CHP has always been a little too complicated for its own good – involving both heat and power markets, systems and regulators; being neither central power generation nor on-site energy use but something in-between; and not being a renewable technology, though it sometimes uses a renewable fuel. Further, the installation of a CHP scheme often increases on-site emissions of carbon dioxide while nevertheless resulting in a net reduction in overall emissions.
So, given the very obvious emissions-reducing qualities of both pure renewable energy technologies and those that simply reduce energy demand, CHP may not be at the top of anyone’s list of technologies to cut carbon emissions in the US.
However, the US Environmental Protection Agency’s (EPA’s) proposed Clean Power Plan, which established state-specific targets to reduce carbon emissions from existing power plants, allows states to use energy efficiency as a means to comply. The American Council for an Energy Efficient Economy (ACEEE) is keen to assist US states to see CHP included, with a new guide to help states claim emission reductions that result from CHP.
Combined heat and power is an underutilized resource in every state of the US, says the ACEEE, and could contribute 70 TWh of electricity savings nationwide in 2030, with corresponding savings in greenhouse gases of nearly 50 million tonnes.
What’s more, obtaining credit for CHP capacity in a state compliance plan is an additional benefit for something that is already a good investment to help business energy users save money and at the same time provide increased reliability and safety during electric grid outages.
Put simply, CHP reduces emissions by shifting electricity loads away from conventional power plants to the more efficient CHP unit sited near the point of use. The overall efficiency of cogenerating heat and power – plus avoided transmission and distribution losses – result in primary fuel savings and reduced carbon emissions. These can be calculated and the EPA CHP Partnership has published a simple method of doing just this.
Putting CHP to work can be a complicated business; as can calculating its effect on emissions. But for well-designed installations the rewards are many, both locally for the host and nationally in terms of environmental gains.