A Review on Solar Thermal Utilization for Industrial Heating and Cooling Processes: Global and Ethiopian Perspective

Abstract

A substantial share of the total energy in various countries is consumed by industries and manufacturing sectors. Most of the energy is used for low and medium temperature process heating (up to 3000C) as well as low and medium cooling capacity (up to 350kW). To meet the demand, the industrial sector consumes most of its energy in either thermal (heat) or electrical energy forms. The use of fossil fuels accounts for about half of the overall share. This resulted in a necessity to commercialize local and clean renewable energy sources efficiently considering the reduction of economic dependence on fossil fuels and greenhouse gases emission. As such, solar energy has proven potential and resulted in considerable development and deployment of solar heating industrial processes (SHIP) and solar cooling systems in recent times. Thus, an attempt to present a review of the available literature on overall energy intensiveness, process temperature levels, solar technology match, and solar thermal system performance and cost have been made in this paper. The review also includes identifying the potential and relevance of involving solar thermal for industrial heating and cooling demand. As a result, at least 624 SHIP including promising large-scale plants and 1350 solar cooling systems most of them in small and medium capacities in operation are identified. Though limited data is available for solar cooling potential and installation, investigations projected the global SHIP potential to 5.6 EJ for 2050. Consequently, given the presence of many low and medium temperature heating processes and cooling capacities in industries with immense solar energy potential, developing counties such as Ethiopia can take experience and pay attention to the development of sustainable industrial systems.

A review on Solar Thermal System Design, Integration, and Techno-economic Modeling for Industrial Heating and Cooling Processes

“…The heated fluid (usually air, water, or oil) is then used for applications and processes based on the specific end-use in water-heating (domestic, commercial, and industrial), space-heating, and pool heating systems (Lund et al, 2008) or to charge a thermal energy storage tank from which the heat can be drawn for use later (at night or cloudy days) (Prakash, 1994). Solar cooling is also identified as a potential application area, especially in the range of middle and small cooling capacities (Gebreyohannes et al, 2021). Solar collectors are the key components of solar thermal systems and can absorb nearly the entire solar spectrum; around 50% of the sun's energy is invisible to the human eye in the infrared spectrum, as heat (Penn State University, n.d.).…”

“…At least 624 SHIP systems, totaling 608,994m² collector areas were in operation at the end of 2017. Investigations projected the global SHIP potential to 5.6 EJ for 2050 (Gebreyohannes et al, 2021).…”

“…In a preceding couple of decades, though the dominant means for supplying cooling capacities have been compression refrigeration systems driven by electrical energy, the use of sorption refrigeration machines, which can be driven with thermal energy in the temperature range of 55-180°C have been used to supply cooling. Having been commercially available, absorption chillers are also mature and reliable technologies (Gebreyohannes et al, 2021). Currently, there is increasing use of solar cooling solutions for large public and private buildings as well as industries.…”

“…These systems show high potential in energy saving compared with conventional electric systems. By the end of 2015, an estimated 1,350 solar cooling systems were installed worldwide (Gebreyohannes et al, 2021).…”

“…Financially, the total investment costs for solar thermal systems, with few exceptions and differences at the national levels range from EUR 180 -500/m 2 . This equates to solar thermal systems in the range of EUR 450 -1100/kWth and leads to an average energy cost of EUR 0.02 -0.05/kWh for low-temperature and EUR 0.05 -0.15/kWh for medium-temperature applications and is comparable to grid-parity in many locations (Gebreyohannes et al, 2021).…”