Geothermal Water Component of Land-Based Fish Farm—A Case Study of the Sustainable Blue Economy Architecture

Abstract

Geothermal water, as a by-product of renewable energy generation, can be appreciated as part of a sustainable Blue Economy in terms of resource effectiveness. This could be part of urban geothermal resource parks in the near future. City aquaculture integrated with urban farms running in a cascading model of energy and material consumption can provide an advanced energy-water-food nexus in densely populated areas, evolving into a refined Nature 4.0 habitat. This case study of the world’s first climate-controlled, closed salmon farm based on geothermal resources presents inclusive, water-sensitive design principles and resilient urban planning, where architecture brings aquatic ecosystems indoors. This is also an example of how to reduce investment risk and integrate geothermal development with sustainable, innovative fish farming based on water circulation systems (RAS) and digital technologies to sustain life-support systems. This greenfield project on Poland’s Baltic coast highlights the potential for geothermal investments, demonstrating that even low-temperature extracted water can serve as both a renewable energy source and a valuable resource. Having operated successfully for over a decade with positive certification, this model of efficient geothermal resource utilization appears to be well-suited for replication and broader implementation.

1. Introduction

Geothermal heat and power production have several advantages over other renewable technologies and conventional methods of energy production. Scientists and experts involved in the research of geothermal resources have emphasized the high potential for their use in Poland, both as a source of renewable energy and for various uses of geothermal water [1,2]. Water, as nature’s lifeblood, is an intrinsic part of ecosystems. Geothermal water is part of the global hydrosphere and is estimated to account for about 4.1% of all planetary water resources in basic storage [3] (p. 153). Historically and currently, geothermal development projects have been dominated by the energy aspect of using geothermal fluids, where water is mainly treated as a heat transfer medium. Water has become a by-product of renewable energy production with social [4] and environmental implications [5,6]. The chemical composition of geothermal water can vary depending on the geological conditions, location, and drilling method. These qualities can influence the manner and scale of their utilization. However, it is a resource that requires greater attention and efficiency. This is particularly important in areas where water resources are scarce or limited. Different perspectives and approaches to the exploration and use of geothermal water deserve further consideration. Water can be considered an energy carrier, polluted effluent, chemical substance, life-sustaining force, or regenerative element that shapes spaces for living beings.

The utilization of selected geothermal waters can also be an important part of the energy-water-food nexus, which is becoming an architectural challenge in the urbanized world of the 21st century. Commonly, the architectural perspective on spatial development [7], including geothermal development and resource utilization, typically follows a thinking model that moves from the general to the specific—a top-down approach—and then reverses. A different, only reversed, model of thinking is the bottom-up, specific-to-general approach, which is sometimes represented among expert engineers who focus exclusively on the technical and economic aspects of achieving a planned goal, for example, obtaining renewable energy resources. The result of this second mindset may include abandoned geothermal investments [8,9,10] or increased risk costs in stand-alone geothermal projects, as noted by van Wees et al. [11]. The present paper employed a process-oriented case study to discuss the relationship between the activities of the various actors involved in strategic investment planning and the results of these activities. The organizational context was found to be crucial for understanding the actions taken and the results. As with other qualitative research methods, case studies provide a holistic picture of the context. In order to comprehend the notion of sustainable Blue Economy architecture, it is imperative to acknowledge the numerous interconnected dimensions that must be taken into account. The definition of sustainable development signifies that economic, social, and environmental aspects form a unified whole, wherein the boundaries between these dimensions become diffuse and intertwined.

