PVC in waste incineration plant; average waste-to-energy plant, without collection, transport and pre-treatment; production mix (region specific plants), at plant; 18,5 MJ/kg net calorific value
This dataset is part of the GaBi 2020 database.
The modeled Waste-to-Energy plant (WtE) is defined based on the treatment of average municipal solid waste (MSW) in Europe. The thermal treatment of a single waste fraction like paper or plastic or even specific wastes like Polyamide 6 is not done in reality in a WtE plant. The waste is always homogenized to obtain a relative constant calorific value and to comply with the emission standards. Nonetheless the used model and the used settings for the average MSW allows to attribute the environmental burden (emissions and also resource consumption of auxiliaries) energy production as well as the credits (metal scrap recovery) to a single fraction or specific waste incinerated within an average MSW. Therefore the LCI data is valid for the thermal treatment of the specific waste within an average MSW. The following technology description explains the settings and technology of the average WtE plant used to generate the LCI data set. The data set covers all relevant process steps for the thermal treatment and corresponding processes, such as disposal of air pollution control residues or metal recycling. The inventory is mainly based on industry data and is completed, where necessary, by secondary data. The system is partly terminated (open outputs electricity and steam). Electricity and steam flows has to be connected and adapted to local specificities in order to take into account these credits. Credits for recovered metals are already included.
The data set represents the incineration of waste, details about the waste composition, water content and heating value can be found in the linked table. The incineration is done in waste-to-energy plants (WtE) for the thermal treatment of municipal waste with dry flue gas cleaning and selective catalytic reduction (SCR) or selective non-catalytic reduction (SNCR) for NOx-removal to meet the legal requirements. Environmental impacts for transport and pretreatment of the waste are included in the data set.
The modeled plant consists of an incineration line fitted with a grate and a steam generator.
Produced steam is used internally as process-steam and the balance is used to generate electricity or exported as heat or steam to industry or households. The energy balance for the plant was modeled country/region specific including information from CEWEP (see sources) representing most waste-to energy plants in Europe. The energy balance for the average combusted waste is extrapolated to the heat input of the specific waste and the waste specific differences on the own consumption of energy (steam and waste) and auxiliaries. The own consumption is partly independent of the waste type (handling of waste before combustion) and partly depending of the waste composition (flue gas volume, treatment of specific emissions etc.).
The flue gas treatment system uses a dry technology with adsorbent and a SCR or SNCR system for NOx-reduction. The NOx reducing agent ammonia is directly injected into the furnace and reacts with the NOx to nitrogen and water. The flue gas is conditioned, adsorbents added and filtered with fabric filters. Lime milk and small parts of hearth furnace coke are used as adsorbents; a part of the adsorbents is re-circulated. The fly ash together with the adsorbent is mixed together with the boiler ash (treatment of APC residues see below).
For the emissions HCl, HF, NOx, VOC, N2O, CO, NH3, SO2, dust, dioxin and the heavy metals As, Cd, Co, Cr, Ni and Pb mean emission values per cubic meter of cleaned flue gas published in the BREF document 'Waste Incineration' of the European Commission are used. Due to the wide range of emissions for some elements and substances the mathematical mean values are adjusted with additional real plant data. The emission of all other elements and the distribution of all elements and substances into the different residues are calculated by means of transfer coefficients.
The bottom ash is quenched, ferrous scrap and partly non-ferrous metals (aluminum, copper, brass, zinc, lead) is recovered and a three month ageing process is done to stabilize the bottom ash. The produced bottom ash after metal recovery and ageing is reused as construction material (and will leave the system as bottom ash for reuse). The APC residues including boiler ash, filter cake and slurries are disposed in underground deposits salt mines. The disposal in underground deposits without free water and contact to ground water reservoirs was modeled as emission free. The operation of the underground deposit is included. Transports for bottom ash and APC residues independent of the different routes are considered.
All important utilities and auxiliaries used in the waste incineration plant are included in the system. Credits for an eventual recovery of ferrous metals are given.
