A truly green ‘energy from waste’ process that converts municipal household waste into a high-value commodity ‘feedstock’, this is then distilled into bio ethanol on a commercial scale. The process does not use any form of incineration, leaves nothing for landfill, is non toxic, safe, ethical, a sustainable long term solution to
Municipal solid waste which should contain as much organic material
as possible – ie: food, green waste, cardboard and paper
The system will not treat hazardous or contaminated waste such as medical waste nor animal-derived products such as carcases. The system can treat sewage cake
These are sorted and recycled.
A standard system, which comprises two EfW Processors, will
handle 20/22 tonnes of shredded waste per hour dependent on mix.
A standard site will require approximately 40,000 square metres ( 4
hectares or 9/10 acres)
There is approximately 63% biomass in municipal solid waste in the UK and Europe. (this varies in other parts of the world.) Based on an input of 22 tonnes per hour, approximately 14 tonnes will be biomass
Of the 92% total solids, organic total solids equal 90% based on dry mass.
First stage hydro-thermal treatment through the EfW processors expands the fibrous matter at the molecular level – this vital heat process opens up the fibres of the waste allowing the hydrolysis stage to work with greater efficiency and at a much faster processing rate. The first stage of EfW processing is an essential step in achieving a substantially higher energy output from the ‘raw’ MSW. Without this first stage, the yield of bio ethanol would be considerably lower. 9 IS THE BIOMASS STERILISED Does the process sterilise the waste
The first stage EfW processors run at a temperature of approximately 180oC – this sanitizes the waste it does not sterilize it. Sanitizing the waste makes it safer for handling in manual sorting processes.
The density of the treated organic fraction of the waste (biomass) will leave the first stage processor at approximately 380Kg/m³
The treated organic fraction of the waste (biomass) contains circa 20% moisture content (this is subject to the moisture content of the feed waste).
The final moisture content of the treated bio-mass will affect the final ethanol yield. The more water that is in the bio-mass, the lower the yield. We would aim to achieve around 10% moisture content.
The MSW can have a high moisture content, however as the first stage EfW Processing is the heating of the waste to a preset level the higher the moisture content the high the energy used to heat the MSW, however, the final result will not be affected.
The first stage EfW Processor reaches an operating temperature of 180°C – this can be adjusted plus or minus 10%.
There is virtually no operating noise from the first stage EfW processors. The only noise is that of the waste as it progresses through the chambers ( not sure this is a word)
The standard package would include a solid fuel boiler which would be fuelled by using the lignin produced as a by-product.of the process. The boiler system is sized to provide 38,890kg of steam @ 10 bar pressure. 40,200 HP (30 mega watt heat)
Firstly, steam is required to heat the mass of waste (this steam is recycled back to the boiler) Secondly, steam is injected into the bed of waste as it passes through the first stage EfW Processor (this is lost in the waste). The quantity of steam @ 10 bar in the first case will be 69.5kg/hr per tonne of waste. The second requirement can be up to 85.8kg/hr per tonne of waste. This can vary depending on the moisture content of the incoming waste
The overall energy consumption of the first stage EfW Processors will be approx 1133kW for the steam production and 15kW for electricity
Approximate energy value of the biomass is 16 MJ per kilogram (and of the ethanol approx 30 MJ per kilogram.)
No. The air used during first stage EfW processing is re-circulated into the system or is passed through an odour control unit. This ensures no unpleasant odours are expelled to atmosphere
The expelled air and remaining water vapour from the first stage EfW processing passes through an odour control unit. This ensures that the emissions from the waste passing through the EfW processors are odour free. Odour is neutralised by utilising ” UV enhanced oxidation “
NO. The first stage EfW processors are non pressurised, open-ended, rotating chambers which do not have the same safety or insurance issues as an Autoclave. THE EfW PROCESSOR IS VERY DIFFERENT TO AN AUTOCLAVE which processes waste in a pressurised vessel in batches. The EfW processor is a continuous feed, non pressurised vessel.
Yes. It is vital to shred the waste down to a maximum size of 150mm (preferably down to 100mm) before it is fed into the first stage EfW processors (one shredder to serve each EfW processor).
