FAQs
- What is Energy from Waste (EfW)?
- How does EfW work?
- What is residual material?
- Is this residual material hazardous?
- Is EfW just another fancy name for incineration?
- How does EfW fit with recycling?
- Does EfW waste valuable resources?
- Will BioGen Power Efw Plants accept hazardous wastes?
- EfW plants have very high chimneys, don’t they?
- How long does it take to build a typical BioGen Power EfW plant?
- Where else is EfW technology used?
- What experience does BioGen Power and ENERGOS have in building and operating EfW plants?
- How do we know that BioGen Power EfW plants do not operate with high levels of pollution?
- Is EfW safe?
- Should we be concerned about EfW emissions?
- Will odours create a problem?
What is Energy from Waste (EfW)?
EfW is the name given to the thermal treatment of waste under controlled conditions in which energy is produced. This energy can either be converted to electricity to boost the National Grid and/or, at times, to provide heat in the form of hot water or steam, for use by nearby developments.
The amount of electricity produced depends on the size of the plant. A typical BioGen EfW plant will treat c120,000 tonnes of waste per year and that will provide an electricity generation capacity of c10.5MWe. This would meet the domestic electricity needs of around 15,000 homes.
How does EfW work?
In the most widely used EfW process, waste is burned on a moving grate. Air is introduced above and beneath the grate in carefully controlled amounts to ensure proper combustion. Good combustion means fewer emissions. The hot gases released are directed to a boiler to recover the heat. Around 600 kilowatt-hours of electricity per tonne of waste burned can be recovered. The combustion gases are then cleaned in several stages to a strict standard set by the Waste Incineration Directive (WID), which are monitored by the Scottish Environmental Protection Agency in Scotland (SEPA) and the Environment Agency (EA) in England, Wales and Northern Ireland.
Around 75 per cent of the waste input in to the EfW facility will be re-used as either energy or residual material. In future, this figure could rise to as much as 97 per cent depending on the development of future facilities.
What is residual material?
There are two residual materials. The main one is bottom ash and the second is air pollution control residue (APCR), which is commonly known as fly ash. Bottom ash is frequently used as material in block manufacture or as a blend component for aggregate, used in road building etc.
Is this residual material hazardous?
Bottom ash, which makes up the vast majority of the residual material generated, is not hazardous. APCR is classed as a hazardous material and is disposed of in the appropriate manner.
Is EfW just another fancy name for incineration?
Unlike today’s modern facilities, a number of plants that were developed during the late 1960s and 70s simply burnt or incinerated waste, using mains gas or other fossil fuels. However, modern facilities recover energy from the process and are therefore classed as EfW facilities, as opposed to being simply an incineration plant. BioGen Power EfW plants utilise Advanced Conversion Technology (ACT) and only use a small amount of natural gas to kick start the gasification process.
How does EfW fit with recycling?
In many cases, our plants provide a way of unlocking the energy in waste that cannot be recycled. This is an environmental improvement over burning scarce fossil fuels such as oil, gas and coal . Energy generated from the biomass within residual household waste (i.e. that remaining after household kerbside recycling) is renewable (carbon neutral) and helps reduce greenhouse gas emissions (to the extent that coal or oil is displaced and methane production from landfill is avoided).
Waste minimisation and recycling are very important, but the fact is that together both of these approaches simply cannot solve our waste problems. Even by meeting the challenging recycling targets set by central government, the UK will still be left with c50 per cent of its waste needing an alternative form of disposal. EfW is a well-proven technology that can provide the opportunity to treat the waste left after recycling and release the energy value contained within the materials. It is the only realistic way of helping authorities achieve diversion of waste from landfill.
Other countries with high levels of recycling – such as The Netherlands and Germany – also have much higher levels of EfW than the UK. Evidence over a long period shows that recycling and EfW can successfully coexist.
Does EfW waste valuable resources?
If all locally generated waste was treated in an EfW facility, it might be considered wasteful. EfW forms an option under the recovery part of the waste hierarchy on which all waste strategy in this country is based and is preferred to disposal to landfill. At the top of the waste hierarchy is waste minimisation, followed by reuse, recycling and composting – but the success of those activities will naturally depend on the public’s co-operation. Since there are limits on how much we can landfill in future, recovering energy from the remaining waste will help us meet our EU landfill diversion targets and avoid large fines from the Government.
EfW disposes of residual waste that would otherwise, in most cases, end up in a landfill, without recovering much of the energy that it contains.
Will BioGen Power Efw Plants accept hazardous wastes?
No, BioGen plants will not be licensed to deal with such wastes.
EfW plants have very high chimneys, don’t they?
Compared to ‘mass burn’ incinerators, which normally accommodate chimneys of between 70 and 120 metres, a typical BioGen plant will, as a consequence of its use of much cleaner ‘gasification’ technology, only require a chimney of approximately 40 metres, depending on any given location.
How long does it take to build a typical BioGen Power EfW plant?
Construction time takes approximately 18 months.
Where else is EfW technology used?
Many European countries utilise EfW technology, with Germany and Scandinavia in particular operating a number of gasification type plants. Within the UK there are over 20 ‘mass burn’ incinerators in operation, however, the Government and many local authorities are now considering ‘gasification’ EfW as a cleaner and more effective way of dealing with waste disposal.
What experience does BioGen Power and ENERGOS have in building and operating EfW plants?
BioGen Power uses ENERGOS EfW technology and there are five ENERGOS plants in operation throughout Norway and one in Germany The oldest plant has been in operation for nearly ten years. In addition, ENERGOS is currently refitting the Isle of Wight's existing EfW plant with their gasification technology and this will be operational in late 2008.
BioGen Power and ENER-G Holdings plc will commence construction on the UK’s first ENERGOS EfW plant in late 2008, subject to contract. The plant will be built at Irvine, Ayrshire, and will dispose of c80,000 tonnes of residual waste.
How do we know that BioGen Power EfW plants do not operate with high levels of pollution?
As ENERGOS technology boasts a ten year track record, actual emissions data illustrates that most emission elements are at less than 10 per cent of EU permitted levels, with NOx at c40 per cent.
Is EfW safe?
EfW is considered by the UK Department of Health to be environmentally safe, and to pose virtually no risk to health. The Royal Commission on Environmental Protection (RCEP) says that EfW offers a long-term, secure and environmentally acceptable Best Practicable Environmental Option (BPEO) for treating residual municipal waste. EfW has been described as “posing a risk to human health which is small in comparison with other known risks”. (DEFRA).
In other EU countries where EfW plays a more significant role in waste management, the process is also considered safe. In fact, a recent report from the German Federal Government says that “without EfW plants, there would be more pollutants in the air” in Germany. That’s because many pollutants are already in waste and, having entered EfW plants with the waste, are extracted during the emissions filtering process. According to the Dutch Government, “EfW plants in rural areas have no damaging effect on agricultural products”.
Should we be concerned about EfW emissions?
Before an EfW plant can begin operating, it must be approved by the EA (Environment Agency) or SEPA (the Scottish Environment Protection Agency) - and requires a PPC license to demonstrate that it can meet the European Union’s strict rules on emissions. Once a facility is built, the EA or SEPA will continue to monitor its operation.
Will odours create a problem?
No. Apart from the loading bunker, the EfW is a sealed unit so odour will not escape. Any odour in the bunker is sucked into the facility and used to assist the gasification process.
