A Very Different Cogen: Keeping it Cool

By MaryAnne Mason

4 min read

The escalating costs of electricity in Ontario, Canada have led many large industrial facilities to consider alternative means to reduce their energy use and/or produce electricity at a lower cost.

In our 2018 article, A Very Different Cogen, we shared our team’s work on a feasibility study for the development and installation of a landfill gas Cogeneration (Cogen) plant for a major automotive manufacturer in southern Ontario. Our unique design for the $30 million project helped the client receive an $11 million grant as part of the provincial government’s “Save on Energy” program. The size of the grant was dependant on the project’s proposed power reduction.

This article provides an update on the Cogen project and the benefits achieved through our novel design.

How our Cogen design works

Cogen, also known as combined heat and power (CHP), uses landfill gas (in this case) to generate both electricity and thermal energy, usually in the form of hot water. The efficiency of a Cogen facility is dependent on the quantity of waste heat that can be recovered: the more heat that is reclaimed, the higher the efficiency that can be achieved.

Generators typically have high temperature heat sources such as the engine cylinder (jacket) water cooling system, but there are also low temperature sources such as the lube oil cooling. These are combined into two output streams – high temperature and low temperature. In addition, a significant amount of heat can be recovered through the engine exhaust. Most Cogens recover the high temperature stream, and may recover part of the exhaust, but allow the low temperature sources to be wasted as they are cooler than the typical hot water return temperature (making recovery impossible). Additional power must be used to reject waste heat, while additional gas must be used to heat the facility.

At the automotive plant in Ontario, there are numerous air-handling units (AHUs) that provide facility heating in winter and cooling in summer using coils that supply chilled water for cooling, and steam or hot water for heating. Instead of retrofitting all the AHUs with hot water coils, we connected the hot water from the Cogen to the piping distribution system that supplies chilled water to the AHUs for space cooling. As hot water is substituted for cold at the “chilled water” coil, these relatively larger coils are able to provide adequate heat at a lower supply temperature than possible with a normal hot water coil. This way, the facility can operate with a much lower return temperature.

Allowing the low temperature heat from the Cogens to be recovered allows our Cogen design to achieve a higher efficiency. Additionally, while the hot water boilers currently on the loop are low capacity, running them at a lower inlet temperature is more efficient.

Project update and benefits

The Cogen project designed for the automotive client was built and has been up and running since late 2020. In fact, our client reports the facility is producing more electricity than originally expected, which is good news. A second phase of the project was originally planned that involved installing new boilers that could run at 95% efficiency.

This is the second major, successful Cogen project Ausenco has designed in southern Ontario in recent years including for a large university.

Our approach to Cogen design is to make optimal use of both existing and new equipment while minimizing cost rather than using a universal design for all systems. This has provided our clients with several benefits including:

  • lower capital costs through repurposing existing equipment
  • improved heating efficiency
  • reduced operating costs
  • reduced emissions
  • lowered carbon taxes
  • efficient design led to higher grants and, in turn, made it easier to get financing

The global shift to a low-carbon economy has forced many sectors, including automotive, to find ways to reduce their carbon footprint and eventually reach carbon neutrality. Improving the efficiency of electricity can go a long way to helping companies like our client reduce their carbon footprint and be part of the solution.

Start your renewable energy journey today!

Cogen projects are often complex and require ingenious solutions to solve the unique challenges they present. With decades of experience helping organizations plan and execute Cogen projects, we’re here to help you find the right renewable energy solutions to meet your needs and environmental targets.

For more information, contact Bill Laughlin today.