Waste-to-Energy
Together with our proven partner offices from related fields, we support and advise you as independent general planners and engineers in all phases of your project.
- Concept design
- Feasibility study and comparison of variants
- Submission planning (basic engineering) in the permit application procedure (including EIA, IPPC, BAT…)
- Specification of components for the tendering procedure, evaluation of suppliers’ bids, support in negotiations with suppliers
- Construction phase, review of the detail engineering provided by plant and component suppliers
- Cold and hot commissioning, test operation, performance tests, acceptance test
- Operating phase, optimization, trouble shooting
- Project management
- Education and training of specialist personnel
- Management of contacts with authorities
- Preparation of operation process data and fulfilment of reporting obligations
In our international projects, we always co-operate closely with local planning partners.
Definitions in accordance with Article 3, lit. 40 and 41 of the EU Industrial Emissions Directive (Directive 2010/75/EU; revised in 2024 by an amending Directive 2024/1785/EU) are:
(40) ‘Waste incineration plant’ means any stationary or mobile technical unit and equipment dedicated to the thermal treatment of waste, with or without recovery of the combustion heat generated, through the incineration by oxidation of waste as well as other thermal treatment processes, such as pyrolysis, gasification or plasma process, if the substances resulting from the treatment are subsequently incinerated.
(41) ‘Waste co-incineration plant’ means any stationary or mobile technical unit whose main purpose is the generation of energy or production of material products and which uses waste as a regular or additional fuel or in which waste is thermally treated for the purpose of disposal through the incineration by oxidation of waste as well as other thermal treatment processes, such as pyrolysis, gasification or plasma process, if the substances resulting from the treatment are subsequently incinerated.
A distinction is made between three types of waste co-incineration plants:
- Cement kilns
- Combustion plants
- Other co-incineration plants
In addition, the operating conditions during incineration, the quality of the incineration residues and many specifics more are regulated in detail.
In addition, special requirements apply to the incineration of hazardous waste, e.g. strict inspection of incoming waste and the generation and storage of retained samples.
The legal framework for waste incineration is primarily defined by Chapter IV and Annex VI of the EU Industrial Emissions Directive (IED; Directive 2010/75/EU; revised in 2024 by an amending directive Directive 2024/1785/EU), which must be applied “from the first kg of waste that is incinerated”. For waste incineration plants above a certain capacity, also the IED’s regulations for IPPC plants apply, which require, among other things, the application of best available techniques (BAT) in accordance with the BAT Conclusions on Waste Incineration (2019).
Furthermore, also the regulations of other EU directives – such as the Waste Framework Directive (Directive 2008/98/EC), the Environmental Impact Assessment (EIA) Directive (Directive 2011/92/EU) or the Seveso III Directive (Directive 2012/18/EU), or their corresponding national legal acts, respectively – apply, if the specific project properties require it.
Waste incineration is based on the principle that a large quantity of contaminated waste can be decontaminated by thermal treatment and released in a purified state in the form of clean flue gas (and clean wastewater in the case that also wet flue gas cleaning devices are being operated), while the pollutants are separated from these bulk material streams and concentrated in the small mass flows of selected solid incineration residues. The latter represent the pollutant sink of the process and are subsequently – if necessary, after further treatment steps – sent to state-of-the art safe disposal (landfilling).
As can be seen, the largest part of the plant serves the environmental protection process steps of flue gas cleaning, wastewater treatment, separation of solid combustion residues and energy generation.
Regardless of whether the furnace is designed as a grate furnace (1a), fluidized bed furnace (1b) or rotary kiln furnace (1c), the furnace/combustion unit (1) itself takes up comparatively little space when compared to the implemented multi-stage environmental protection measures and equipment.
- Furnace (1a. Grate, 1b. Fluidized bed, 1c. Rotary kiln)
- Storage and dosing of fuel and waste
- Collection of solid residues from the furnace
- Boiler for heat recovery
- Various solid residues going to recovery and disposal
- Combined Heat and Power Production (CHP)
- Typical multi-stage system for (wet) flue gas cleaning
- Stack for release of clean flue gas
- Typical multi-stage wet waste-water treatment cleaning system
- Release of clean wastewater/effluent
- Combustible waste is a safe, available, and cost-effective source of energy.
- The calorific value of household waste is about as high as that of lignite.
- Waste incineration can generate energy in the form of electricity, process steam, district heating and district cooling.
- Thermal treatment reduces the volume of municipal solid waste by around 90% and the mass of waste by around 75%.
- Incineration sanitizes the waste by destroying organic pollutants and pathogenic germs.
- A waste incineration plant using the best available technology acts as a device for the destruction of polychlorinated dibenzo-para-dioxins and dibenzofurans (“dioxins”, PCDD/F). The results of a balance test carried out in the 1990s at an Austrian waste incineration plant show a PCDD/F reduction of >90%, see figure below (source: White Book Thermal Waste Treatment in Austria (2009), p. 50).
