Co-generation: doing double duty for more efficiency - EarthCare Expert

Q: What are co-generation and biomass co-generation facilities? Does Sudbury have any?

A: Co-generation plants produce two useful forms of energy from a single base fuel energy source. Base fuels can include natural gas, oil, coal, or biomass.

These base fuels can be converted into a combination of at least two new forms of usable energy, such as electricity, heat, or mechanical energy.
An automobile’s engine is a good small-scale example of a co-generator.

The engine produces electricity and mechanical energy to propel the car, while capturing the engine’s heat to provide space conditioning for the occupants. This is all from one base energy source, gasoline.

Currently there are two co-generation plants in Greater Sudbury. Both use natural gas to power a reciprocating piston engine that produces electricity, captures the hot water from the engine cooling system and pipes it to users who buy the heat. Both facilities export all or excess electrical power to the grid.

The first is a co-generation plant at Health Sciences North that provides electricity, steam, and hot water to offset requirements for the new and expanded facility.

The second is the Downtown Central Utility Plant, which exports all the electricity it produces to the grid and provides high temperature hot water heating to seven of the buildings in the downtown core. These are: the Centre for Life, St. Andrews Place, Sudbury Medical Centre, Tom Davies Square, Sudbury Arena, 128 Larch St., and the Federal Building.

St. Andrew’s Place is an excellent example of co-generation’s greater efficiency. In the past, this building operated three large boilers and ten hot water heaters. Today only a heat exchanger is necessary.

Although the heat exchanger is much smaller, it is capable of heating the entire building and does not require a smoke stack. St. Andrew’s Place now relies entirely on the Downtown Central Utility Plant for heating needs.

Biomass co-generation plants use renewable biomass (e.g. yard clippings, left-over crops, wood chips, sawdust from lumber mills and/or livestock manure) to simultaneously produce both electric power and steam. These facilities may be 50 to 70 percent more efficient than conventional fossil fuel power.

The city has a power plant at the Sudbury Landfill that uses methane gas collected from the landfill to generate electricity that is exported to the grid. Although the plant uses methane (biomass) and is renewable, it is not considered a biomass co-generation facility because it has only the one export (electricity) without a second export (steam or other usable energy).

Larger communities use sewage treatment plants or waste burning plants to provide methane gas or steam heat, but the City of Greater Sudbury does not currently have any biomass co-generation facilities.

Thanks to EarthCare Sudbury Partners Greater Sudbury Hydro Inc., Toromont Energy Ltd., Union Gas Ltd., and the City of Greater Sudbury for their assistance in responding to this question.

EarthCare Sudbury is a network of over 100 local businesses, organizations and agencies that have committed to help Greater Sudbury become greener, cleaner, healthier and more sustainable.

Find out more about EarthCare Sudbury, our partners and how to get involved by visiting our website at greatersudbury.ca/earthcare.

Do you have a question about an environmental issue? Ask an EarthCare Expert! Submit your question online at www.greatersudbury.ca/earthcare, then watch for this column published in the Northern Life for an “expert” response.

Posted by Vivian Scinto