Generation of heat and power from biogas for stationary applications: boilers, gas engines and turbines, combined heat and power (CHP) plants and fuel cells - The Biogas: Science, Production and Applications - page 406

Table 17.2 Comparison of biogas power generation in stationary applications

Parameter Engine Gas turbine Micro turbine Stirling engine Fuel cell

Unit capacity (kW el ) a

110-3000 3500-15 000 30-300 < 150 300-1500

Plant size Small to

medium

Large Small Small Small

Electrical efficiency (%) 30-42 25-40 25-30 30-40 40-45

Thermal efficiency (%) b 40-50 30-50 30-35 35-40 30-40

Overall system efficiency (%) 70-80 70-75 55-65 65-80 75-80

Power/heat ratio production control Not possible Very good Very good Very good Good

Biogas purification requirement Medium Medium Medium Low-medium High

Emissions NO x High 500-700

mg/Nm 3

Low 25-50 mg/
Nm 3 flue gas

Low Very low Extremely low

(3mg/Nm 3 flue
gas)

Alternative fuel source Liquid gas Natural gas Natural gas,

kerosene, fuel
oil

Natural gas, fuel
oil, biomass

Natural gas

/kW el ) c Investment costs ( 400-1100 900-1500 600-1200 1300-1500 3000-4000

€

/kWh) d Operation and maintenance cost ( 0.01-0.02 0.005-0.010 0.008-0.015 0.003-0.005 0.003-0.010

€

a Unit capacity varies depending on manufacturer.
b Heat recovery is estimated as a percentage of fuel input.
c Installed costs vary with type and amount of auxiliary equipment.
d Maintenance costs are dependent on gas quality.
Source: adapted with permission from Chambers and Potter (2002), Obernberger

et al. (2003) and Deublein and Steinhauser (2008);

Wiley-VCH Verlag GmbH & Co. KGaA, Germany.