- The environmental legal regulations applicable to waste incineration plants are stricter than those for other industrial sectors and meet the highest requirements.
- Thermal waste treatment represents a pollutant sink and enables the safe removal and disposal of small quantities of contaminated incineration residues.
- In many countries, it is unfortunately still common practice to deposit waste in unsecured landfills and/or even in illegal waste dumps, and to allow uncontrolled burning of the waste on these sites. The resulting massive release of pollutants into the air, soil and groundwater poses a considerable threat to the environment and human health. Compared to this practice, the protective effect of thermal waste treatment on the environment and on human health is particularly evident.
- Waste incineration contributes to climate protection, as the CO2 produced during incineration has a global warming potential around 28 times smaller than the same amount of methane CH4 arising from the same waste, when being landfilled. Combinations of waste incineration with subsequent carbon capture utilization and storage (CCUS) or with the production of hydrogen using the electrical energy generated by waste incineration are possible.
- In the process of thermal waste treatment, several secondary raw materials can be recovered and subsequently recycled, for example by:
- Utilization of fluidized bed ash and bottom ash from grate incinerators (the latter after aging) as construction material;
- Pre-separation of valuable, low-pollutant fly ash from the flue gas at higher temperatures above 400°C for material recycling (e.g. CaO-containing ashes from the incineration of lime-rich waste such as paper fibre residues; or phosphorus-rich ashes from sewage sludge incineration);
- Recovery of ferrous metals, steel, aluminium, copper, copper alloys, and other metals from the solid incineration residues;
- Separation of glass particles from fluidized bed bottom ash for use in foam glass production.
Dioxin balance of an Austrian waste incineration plant (Source: Thermische Abfallbehandlung. Weißbuch. Zahlen, Daten, Fakten (2009)
Waste-to-Energy and high recycling rates go hand in hand.
Yellow: Incineration (Waste-to-Energy)
Red: Landfill
Gray: Not specified
Only a few EU countries currently already meet this target, among them Austria.
In 2022, this proportion was around 23% on average in the EU Member States, with individual countries still landfilling significantly more than half of their municipal waste untreated, with some of them even exceeding 80%.
Due to the content of corrosion-promoting elements such as chlorine or sulphur contained in the waste, as well as the formation of ashes with comparatively low ash melting points, the steam parameters in waste incinerators are lower (typically about 400°C and 40 bar) than those in conventional thermal power stations operated on regular fuels. As a result, the possible electrical efficiencies are lower than those of conventional power plants.
Generally, combined heat and power generation enables significantly higher fuel utilization rates than mere electricity production, which is encompassed by significant energy losses. In waste incinerators, CHP installations can reach fuel utilization rates of more than 80%, whereas mere electricity generation in a condensing turbine can typically only utilize around 26% of the energy contained in the incinerated waste.
It is therefore of utmost importance for the fuel utilization rate whether heat consumers – such as industrial companies with process heat requirements or the possibility of decoupling district heating and/or district cooling – are available at the site of a waste incineration plant.
Austria is one of the European countries in which the recovery of the scarce resource phosphorus from sewage sludge will be mandatory for municipal sewage treatment plants in the future. According to the newly issued Waste Incineration Ordinance (AVV 2024, Federal Law Gazette II No. 118/2024), this obligation will come into force in Austria for sewage treatment plants with a population equivalent of 20,000 PE60 or more on January 1st, 2033.
Phosphorus can either be recovered from the ash produced during sewage sludge incineration, whereby at least 80% of the phosphorus contained in the sewage sludge must be recovered;
or directly at the site of the sewage treatment plant or in its vicinity, whereby at least 60% of the phosphorus contained in the sewage treatment plant influent must be recovered.
In both cases, thermal, chemical or physico-chemical processes can be used.
Alternatively, the entire amount of fly ashes from sewage sludge incineration can be recycled as input material to the fertilizer industry.
The Plasma Process is a thermal treatment process in which the waste is incinerated or gasified at around 2000°C in an electric arc furnace. This produces vitrified incineration residues with improved eluate behaviour but requires enormous amounts of energy to generate the electric arc in which the incineration or gasification, respectively, takes place. Plasma systems are mainly used in Asia, but have not caught on in Europe.
Gasification and Pyrolysis are two thermal processes which – unlike incineration (complete oxidation) – take place with a lack of oxygen (gasification: incomplete oxidation) or exclusion of oxygen (pyrolysis: no oxidation, with the exception of reactions of any traces of oxygen contained in the waste).
Legally, gasification and pyrolysis of waste are treated equivalently to incineration. Both processes must comply with the same emission limits as incineration plants, provided that the resulting products are incinerated and produce higher emissions than the combustion of natural gas, which is usually the case.
Contrary to respective claims that are often stipulated by some suppliers of pyrolysis equipment, pyrolysis oil is not a product that can be sold on the market as a diesel fuel or similar, but a hazardous waste that must be treated accordingly.
(© UVP GmbH)
