Location: BG - Bulgaria
This technology currently does not contribute to power generation in this country. However, it is supposed to contribute to expansion/replacement of power generation capacity between today and 2030; therefore, electricity is the reference product. 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 a global average (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. 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.
Undefined unit processes (UPRs) are the unlinked, multi-product activity datasets that form the basis for all of the system models available in the ecoinvent database. This is the way the datasets are obtained and entered into the database by the data providers. These activity datasets are useful for investigating the environmental impacts of a specific activity (gate-to-gate), without regard to its upstream or downstream impacts.