Features & Benefits

Key Operational Features and Benefits of Autoclaving Waste

• 2 autoclaves operating in parallel, capable of handling 15 tonnes MSW per load each (for this example only) means that with 24 hour operation the plant can handle up to 300 tonnes per day assuming the mass density to be 225 kg/m³.
• As steam is recycled between the 2 autoclaves it significantly reduces the amount of energy the system requires.
• The steam can be generated from waste heat from the electricity generation plant, powered by the production of methane gas.
• There is minimal operational noise, offensive odours are reduced and harmful toxins are not released into the atmosphere.
• Autoclaved waste has on average a 60% reduction in volume and with the liquid fraction separated at this point, the mass can be greatly reduced.
• For a plant managing 100,000 tonnes per annum the site requirement is a minimal three acres.  Land take should be considered to be on a “sliding scale”, meaning that a 30,000 t.p.a plant will only require one acre.
• As the process can handle totally unsorted, black bag municipal solid waste at the same time as high organic fraction supermarket waste and kitchen food waste, it is possible to combine industrial, commercial and residential waste management strategies.
• The system will process the waste at conditions that satisfy the Clinical Waste Regulations and both Category Two and Three of the Animal By-products Regulations. Category One is also obtainable, should the in-feed be pre-shredded, subject to site approval.
• All recyclable materials will be gathered and sorted after the process and will be sterile and clean, therefore commanding a better price within the open market.

Post Process Options.

• Post process options are one of the key benefits of autoclaving. The output can be dried, and subject to the amount of organic fraction present, the liquid used to produce sufficient biogas to meet the energy requirements of the plant. The dried cellulose floc can then be sent for recycling within the paper and cardboard industry or it can be turned into a solid biomass fuel for thermal treatment feed stock and used to produce further green electricity.
• As autoclaving produces a hydrolysed, homogenised waste stream it is perfect for use in anaerobic digestion systems.
• It will increase the potential gas volume by as much as 100% with a far faster rate of production.
• Peak gas flow can be attained in as little as a quarter of the time of a standard AD system.

Key Financial Features and Benefits of our system are:

• DEFRA estimates that electricity output per tonne of waste is between 75 – 225 kw-hr, dependant on the quality of the waste stream received (the higher the organic fraction, the higher the energy).  With autoclaving the benefits are such that the system will operate closer to the top of this range at about 200 kw-hr per tonne.
• With a feed rate of 12.5 tonne/hr we will generate 2.5Mw.
• With the allowances for green electricity, this is worth up to 15p/kw-hr or £24 per tonne of waste.
• The plant is totally self sufficient in its own energy needs.
• In 2009 England will see the introduction of the Landfill Allowance Trading Scheme (LATS) charged at £150 per tonne over and above the current cost of disposal. Thus potential revenues for those with a robust waste strategy in place can only be beneficial.
• With an annual capacity of approximately 100,000 tonnes, this plant is well suited to service the needs of 200,000 people, negating the requirement for any long distance transport or waste movement across local authority boundaries.

Post Process