Frequently asked questions
How Much Do You Know About Waste-to-Energy?
Ecologically Sound, Cost-Effective Energy Waste to energy (WTE) is a vital part of a strong and sustainable waste management chain. Fully complementary to recycling, it is an economically and ecologically sound way to provide a renewable source for energy while diverting waste from landfills. WTE technology has been developed and proven around the globe, including: 100 plants in North America, 500 in Europe and 1,600 in Asia. Growing strongly as the world wakes up to the need for change!
Waste-to-Energy (or energy-from-waste) reforming technology provides a safe, technologically advanced means of waste disposal that reduces greenhouse gases, generates clean energy and recycles metals and many hazardous waste streams. Waste-to-Energy (WTE) is widely recognized as a technology that can significantly help mitigate climate change.
Just like mobile phones evolved a lot since the 1980s, Waste-to-Energy plants have also seen tremendous changes since they were first introduced more than 120 years ago. The core purpose of both has not changed, but new technologies and developments have significantly expanded their range of application. Reduction of volume, weight and hygienic concerns were the first reasons to build waste incineration plants. Even though the composition and quantities of waste have changed considerably, these reasons still apply.
During the last decades, public opinion and political will for a stronger emphasis on environmental protection have increased. Usage of Best Available Techniques ensures very low emissions, meeting the strictest emission limit values of all combustion industries. Another opportunity arose and was seized when concerns over the cost and security of energy supply made the recovery of the energy contained in residual waste ever more important. At the same time this valuable energy recovery helps reducing greenhouse gas emissions significantly, through decreased use of fossil fuels and reduced landfilling. Growing worldwide demand for material, especially metals, is another challenge being currently tackled by Waste-to-Energy plants.
Waste-to-Energy plants have a long history of continuous improvement and are sure to contribute to meet the next challenges. (Source: ESWET)
Waste-to-Energy plants are designed to incinerate unrecyclable Municipal Solid Waste as well as other accepted industrial or commercial waste. They also simultaneously recuperate the energy and clean the gases generated by the combustion. So…. how does it work?
Waste is deposited into the combustion chamber. The waste is also mixed and burns out completely. Unburnable material is left as bottom ash (usually inert) at the end of the process. Metals and construction materials can be recovered from this bottom ash and returned to the material cycle, thereby saving other raw materials.
The boiler recovers over 80% of the energy contained in the waste and makes it usable as steam.
Flue Gas Cleaning
Highly sophisticated processes assure that all pollutants contained in the waste and transferred into the flue gas through combustion are eliminated in an efficient, sustainable and reliable way.
Energy utilisation, e.g. turbine, heat pump.
The energy recovered is usable as electricity and/or heat (e.g. District Heating and Cooling, Industrial Processes). Roughly half of the energy produced is renewable because it comes from the carbon-neutral biogenic fraction of waste.
A waste-to-energy facility may generate a range of outputs: electricity, district heating, steam for industrial processes, desalinated seawater or even district cooling. Where it is uneconomic or unsound to recycle, residual waste becomes a valuable local source of energy. The carbon footprint and environmental performance of a modern waste-to-energy facility is superior to many alternative waste treatment processes. The most widely used and well proven waste-to-energy technology, is a moving grate on which the waste is combusted. This process is flexible and can be used with or without pre-treatment such as material recovery. For special types of waste, fluidized bed technology may be an option.
Besides energy, the output includes flue gas, bottom ash and residues from flue gas treatment. The flue gas and any wastewaters are cleaned according to the local environmental standards prior to discharge. Metals can be recovered from the bottom ash which may be used for construction purposes, while the residues from flue gas treatment are sent to specialised treatment facilities for re-use, recycling or disposal. Recovering energy from waste isn’t just a waste disposal method. It’s a way to recover valuable resources.
