura Burke, director general, Environmental Protection Agency
Naoise Ó Muirí, Lord Mayor of Dublin
Brendan Lynch, managing director, Group Technology, eircom Ltd
Eamonn O’Reilly, chartered engineer and chief executive, Dublin Port
Michael Cawley, chief operating officer and deputy chief executive, Ryanair Ltd
Brian Brennan, managing director, Veolia Transdev Ireland
Michael Crothers, managing director, Shell E&P Ireland
Fintan Slye, chief executive, EirGrid