Shredding the waste is important to allow the EfW Processors to break down/open up the fibres during processing and to ensure an element of consistency throughout the initial processing..
The Biomass can be sorted either pre or post first stage EfW processing, It is preferable to sort the waste before loading it into the EfW processors but it is not compulsory
Providing annual maintenance is carried out, the only major moving part in the system is the rotating drum which is capable of at least 212,500 hours continuous operation
SECOND STAGE – PRODUCING THE BIO ETHANOL
Shredded organic waste is fed into the first stage EfW Processors where it is subjected to temperatures @ 180oC with steam injected at 10 bar pressure revolving at circa 70 revolutions per hour. When exposed to this heat and steam, the fibres of the waste expand facilitating access by the acid solution, thereby promoting the release of sugars from the organic matter. The next stage is acid hydrolysis which breaks down the organic biomass to which the sugars produced can be extracted. Once this has occurred, we are left with an acid sugar solution and a solid material which is largely lignin. This lignin has a high calorific value and can be used in the boiler in order to produce steam for the plant. The acid sugar solution is treated with lime which neutralizes the acid and produces a sugar solution of around a PH of approximately 6. It is the sugar solution
that forms the feedstock of the fermentation which produces low-grade ethanol. This then passes through for distillation and final polishing which produces the high-grade bioethanol
Taking an average municipal solid waste, 63% will be biomass ie; food/cardboard/vegetation etc. One tonne of biomass will produce approximately 300 litres of bioethanol.
The final quality of ethanol will be as specified in EN15376 the European standard for blending ethanol. This is the standard that the major fuel suppliers work to (98.7% proof)
Both the first and second stages have been configured to provide continuous flow. Although processes like hydrolysis and fermentation are batch processes, there will be several vessels operating in phases which means that the final ethanol production is virtually continuous
Approximately 48 staff – based on 12 staff working a 4 shift rota.(based on UK)
None. CO2 is a bi-product of the bioethanol process, but this can be recycled and sold to produce income or converted to methanol. Does this statement need to be expanded?
The main consumables are:- water, sulphuric acid, lime (calcium hydroxide), electricity
There are no catalysts used. We use purely heat and steam injection. This is the first stage of creating bio-ethanol
The fermentation process is maintained at about 25°C fractionation carried out at the boiling point of ethanol which is 78.4°C
Ethanol is concentrated in “light” ethanol−gasoline fractions and it is almost completely absent in “heavy” ones
Some will come out in the lignin, and ultimately will appear in the boiler ash/effluent. Some will pass through the system and end up in the sugar solution. This fraction will ultimately be precipitated with the
gypsum, very little ends in the stillage which will be largely surplus yeast. As yeast has a reasonably high calorific value this will end up as a fuel for the boiler.
There is virtually no unusable waste left from the process. The main residue will be from the distillation process. Once the water has been recycled there will be some solids that can be disposed of via the boiler. The boiler flue will have a flue gas scrubber fitted to eliminate any discharge to atmosphere
The plant will need a kick-start. As the lignin fired boiler is a solid fuel boiler we would use a bio-mass fuel such as a wood chip or a suitable fuel such as gas or oil. The cost will be dependent on local availability. Relatively small quantities will be required to start the system. As the system comes online lignin will be produced after about 5-6 hours. This will be increased as the plant reaches full capacity.
Based on a minimum calorific value of lignin of 13MJ/kg, our calculations show there will be sufficient lignin to meet the heating load of the plant. In reality, the calorific value is likely to be higher. There will be a surplus of yeast from the fermentation process. This yeast can also be used as a fuel.
The entire process is monitored by a computer-controlled system designed to control flow rates, monitor any hold-ups, and adjust the production flow as necessary. The use of manual involvement will be minimal.
The system will be capable of remote monitoring and adjustment
The system is based on 8500 hour operation per year. This means there will be 260 hours available for maintenance per annum
All equipment is based on standard products, for example, motors, valves bearings, etc However this does not mean that they are available “off the shelf”. It is suggested that each plant carries a stock of parts that are on longer deliveries. Also, there may be some areas of the world where parts are not so readily available Delivery times will vary from several days to 6 weeks depending on the item.
