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Quadrennial Technology Review 2015
Chapter 6: Innovating Clean Energy Technologies in Advanced Manufacturing
Advanced Materials Manufacturing
Advanced Sensors, Controls,
Platforms and Modeling for
Combined Heat and Power Systems
Direct Thermal Energy Conversion
Materials, Devices, and Systems
Materials for Harsh Service Conditions
Roll-to-Roll Processing Sustainable Manufacturing - Flow of Materials through Industry Waste Heat Recovery Systems Wide Bandgap Semiconductors for Power Electronics U.S. DEPARTMENT OF
ENERGYQuadrennial Technology Review 2015 Combined Heat and Power Chapter 6: Technology Assessments NOTE: This technology assessment is available as an appendix to the 2015 Quadrennial Technology Review (QTR).
Combined Heat and Power (CHP) is one of fourteen manufacturing-focused technology assessments prepared in support of Chapter 6: Innovating Clean Energy Technologies in Advanced Manufacturing. For context within the 2015 QTR, key connections between this technology assessment, other QTR technology chapters, and other Chapter 6 technology assessments are illustrated below.
Connections to other QTR Chapters and Technology Assessments Fuels Grid Electric Power Transportation Buildings Critical Materials Direct Thermal Energy Conversion Sustainable Manufacturing / Materials, Devices and Systems Flow of Materials through Industry Wide Bandgap Semiconductors Combined Heat and for Power Electronics
1 Quadrennial Technology Review 2015 TA 6.D: Combined Heat and Power Introduction to Combined Heat and Power What Is Combined Heat and Power?
Combined heat and power (CHP) is the concurrent production of electricity or mechanical power and useful thermal energy (heating, cooling, and/or process use) from a single energy input. CHP technologies provide manufacturing facilities, commercial buildings, institutional facilities, and communities with ways to reduce energy costs and emissions while also providing more resilient and reliable electric power and thermal energy.1 CHP systems use less fuel than when heat and power are produced separately. CHP can operate in one of two
ways as follows:
Topping cycle: Engines, turbines, microturbines, or fuel cells generate electricity and the waste heat is
is used to drive an electricity generator, frequently a steam turbine or organic Rankine cycle (ORC).
Bottoming cycle CHP is often referred to as waste heat to power (WHP) and is one way to use waste heat recovered at industrial facilities. (See the “Waste Heat Recovery” technology assessment for additional details.) The efficiency of a CHP system is most commonly calculated by dividing the total usable energy output (electrical and thermal) by the total fuel input to the system. Today’s CHP systems are generally designed to meet the thermal demand of the energy user. CHP systems can achieve energy efficiencies of 75% or more compared to separate production of heat and power, which collectively averages about 50% system efficiency (Figure 6.D.1).2 Figure 6.D.
1 CHP systems produce thermal energy and electricity concurrently from the same energy input and can therefore achieve higher system efficiencies than separate heat and power systems. In a traditional (separate) system, waste heat from the power generation cycle is discharged to the environment and provides no useful energy service.
2 Quadrennial Technology Review 2015TA 6.D: Combined Heat and Power
CHP systems can be used in a range of settings and power levels, ranging from multifamily residential and commercial/light industrial systems typically producing as little as 50 kW of power to large industrial systems
that produce more than 20 MW of power. Applications include the following:3
Industrial (e.g., chemical production plants, refineries, pulp and paper manufacturing facilities, and biorefineries) Critical infrastructure (CI) (e.g., emergency services facilities, hospitals, and water and wastewater treatment plants) Institutional (e.g., retirement homes, research institutions, and government buildings)
The Value Proposition of CHP CHP is a commercially available technology that provides a fuel-flexible source of clean electricity and thermal energy, and the expanded use of CHP in the U.S. can offer benefits from greater efficiency to improved grid stability. In 2012, an executive order set a national goal of deploying 40 GW of new, cost-effective CHP (capacity) by the end of 2020, a nearly 50% increase from the 2012 baseline installed CHP capacity of 82 GW.4 Additionally, as of May 2013, 34 states and the District of Columbia have incentives or regulations encouraging the deployment of CHP and district energy, though the approach is not integrated at the national level.3 CHP is first and foremost an energy-efficiency resource and provides efficiency, performance, and reliability advantages. It allows users to produce needed electricity, heat, cooling, and mechanical energy while minimizing fuel consumption. CHP can lower overall energy demand, reduce reliance on traditional energy supplies, make businesses more competitive, cut greenhouse gas (GHG) emissions,5 and reduce the need for capital-intensive utility infrastructure improvements.
