Cogeneration – Natural Gas


Natural Gas Cogeneration

What is Cogeneration

Cogeneration or Combined Heat and Power (CHP) is the simultaneous production of both electrical power and heat utilising a single fuel source.

A piston or turbine engine is fueled by natural gas which turns a generator to produce electrical power. This power is either connected and synchronised to the electrical grid (parallel operation) or is disconnected from the grid and is known as island operation.

This process also produces heat in the form of hot coolant and hot exhaust gasses, both of which are passed through heat exchanges to a Secondary Circuit. It is this Secondary circuit which distributes heat captured from the Cogeneration unit to the site or plant to be utilised.

Why Cogeneration?

Cogeneration has the benefit of saving a site or plant OPEX by reducing the amount of power supplied from the grid while also producing heat which would otherwise be created by burning natural gas in a conventional gas boiler or heater.

Natural Gas Power Generation is also 50-60% cleaner then Australia’s current electrical grid which is predominantly supplied by Coal Fired Power Stations. By using an onsite Natural Gas generator you will instantly half your business’s electrical carbon footprint.

Is Cogeneration right for everyone?

The simple answer is no and there are many factors that play into this, these are:

  • Base Load Power
  • Heat Demand and Heat Distribution
  • Gas Price vs Electricity Price
  • Grid Reliability / Supply Restrictions
  • Access to skilled Technicians

Base Load Power

Base load power is the average power a site consumes constantly in a set period or 24/7. Most energy retailers will offer 30 minute interval data so a detailed analysis can be completed for the average site load. A live test should also be completed to ensure the 30 minute interval data lines up to site load.

For example: In 30 minutes a sites load could be 250 kW for 5 minutes and 100 kW for the remaining 25 minutes. The Cogeneration units base load would typically be between 90 kW which also allows a buffer for imported power of 10 kW.

On all grid parallel installations the energy network provider will stipulate if power can be exported. Generally the answer is no, so a power buffer is maintained to prevent any exported power. This buffer will depend on the site load and how quickly it and the generator respond.

Cogeneration engines should not be designed to offset 100% of the imported power in a grid parallel installation.

Heat Demand and Heat Distribution

The heat demand from a site is very important, it greatly increases the return on investment for a project and turns a natural gas generator into a cogeneration generator.

Once the heat is in the secondary circuit, it needs to tie into the existing site heating loop to become effective. This integration is crucial and unfortunately in many Australian installs this has been completed incorrectly.

Gas Price vs Electricity Price

Cogeneration in Australia is very much dependent on Gas price vs Electricity price. This essentially creates an opportunity to save on OPEX by purchasing gas and converting it to electricity on site rather then importing electricity from the grid.

Network charges also have to be added to give a true price kWH price in the case of electricity and GJ/H price in the case of gas.

Please contact us for a detailed analysis of your site.

Grid Reliability / Supply Restrictions

In rural areas, Cogeneration could be a great source of power generation for manufacturing to ensure the lights don’t go off during production.

Cogeneration is also a good source of additional power if there are electricity supply restrictions. For example, a manufacturing plant may want to upgrade it’s facility but it’s current HV transformer or network can not support this. Installing a cogeneration unit will decrease the amount of power imported from the grid, thus allowing expansion of the facility.

Access to skilled Technicians

Cogeneration units are a complicated piece of equipment and need to be maintained by skilled technicians however often the faults that occur are very basic and can be resolved by onsite staff if they have had the appropriate training. Ensure your supplier has skilled local technicians or provides an appropriate level of training and access to the equipment.