1.1. The World’s First Indoor Salmon Farm Based on Geothermal Resources—The Case Study from an Architectural Perspective

The specific case study presented here describes a geothermal development project in which low-temperature thermal water was delivered to a large, land-based, indoor fish farm. The establishment of this Atlantic salmon farm was related to a change in the primary investment plans of a local investor. The intention was to use a single geothermal well system to supply heat directly to a hotel complex under construction, with outdoor thermal pools in an attractive seaside tourist destination in northern Poland. The cooled spent water after basic treatment was planned to be discharged directly into the Baltic Sea, following the relevant legal regulations. Ultimately, the low temperature of the extracted geothermal fluidsejected from the well under high pressure, combined with their suitable chemical composition, convinced the investor to create a unique salmon farm based on geothermal resources in a closed, controlled environment. The completed salmon farm has become a specialized building-filter for septic, mineralized geothermal water resources, which undergo treatment and mixing with fresh water to create a safe environment for salmon farming. The recycled water is then purified to a high grade of purity and cooled to flow into a nearby coastal brackish lake. In this environmentally friendly manner, the natural water cycle is closed. The two scenarios for geothermal development presented here, in which geothermal water is the primary agent, can therefore be described by their divergent impacts and levels of environmental effectiveness. Using a speculative design method and comparative analysis, the potential for exploiting geothermal resources in land-based closed fish farms in a built environment was indicated. This can be characterized by contrasting effects on the pattern and intensity of land use, the density and type of planned infrastructure, or the architectural expression with spatial organization of the designed buildings and their surroundings. In the context of water resource use, including geothermal water, the need for a shift in awareness regarding its perception was emphasized as early as the initial planning and architectural design stage. Examples of well-known architectural projects in which the perception of a valuable water resource has become a key element in the design process are cited as the background. The cited examples, along with the study described in this case, form part of the broader definition of the Blue Economy. Within this definition, the efficient management of geothermal water and cascading its use provide a basis for considering the level of sustainability. This text presents an analysis of the potential for exploiting geothermal resources in Poland in comparison with the European context. This demonstrates the feasibility of replicating the technological and planning solutions employed at the land-based Jurassic Salmon farm. As part of efforts to expand the sustainable Blue Economy, the feasibility of land-based indoor fish farms using geothermal resources in rural and urban areas was analyzed. The greater ecological effectiveness of implementing such projects in urbanized areas was highlighted. However, this approach is associated with a more complex development process and significant investment costs. Nevertheless, the reduction in supply chain length, coupled with the potential for cascading energy and water resource use within an environment characterized by extensive grid infrastructure, can reduce operating costs. This, in turn, will ensure the sustainability of the project while concurrently contributing to the development of the circular economy and the regeneration processes of the built environment. Notably, the location of the Jurassic Salmon farm is not optimal and, in fact, somewhat fortuitous. However, on a symbolic level, a hermetically closed salmon farm has been established in the area of Trzęsacz, a former fishing village, where traditional fishing with boats that form the basis of the Blue Economy has not been practiced for many years. This development has the potential to pave the way for the emergence of a sustainable Blue Economy in the 21st century.

The potential for the use of geothermal water for land-based, controlled fish farming is expanding the boundaries of Blue Economy activity from coastal areas to areas associated with developing geothermal enterprises, often far from natural water bodies. Given the increasing urban demand for renewable energy sources, including geothermal energy, there is a growing need to explore the potential for developing urban fish farms in conjunction with geothermal investments. The Jurassic Salmon farm, regarded as a pioneering model, has been operational for more than a decade. The farm’s salmon is now a recognizable product in the market, competing successfully with salmon from non-sustainable sources. The Jurassic Salmon farm’s well-established position in the consumer market, as well as its environmental certifications related to fish farming, attest to the sustainability of the project and its potential for further implementation. This is a fundamental reason for promoting further research into combining closed fish farms with geothermal water resources, thus creating an innovative architecture for a sustainable Blue Economy.

1.2. The Main Research Problem and Related Open-Ended Questions for Investigation

Assuming that global geothermal water resources are part of the broadly defined Blue Economy, one significant research challenge is to develop strategies and identify methods to achieve and regenerate a targeted, sustainable Blue Economy. The key aspect is the utilization of effluents, especially the reduction of environmental risks. This problem is intensified in the geothermal investment model, wherein a single well is utilized as the production well and the spent geothermal water is discharged into open natural reservoirs, thereby exposing them to thermal pollution. The primary version of geothermal development in Trzęsacz may have been such a case.

Another aspect of a sustainable economy is the efficient use of water resources and effective methods of water conservation. The land-based fish farm located in Janowo village, which is the focal point of this study, has the potential to serve as a model for the future expansion of similar initiatives.

The following questions were posed in an open-ended manner to establish the parameters for discussion and the exchange of information among interested parties. The overarching question pertains to the definition of sustainable geothermal investment and sustainable fish farming within the Blue Economy from a long-term perspective. The concept of sustainability has been debated for more than 30 years (at least since G.H. Brundtland’s 1987 report), which has resulted in many definitions and contested opinions to date [12,13]. In this case study, we attempt is to answer this question. This is regarded as a modest contribution to the recognition of the phenomenon of the indicated terms against the background of a vast area of research.

Another question pertains to the need for an interdisciplinary approach that integrates diverse research domains and perspectives on reality. This raises the issue of whether the exploitation and utilization of geothermal water resources might challenge sustainable architecture and urban or regional regenerative planning. This issue appears to be of significance, primarily in terms of promoting best practices and expanding the domains of implementation and replication of this way of thinking.

The increasing trend of incorporating eco-effectiveness principles into architectural design has led to further inquiries. Does geothermal energy development embody a water-sensitive design approach and water-wise planning? In what ways can the eco-effectiveness of geothermal water utilization be enhanced?

