3 Current fossil technologies
3.3 Description of the fuel chains
In the context of NEEDS integration between RS1a and RS2a, each energy chain has been structured in four main phases: operation, production and dismantling of the power plant, and fuel supply. Each of these parts is represented by one process dataset. These parts are assembled in one dataset which represents the electricity production at the busbar by a specific plant technology (Figure 3.11). Although Fuel Supply should naturally be one input of power plant “Operation”, it is here connected with “Electricity” in order to facilitate the contribution analysis of cumulative results into emissions associated with the power plant infrastructure and operation separately from emissions associated with the upstream fuel chain.
Power Plant
Figure 3.11 Generic structure of the fossil energy chains according to the scheme adopted for integration within NEEDS.
The dataset Fossil Fuel Supply represents the delivery of fuel to the power plant. Therefore, it connects to the ecoinvent dataset representing the end of the upstream energy chain, which is in general made of mining, processing, and transport of the fuel to the power plant (Dones et al. 2004 a,b). Therefore, the Fossil Fuel Supply dataset as such is made of one link rather than of a list of elementary flows, like it is the case for the other datasets depicted in Figure 3.11.
The results for such dataset represent the cumulative burdens associated with the whole upstream chain up to the supply to the power plant.
3.3.1 Hard Coal
3.3.1.1 Fuel characteristics
Assumptions on fuel characteristics may somewhat differ for the modeling of the USC-PC and IGCC power plants. Although this may be consistent with the characteristics of the technologies (IGCC is designed to cope with high sulphur coal), what is important in LCI is that the primary emissions from the stack and from other sources within the plant describe the overall burdens from a typical best-technology plant.
In particular, for the USC-PC units, a coal with the characteristics of average supply to the Rostock power plant have been assumed, which are summarized in Table 3.23.
Table 3.23 Selected fuel characteristics of the hard coal used in the Rostock power plant (Röder et al. 2004 after Hojczyk et al. 1997) and assumed here for USC-PC units.
Hard coal
1 Calculated from the LHV multiplying it by 1.05.
For the IGCC reference power plant, hard coal with the characteristics indicated in Table 3.24 has been used
Table 3.24 Selected fuel characteristics of the hard coal used in the IGCC reference power plant.
Hard coal burned in USC-PC Upper Heating Value MJ/kg 27.7 1
Lower Heating Value MJ/kg 26.4
Water content % weight 10
Ash content % weight 6
S content % weight 3.21
1 Calculated from the LHV multiplying it by 1.05.
3.3.1.2 Upstream Chain
Figure 3.12 shows a schematic of the structure of the hard coal chain for the USC-PC and IGCC reference power plants. The hard coal supply chain to European power plants around year 2000 is taken from the ecoinvent database v1.3. It is described in detail in (Röder et al.
2004) and will not be reproduced here.
Hard Coal at Regional Storage (production region Xi)
Hard Coal at Mine (production region Xi)
Electricity at Power Plant busbar (EC average or EC country-specific) Power Plant Operation
Power Plant Infrastructure (Construction & Dismantling)
Hard Coal Supply Mix, (EC average or EC country-specific)
from production regions Xi
Other Supply Regions Xj
Figure 3.12 Structure of the hard coal chain for the USC-PC reference power plants;
modeling of the power plant follows the scheme adopted within NEEDS.
3.3.2 Lignite
3.3.2.1 Fuel characteristics
Average German lignite, described in (Röder et al. 2004), is chosen as average fuel for the reference European lignite power plant. This assumption is based on the high share of German lignite electricity production in total European lignite electricity production in (about 41% in EU-25 in year 2000). The main characteristics of the average German lignite are given in Table 3.25 (Röder et al. 2004).
Table 3.25 Fuel characteristics of the German lignite used as reference fuel (Röder et al.
2004).
Raw lignite
Upper Heating Value MJ/kg 9.9
Lower Heating Value MJ/kg 8.8
Water content % weight 58
Ash content % weight 2.5
C content % weight 27.1
N content % weight 0.3
S content % weight 0.2
3.3.2.2 Upstream Chain
The power plant is directly located at the mining site (“mine-mouth”). Therefore, the upstream chain is made of mining only. Figure 3.13 illustrates the structure of the lignite chain for the BoA reference power plant.
Electricity at Power Plant busbar (EC average or EC country-specific) Power Plant Operation
Power Plant Infrastructure (Construction & Dismantling)
Lignite Supply from Mine
Figure 3.13 Structure of the lignite chain for the BoA reference power plant; modeling of the power plant follows the scheme adopted within NEEDS.
3.3.3 Natural Gas
3.3.3.1 Gas Combined Cycle (GCC) power plant and Gas Turbine
In order to represent a natural gas combined cycle plant and a gas turbine in an average European site, the average gas supply for Europe in year 2000 is used. These power plants are attached to the high pressure natural gas network. The corresponding data is provided by the ecoinvent module “natural gas, high pressure, at consumer, RER” (RER = Region Europe).
The gas supply chain and the gas characteristics are described in (Faist Emmenegger et al.
2004) and will not be reproduced here. The scheme of the natural gas supply chain for the natural gas combined cycle power plant as modelled in ecoinvent is illustrated in Figure 3.14.
In principle, the same structure of the upstream supply chain applies to the gas turbine as well.
3.3.3.2 Combined Heat and Power (CHP)
It is assumed that the small CHP plant is attached to the low pressure natural gas network.
The local distribution in the low pressure network has been modelled in detail for Switzerland. Therefore, the natural gas supply for Switzerland is used for the gas CHP plant.
The corresponding data is provided in the ecoinvent module “natural gas, low pressure, at consumer, CH”. The origin and characteristics of the Swiss natural gas supply are similar to the origin and characteristics of the average European gas supply. The gas supply chain and the gas characteristics are described in ecoinvent (Faist Emmenegger et al. 2004). The scheme of the natural gas supply chain for the natural gas CHP plant as modelled in ecoinvent is
shown in Figure 3.15.
Purification
Exploration and Production of Natural Gas
Electricity
at GCC Power Plant busbar Power Plant Operation
Power Plant Infrastructure (Construction & Dismantling)
Long Distance Transportation
Regional Distribution (High Pressure Network)
Figure 3.14 Structure of the natural gas chain for the GCC power plant; modeling of the power plant follows the scheme adopted within NEEDS.
Purification
Exploration and Production of Natural Gas
Electricity & Heat at CHP Plant busbar
(Allocation Exergy) CHP Plant Operation
CHP Plant Infrastructure (Construction & Dismantling)
Long Distance Transportation
Regional Distribution (High Pressure Network)
Local Distribution (Low Pressure Network)
Figure 3.15 Structure of the natural gas chain for the CHP plant; modeling of the CHP plant follows the scheme adopted within NEEDS.