Ed Mant describes how renewable electricity is produced on a large scale using EnCycle technology. Central to the projects is a patented conversion stage, “abrasive drying”, which removes the moisture from shredded and macerated waste food and non-recyclable packaging. In this way, an abundant waste stream liability is converted into a power generating asset.
Inetec have grown to be a major waste management alternative for waste food and non-recyclable packaging since their inception in 1997. Inetec wholly own the subsidiary company EnCycle. The EnCycle project aims to provide large scale solutions in the UK for the generation of renewable energy from food manufacturing waste through the commissioning of large scale plants to manufacture biomass fuel from materials currently designated for landfill, incineration or composting. The large amount of energy so generated will be returned to the national grid, reducing the reliance on more problematic power sources such as nuclear or fossil fuels.
Inetec have developed the patented technology over the past decade which generates biomass from food and packaging waste, and have installed a number of on-site TherMec units at factories that generate renewable energy in the form of steam, hot water and thermal energy (see Figure 1). EnCycle are adapting this experience to embark upon an ambitious project to build ten large food waste-to-energy centres in the UK over the next five years which will all use their unique “abrasive drying” technology.
Figure 1
The TherMec 8000 unit processes up to 8 tonnes of waste daily, creating 4 tonnes of biomass to generate 3.0 MW energy (based on 50% moisture content waste, approximate figures).
The vast quantities of raw materials for EnCycle biomass fuel themselves currently impose a strain on existing waste management systems. Food manufacturers generate 7 million tonnes of food and non-recyclable packaging waste every year, whilst retailers generate a further 9 million tonnes through out-of-date products or surplus stock. This waste stream is mixed or contains animal products, and as a result much must go to landfill. The trend for generation of this waste is upwards, with an estimated 30,000 extra pre-packaged food products being sold per month compared with corresponding months in 2005. EnCycle plants can treat this waste stream and generate a useful product.
Abrasive drying, a patented novel technology, converts waste food and non-recyclable packing into useful biomass fuel. The waste is first shredded and then loaded into a TherMec unit. Here low-level heating is conducted at the base of the unit. A series of large paddles rotate and macerate the waste through abrasion against itself. Early in the 20-hour process, surface moisture is evaporated before cellular level moisture loss results in a fine dry powder (4% moisture content) final product. The powder is released from the TherMec unit into a hopper for subsequent storage, whilst extracted moisture is drawn from the chamber, condensed and becomes a final effluent of a quality generally suitable for discharge to sewer. The highly prepared biomass fuel generated by this process is suitable for use in a variety of energy recovery systems.
The first EnCycle large scale plant, based near Immingham Docks, North East Lincolnshire, has recently been granted planning permission (see Figure 2). Construction begins at the 11-acre site in October 2007, entailing projected costs of £80 – 100 million. The plant will process up to 500 tonnes per day (diverting 180,000 tonnes from landfill annually), generating biofuel for the production of 22 MW of renewable energy for the national grid. This represents a significant renewable electricity contribution, being the third largest renewable energy plant in the UK generating enough for around 39 000 homes, the equivalent of a small nuclear power station. Once operational, the plant will provide about 70 full-time jobs.
Figure 2
The first large-scale EnCycle plant near Immingham Docks (impression post construction), to process 500 tonnes of food and non-recyclable packaging waste daily to generate 22 MW power.
Plant design ensures sympathetic visual impact and, once received, food and packaging waste is entirely contained to ensure minimal odour impact. Process areas are within buildings, and fully automated waste transfer is conducted using enclosed conveyor systems. Projects also maximise the use of energy generated during the gasification and electricity generation stages, providing heat for the waste drying process. Overall, EnCycle plants require near zero external energy.
Supply of a reliable waste stream input is secured. EnCycle already have national contracts in place with several large food manufacturers and retailers, including Greencore, Northern Foods and Greggs, with further contracts under negotiation.
Large-scale power generation from a previously problematic waste stream is now a reality. Using patented abrasive drying technology, EnCycle projects, the first of which is near completion, will produce significant quantities of renewable energy from food and non-recyclable packaging. This will reduce the UK's reliance on fossil fuels and other controversial power sources whilst reducing the quantity of waste sent to landfill. Diversion of waste streams for processing at EnCycle plants will improve the carbon footprint of many food manufacturers and retailers.
Useful Links
Inetec website: www.inetec.co.uk
About the Author
Ed Mant is marketing manager at Inetec, contact via their website.