The main aspects in which the innovation takes places within SHIP2FAIR are: (1) the design and development of the Replication Tool, (2) the solar technologies involved, (3) the solar heat integration in the industrial processes, (4) the control strategies and systems for operating the complete industry and (5) the capacity building programme linked to the project.
Most software tools developed for energy system simulation and sizing, focus on electricity generation or on building integration instead of heat for industrial processes. In addition, tools for processes simulation are capable to run integration calculations and optimization, but they do not include solar heat as an available module for heat source.
SHIP2FAIR will be able to gather all the steps required to develop a complete tool featuring the main processes from agro-food industries and integrating the solar resource evaluation, the selection of technologies, the design solar field size and optimal integration within the process to maximise the profitability of the solution. Furthermore, it will facilitate the economic evaluation of the proposed solution.
SHIP2FAIR involves two solar heating technology providers in the consortium, one of linear Fresnel (ISG) and one of ultra-high vacuum FPC (TVP). In addition, a reduced deployment of FPC will be considered in the smallest demo-site.
To select the best solution for each of the for demo-sites, a preliminary study has been developed (These technologies will be suitable for a large spectrum of process heat temperature (50-250 ºC)):
Linear Fresnel Collectors for RAR and M&R plants, as these collectors are more suitable for steam production and they have a high demand, so, if SHIP2FAIR is successful, future enlargements are possible.
Ultra high-vacuum FPC for ABC plant, as they show a high production rate for the location weather conditions and the process requirements.
Conventional FPC for RODA, since other options required too high upfront costs for such a small plant, so the most cost effective and simple technology has been considered, since the objective of the demo-site will be to test both the replication and the Control Tool. In addition, solar field visual impact is a key factor for wine cellars, and therefore FPC collectors are especially suitable as their impact is minimum.
Nevertheless, the final solution about the implementation is to be made during the project execution, once there is more accurate information about cost, characteristics and production rates of each collector technology, and depending on the demo-sites requirements.
May be done at two levels:
direct integration to individual heat sinks (process level)
and indirect integration to the hot utility system and then to the heat sinks (supply level).
Solar heat intensity and quality are not predictable on the short term, and its integration requires the variability of solar heat to be modelled seasonally; making the search for energy and cost-efficient solutions a complex combinatorial problem. Muster-Slawitsch et al.6 proposed a methodology based on pinch analysis for the evaluation of suitable integration points to aid in the design of the heat exchanger and storage system.
By combining pinch and exergy approaches, taking into account the time-variability of solar heat, optimum paths for heat integration can be identified. Nevertheless, the exergy approach and the combination of pinch and exergy methodologies on the solar heat integration into industrial processes is scarce.
The novelty of the study is based on the fact that demo sites could have different seasonal productions and solar collector solutions operate in transient state. The application of exergy and thermo-economic analyses will be adapted to the transient nature of the solar systems analysed. The exergy and thermo-economic analyses will provide conclusions about how the exergy efficiency varies in different operation conditions of the integrated system in order to compare them from the exergy and exergy cost point of views all over the year. Those results also allow identifying the maximum efficiency and figure out how to keep it in reasonable levels along the whole year.
Finally, it is worth to emphasize that unlike most of the classical exergy analysis found in literature which only leads with identification of exergy losses (irreversibilities), while in SHIP2FAIR a more meaningful for industry set of objectives is included, as it is presented SHIP2FAIR Replication and Control Tools will integrate easy-to-use modules to consider exergy and thermoeconomic analyses in order to optimize the SHIP design, as well as to draw conclusions to support the control of the overall system. Relying on these analyses, an optimal use of the solar heat will be made, thus optimizing the global installation. These assessments have been used in previous projects showing their capability to reduce the energy consumption up to 21% in industrial processes, while increasing the production by 14%.
Agro-food industries are continuously looking for new strategies to increase the efficiency and reliability of their processes in order to ensure their product quality. For that, the permanent monitoring and control of the processes is essential. When solar heating technologies are integrated, a precise control and monitoring of operating conditions is a key factor for ensuring the product quality and to avoid unexpected behaviors or instabilities.
Solar thermal systems exhibit features which make the development of suitable control strategies a challenge. These are in particular inertia effects, delays and the strong influence of fluctuations of radiation. Standard methods like the use of several independent Proportional-Integral-Derivative controllers (PID) have been used for solar thermal systems, but these approaches exhibit several weaknesses, in particular a susceptibility to oscillations. Thus, there is a strong tendency to employ more advanced control methods: Model-based methods from nonlinear control are used to improve the performance of basic control. For improved efficiency of the complete system, methods for basic (subordinate) control are embedded in a superordinate energy management system, often based on linear Model Predictive Control (MPC) or hybrid MPC approaches, making use of weather forecasts and load predictions. Combining model-based subordinate and model-predictive superordinate methods, the solar yield can be improved by roughly 10% for a large-scale solar plant.
Even these advanced approaches can be elevated to a higher level by making use of machine learning, adaptive algorithms, trans-sectoral energy optimization, taking into account time dependent energy prices for backup heating and heat upgrading systems. Also, developing improved and transparent user interfaces has become an important issue.
In the SHIP2FAIR project, the optimal performance of the solar thermal system will be achieved by implementing advanced control algorithms on all three levels discussed above, taking into account weather forecasts as well as the load forecast split into uncontrollable and deferrable loads maintaining as constraints both quality and volume of the production. Innovative controls will take dynamic prices of backup-up energy into account for their control strategy. Performance monitoring and determination of solar gains as a basis for solar incentive tariffs or guaranteed solar results, as well as fault detection by means of online analysis, will also be implemented.
The capacity building program is one of the cornerstones of SHIP2FAIR, as complement the demonstration of the technical developments made on the project to guarantee a strong promotion of the SHIP systems. In this sense, the presence of partners with strong dissemination and training capacities has been greatly encouraged in order to maximize the reach of these activities to multiple sectors, including current technical staff such as engineers and operators, plant managers, investors and stakeholders, as well as in the academic world in order to encourage students to specialize in this area.