A more specific question relates directly to the case study described. Can geothermal waters be directly used as a vital part of life-support systems in natural and novel ecosystems? The case study addresses the issues identified in the following questions; however, due to the experimental nature of the investment and the strong support from EU funds, it is difficult to determine the validity and representativeness of the measures applied. Conversely, the high effectiveness of the use of water resources in this project, the adopted functional and spatial design, and advanced technological solutions result in high quality of reared fish and can probably become a good example to follow under favorable circumstances. The value of a case study as a qualitative research method is determined by its transferability to other contexts. The phenomenon of land-based indoor fish farming is characterized by dynamism and is not yet a mature or well-established practice. The case study presented also serves as a pretext for conducting speculative design [14]. It addresses the issue of urban agricultural development in conjunction with city aquaculture based on geothermal resources. The rationale for the cascading model of geothermal energy consumption also applies to water resources within a circular economy. Speculative engineering of aquatic food production, soilless cultivation techniques, vertical hydroponic farms, and algae culture accumulated in urban geothermal resource parks [15] are perhaps no longer a distant future in which the underestimated value of geothermal water deserves special attention. The utilization of this process-oriented case study facilitates the operationalization of knowledge, thereby enabling its transfer to alternative contexts.

2. Materials and Methods

2.1. The Field of the Study and Methods

The rationale for using a case study is predicated on the potential to concentrate on the phenomenon under investigation while concurrently considering its operability within the context of the specific case. The presented material should be regarded as a report from an architectural point of view, in which the author, as an architect, took part in the process of urban planning, architectural design, and building supervision during the implementation of the geothermal investment and construction of the Jurassic Salmon farm. This is a synthesized, process-oriented, single case study of a relational and evidence-based nature. A comprehensive range of evidence and data collection techniques were employed, encompassing field observations, analysis of public and company documents, and review of technical drawings, architectural plans, and specifications. This paper uses an exploratory speculative design method to enrich the planning process and identify design assumptions in other contexts. The willingness to achieve high ecological standards in the geothermal project was shown by all parties involved in this enterprise. A key aspect of the investment process undertaken here was the shift in focus from energy concerns to the efficient utilization of geothermal water. From an architectural perspective, water is a central and defining resource for the project. This consideration played a crucial role in developing design solutions that ensure an affordable and suitable environment for salmon farming within a single facility in greenfield development. The principles of integrated design and adaptive architecture have brought together a wide range of specialized scientific disciplines and practical applications. The construction of the necessary infrastructure in a vast rural area, with consideration given to the possibility of its expansion, and the analysis of its rational use, involve an efficient local urban planning process. Regional spatial planning issues concern the environmental and economic impact of geothermal investment, as well as the construction of a large-scale fish farm, its transport service, and logistics. The project also touched upon social aspects and the related involvement of local municipalities. An environmental impact assessment was conducted before initiating both the geothermal investment in Trzęsacz and the land-based fish farm in Janowo. The positive outcomes of these assessments enabled the relevant authorities to issue a building permit to the County Office of Gryfice. Following the successful completion of the construction phase, the farm underwent a series of rigorous acceptance procedures, which were passed. During the subsequent decade of operation, the Jurassic Salmon farm obtained positive environmental certificates, including an international certificate for sustainable fish farming, thus confirming the resilience and stability of this innovative investment.

Aspects of modern aquaculture were combined with advanced technological solutions, including the digitization process, where a key element was to ensure high-quality geothermal water with the required composition and beneficial temperature for fish farming. After the completion of construction and putting into operation of the Jurassic Salmon farm, reflections and questions arise about the further development of this type of geothermal energy investment and its broader implications, mainly in urban areas

