Our carbon footprint

Carbon footprint and Resource Recovery

AES operates a Resource Recovery business, which manages waste in a manner which maximises the segregation, reuse and recycling of materials while minimising the volume sent for disposal. This is achieved by utilising the most modern technologies, ensuring regulatory compliance and working in partnership with customers. The overarching objective is to minimise the volume of waste going to landfill.

Resource Recovery operates five waste transfer centres, a mixed dry recyclables recovery facility and a landfill site. A range of technologies are deployed at the waste transfer centers, including:

• Mechanical grabs
• Trommels
• In-vessel bio-stabilisation units
• Magnets (ferrous metals)
• Eddy currents (aluminium)
• Laser optical equipment (identifying and sorting plastic materials based on their molecular density) and
• Balers (baling materials to customer specifications).

Landfill diversion strategy

While landfill has a role to play in Ireland’s waste management system, it is the lowest priority in the waste hierarchy as it is the least efficient at recovering materials and energy from the waste stream. It also has the greatest environmental impact. However, we are responding to this in a number of ways:

Biodegradable waste management

When biodegradable wastes decompose in the anaerobic environment of a landfill, methane, a greenhouse gas, is produced. To provide an alternative treatment for these biodegradable wastes from current gas capture and management systems, we are in the process of developing a ‘Brown Bin’ waste composting facility adjacent to our Drehid landfill. The plant will have a capacity to handle 25,000 tonnes of biodegradable waste per annum and construction is targeted to commence later this year.

Brown bin roll out

Segregation at source is key to effective recovery and reuse of waste materials. To this end, we are in the middle of a roll out of brown bins to all of our domestic customers. Early segregation and capture of this domestic kitchen and garden organic waste stream allows for the creation of a quality, low-reject compost from the waste material.

To date, customers have been positive regarding the uptake of brown bins. In March 2009, those availing of brown bin collections accounted for 8% of domestic customers, which had increased to 26% by March 2010. Composted organic waste material will be made available to our horticulture business as a feedstock for growing media, thus supporting that business in meeting its peat-dilution targets.

Mechanical biological treatment (MBT)

MBT is a term that describes a sequence of processes that includes mechanical separation of co-mingled (i.e. nonsegregated) waste streams and treatment (typically composting or anaerobic digestion) of the biodegradable fraction. MBT plants are designed to process mixed household waste as well as commercial and industrial wastes. The components of the mixed waste stream recovered typically include metals, plastics and glass. There is also the manufacture of waste-derived fuels - commingled wastes with relatively high calorific values - that are screened to create a specific fuel for use as carbon-fuel substitutes in solid fuel applications such as coal-fired power plants or cement kilns.

It is our intention to supplement our existing mechanical sorting processes with an appropriate MBT technology by 2013. This will be a significant enabler in the implementation of our landfill diversion strategy with the potential to handle over 200,000 tonnes of material.

Changing consumer behaviour

Resource Recovery has over 90,000 domestic customers. One initiative to change behaviour is to provide bins for different waste streams. It has been shown that the recycling/recovery rate correlates directly with the number of bins provided. Hence a one-bin system has zero recovery, whereas a four-bin system can achieve a 60% recovery rate.

Additionally, switching customers over to pay-by-use billing options rewards customers who reduce absolute waste volumes and who recover recyclable materials. Over the last 18 months, we have invested in radio frequency identification (RFID) based technology which allows for location and customer identification of all waste bins collected and of related bin weights. This tracking and visibility allows us to put in place innovative pay-by-use billing mechanisms and in turn will incentivise waste reduction and maximum segregation.

Landfill diversion - progress

Total waste collected in 2009/2010 saw a 4.4% decline on 2008/2009 volume. This reduction largely reflected the decline in activity in key sectors such as construction, retail, hospitality and manufacturing.

Despite the reduction in overall waste volumes managed, the volume of waste treated at our organic waste treatment facilities increased by 12% over the year. Most of this waste was composted at our Kilberry composting facility for inclusion in our horticultural product range. Overall landfill diversion increased to 54% as we continue our journey to 80% diversion by 2013.