The plant will comply with the post Bunsfield requirements relating to COMAH and COSHH regulations in the UK, with containment; bunding, and fire prevention measures commensurate with the risk profile. The fire risk with ethanol is reduced due to its miscibility with water – rapidly doused by water, mist, or dilution.
We need 16 l/s gross for ethanol, say 20 l/s including Powergen, this is 5 gals per second or 300 gals per minute over 8500 hours. With maximum recycling, this can be reduced to about 80 gals per minute
Water can be recycled through the system but the overall consumption of the first operating stage is a maximum of 3 cubic meters per hour in the waste to processed biomass stage
Water consumption will be up to 18800 litres per hour (this includes wash water and recycling) The overall consumption in the bio ethanol production stage is circa 37cubic metres per hour
We expect to recycle as much as possible and strive for zero wastewater discharge. Water is lost in the moisture content of by-products, lignin; gypsum; yeast; stillage; fumes, and exhausts. This leaves maybe only 2 litres per second to the sewer which will be treated to satisfactory public health levels and temperature in our proprietary Effluent Treatment Plant.
The process can run on greywater, water that is clean but not suitable for drinking. The waste input and the quality of the water will affect any effluent treatment required if any. The system includes hydrolysis and this stage allows a lot of the water to be recycled. After the washing of the Lignin for example we would expect to recycle that water. However, it is possible that some elements can remain in suspension in liquid up to the output of the distillation stage (some effluent treatment may be required at this stage)
This will be a bespoke design and a function of the components in the waste stream. We will utilize a combination of biological and chemical treatment together with membrane/ ultra-filtration, to achieve requirements, either for discharge to sewer or watercourse. The water treatment will comprise basic filtration for the removal of solids, activated carbon filter to remove the VOC, and reverse osmosis to provide the water purity.
The major source of waste steam will be the steam that is injected into the lst stage EfW processor. This will be in the region of 1.5 tonnes per hour, for a 2 chamber EfW processing system. Some of this can be collected via an evaporator coil mounted in the discharge duct prior to the odour removal system and prior to
discharge to atmosphere. The condensate from this system will be recycled into the water purification system and reused in the boiler feed.
The technology has been proven in scientific rials undertaken by Coventry University, PERA Laboratories eminent Chemical Scientist Dr. G.V. Garner. Each independent body has verified high yield bio ethanol from the processed waste.
The acid will be recycled as much as possible with any excess being neutralized with lime to form Gypsum. This can be sold to the building industry
Gypsum is produced at a rate of approximately 1.2 tonnes per hour from the bio ethanol production process
Our system is not suitable for producing liquid syngas
Approximately 50,000 tonnes is produced from the bio ethanol production process. This will be conveyed to the boiler in its fibrous state and injected on a fluidized bed into the boiler.
Approx 33,000 tonnes of CO2 can be captured from the fermentation process and sold to industry. The Energy from the Waste process is carbon neutral.
Although fairly pure, the captured CO2 will contain small traces of ethanol and water. If using CO2 for soft drinks it would need to pass through a purification plant. It is estimated that approx 33,000 tonnes of CO2 is produced per annum from the Energy from the Waste process – after purification treatment, circa 29,000 tonnes would be pure CO2.
The power for the plant is provided by the lignin that is separated from the waste supply. Lignin is derived from the atmosphere – combustion of lignin results in zero net carbon dioxide release
Approximately 700 tonnes of yeast is used and recycled per year.The yeast is recycled four times after which it can be used as a solid fuel to generate electricity via a small generator
Our system is not equipped to deal with hazardous waste
No, however, the waste could be scanned on entry (this is not part of he remit for Energy from Waste Limited )
Yes it is possible to process waste from landfills. However, the older the waste material, the lower the calorific value.
Ethanol does have corrosive elements as with all petroleum products due to the Halide ions contained in the ethanol. Inhibitors can be used to eliminate the corrosion effect. It is recommended that ethanol is transported by tanker rather than pipeline and that the tankers are cleaned regularly
Environmental, Health & Safety, and other considerations are all subject to ”Environmental Impact studies bespoke to specific projects