2.1.1. Aquatic Environment Transformed by Architecture—Design Inspired by Water

In this case study, the architectural aspects and the way the space is configured are focused on integrating exploited geothermal resources with the requirements of modern aquaculture. In this context, the role of architectural design extends beyond the standard dictionary definition of architecture as “the profession of designing buildings, open areas, communities, and other artificial constructions and environments, usually with some regard to aesthetic effect” [16]. As architect Oscar Niemeyer states, “Architecture is invention”, while Francis Kéré emphasizes that “Architecture is not just about building; it’s a means of improving people’s quality of life” [17]. In the case presented, it appears that the adaptive architecture contributes to the quality of life and the creation of the right conditions for the rearing of the valuable fish species Atlantic salmon [18] based on the use of geothermal water. Appropriate design solutions made it possible to create stable bioclimatic conditions, which differed for each stage of fish breeding inside the farm building. Ensuring the efficient distribution of external and internal infrastructure supplying the fish farm with geothermal water, fresh water, or electricity was a design challenge both on a micro scale—the compact architecture of the farm building—and on a macro scale—the urban network of pipes and lines across two neighboring communities. In order to comprehend the expanding field of interest in architecture, it is necessary to consider the argument advanced by the author of Organization Space, Easterling [19], that architecture is essentially a matter of organization. In a broad sense, architecture encompasses the dynamic planning of the investment process, its structuring, and the analysis of the life cycle of designed objects and their surroundings. Alternative simulations of project development and building scenarios for project implementation, considering the availability of resources, potential of the site location, or defining target user groups, are currently an integral part of architectural services. The selection of resources, materials, and technological solutions influences the final character of the architecture, its aesthetics, its use, and its impact on the environment. In the case study, the planned acquisition of geothermal resources was intended to be distinctly reflected in the designed architectural structures.. The main resource influencing the chosen architectural convention and space organization is geothermal water. Warm thermal water influences the architecture of the recreational and free leisure environment, just as cool geothermal water influences the architecture of the artificial aquatic environment of the fish farm in a separate manner.

For most architects, water has traditionally been seen as a crucial element of architectural expression, as a medium that affects our senses, is essential to life, and influences the microclimate and our well-being, as Nichols emphasized in his book, Blue Mind [20]. Water as an essential element of architectural composition has been exploited in Frank Lloyd Wright’s Fallingwater residence, Louis Kahn’s amphibious Capitol complex in Dhaka, Peter Zumthor’s atmospheric Therme Vals, or Carlo Ratti Associati’s dripping Digital Water Pavilion. Leaving aside aesthetic and compositional considerations, a quarter of a century ago, architect Richard Rogers recognized clean water as a critical resource [21]. When Barlow calls for the creation of a global water ethic, pointing out that “available freshwater is less than half of one percent of the world’s total water stock“ [22] (p. 213). Thackara stresses that people are cut off from “water as a living system by design” [23] (p. 36). Kellert, author of Nature by Design, highlights the excessively narrow view of water as a technological product and the result of engineering that separates humans from the natural world [24]. Architects Brownell and Swackhamer reflect on the growing awareness of the depletion of global water resources. This encourages architects to consider hydrospheric processes in contemporary design and to change their perception and value of water as a life-sustaining resource [25]. According to the World Business Council for Sustainable Development, “valuing water means recognizing and considering all the benefits provided by water—including economic, social and ecological dimensions” [26]. For some years now, the standard in sustainable architectural design has been the introduction of ‘water sensitive design’ or ‘water wise planning’ principles [27,28]. The rational and effective use of resources will also extend to geothermal water by design. Viewing design as a process for shaping the future, the concepts of resilience and eco-efficiency are becoming increasingly integral to our planning and agile organization. The design thinking must therefore be changed “from doing less harm to leaving things better”, following the “Cradle to Cradle” approach [29]. The primary focus of this study is the reduction of failure and uncertainty risks, with the introduction of concepts aimed at adaptability, long-term regeneration, and the restoration of natural or novel ecosystems in which water, including geothermal water, plays a fundamental role.

2.1.2. Inclusive Concepts for a Sustainable Blue Economy in the Context of Geothermal Resources

Geothermal water as part of planetary “Blue Gold” “can be a limiting resource in many areas of the country and world, and given the growth in competing demands for its availability, care must be taken to ensure geothermal development takes place such that alternative water uses are adequately taken into account” [30] (p. 2). Water is an extremely important resource, with an impact on social relations and is the basis for what is often called the Blue Economy. Today, the aforementioned terminology is used in diverse ways. Gunter Pauli, author of the book The Blue Economy: 10 years—100 innovations—100 million jobs, in which the term “The Blue Economy” first appeared, stressed that the main inspiration for his attitude was nature with its principles and processes, where interconnected problems are opportunities [31]. Another extensive definition characterizes the Blue Economy as “a concept that envisages the more effective and efficient use and management of water resources within a more sustainable circular economy” [32]. The Blue Economy is a consequence of the development of the Green Economy idea, transferred to the marine and aquatic environment, and is an attempt to define sustainable methods for managing the resources of oceans and terrestrial water basins. Diverse activities related to ocean services or complex aquatic ecosystems can be considered targeted areas for sustainable Blue Economy development. One of these activities is the exploitation of geothermal water and its sustainable use as part of the global water cycle. Water extracted from geothermal boreholes can play a regenerative role in spa facilities or be a significant resource for the productive regeneration of green spaces, urban forest plantations, or crop development in urban agriculture and aquaculture. For this reason, the sustainable use of geothermal water will need to follow the principles of effective local resource management and sensitive-water design [33].

