Energy harvesting, reuse and upgrade to reduce primary energy usage in the USA

Two-thirds of input energy for electricity generation in the USA is lost as heat during conversion processes. Additionally, 12.5% of primary fuel and 20.3% of electricity are employed for space heating, water heating, and refrigeration where low-grade heat could suffice. The potential for harnessing waste heat from power generation and thermal processes to perform such tasks is assessed. By matching power plant outlet streams with applications at corresponding temperature ranges, sufficient waste heat is identified to satisfy all USA space and water heating needs. Sufficient high temperature exhaust from power plants is identified to satisfy 27% of residential air conditioning with thermally activated refrigeration, or all industrial refrigeration and process heating from 100 to 150 degrees C. Engine coolant and exhaust is sufficient to satisfy all air conditioning and 68% of electrical demands in vehicles. Overall, this study demonstrates the potential to reduce USA primary energy demand by 12% and CO2 emissions by 13% through waste heat recovery. A detailed analysis of thermal energy demand in pulp and paper manufacturing is conducted to demonstrate the methodology for improving the fidelity this approach. These results can inform infrastructure and development to capture heat that would be lost today, substantially reducing USA energy intensity. (C) 2011 Elsevier Ltd. All rights reserved.