Exergy as Criteria for Efficient Energy Systems—A Spatially Resolved Comparison of the Current Exergy Consumption, the Current Useful Exergy Demand and Renewable Exergy Potential

Abstract

The energy transition from fossil-based energy sources to renewable energy sources of an industrialized country is a big challenge and needs major systemic changes to the energy supply. Such changes require a holistic view of the energy system, which includes both renewable potentials and consumption. Thereby exergy, which describes the quality of energy, must also be considered. In this work, the determination and analysis of such a holistic view of a country are presented, using Austria as an example. The methodology enables the calculation of the spatially resolved current exergy consumption, the spatially resolved current useful exergy demand and the spatially resolved technical potential of renewable energy sources (RES). Top-down and bottom-up approaches are combined in order to increase accuracy. We found that, currently, Austria cannot self-supply with exergy using only RES. Therefore, Austria should increase the efficiency of its energy system, since the overall exergy efficiency is only at 34%. The spatially resolved analysis shows that in Austria the exergy potential of RES is rather evenly distributed. In contrast, the exergy consumption is concentrated in urban and industrial areas. Therefore, the future energy infrastructure must compensate for these spatial discrepancies.

Interlinking the Renewable Electricity and Gas Sectors: A Techno-Economic Case Study for Austria

“…Accordingly, the production of 2018 [38] is assumed to remain constant until 2050, as no significant increase is expected based on the current land use. However, additional expansion potential is theoretically available [25,39]. The trend of renewable generation of solar thermal energy and the availability of waste is defined by the Environmental Agency Austria (EAA) [40].…”

“…As mentioned before, in this scenario the useful exergy demand is used to define the need for energy services. The useful exergy demand for 2030, 2040 and 2050 is based on the Austrian current useful exergy demand, which has already been published by the authors [25]. These data include all economic sectors (industry, residential, transport, private and public services as well as agriculture) as well as all statistically considered energy service classes of Austria (heat demand at different temperature levels between 25 and 1500 • C, transport demand of cars, light-duty trucks, heavy-duty trucks, railways, navigation, aviation, stationary work engines, lighting, information and communication technology as well as process demands).…”

“…assumed [48]). The only change compared to the useful exergy demand published in [25], efficiencies adopted and to achieve full decarbonisation, the blast furnace route for crude steel production is replaced by a direct reduction process including an electric arc furnace. All used data and additional information about this scenario can be found in Appendix A.1.…”

“…Due to the enormous renewable electricity demand required to produce this amount of hydrogen, imports of green hydrogen will probably be necessary in addition to European production of green hydrogen [24]. Eventually, various European countries such as Germany [24] or Austria [25] do not have accessible renewable potentials to cover their current national primary energy demand.…”

Modelling Grid Constraints in a Multi-Energy Municipal Energy System Using Cumulative Exergy Consumption Minimisation

“…and storages (e.g., batteries, pumped hydro, thermal energy storage, etc) are necessary to provide the flexibility for the integration of variable RES [9]. In addition, the necessary energy networks must be taken into account, since renewable potentials and consumers are usually located in different places [10]. In such cases, MES can also reduce the strain on energy transmission and distribution infrastructure [11].…”