2.2. Location of a Coastal Geothermal Development, Its Implications, and Background

The case study presented in this article on the use of geothermal water for salmon farming in Janowo can be considered an innovative example of Blue Economy research. It is a good practice in water treatment within the positive impact planning process and architectural regenerative design. Geothermal water is a source of clean energy that could be relevant to a range of regions in Poland and Central Europe, as Rem Koolhaas’ OMA architecture studio discovered for the Geothermalia region on the redrawn map of Europe entitled Eneropa. Other European regions with potential for different renewable energy capabilities include the Mediterranean land of Solaria, the Tidal States, Biomassburg, and New Hydropia [34], where the management of water resources must follow the principles of a sustainable Blue Economy. The possibilities of using geothermal resources in Poland are relatively good, as deposits with temperatures of 30–130 °C are estimated to cover about 40% of the area in Poland [35]. This gives a possibility of producing about 1512 PJ/year, which would satisfy the national heat demand at the level of about 30%. At present, the total installed geothermal power of the six operating geothermal heat plants supplying central heating networks in Poland is about 76 MWt annually [8]. Two such heat plants are located in the same region (West Pomeranian Voivodeship) as the case study described. The geothermal heat plant in Pyrzyce (started up as the second one in Poland in 1996) and in Stargard (heat plant started up in 2005), which is the second largest geothermal heat plant in Poland in terms of power produced (approx. 11 MW with an annual heat production of 187 TJ). In Pyrzyce, a town with a population of 12,000, geothermal water is extracted from a borehole 1640 m deep. The water is characterized by a high mineralization level (121 g/L) and a temperature of 64 °C. In 2019, the share of geothermal water was 73% of the heat production required by the city of Pyrzyce [36]. In Stargard (86 thousand inhabitants), the water is also characterized by high mineralization (150 g/L) and a temperature of about 84 °C. It is extracted from a depth of 2670 m and satisfies about 30% of the heat demand in the heating season, while in summer, it becomes the only and sufficient source of hot water for the city [37]. It is estimated that the development of thermal energy based on geothermal resources is too slow, which ranks Poland only 12th in Europe in terms of the use of geothermal energy [8,38]. With regard to the use of geothermal resources for fish farming, there is only one such farm in Poland in Janowo near Trzęsacz, which is the subject of this process—oriented case study. The use of geothermal resources for recreational purposes, including spa bathing and hydrotherapy, is developing more dynamically [39,40]. Some places try to attract tourists all year round. A factor encouraging people to stay regardless of tourist season is having, among others, a rich offer of thermal baths. Established Terma Uniejów, Termy Maltańskie in Poznań, Terma Bania in Białka Tatrzańska, Terma Bukowina, Termy Cieplickie, or Tarnów Termy offer bathing in waters often obtained from single geothermal boreholes, where temperature at the well outlet ranges from 45 to 87 °C, depending on the location. The frequent absence of return injection wells is linked to the relatively high cost of drilling works in Poland, which raises both investment risk and capital expenditure [38]. Unfortunately, these facilities do not operate in a cascading model of energy consumption and water resource use. Not all geothermal bath developments in Poland are profitable ventures, as exemplified by Termy Warmińskie, which was completed in 2015 in Lidzbark Warmiński and put up for sale [41]. The geothermal risk insurance fund, which has been postulated for a long time, does not work in the country [38]. This situation does not deter investors from taking on high risks and planning further developments to harness the untapped potential of geothermal resources in Poland. Currently, there is a government program supporting the development of geothermal investments in the state called “Poland Geothermal Plus” under which 15 municipal geothermal projects are financed [42]. Therefore, it can be concluded that the trend in the use of geothermal resources in Poland is increasing, and further new investments are expected soon. The analyzed case study is a part of this somewhat spontaneous mechanism of planning and implementation of geothermal investments in Poland in the recent period and at the same time becomes a subject of speculative scenarios for their effective continuation. The location of the case study is marked on a map of geothermal resources in Europe (Figure 1). Initially, this renewable energy project was planned to support the expansion of a popular seaside resort, enhancing its appeal for domestic and international tourism. It was planned in the village of Trzęsacz on the Baltic coast in north-western Poland.

