Heat Waste Not, Want Not

Using waste heat to generate electricity, or Waste Heat To Power (WHP), the technology has been around in the United States for more than 100 years. In fact, about 8% of our country’s power generation capacity comes from approximately 82,000 megawatts (MW) of installed WHP. In Denmark, 43% of total electricity generation comes from WHP facilities.

Manufacturing processes waste as much as 20 to 50% of the energy consumed via waste heat contained in streams of hot exhaust gases and liquids. Implementing one of Benjamin Franklin’s memorable quotes, “waste not, want not”, WHP facilities currently reduce the US’s carbon dioxide emissions by 300 million metric tons per year – the equivalent of taking 50 million cars off the road. (Source: “The Energy Opportunity in Wasted Heat”, by Melissa C. Lott, 8 November 2012)

Since about 87% of WHP facilities are found at U.S. manufacturing facilities, this reduces the need for additional transmission and distribution capacity to deliver the energy while also reducing line losses.

But there is still more we could do in the WHP area to use energy wisely. Industrial waste heat should no longer be considered just a by-product of the manufacturing process, it is really a valuable resource for emission-free electricity.

If we look at the overall use of energy in the U.S. in Figure 1, we see that total energy consumption is around 98 quadrillion British Thermal Units (BTUs). The U.S. would need over 1,920,000 MW of generating capacity to supply the non-renewable/non-petroleum base energy demand of 98 quadrillion BTUs. Of this 1,920,000 MW, approximately 2,904 MW to 8,840 MW could be supplied by re-using waste heat from our industrial plants.

Figure 1 – U.S. Energy Consumption By Energy Source, 2015

This range of approximately 2,904 MW to 8,840 MW is shown in Graph 1 below for Waste Heat and Power projects.

Graph 1 - Remaining Technical Potential and Market Penetration Estimates

Source: “Waste Heat to Power Market Assessment”, March 2015, by ICF International, prepared for Oak Ridge National Laboratory.

The selected range in MW capacity for new WHP projects with waste heat resources above 450 °F represents the most economically-viable market for existing commercially-available technologies.

Drawing additional information from the ICF International study, the project payback for 6,760 MW of the total 8,840 MW of technically-potential projects is under 5 years as shown in Table 1.

Table 1 – Technical Potential With Breakdown By Payback Range (>450° F.)

When we compare those projects with a payback under 5 years, the potential WHP contribution to the U.S. energy demand is 2,736 MW as shown in Table 2.

Table 2 – Expected Market Penetration (>450° F.)

Should U.S. industry implement the most economical WHP projects of 2,736 MW, this would be approximately 0.14% of the national energy demand, supplied without the need for fossil fuels. Using the same metrics as stated earlier, the 2,736 MW of WHP projects would represent a reduction of 10 million metric tons per year of U.S. carbon dioxide emissions while taking the equivalent of 1.7 million cars off of U.S. highways.

Although new power generation projects receive a great deal of excitement and press when commissioned, some of the best energy project paybacks are in using the waste heat to produce power used internally at an industrial facility. Benjamin Franklin was right about energy years ago when he said, “Waste Not, Want Not”.

I am the principal at Reliant Energy Solutions LLC, a Certified Energy Manager, and can be reached at [email protected], or at www.reliantenergysolutions.com.