Generating energy from waste

EU targets on waste mean the waste treatment sector is seeing sustained growth as nations look to enhance their infrastructure. Sustainability Live's David Copeland highlights how innovative British companies are driving progress in the waste-to-Energy (WtE) market, ahead of Energy Recovery 2014.

Waste to energy (WtE) means taking residual waste and turning it into a useable form of energy. This can include electricity, heat and transport fuels, and can be achieved using a number of different processes. Incineration of municipal solid waste (MSW) in a combined heat and power (CHP) plant is the most common form of WtE today, but Advanced Thermal Treatments (ATTs) such as gasification or pyrolysis are also in development.

In Europe and worldwide, WtE has become big business. According to analysts at Frost & Sullivan, revenues in the global WtE plant market could reach $29 billion by 2016, up from $19 billion at the end of 2012. WTE thermal solutions are witnessing robust demand from regions with high population density but limited area, such as Europe and Asia. Upcoming WTE plants are likely to be in China, the UK, Central Eastern Europe, and India.
The European market is expected to expand at an exponential rate for the next decade, primarily due to the EU's efforts to replace existing landfills with WtE facilities. Limited availability of land for landfilling and rising public awareness on recycling have stepped up interest in renewable energy sources, while MSW has been recognised as an attractive energy carrier. In addition, the private sector is becoming increasingly active in developing WtE projects, a trend that should drive down prices and accelerate technological development.
Profitable fuel production
The manufacturing of Solid Recovered Fuels (SRF), which can be burned for energy instead of coal, oil and gas, represents one area of great potential. With the UK government committed to increasing the proportion of energy obtained from renewable sources to at least 15 per cent by 2020, it is widely acknowledged that more must be done to reduce landfill contributions. Developing sustainable sources of renewable energy such as SRF would enable a shift in focus from waste processing to profitable fuel production.
Waste and recycling company Yorwaste for example, is supporting such a step-change at its flagship Resource Recovery Facility near York. Here, electricity is generated from landfill gas, green waste is composted, waste wood is recycled and liquid waste is treated. Yorwaste handles close to 1 million tonnes of MSW and commercial & industrial (C&I) waste each year, and produced 60,000 MWh of green electricity from landfill gas in 2011/2012.
The company now has 9.6MW of electricity generating capacity at its landfill sites, and continues to invest further in the latest technology, developing a C&I waste recycling and processing facility to produce SRF. The facility comprises a variety of sorting equipment, picking stations, trommels, screens, an eddy current separator, air density equipment and a single shaft secondary shredder. The shredder was developed by Energy Recovery 2014 exhibitor UNTHA UK specifically for post shredding to a consistently-sized fraction (<30mm) with a high calorific value and very low fines content. This capability is critical as a precise and refined particle size is needed to satisfy the requirements of end users, currently European cement kilns.
On-site bio-energy
Another form of WtE technology making progress in the UK is on-site anaerobic digestion (AD). This can provide a valuable source of renewable energy, with the biogas produced used to generate electricity that can either be used on site (to replace bought-in power), or sold to the national power grid at a premium over purchased electricity costs. In addition, treated biogas can be fed directly into the gas grid. With access to Feed in Tariff (FIT) and Renewable Heat Incentive (RHI) payments, generation of biogas from liquid wastes could have a substantial impact on the economics and environmental footprint for a number of industrial processes.
British technology company Clearfleau for example, is working with a provider of CHP generators to build customised treatment plants for treating liquid effluents and residues from biofuel production and other industrial processes. Materials with significant biogas potential include thin stillates from the production process, wash down residues and bio-effluents, and gums and other high chemical oxygen demand (COD) residues. This technology will be showcased by Clearfleau at Energy Recovery 2014.
A good example of effective on-site anaerobic digestion is BV Dairy's plant in Dorset, where a reduction in COD load of more than 95% has been achieved using Clearfleau's plant technology. Clearfleau is working on several UK dairy projects, as well as building plants for Nestlé at one of its main UK sites, and for Diageo at a malt distillery in Speyside. The latter's on-site system can handle a range of materials including sugars, oils and fats, as well as reject product or ingredients, and won the Best Project Award at the Scottish Green Energy Awards for 2013.
The recycling and recovery debate
Despite the progress being made in the energy recovery sector, not everyone agrees with the concept. Critics of WtE for example argue that recycling and re-use should be prioritised instead, and that a dependency on waste risks more demand at a time when companies should be reducing consumption.
However, industry commentators point out that there is no competition between sustainable recycling and WtE, as the latter only treats residual waste – i.e. the waste that remains once the environmental or economic costs of further separating and cleaning it are larger than any potential benefit of doing so.
According to the Confederation of European Waste-to-Energy Plants (CEWEP), each year its members treat about 63 million tonnes of household and similar waste that remains after waste prevention, reuse and recycling. Moreover, WtE plants are said to create well paid, highly-skilled jobs in good, clean working conditions. CEWEP estimates that the average WtE plant in Europe creates 62 direct jobs and at least as many indirect jobs.
Certainly, WtE plants have established themselves as an essential part of both the waste management and energy supply network, providing waste treatment solutions that shift limited recycling value to recycling with energy recovery. This is vital given the rising cost of landfill, higher energy costs, and the EU's 2020 Directives. There are now more than 450 WtE plants in operation across Europe, according to the latest figures from the International Solid Waste Association (ISWA), with countries such as France, Germany and Italy leading the way.
However, challenges remain. These include the need for refurbishment and modernisation of WtE plants, lack of clarity in economical incentives, and lack of effective regulatory structures for WtE conversion and sustainable waste management in some markets. The high investment required for advanced WtE techniques is also said to limit adoption.
Nevertheless, there will continue to be a much greater focus on turning waste into something useful and recovering it to another format. As the industry matures and investment in WtE infrastructure grows, it will be essential for companies and stakeholders to come together to share their experiences and ideas, and ensure that their innovations are aligned with the evolving demands of energy recovery market.

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