Pick the right cogeneration technology

COGENchallenge - European Campaign for the Development and Documentation of 1000 Small-scale Cogeneration Projects in European Cities and Towns Pick ...
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COGENchallenge - European Campaign for the Development and Documentation of 1000 Small-scale Cogeneration Projects in European Cities and Towns

Pick the right cogeneration technology

A technology checklist of small-scale cogeneration July 2006

Table of contents

Choose your technology ....................... 2 Gas turbine............................................ 3 Gas engine............................................ 4 Heating oil engine ................................. 5 Biogas engine ....................................... 6 Steam turbine........................................ 7 Stirling engine ....................................... 8 Fuel cell................................................. 9 COGENchallenge Facilitators ............. 10 Who we are ......................................... 11

1

Choose your technology You can produce heat and electricity together with different technologies: you just recover heat from the traditional electricity production unit. As the heat must be used close to the consumer, the cogeneration units needs to be approximately sized to the size of the consumer. The range of the available technologies is quite wide. You will choose your cogeneration technology according some criteria, specific to your activity and your heat demand. The table below lists the technologies: "++" means the technology is very suitable to produce the heat you need, and "+" means less suitable. No quotation means the technology can not produce the type of heat you need, such as the Stirling engine or the fuel cell which cannot (yet) produce steam.

Cogeneration

Fuels (not exhaustive)

technologies Gas turbine

Natural gas, biogas, heating oil

You need

You need

You need

hot water?

steam?

hot air?

++

++

++

++

+

+

++

+

+

++

+

Natural gas, biogas, heating oil, Gas Engine

vegetable oil, wood

Heating oil

Natural gas, biogas, heating oil,

Engine

vegetable oil, wood Natural gas, biogas, heating oil,

Steam turbine

vegetable oil, wood, etc.

++

Stirling engine

Natural gas, biogas, heating oil, wood

++

Hydrogen or, via reforming, all others Fuel cell

fuels

++

2

Gas turbine Gas turbines have become the most widely used prime mover for large-scale cogeneration in recent years. Gas turbines are not only used in large-scale applications. Smaller units, starting at around 400 kWe are available on the market. Since the late 1990s microturbines have become available. They are derived from automotive turbochargers and are available from 30 kWe. Microturbines use less space than conventional engines and maintenance costs are lower. Moreover, the emission of pollutant gases is reduced, especially those gases that cause acid rain and ozone layer depletion. Electrical efficiencies are typically lower than in internal combustion engines. Smallest unit

Typical small-scale unit

28 kWe

250 kWe

26%

30%

52 kWth

330 kWth

47%

40%

NOx emission:

< 9 ppmV

< 9 ppmV

CO emission:

< 10 ppmV

< 9 ppmV

1.3 x 0.7 x 1.9 m

4 x 2.2 x 2.3 m

0.5 tons

235 tons

2 500 € /kWe

1 500 € /kWe

Electrical power: Electrical efficiency: Thermal power: Thermal efficiency:

Size (L x W x H): Weight: Investment:

Exhaust gas Water feeding Heat recovery boiler Steam

Post-combustion (eventualy)

Natural gas

Steam consumption

Natural gas

Burning Air

Filter

Generator

Gas turbine Gas turbine

3

Gas engine Most small-scale cogeneration units are internal combustion engines operating on the same familiar principles as their petrol and diesel automotive counterparts. Engines run with liquid or gaseous fuels, such as heating oil, natural gas or biogas, and are available from 5 kWe to more than 1,000 kWe. Internal combustion engines have a higher electrical efficiency than turbines, but the thermal energy they produce is generally at lower temperatures and so they are highly suited to buildings applications. The usable heat to power ratio is normally in the range 1:1 to 2:1. Smallest unit

Typical small-scale unit

5 kWe

250 kWe

26%

36%

12 kWth

368 kWth

62%

53%

NOx emission:

350 mg/Nm3

250 mg/Nm3

CO emission:

300 mg/Nm3

300 mg/Nm3

Size (L x W x H):

1 x 0.7 x 1 m

3.5 x 1.8 x 2.2 m

0.5 tons

5 tons

3 000 € /kWe

800 € /kWe

Electrical power: Electrical efficiency: Thermal power: Thermal efficiency:

Weight: Investment:

Exhaust gas

Heat recovery boiler

Hot water and/or steam consumption

Exhaust gas Cooling water Generator

Engine

Gas or heating oil or biogas engine Heat exchanger

Fuel

Water feeding

4

Heating oil engine When natural gas or biogas is not available, you can choose an heating oil engine.

Smallest unit

Typical small-scale unit

5.3 kWe

250 kWe

30%

37%

10.5 kWth

314 kWth

59%

47%

NOx emission:

2 150 mg/Nm3

250 mg/Nm3

CO emission:

300 mg/Nm3

300 mg/Nm3

Size (L x W x H):

1 x 0.7 x 1 m

3.2 x 1.5 x 2.2 m

0.5 tons

4 tons

3 000 € /kWe

800 € /kWe

Electrical power: Electrical efficiency: Thermal power: Thermal efficiency:

Weight: Investment:

Source: 5 kWé heating oil engine in a Municipality house (Amel - Belgium)

5

Biogas engine When biogas is available, you can choose a biogas engine.

