Electricity generators use a fossil fuel in an engine that turns an alternator to generate electricity.  Generators are dispatchable – meaning they generate electricity when it is needed and do not depend on external factors such as the weather.

 

Generators are generally fuels by:

• Natural gas

• Diesel 

• Hydrogen

 

Natural gas generators are more expensive than diesel generators but have a much lower operating cost. As such, natural gas generators are used in applications where the generator operates more frequently. Further, natural gas does not require the onsite storage of fuel.

 

Natural gas generators are not as electrically efficient as diesel generators (typically 35-40% electrically efficient). However, natural gas has much lower emissions than diesel  (52 kg/GJ for natural gas, 75 kg/GJ for diesel).  

 

As natural gas generators are designed for more continuous operations, they are good fit for combined heat and power (CHP) applications.  If the heat is captured and reused, the overall efficiency of the system in typically over 85%.

 

Diesel generators have a lower capital cost than natural gas generators but a much higher operational cost. Often diesel generators achieve over 50% electrical efficiency.  These generators are designed for infrequent use and are typically used for backup systems. 

 

Many of the natural gas generator manufacturers are now providing systems that are “hydrogen ready”. With a minor upgrade, the natural gas generator can operate on 100% hydrogen. While this eliminates the emissions issue, access to hydrogen remains very expensive.