All incineration data is based on an incinerator model initially calibrated with the same emission data based on the elementary composition of European household waste input and the two main NOx treatment technologies. The given table in the documentation represents this calibration data with its NOx variation according to the technology and represents the same consistent basis of all incineration datasets. This calibration is important, because naturally only emission data for mixed waste is measurable in incinerators, as never pure materials (like only wood or only polypropylene) is incinerated. Combustion calculation from waste input to output as electricity, heat, emissions, slag and ashes allows to get material specific data.
The calibrated model is adapted with parameters according to the desired material composition in the input, the country specific share of the NOx treatment technologies, the country specific energy efficiency and energy recovery rates of electricity and heat and the crediting of the country specific residual electricity mix. Thus in the LCI of each dataset, material and technology specific data is representing the situation of each individual material and country.
Firstly the elementary composition in the input is defined depending on the incinerated material. Combustion calculation and tracking of the input specific substances through the plant is done on basis of the defined elementary composition. The plant is set to the respective country technology share and the country specific energy efficiencies and recovery rates of electricity and heat. The LCI emission reported in the dataset represents now the specific emission profile of that material in that country (and can be easily compared to the initial data for household waste documented as calibration data in the respective table). So the user can see how the emission profile is changing due to the “virtual” incineration of a single material.
Main data sources are from 2004 to 2009 for (see data sources field: Best Available Techniques for the Waste Treatment Industry by the European Commission, Best Available Technologies in incineration by IPCC and CEWEP report II), 2011 for the calibration data derived from various sources (CEWEP reports 2004-2007 which were updated in 2011 and the abovementioned BREF data from 2004 and 2006) and incineration experts. 2017 for incineration data (for the element composition of materials and combustion calculation as actual physical and chemical facts).
Materials reacting exothermic in the incineration plant lead to energy generation (electricity and steam OUTput).
Materials reacting endothermic in the incineration plant lead to energy consumption (electricity and steam INput).
Electricity: Electricity from renewable and non- renewable powerplants is modelled so that it represents a country’s specific consumption mix including transmission / distribution losses, own consumption, imports, emissions and efficiency standards, and energy carrier properties. Several factors are taken into account. (1) Energy carrier production - The exploration, mining / production, processing, and transportation of energy carrier supply chains are modelled for each country. The models account for differences among countries in production and processing, including crude oil production technologies, flaring rates, production efficiencies, emissions, etc. (2) Energy carrier supply - Each country’s specific energy carrier supply is modelled, taking into account domestic supply versus imports from abroad. Energy carrier properties (e.g. carbon and energy content), which can vary depending from where an energy carrier is sourced, are adjusted accordingly. (3) Power plants - Models are created to represent energy carrier-specific power plants and electricity generation facilities specific to different renewable energy resources. Energy carrier production and supply models are used to represent power plant inputs. Combined heat and power (CHP) plants are also considered. (4) Electricity grid - Models representing the electricity generation facilities are combined into a larger model that reflects a country’s consumption mix. The larger model accounts for a country’s production mix, internal consumption (e.g. pumped storage for hydro power), transmission / distribution losses, and imported electricity. The country model is also adjusted according to national power plant emission and efficiency standards, as well as the country’s share of electricity plants versus CHP facilities.
Thermal energy, process steam: The thermal energy and process steam supply is modelled to reflect each country’s emission standards and typical energy carriers (e.g., coal, natural gas, etc.) Both thermal energy and process steam are assumed to be produced at heat plants. Thermal energy datasets assume energy carrier inputs are converted to thermal energy with 100% efficiency; process steam datasets assume conversion efficiencies of 85%, 90% to 95%. The energy carriers used for the generation of thermal energy and process steam are modelled according to each country’s import situation (see electricity above).
Transportation: All relevant and known transportation processes are included. Ocean-going and inland ship transport as well as rail, truck and pipeline transport of bulk commodities are considered.
Energy carriers: The energy carriers and their respective properties are modelled according to the specific supply situation (see electricity above).
Refinery products: Diesel fuel, gasoline, technical gases, fuel oils, lubricants and residues such as bitumen are modelled with a parameterised country-specific refinery model. The refinery model aims to represent each country’s refining processes (e.g. emissions levels, internal energy consumption, etc.), as well as the country’s product output spectrum, which can vary significantly among countries. The supply of crude oil is likewise modelled according to the country-specific situation and accounts for differences in resource properties (e.g., crude oil energy content).