The former fishing village of Trzęsacz is situated on the cliff coast of the Baltic Sea in the Rewal municipality of the West Pomeranian Province (Figure 2). The area belongs to the Polish Lowlands, where the main geothermal water resources are associated with Mesozoic formations, with Lower Jurassic and Lower Cretaceous formations being particularly promising. Pomeranian geothermal resources are characterized by considerable geothermal potential and low enthalpy [44]. It has been found that some areas may hold geothermal waters with varying reservoir temperatures, ranging from 20 to 80–90 °C, and even above 100 °C [45]. A private investor’s original plan for the seaside resort of Trzęsacz was to build a year-round holiday resort on the premises of the historic palace. The aim was to revitalize the degraded 17th-century palace with its extensive historical park complex as an exclusive hotel. The investment was complemented by the construction of a congress center with a recreational swimming pool complex in the form of an aqua park on the edge of the palace park. One of the main attractions was a complex of indoor and outdoor thermal pools, covering a total water surface area of approximately 1500 m² and supplied by geothermal sources. Architecturally, the planned buildings were inspired by historic farm buildings, with an inner courtyard where the largest natural pool with salt geothermal water was designed to be open all year round. Some treatments were designed to relieve allergies, respiratory ailments, and skin problems (Figure 3). An analogous water park, the Ostsee Therme [46], supplied by geothermal resources (the thermal water in the pools is about 36 °C), operates in the German frontier town Ahlbeck—a famous imperial spa—3 km west of the Polish harbor of Świnoujście in the Odra River estuary.

It was assumed that the commercial use of geothermal energy for heating the hotel and swimming pool complex would be an important part of the development of the Trzęsacz investment. The direct use of geothermal water for hydrotherapy, with special attention to balneology understood as “the practice of using natural mineral water to treat and cure diseases” [49] (p. 172), was an attractive offer for future customers. As medical experts have stated: “Health benefits due to the thermal effects of balneological water can also be quite significant. The pulse rate and cardiac output begin to increase once the water temperature reaches 38 °C or higher. Capillary vessels, arterioles, and venues begin to dilate in the peripheral circulatory system, and an increase in volume and the rate of blood flow and a decrease in systemic vascular resistance are noted. This reduces the load on the heart, as the dilation of the venous system reduces the cardiac preload due to an increase in the venous blood pool and a decrease in venous return. The use of thermal waters in hot pots is, thus, useful for relaxation and the treatment of some nervous disorders” [50] (p. 240).

3. Findings

The increase in clean energy production standards globally is driving the dynamic development of geothermal energy. It is evident that the nature of these projects is characterized by a high degree of risk, which is attributable to three principal factors. Firstly, the methods employed in drilling are inherently risky. Secondly, there is a degree of uncertainty with regard to the temperature of the heated water and its chemistry. Thirdly, there is a risk associated with the availability of resources. An essential element in this type of investment is the estimated level of losses and gains, entropy rate, and syntropy rate. Risk mitigation scenarios are key to avoiding the failure of investments with high entropy levels. It is recommended that entropy reduction methods, complemented by syntropic development models, be considered in emerging urban plans, feasibility studies, and multidisciplinary construction projects. This approach is also consistent with investment risk assessment strategies [51].

3.1. Specification and Evaluation of Geothermal Resources in Trzęsacz

In Trzęsacz, based on preliminary analyses, high geothermal water temperatures of 35–38 °C were expected, especially since geothermal intakes for municipal heating systems in Pyrzyce and Stargard have been successfully implemented in the region. With financial support and subsidy from the National Fund for Environmental Protection and Water Management (NFOŚiGW), the investor developed a geothermal water intake—Trzęsacz GT-1. A 1224.5 m deep borehole was drilled in the outskirts of the palace park, and a geothermal fluid with a flow rate of 180 m³/h and a working temperature of 25.4 °C was extracted (

Table 1. Physical and chemical characteristics of geothermal fluid from the Trzęsacz GT-1 borehole. Source: Sadowski J. [53].

Sequence Number	Parameters	Values
1	Temperature	25.4 °C
2	Salinity	16‰
3	Self-Outflow Rate	180 m3/h
4	pH	7.7
5	Nitrites	0.05 mg/L
6	Nitrates	2 mg/L
7	Ammonia	1.85 mg/L
8	Manganese	0.06 mg/L
9	Iron (total)	1.32 mg/L
10	CO2	20.7 mg/L
11	Phosphates	<0.15 mg/L
12	Alkalinity	8.10 mmol/L

) [52]. The obtained thermal parameters of the geothermal water were lower than assumed, although the chloride-renin-sodium brine extracted from the Lower Jurassic aquifer had a mineralization of 13.5 g/L. The exploited and evaluated geothermal water has positive properties for balneological purposes, which was confirmed by a relevant certificate issued by the Institute of Balneology in Poznań.

In terms of private commercial investment, the insufficient temperature of the extracted geothermal fluid and the excessive cost of a second borehole for the spent return water did not guarantee the economic viability of the planned outdoor thermal baths in the palace complex. (Figure 4). This meant that more heating of the pool water by other energy sources would be necessary.

