Reference product: heat, district or industrial, other than natural gas [MJ]
Location: PT - Portugal
This dataset represents the production of heat and electricity with wood chips in a state-of-the-art (as of 2014) co-generation plant with a capacity of 6667 kW (referring to fuel input) in Switzerland and was used as approximation for this dataset valid for in Portugal (uncertainties adjusted accordingly). The technology corresponds to a modern unit to be installed in 2014 in Switzerland, which is equipped with an electrostatic precipitator for particulate matter (PM) emission reduction and an SNCR device for reduction of NOx emissions. It is assumed that the plant is operated mainly producing heat, i.e. following the heat demand. Heat is therefore considered as the main product and therefore the reference product, whereas electricity is a by-product. Electricity is produced with an organic rankine cycle (ORC) steam generator.
Wood chips are burned in a boiler at a temperature of 800-1300 °C under excess air conditions and turned into carbon dioxide and water. Energy is set free in form of heat. Burning takes place with the following steps:
1. Drying
2. degradation of the wood into carbon and gases
3. degradation of the carbon into gases
4. oxidation of the gases
These phases overlap. The produced heat can be used directly or for steam production in order to generate electricity with a turbine.
Emissions vary with quality of the combustion (temperatur, mixing of the combustion gases and the added fresh air, retention time of gases in the combustor), filter technologies and with the efficiency of the plant. Emission data in this dataset are taken from measurements and literature as well as from communication with experts.
CO2 emissions were calculated out of the carbon content of the wood used as combustible. Carbon emitted in carbon monoxide was subtracted from the result.
Key emissions factors for CO, NOx, CH4, NMVOC and particles were updated according to latest data.
All other emission factors (per MJ fuel input) correspond to the 1000 kW boiler fuelled with wood chips from forest. Other exchanges correspond to the LCI data for the 6400 kW co-generation unit in ecoinvent v2.2.
Good J., Nussbaumer T., Bühler R., Jenni A. (1996) Erfolgskontrolle des SNCRVerfahren
zur Entstickung von Holzfeuerungen. Schlussbericht des BEWProjektes
53894. Zürich, Schweiz.
[This dataset has been generated using the system model "Allocation, cut-off by classification". A system model describes how activity datasets are linked to form product systems. The allocation cut-off system model subdivides multi-product activities by allocation, based on a physical properties, economic, mass or other properties. By-products of waste treatment processes are cut-off, as are all by-products classified as recyclable. Markets in this model include all activities in proportion to their current production volume.
Version 3 of the ecoinvent database offers three system models to choose from. For more information, please visit: https://www.ecoinvent.org/database/system-models-in-ecoinvent-3/system-…)]