Smallest unit

Typical small-scale unit

20 kWe

250 kWe

31%

37%

34 kWth

340 kWth

53%

50%

NOx emission:

250 mg/Nm3

500 mg/Nm3

CO emission:

1 000 mg/Nm3

650 mg/Nm3

Size (L x W x H):

1.8 x 0.8 x 1 m

3.5 x 1.6 x 2.3 m

0.8 tons

5 tons

4 700 € /kWe

700 € /kWe

Electrical power: Electrical efficiency: Thermal power: Thermal efficiency:

Weight: Investment:

Source: 1.25 MWé biogas engine in a Food Industry Lutosa (Electrabel – Belgium)

Source: 102 kWé biogas engine in a small village (La Surizée - Belgium)

6

Steam turbine Steam turbines have been used as prime movers for large-scale cogeneration systems for many years. Typically, steam turbines are associated with larger power stations but also smaller units starting with 200 kWe are frequently used. The overall efficiency generally is very high, achieving up to 84%. Steam turbines run with solid, liquid or gaseous fuels, both fossil and renewable. The typical heat to power ratio of steam turbines is around 6:1. Typical small-scale unit Electrical power:

500 kWe

Electrical efficiency:

10%

Thermal power:

3,000 kWth

Thermal efficiency:

70%

NOx emission: CO emission: depending on the boiler

Size (L x W x H): Weight: Investment: Exhaust gas

Water feeding High pressure boiler

Steam turbine

High pressure steam Generator

Fuel Low pressure steam

Steam turbine

Steam consumption

7

Stirling engine For very small-scale applications with a capacity between 0.2 kWe and 9 kWe, Stirling engines can be used. These engines are external combustion devices and therefore differ substantially from the conventional models. The Stirling engine has fewer moving parts than conventional engines, and no valves, tappets, fuel injectors or spark ignition systems. It is therefore quieter than normal engines. Stirling engines also require little maintenance and the emission of pollutants is low. Smallest unit

Typical small-scale unit

1 kWe

7.5 kWe

11%

24%

7 kWth

22 kWth

79%

70%

NOx emission:

80 mg/Nm3

80 mg/Nm3

CO emission:

50 mg/Nm3

50 mg/Nm3

0.5 x 0.6 x 0.85 m

1.3 x 0.7 x 1 m

0.15 tons

0.46 tons

6 000 € /kWe

2 600 € /kWe

Electrical power: Electrical efficiency: Thermal power: Thermal efficiency:

Size (L x W x H): Weight: Investment: Heater

Regenerator Cooling water

Expansion cylinder

Cooler

Expansion piston

Compression cylinder

Generator

Compression piston

SOLO 161

Note this is new technology as the investment costs are still falling.

8

Fuel cell A new development is the use of fuel cells for cogeneration. It needs to be said, however, that fuel cells are not yet commercially available. Fuel cells convert the chemical energy of hydrogen and oxygen directly into electricity without combustion and mechanical work such as in turbines or engines. The hydrogen is usually produced from natural gas by a process known as reforming. The total efficiencies of cogeneration systems reach 85 to 90%, while the heat to power ratio is in the range 5:4 and tends towards 1:1. Fuel cells with a capacity of 1 kWe provide heat and power to single family houses, whereas bigger applications of around 200 kWe can be used in hospitals for example. Smallest unit

Typical small-scale unit

1 kWe

200 kWe

38%

36%

1.2 kWth

217 kWth

47%

39%

NOx emission:

< 2 ppmV (if natural gas)

< 1 ppmV (if natural gas)

CO emission:

< 2 ppmV (if natural gas)

< 2 ppmV (if natural gas)

0.9 x 0.9 x 1.8 m

5.4 x 3 x 3 m

0.5 tons

19 tons

up to 100 000 € /kWe

up to 5 000 € /kWe

Electrical power range: Electrical efficiency: Thermal power range: Thermal efficiency:

Size (L x W x H): Weight: Investment:

ELECTRO LYTE

EXH AU ST

Source: Fuel Cell Hand

Note this is new technology as the investment costs are still falling.

9

COGENchallenge Facilitators

GERMANY:

AUSTRIA:

Paul Fay

Jan Bleyl

Stadt Frankfurt am Main - Energiereferat

Grazer Energieagentur

Galvanistraße 28

Kaiserfeldgasse 13/I

D- 60486 Frankfurt am Main (Germany)

A-8010 Graz (Austria)

Tel: +49 69 212 39199

Tel: +43 316 811 848-20

Fax: +49 69 212 39472

Fax: +43 316 811 848-9

Email: [email protected]

Email: [email protected]

FRANCE:

SPAIN:

Reinhard Six Rhônalpénergie Environnement (RAEE) 10 rue des Archers FR-69002 Lyon (France) Tel: +33 4 78 37 29 14 Fax: +33 4 78 37 64 91 Email: [email protected]

Carlos García Fundación Asturiana de la Energía (FAEN) Área de Relaciones Externas C/ Fray Paulino, s/n E-33600 Mieres (Spain) Tel: +34 985 46 71 80 Fax: +34 985 45 38 88

BELGIUM:

Email: [email protected]

Ismaël Daoud

SLOVENIA:

Cogeneration Facilitator for Wallonie COGENSUD asbl Bd Frère Orsban, 4 B-5000 Namur (Belgium) Tel: +32 81 250 480 Fax: +32 81 250 490 Email: [email protected]

Stane Merse "Jozef Stefan" Institute - Energy Efficiency Centre Jamova 39 SI - 1000 Ljubljana (Slovenia) Tel: +386 1 5885 250 or 210 Fax: +386 1 5885 377 Email: [email protected]

10

Who we are

11