A similar case occurred in a public investment project for a water park in Lidzbark Warmiński, in the north-eastern part of Poland. The temperature of the water extracted from the geothermal borehole was only 21 °C. This did not stop the municipal authorities from building thermal baths and heating the pools in the aqua park, including outdoor pools, using heat pumps, which increase operating costs [10,41]. An entrepreneur in Trzęsacz revised his development plans and decided to use geothermal water in a unique way. Suddenly, the heavy risk of investing in geothermal energy was transformed into another investment risk associated with the live, vulnerable Atlantic salmon rearing stocks.

3.2. Transfer of Geothermal Resources and Capital from Trzęsacz to the Salmon Farm in Janowo

Initially, it was planned to recover heat energy for the heating system in the palace building and then pump geothermal water for agricultural production on the investor’s land located in Janowo (Karnice commune) at a distance of about 5 km from the geothermal production well Trzęsacz GT-1. The currently pumped and already partially cooled geothermal fluid is utilized after treatment, mainly for technological purposes, in fish farming. The idea of fish farming based on thermal water resources was born in 2010 because of analyses conducted by local investors who postponed their plans to build thermal pools in Trzęsacz. The fish farming project was implemented with EU funds under the Operational Program “Sustainable Development of Fisheries and Coastal Fishing Areas 2007–2013” measure 3.5 Pilot Projects and the research program “Using geothermal saline water for fish farming and breeding”. The scientific part of the project was led by a team of scientists from the West Pomeranian University of Technology in Szczecin under the direction of Sadowski J., a renowned local expert in this field [53]. The construction project was conducted with the procedural involvement of the municipalities of Karnice and Rewal. The analyzed project, due to its location in a rural area, is naturally a greenfield investment. Geothermal renewable energy has been applied for fish farming, and the primary resource used is mineralized geothermal water, which is in line with the goals of the sustainable Blue Economy and eco-effectiveness principles (Figure 5).

The farm was designed to operate under strict biosafety regulations and responsible production principles. It is the first indoor farm in the world where salmon thrive and grow in pure, high-quality, microbiologically safe geothermal water from the Lower Jurassic period, extracted from a depth of over 1.2 km. This farm is the third in the world to raise fish from roe to adults under a single roof [54]. The development was founded on Danish novel aquaculture technology for closed land-based farms with RAS (Recirculation Aquaculture System) and water re-purification. Dedicated water filtration and treatment systems are employed for the purpose of recycling and reuse in fish farming tanks. These systems are intended for use in instances where it is necessary to minimize water changes in order to maintain water quality that differs from the feed water. Consequently, geothermal water is being used in an effective way not only to generate thermal energy but also to supply a controlled aquatic environment for rearing Atlantic salmon.

3.3. Life Support Environment Based on Geothermal Water for Indoor Fish Farming

The Jurassic Salmon Breeding Centre was launched in Janowo in 2013. The primary fish farming based on geothermal water takes place in an enclosed two-storey building with a floor area of approximately 9000 m². The largest area of the building is occupied by cylindrical tanks of diverse sizes, in which salmon are reared at various stages of their life cycle (Figure 6). An artificial ecosystem has been created for the breeding of fish, from arranging the right conditions for selected eggs (delivered by air from Norway or Iceland) to providing adequate habitats for fry, smolt, and the adult fish life cycle. Finally, in the largest pools, adult salmon weighing 5–6 kg are reared in the sterile environment of geothermal water for further sale. The rearing cycle lasts for 20–22 months. Every week, a new cycle is started for another batch of eggs.

Extensive RAS technology, installed in a number of technical rooms, is responsible for maintaining the correct microclimatic conditions throughout the building and, in particular, in the dynamically changing water environment of the individual pools. (Figure 7). The most important of these are water processing units, de-ironing facilities, filter stations, wastewater treatment plants, denitrification systems, and sewage sludge treatment [55]. The building was planned using an integrated design formula supported by the BIM (Building Information Modelling) system. An updated digital spatial model of the building and its infrastructure was made available in a virtual cloud. This enables the remote management of the building and its installations. It also simplifies the service and maintenance of equipment and improves technical inspections and life cycle management of specific components of this complex building. The proposed solution fits into the formula of innovative production methods referred to as Industry 4.0.

The completed facility can be compared to a complex research apparatus designed to create, check, and control a unique salmon farming environment. An artificial ecosystem was generated, a type of Nature 4.0 hybrid [55], in which the typical life and development cycles of fish evolved. Five closed water circuits were planned, whose hydrological characteristics, including chemical composition and temperature, corresponded to the distinct phases of fish life. The cylindrical pools distinguish between two basic environments: cold freshwater and warm Jurassic geothermal water. The breeding hall is illuminated by artificial light of varying intensities. Inside the pools, where the direction and intensity of water movement are controlled, colored LED lights are used. The changing colors of the light and water temperature influence the behavior of salmon swimming upstream at different depths of the pools.

