Households Scenarios

The Federal Republic of Germany is a densely populated country with approximately 83 million inhabitants (2003), which corresponds to a population density of 230 persons per square kilometres. The Federal Republic of Germany is characterized already today as an industrialized country with having a low number of young people. The population development shows that in a few years there will be more people aged 65 years than aged 15 years or less. Low numbers of births and a declining propensity to get married also affect the size of households, which have shown a tendency to decrease for years in the Federal Republic of Germany. Households with more than 5 persons have become very rare, while the number of one-person households is growing continually. There is an above-average number of one-person households especially in large cities.

Table 2-10. Numbers of the German households (x 1000) [176]

1997

1998

1999

Households (in April)

37457

37532

37795

1-person households

13259

13297

13485

2-person households

12221

12389

12554

3-person households

5725

5643

5645

5-person households

4537

4527

4444

Households with 5 or more persons

1715

1676

1666

2.4.2.1 Households

Nearly 98% of the about 37 million dwelling units in Germany are located in residential buildings, the remaining 2% in residential homes, other buildings with housing space and inhabited provisional accommodations (Table 2-10). More than half of the inhabited dwelling units are located in buildings with 3 or more dwelling units, a good fourth in buildings with one dwelling unit, and just under one fifth in residential buildings with 2 dwelling units. A share of 86.9% of the about 33.8 million inhabited dwelling units in residential buildings was equipped with some form of centralized heating system. The remaining 13.1% have to be heated with single or multi-room stoves or did not give details on how their dwelling unit was heated. Among the type of energy indicated for heating, gas ranked first (43.3%), followed by oil heating (34%), and district heating (13.1%). The remaining 9.6% were distributed over energy types of electricity (4.6%), coal (3.8%), wood and other renewable energies (1.1%) or there was no information available 0.1% [176].

2.4.2.2 Household Final Energy Consumption

The share of household energy consumption (in 1999) was 28.5% or 2647 PJ (Table 2-11). Mineral oil and natural gas are the most important energy carriers of household energy consumption. Both have a share about one third. Since the middle of the 90s natural gas took the leadership. Electricity is about 1/6 of the total energy consumption. Coal and mainly brown coal are loosing importance in the German household energy mix. Only 0.7 % of household energy consumption was still from coal, 1.0 % from brown coal in 1999.

Table 2-11._Energy carrier of household energy consumption in % [176]

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

Final energy consumption in PJ

9484

9367

9127

9232

9109

9323

9689

9543

9481

9288

Industry in %

31,4

28,8

28,1

26,4

27

26,5

25

25,7

25,4

25,6

Traffic in %

25

25,9

27,6

28,1

28

28,1

27,2

27,7

28,3

29,9

Households in %

25,1

26,8

26,7

28,3

28,1

28,5

29,8

30,2

29,6

28,5

Small bussines in %

17

17,4

16,8

16,6

16,3

16,4

17,7

16

16,4

15,7

Military in %

1,5

1,1

0,8

0,6

0,6

0,5

0,3

0,4

0,3

0,3

Households in PJ

2380

2510

2437

2613

2560

2657

2887

2882

2806

2647

Figure 2.20 shows that nearly 80 % of the household energy in Germany is used for heating purposes. Information or communication and lightning add only a little more than 3 % of the energy consumption. If private car use is taken into account heating and car driving need 86 % of household energy and information, communication and lightning fall back to 1 % each. Primary energy used for heating includes heating oil, natural gas, electricity, and renewable energies.

The household final energy demand =2647 PJ (1999)

Heating 76.2 %

Process heat 15.3 %

Mechanical energy 5.1 %

Information and comm. 1.9 %

Lighting 1.5 %

Information and comm. 1.9 %

Fig. 2.20 Final energy consumption in households, Germany 1999 [176]

The market for heating oil decreased in size during the last years. The main reason is the shift in domestic heating from oil to natural gas. The share of natural gas as an energy carrier increased for the economy in general as well as for household purposes. Gas demand increased by 400 % since 1975. In 16.5 Mio households heating systems are based on natural gas [121]. These are 42% of all dwellings. Electricity market was open for household demand since 1998. According [26] renewable energies held a share of 4.5 % of electricity production and 1 % of warming.

2.4.2.3 Hydrogen Scenarios for Households

In general, hydrogen use in the households sector can replace all of today's uses covered by natural gas, town gas or by liquid petrol gas. Thus hydrogen can be used for boilers, for cooking stoves, for catalytic heater devices, for central heating furnaces as well as for efficient decentralized cogeneration applications for combined heat and electricity. But, the most efficient conversion concepts for households will be catalytic heat and hot water production, and fuel cell combined heat and power (FC-CHP) production. Both technologies, catalytic heaters and fuel cells, can be configured from very small initial power capacities to larger ones in modular form. Therefore, high flexibility and efficiency can be achieved from the very beginning. Catalytic heaters operating with hydrogen and air easily achieve 75% efficiency at the site of application. With hydrogen oxygen operation 99% are the present state of the art.

Immersion coil, if needed

Immersion coil, if needed

Electrical Energy Diagram

Electrical energy

Fig. 2.21 Diagram of fuel cell - combined heat and power

Electrical energy

Fig. 2.21 Diagram of fuel cell - combined heat and power

2.4.2.3.1 Operational Principles of FC-CHP

The main component of FC-CHP is a fuel cell. In contrast to mobile applications, for this purpose phosphorus acid fuel cells are advantageous. They operate at temperatures between 160 and 220°C and thus supply enough thermal energy for heating rooms and water. Figure 2.21 show a simplified schematic diagram of FC-CHP. Heat is generally recovered in the form of hot water or low-pressure steam (< 0.2 MPa), but the quality of heat is dependent on the type of fuel cell and its operating temperature. The one exception to this is the PEM fuel cell, which operates at temperatures below 100°C, and therefore has only low quality heat. Generally, the heat recovered from FC-CHP systems is appropriate for low temperature process needs, space heating, and water heating. In the case of SOFC and MCFC technologies, medium pressure steam (up to about 1 MPa) can be generated from the fuel cell's high temperature exhaust gas, but the primary use of this hot exhaust gas is in recuperative heat exchange with the inlet process gases.

2.4.2.3.2 Development Scenarios

In the first stage, fuel options required for the CHPs will be natural gas transformed to hydrogen in a separate reformer unit. Based on this, the Vaillant GmbH is currently developing systems for single households, which are supposed to be available within the next years. In these systems, hydrogen currently is produced from natural gas, which is already distributed over the existing infrastructure. Later on, it is conceivable to distribute pure hydrogen through the same pipelines. On other hand, the local power company, HEW in Hamburg, is now running one fuel cell plant supplying clean energy to the whole block of buildings working on pure hydrogen.

Fermentation Market Growth
Fig. 2.22 Market growth prognosis of FC-CHP from the Vaillant [194]

As a starting point Vaillant together with the partners Ruhr gas, EON engineering, ELE Energy and EUS Society for Innovative Energy Conversion tested several low-temperature cells with protons of leading diaphragm (PEM) install in North Rhine-Westphalia in 2001. On the basis of the field test results Vaillant started to produce CHPs at a pilot scale in 2003. In 2004/2005 the series production and marketing were started. Vaillant proposed to continue the CHPs production, as shown in Figure 2.22.

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