CHP can be a cost-effective solution in many applications, particularly in large, thermally-intensive process facilities. When using the following assumptions, Figure 6.D.2 shows an example of the overall cost of electricity (COE) for three CHP systems when compared to the average retail price of electricity for industrial and commercial facilities. The total COE, including capital, operations and maintenance, and fuel for a large CHP system is $0.080 per kWh (however, the net COE is $0.058 per kWh because less fuel is being used by the onsite boiler system).6 The net COE for the large CHP system is $0.058 per kWh, and the medium CHP system is $0.067 per kWh, which is slightly less than the typical price paid by industrial customers ($0.070 per kWh). The small CHP system COE is $0.099 per kWh, which is just below the average price paid by commercial customers ($0.103 per kWh).
2 demonstrates the current value proposition for CHP and shows potential opportunities to reduce system capital costs, particularly in smaller size ranges. The natural gas and electricity prices used in this analysis are based on typical retail prices from 2010–2015.7 Although the COE of CHP compares favorably with grid prices for electricity, costs can vary substantially by site and application. Also, the gap between CHP COE and grid prices is narrow, and such narrow margins alone may not be attractive to those considering CHP. The value proposition for CHP is improved when ancillary benefits such as increased reliability and resiliency, emissions reductions, and other benefits are included. CHP is typically most cost-effective in an environment where electricity prices are high relative to natural gas or other fuel prices (sometimes called the “spark spread”).
3 Quadrennial Technology Review 2015 TA 6.D: Combined Heat and Power Figure 6.D.
2 CHP Cost of Electricity (COE) Relative to Retail Prices.8 The thermal credit is the value of the displaced energy (e.g. boiler fuel) not needed in a CHP system.
Benefits of CHP Achieving national goals for climate, competitiveness, energy security, and resiliency will require a broadreaching strategy addressing both energy supply and end-use efficiency, including CHP. A significant portion of United States electricity generation does not make effective use of waste heat. Electricity is also typically generated far from the point of use, resulting in additional losses during transmission and distribution. The average efficiency of utility generation from fossil fuels has increased from roughly 32% in the early 1960s to nearly 36% today.9 Despite these efficiency gains, the energy lost in the United States from wasted heat in the power generation sector is still greater than the total energy use of Japan.10 CHP is a technology pathway to use otherwise wasted energy.
Installing an additional 40 GW of CHP (about 50% more than the current levels of U.S. CHP capacity) would save approximately one quadrillion Btu (one quad) of energy annually and eliminate over 150 million metric tons of CO2 emissions each year. The additional CHP capacity would save energy users $10 billion a year relative to their existing energy sources. Achieving this goal would also result in $40–$80 billion in new capital investment in manufacturing and other U.S. facilities over the next decade.11 CHP systems can provide effective, efficient, reliable, and less costly power to businesses across the nation.
3 shows the relative cost per ton of potential CO2 abatement of CHP compared with other energy efficiency and renewable energy technologies. These estimates are interpreted as the additional cost of producing electricity for technologies when compared to a “business-as-usual” baseline of conventional fossil fuel technologies. Given the high efficiency of CHP, these technologies can provide an economic pathway to CO2 emissions reductions.
4 Quadrennial Technology Review 2015 TA 6.D: Combined Heat and Power Figure 6.D.
3 Cost of CHP for CO2 Abatement Relative to Other Efficiency and Renewable Technologies12
CHP can provide a variety of benefits as follows:
Improved resiliency to electric grid disruptions, enhancing energy reliability and allowing for business
Improved U.S. manufacturing competitiveness by lowering energy operating costs to manufacturers. In many parts of the country, CHP provides not only operating savings for the user but also represents a cost-effective supply of new power generation capacity.
A path to lower GHG emissions through increased energy efficiency. Use of CHP currently avoids 248
Resiliency and Security CHP systems, when designed to operate independently from the grid, can provide critical power reliability for a variety of businesses and organizations while providing electric and thermal energy to the sites on a continuous basis, resulting in daily operating cost savings. A CHP system that runs every day and saves money continuously is often more reliable in an emergency than a backup generator system that only runs during emergencies.14 By installing properly sized and configured CHP systems, critical infrastructure facilities can effectively insulate themselves from a grid failure, providing continuity of critical services and freeing power restoration efforts to focus on other facilities. The use of CHP systems for critical infrastructure CI facilities can also improve overall grid resiliency15 and performance by removing significant electrical load from key areas of the grid. This is possible when CHP is installed in areas where the local electricity distribution network is constrained or where load pockets exist. The use of CHP in these areas eases constraints by reducing load on the grid. For this reason, CHP placement can be coordinated with the utility; this allows CHP design to be based on the conditions and needs of the host facility and also on the conditions and needs of the local grid system.
5 Quadrennial Technology Review 2015TA 6.D: Combined Heat and Power
State of the CHP Market The United States currently has an installed CHP capacity of over 82 GW of electric capacity at over 4,400 facilities, which represents 8% of current U.S. electricity generating capacity (by MW).16, 17 More than twothirds of these facilities are fueled with natural gas, but renewable biomass and process wastes are also used.