Session: 12-02: Process Heat for Industrial Decarbonization

Paper Number: 156250

156250 - Technoeconomic and Greenhouse Gas Impact Analysis of a Twin-Screw Compressor High Temperature Heat Pump for Spray Drying 

Abstract: 

25.05% of global energy is used for industrial heat[1]. As 90% of global heat energy is provided by fossil fuels, industrial heat is a massive contributor to greenhouse gas emissions[1]. High temperature heat pumps(HTHP) can reduce this carbon burden if they are used to replace natural gas burner systems. These systems could reduce industrial heat fuel usage in the United States by 38%[1]. Spray drying processes require the heating of large volumes of ambient air to high temperatures using natural gas. In this study, we analyzed the cost and emissions impact of using a HTHP for a spray drying application by modeling the energy use of a HTHP system to provide an equivalent quantity of heat currently supplied by natural gas[2].

We consider a case study of a spray drying facility that requires 880 kW of heat from 8AM-5 PM every day [1]. For this type of facility, we generate the natural gas and electricity demand, accounting for both heating efficiency of a natural gas burner system or the coefficient of performance (COP) of the HTHP system, respectively. The HTHP system uses cyclopentane as a refrigerant and a Herrick system architecture. We model the HTHP system in python to find the coefficient of performance.

Using this information about the quantity and timing of natural gas and electricity demand, we then consider the private energy costs to operate HTHPs and natural gas systems. We use statewide average costs of industrial natural gas and industrial electricity. We combine market data and literature component costs with outputs about the equipment sizing of the HTHP performance model to find the system capital costs [3].

In addition to the private costs of operating spray dryer systems, we consider the greenhouse gas emissions of both natural gas and HTHP alternatives. We estimated HTHP emissions for all locations in the continental US by summing the hourly electrical emissions for the HTHP system across a year. Our analysis uses each of the continental US’s 13 EIA grid regions included in their Hourly Grid Monitor [4]. We also consider the climate impacts of annual refrigerant leaks, and the refrigerant emissions generated during decommissioning. We calculate natural gas burner emissions with a similar emissions factor and the natural gas energy demand curve. We use the social cost of GHG emissions to quantify the economic impact of these emissions sources.

Using both the private and social costs associated with natural gas and HTHP spray drying systems, we calculate the net present value of each alternative. By finding the difference in net present value, we can estimate the overall savings of electrifying the spray drying heat supply. We find that 500 kW HTHPs generate more than $10,000 in yearly utility cost savings for industrial facilities in New York, Washington, New Mexico, and Arkansas when compared to natural gas. We also see emissions reductions in all states due to electrification of heat supply. 

[1]J. K. Jensen, W. B. Markussen, L. Reinholdt, and B. Elmegaard, “Exergoeconomic optimization of an ammonia–water hybrid absorption–compression heat pump for heat supply in a spray-drying facility,” Int. J. Energy Environ. Eng., vol. 6, no. 2, pp. 195–211, Jun. 2015.

[2]T. Gilbert, A. K. Menon, C. Dames, and R. Prasher, “Heat source and application-dependent levelized cost of decarbonized heat,” Joule, vol. 7, no. 1, pp. 128–149, Jan. 2023.

[3] G. Kosmadakis, C. Arpagaus, P. Neofytou, and S. Bertsch, “Techno-economic analysis of high-temperature heat pumps with low-global warming potential refrigerants for upgrading waste heat up to 150 °C,” Energy Convers. Manag., vol. 226, p. 113488, Dec. 2020.

[4] “Hourly net generation by balancing authority and energy source.,” Form EIA-930 Prod. Hour. Electr. Grid Monit., Jul. 2024, [Online]. Available: https://www.eia.gov/opendata/browser/electricity/rto/fuel-type-data?frequency=hourly&data=value;&facets=respondent;&respondent=CAL;CAR;CENT;FLA;MIDA;MIDW;MISO;NE;NW;NY;SE;SW;TEN;TEX;&start=2022-01-01T00&end=2023-01-01T00&sortColumn=period;&sortDirection=desc

Presenting Author: Joseph Tenpenny Purdue University

Presenting Author Biography: Joseph Tenpenny is a PhD candidate at Purdue University studying the economic impact of technologies related to the transition from fossil fuels.