Abstract
1. State of the art In the framework of the European effort to expand the Renewable Energy capacity and to push towards a new meshed-grid approach to the grid infrastructure (“Supergrid”), the introduction of superconducting (SC) cables is considered a credible alternative to overhead power transmission. DC superconducting transmission lines have been implemented on small-scale pilot projects in China, Japan, Russia, Europe and South Korea. Besides reducing the environmental impact, they have resulted in reduced cable losses compared to the HVDC and HVAC copper cables, where losses can achieve up to 10% of the transmitted power. Hydrogen (H2), from the other side, is expected to become a game changer in the energy transition, especially for decarbonization of hard-to-abate end-use sectors (as a substitute for natural gas, NG) and for storage of renewable electricity. The Airbus company, for instance, has recently announced that the first airplane prototype fuelled by H2 only is expected by 2026. At policy level, the European Union aims at increasing the H2 share in the energy mix from the current 2% up to 14% in 2050. The possibility to couple the transmission of chemical energy in the form of liquid H2 (LH2) or liquid fuel (such as LNG) to the transmission of electrical energy in a “SC Energy Pipeline” (SCEP), or “Supercable” or “Hybrid energy transfer pipe” is not new in the field of electrical engineering and applied superconductivity. The MgB2 material seems the most suited for the LH2 cooling, given that its critical temperature is 38 K, while the H2 liquid-gas saturation temperature at ambient pressure is 20 K. Therefore, a SC cable based on MgB2 can be conveniently cooled by a flow of LH2. Several possible MgB2 cable configurations have been proposed in the literature. 1) Two SC layers separated by a high voltage insulatio. In each layer, 6 MgB2 tapes are divided by flattened copper strands. 2) In a completely different configuration tested at CERN (Geneva, Switzerland) in a helium gas flow, round strands are twisted around a copper core and wound in a rope-type cable. This cable was used to manufacture and test the 100-m-long SC links with currents up to 18 kA. 3) A similar cable architecture was also studied in the framework of the European BestPaths project, a project led by Nexans in conjunction with other industrial partners, including Columbus Superconductors, and CERN. A 30-m-long demonstration cable was tested with its termination and cooling system under high voltage and in realistic scenarios. Italy is the fourth largest energy-consumer in Europe, with a strong dependence on oil and NG (importing more than 90% of them), with also a considerable contribution of renewable energy. In the perspective of the decarbonization of the economy, with an eye on the increase of energy security, also in view of the recent events related to the possible unavailability of Russian oil and gas providers, energy system models have become crucial to assess the effectiveness of possible energy policies in pursuing the declared environmental objectives. Typically bottom-up Energy System Optimization Models (ESOM)) are used to conveniently examine the development of the energy systems based on the extensive techno-economic description of a wide variety of technologies spanning from the upstream and power sector to the end-use sectors. Note that many of the technologies in the iron and steel, non-ferrous materials and non-metallic minerals use both electricity and NG as input commodities and, as such, are the ideal candidates to benefit from the introduction of a SCEP in the industrial system, also in the perspective of reducing the national dependence form NG import. Typically, the engineering aspect of designing, developing or optimizing new technologies, such as the SCEP, when the Technology Readiness Level is still 2-3, does not come together with an assessment of its possible penetration in the energy system of a country, mainly because the two know-hows belong to different scientific communities with a loose connection, at least in Italy. The implementation of technical and economic features of SCEP systems in ESOMs would make it possible to understand their possible future role and contribution in the Italian energy system in decarbonization scenarios under different assumptions. The advantage of the coupling between the design activity and energy system modelling at an early stage of the conceptual technology development lies in the fact that the SCEP could earn from the energy system analysis clear indications about the conditions (e.g., minimum cost) at which it starts becoming an interesting option for any sector of the energy system. However, the combination of the engineering design of the SCEP and, at the same time, the techno-economic evaluation of its impact on the energy system has never been addressed so far. 2. Project activities The activity proposed here aims first at developing the conceptual design of a superconducting (SC) cable cooled by a flow of liquid nitrogen (LH2), for the combined transport of electricity and LH2 from the production sites to end-users. In fact, high-critical-temperature SC materials are capable of substituting resistive conductors in the power distribution, reducing electric losses and environmental impact. Their need for cooling at cryogenic temperature is typically met by liquid nitrogen or gaseous helium. However, the use of LH2 as the cryogen for such cables, when MgB2 is used as SC material, adds the distribution of LH2 to the benefits coming from the use of SC cables. The conceptual design of a Superconducting Energy Pipeline (SCEP), combining SC cable with the LH2 cryogenic cooling, is carried out first developing a simulation tool capable to address the best SCEP layout based on the identification of proper operating parameters (voltage level, power, LN2 flow rate, length, etc). The robustness of the design is checked by detailed electric and thermal-hydraulic analysis, realized with state-of-the-art numerical tools. Figures of merit for the SCEP and its techno-economic characterization are the main outcome of the design activity. The proposal goes well beyond the mere SCEP conceptual design, addressing also the issue of the possible penetration of SCEPs, as resulting from the design phase, in the Italian energy system by means of a bottom-up technology-rich optimization model, under the assumption of partial equilibrium of competitive markets for the energy commodities. Two different categories of final end-users are considered for the SCEP. First, electricity and LH2 together can feed existing or new technologies in energy-intensive industrial sectors needing both electricity and natural gas (NG), or directly hydrogen, assuming a 50% blending of NG and LH2. Second, the two commodities (electricity and LH2) can split at the outlet of the SCEP to cover separate end-use demands. The possible contribution of SCEPs to the decarbonization of the Italian industrial sector and to the decrease of the dependence on NG is investigated through the definition and simulation of suitable scenarios constraining the CO2 emissions and NG availability to progressively lower levels. The analysis is based on the open-source TEMOA-Italy tool, recently developed and positively benchmarked against the TIMES-Italy model, used in turn by ENEA to support the Quarterly Analysis of the Italian Energy System. Eventually, based on the identification of the industrial processes that could benefit more from the availability of SCEP, the most suitable locations in Italy for the SCEP are identified, based on the planned availability of Renewable Energy Parks and on the presence nearby of industrial installations that, according to the TEMOA analysis, would become suitable end-users for the SCEP.
Dettagli del progetto
Responsabile scientifico: Marco Breschi
Strutture Unibo coinvolte:
Dipartimento di Ingegneria dell'Energia Elettrica e dell'Informazione "Guglielmo Marconi"
Coordinatore:
Politecnico di TORINO(Italy)
Contributo totale Unibo: Euro (EUR) 80.341,00
Durata del progetto in mesi: 24
Data di inizio
28/09/2023
Data di fine:
28/02/2026