Today, it is possible to reuse 90% of the metals contained in the bottom ash. And the remaining ash or clinker can be reused as road material. Some benefits are proven:
- Avoids methane emissions from landfills
- Offsets greenhouse gas (GHG) emissions from fossil fuel electrical production
- Recovers/recycles valuable resources, such as metals
- Produces clean, reliable base-loaded energy and steam
- Uses less land per megawatt than other renewable energy sources
- Sustainable and steady renewable fuel source (compared to wind and solar)
- Destroys chemical waste / conventional HAPs
- Results in low emission levels, typically well below permitted levels
- Catalytically destroys NOx, dioxins and furans using an SCR
Where heat produced by burning waste produces heat, driving a turbine to generate electricity. This indirect approach to generation currently has an efficiency of around 15-27%, albeit with a lot of potential for improvements. Whether any approach to generating energy from waste can be considered sustainable depends on the ‘net calorific value’ of the waste going into the process. Where incineration of waste is concerned, that figure must be 7 MJ/kg, meaning the likes of paper, plastics and textiles are best suited to the combustion method of generating energy from waste. Combustion produces emissions – 250-600 kg CO2/tonne of waste processed – but this is offset by the fact that fossil fuels don’t need to burned. There are, however, other pollutants emitted from combustion in the form of flue gas.
The production of gas from waste. Everyday waste (‘municipal waste’) consisting of product packaging, grass clippings, furniture, clothing, bottles, appliances and so on, is not a fuel as much as the feed for chemical conversion at very high temperature. The waste is combined with oxygen and/or steam to produce ‘syngas’ – synthesised gas which can then be used to make numerous useful products, from transport fuels to fertilisers or turned into electricity or heat.
No oxygen, no trouble? Where pyrolysis is different from other methods listed so far is that decomposition of various solid wastes takes place at high temperature, but without oxygen or in an atmosphere of inert gases. This means the process requires lower temperatures and has lower emissions of some of the air pollutants associated with combustion. Anaerobic Digestion… Can be used to generate energy from organic waste like food and animal products. In an oxygen-free tank, this material is broken down to biogas and fertiliser. Statistics suggest that if we treated 5.5 million tonnes of food waste this way, we’d generate enough energy to serve around 164,000 households while saving between 0.22 and 0.35 million tonnes of CO2, in comparison to composting. But there are consequences from the release of other harmful gases.
Extracting the biogas produced by biodegrading materials on landfill sites is another way of getting useful energy from waste. Although it’s an approach that’s in decline due to the reduction of the amount of organic matter going to landfill, it’s making a notable contribution to UK energy supply: it is believed to be the source 3.04TWh of green electricity in the last year. However, the release of harmful gases suggests burying waste in landfill sites is hugely expensive and unsustainable due to the undesirable environmental impact.
It’s important to place the idea of generating energy from waste in its proper context: The generally held view is that energy generation (recovery) sits below reducing waste, re-use, and recycling and composting, meaning it’s those options that should be considered first when managing waste; but importantly, above waste disposal, meaning that waste-to-energy is preferable to landfill. The extent to which reforming waste-to-energy is ‘green’ depends on the efficiency of the plant reforming the waste into energy, and the proportion of the waste that is biodegradable. This affects whether the approach is considered to be ‘recovery’ or simply ‘disposal’ of waste. There are number of ways of generating energy from waste. (See below)
Waste-to-Energy hinders recycling
European countries with the highest recycling rates are also the ones where waste-to-energy is most present. This may be explained by the fact that waste-to-energy is an essential part of the waste management process.
Subjected to strict emission regulations, waste to-energy plants have the lowest emission rates in the industrial sector.
Waste-to-Energy is no better than handling
While removing the pollutants from the ecocycle safely, waste-to-energy does not emit methane, unlike landfilling. It recovers the energy, therefore offsetting Greenhouse gas emissions.
Waste-to-Energy = Dioxins?
Waste is treated at high temperatures and, due to advanced flue gas cleaning treatment, dioxin emissions are no longer a concern.
Plastic waste has risen to significant levels of public consciousness in recent years, for its negative impact on habitats and species. In response, the world is waking up and making noises. The UK Government’s 25-year Environment Plan pledges to eliminate all ‘avoidable’ plastic waste by the end of 2042 – and it’s not alone in making such political commitments.
Can waste-to-energy step in here?
