Case Studies of Environmental Impact Assessment:
Air Quality Issues
To provide practical guidance and document environmental
impact assessment practice in the domain of air quality,
AIR-EIA provides a collection of typical case studies
in common, standardised framework for better comparability.
EIA Case study: TPS Donaustadt: district heating
Category: Thermal Power Station
The impact assessment was developed for the new (planned) 350 MW gas fired plant
(gas/steam turbine) which will supply up to 250 MW of district heat.
With an efficiency of up to 86% (power and heating combined), it will be
one of the most modern and efficient plants in operation: older power plants reach
an efficiency of around 40%.
The new block 3 of the Donaustadt TPS complements the existing blocks in
Vienna's three major power stations,
including Simmering (5 blocks with a total of 1050 MW electrical,
and heat capacity of up to 630 MW)
and the TPS Leopoldau with 155 MW electrical and 170 MW thermal.
- BGBl. 1995/679
- Bundesgesetz über die Prüfung der
Umweltverträglichkeit und die Bürgerbeteiligung
(Umweltverträglichkeitsprüfungsgesetz - UVP-G)
The technical planning data for the new, third block for Donaustadt
(current capacity in blocks 1 and 2 is 304 MW electrical) are as follows:
| Gas turbine
|| electrical output
|| heat output
(without heat coupling)
(with heat heat coupling)
| 240 MW
|| 350/300 MW
|| 0/250 MW
|| 58 %
|| 86 %
The building and emission data base covers more than 7,000 blocks,
and includes data for SO2, NOx, CO2, CO, PM10,
heavy metals (lead and cadmium), and HCH0 and PAH.
Residential and commercial use, heating systems
(individual or central) and fuel types (solid (coal),
liquid (oil) and gas), all expressed as fractions of the
total energy consumption, are recorded for each building.
Very restricyed access to the available data and study results;
since the assessment is closed, no more public access to
the relevant docuemtnts is being granted.
EIA study results:
The main issues was to demonstrate the effects of
The approach involves:
- an additional stack and emissions from the new
power plant block;
- the reduced emissions from the building blocks now connected to
the district heating scheme.
- simulation of the status quo;
- simulation of the new TPS design;
- simulation of the reduced block emissions;
- impact analysis or building of the deltas:
1 + 2 -3
To support the sudy, a special application of the
AirWare air quality assessment
and management information system was configured.
It includes the following
major modules and functions:
A building heating data base that manages the energy and emission data
for individual buildings or blocks of buildings.
The data include basic information on the building or block of buildings,
energy data, and heating system (fuel and type) specific emission rates
for a group of substances.
A scenario editor that supports the selection of
The selection of buildings (that will or will not contribute
to the emission scenario) can be based on their attributes,
using a multi-criteria filtering and ranking approach,
or manually, from the map display.
Selecting a building represents its connection to the district
heating system, and thus switching off its individual emissions.
A special case it the automatic multi-criteria selection
(up to the available heating capacity provided by an appropriate power plant
or set of plants) of buildings,
sorted by user defined selection criteria, including proximity to
an existing or planned pipeline system.
The basic simulation module; this involves the simulation of a base
line scenario (no buildings connected), the selected scenario (some buildings
connected to the power plant), and the simulation of the power plant itself.
The emission and dispersion simulation is based on a Gaussian long-term model
(ISC-3/AERMOD with complex topography corrections), and a long-term weather
scenario (frequency distributions) for the default period of
October 1 to March 31 (compatible with 96/62/EC and COM(97)500).
An assessment module, that compares the two scenarios,
with and without the district heating scheme, and calculates the
resulting difference in terms of ambient air quality and
All scenarios show a marked improvement of the overall
air quality due to the substitution of local household emission
(emitted at a low height) with the district heat supplied by the TPS.
Depending on the weather situation, the improvement is largely local,
that is at and around the areas connected to the district heating supply,
but it is big enough to influence the overall immission situation
(global average and maximum concentrations observed).
The additional emission introduced by the TPS are negligible
in comparison, due to both:
- the much higher efficiency of the new plant;
- the high stack and its location.