Converting plastic waste to energy certainly makes sense from a chemical perspective, given plastics come from the same origin as fossil fuels. The two core techniques involved in reforming plastics are pyrolysis, where plastic is heated in the absence of oxygen, and gasification, where air or steam heats the waste, creating gases that usually either produce petrol or diesel, or are burned to generate electricity, but there are new techniques such as cold plasma pyrolysis, and cyclone furnace burning that provide the potential to create fuels such as hydrogen and methane, as well as useful chemicals for industry.
An educated guess suggests people will look for novel approaches to waste management in the UK in the coming years. Current recycling rates seem to be plateauing, with only minor increases seen over the past year or so. However, innovation is coming to the fore as people realise that generating energy from waste has a lot of promise. Everyone knows that we need to focus on making products last longer, and when they really can’t be fixed, finding ways to recycle and reuse them.
The fact remains that the volume of waste produced in the UK and virtually everywhere around the world is increasing, and increasing faster than our ability to dispose of the waste in an ecologically friendly and safe manner.
Waste-to-Energy plants are designed to incinerate Municipal Solid Waste (MSW), but similar waste from industry and commerce can be treated as well. Sewage sludge and medical waste can be co-incinerated in certain percentages, but they need special storage and handling facilities. No pre-treatment is needed, except that very large particle size (more than around 1 m) and bulky items have to be shredded. Hazardous and radioactive waste is not permitted, it has to be treated in dedicated facilities.
In the EU, the average citizen generates 500 kg of waste per year. Assuming a recycling rate of 50% (today it is 40%), still 250 kg of residual waste per citizen per year needs to be treated. Thus a city with 500,000 inhabitants will need a Waste-to-Energy plant capable of treating 125,000 tons of waste per year.
The minimum size, from an economic viewpoint, for a Waste-to-Energy plant is around 40,000 t/year. The largest plants have capacities of more than 1 million t/year. Individual combustion lines can have capacities from around 2.5 – 50 t/hour (20,000t/year to 400,000t/year), whereby the more typical range is 5 – 30 t/hour (40,000 to 240,000t/year). A Waste-to-Energy plant is expected to run for at least 8,000 hours per year, roughly 94% of the time.
Waste-to-Energy plants are most often tailor made, depending on very specific local requirements. Construction costs hence vary widely, but a typical range in Europe is around 500 – 700 € per ton per year installed capacity, not including cost for the site and for project development.
Alternative Waste Management is constantly looking for attractive investment propositions on behalf of clients. The firm prides itself on its experience and ability to explore leading edge solutions, seeking to be at the forefront of disruptive industry and innovation where, generally, margins are high and opportunity exists to earn high returns for investors.
The Waste-to-Energy sector is so important to the world which is becoming ever more aware of the need to become more efficient. We have partnered with one of the most advanced Waste-to-Energy engineering specialists out there.
There are barriers to entry in waste-to-energy sector due to the often significant costs involved in virtually all established techniques. Gasification often requires significant investment, including advanced controls and pre-treatment facilities. Plasma arc and anaerobic digestive pants are be expensive with longer pay-backs putting investors off.
Developing specific single feedstock waste-recycling plants presents a risk of limiting those facilities, when decision-makers may instinctively opt for waste strategies where general waste can be processed together with other feedstocks, creating greater efficiencies and returns for investors.
There are risks associated with all investments. The Waste-to-Energy sector is no exception. We have worked hard to research opportunities for our investors and we understand where the potential pitfalls are.
What to look out for and what to avoid. ‘Not everything that glistens is gold’ and we understand that there is a need to evolve as global sentiment changes and legislation evolves to meet ever higher standards and emission controls to which we must all adhere.
It is important for investors to understand the difference between established tried and tested methods and equipment which may work perfectly well and have acceptable returns, however we believe in looking to the future. Exploring innovative technology that in some cases will be added to established proven technology to improve efficiency at lower cost and so disrupt the status quo and achieve higher returns with less risk to investors.
You can learn more about Waste-to-Energy, our company and our partners in our Due Diligence Pack, which can be made available upon request.
Please do not hesitate to contact us if you need anything else clarified.