3.4. Monitoring the Water Resources of the Jurassic Salmon Farm—Water 4.0 on the Basis of Industry 4.0

A Building Management System (BMS) has been implemented throughout the building to monitor signals from sensors measuring water and rearing room temperature, oxygen dosage, and stability of the biological bed in local water treatment plants. This system controls technological processes and manages the salmon farming environment. An important task of the BMS is to signal critical emergency conditions in particular water circuits and quickly report emergency situations via mobile devices directly to the staff on duty on-site 24 h a day [57].

The integration of smart systems, devices, and machines and the implementation of new procedures in production processes to increase productivity and the ability to flexibly transform products are consistent with the definition of Industry 4.0. Its defining feature is the confluence of the physical and virtual worlds (cyberspace) in the form of cyber-physical systems (CPS).

This applies not only to technology but also to innovative ways of organizing work, including human work in the broad sense of 21st century industry. This is why Industry 4.0 is becoming a platform for connecting representatives of the industry and the service sector, politics, business, or science in the R&D formula. This platform aims to standardize and increase the security of networked systems and promote research and innovation within an adequate legal framework or bioethical principles [58].

The water composition of each salmon farming cycle is continuously monitored and controlled by a system of sensors using BMS and mobile phone links. “For the research program, water quality parameters and its physicochemical parameters such as pH level, ammonia, nitrites, nitrates, CO2, BOD5, CODcr, total phosphate and phosphorus content were analyzed within the tolerance range for fish with the highest environmental requirements” [53] (pp. 32–34).

The real-time information collected on the hydrological environment creates a digital model of the water resources in use, both at the conventional input and output of an operational fish farm. The networking of services and devices that affect water quality in the breeding process, aided by software applications, is part of the modern formula for efficient water resource management, referred to as Water 4.0 [59]. This is analogous to the Industry 4.0 initiative [60]. It is based on similar assumptions and practices of connecting the real environment to the virtual one. The geothermal water used in the farm’s recirculation systems has a digital representation—a real-time digital shadow that is continuously updated with information on its quality, composition and suitability for meeting the requirements of successive salmon life cycles. Water digital shadow is a digital security software that provides a real-time view of the aquatic environment, which is of crucial importance for the indoor fish farming industry. It reflects the current status, data, and processes, with a particular focus on water quality, oxygenation, salinity, ammonia, nitrite, and temperature, all of which are collected from Building Management System (BMS) sensors. The digital shadow helps avoid critical alarm situations and improves preventive measures, thus protecting biosecurity levels. Based on Water 4.0, creating a digital twin of water and a water digital shadow increases the productivity of this resource through better and more transparent management. Optimizing the links between virtual and natural water systems will foster the process of valuing water, considering geothermal resources and their eco-efficient use.

3.5. Local Communities and Partnerships in the Enhancement of Water Initiatives

The pilot facility of the company Jurassic Salmon in Janowo, which innovatively utilizes geothermal water for salmon breeding, has received EU funding of 5.8 million euro, with a total investment volume of approximately 10.4 million euro [54]. The investor’s individual participation was mainly related to the implementation of extensive infrastructure to supply the necessary utilities, including geothermal water, to the investment area. The local authorities of the two neighboring municipalities, Rewal and Karnice, supported the investment and development of infrastructure, especially at the planning and design stage of the project. With the favorable parameters of the extracted geothermal water, the municipality of Rewal was interested in the potential distribution of thermal energy from the renewable source to the nearby hotels and guest houses along the Baltic coast. For this reason, the investor efficiently conducted the construction of infrastructure in the lanes of municipal roads. Line investments include geothermal water supply and return installations, as well as a drinking water pipeline from the investor’s private water intake. The municipality proactively addressed challenges related to environmental procedures under the current water law, facilitated mediation in neighboring property matters, and participated in formal legal discussions. The investor collaborated with the municipality of Karnice to develop a local spatial plan for a 13-hectare area near Janowo, where a local Agropark was planned. The salmon farm and supply of geothermal water to the Agropark were the first investments in the formula of an industrial eco-park. The municipality of Karnice extended its water supply infrastructure toward the village of Janowo to provide the fish farm with potable water in the first phase of the investment. The Agropark project was supported by the District Office in Gryfice, which allowed for the reconstruction of the district road. The improvement of the technical parameters of the road was a crucial element of the investment activities, as it ensured the continuous delivery and regular collection of fish grown on the farm. The use of purified geothermal water at the Jurassic Salmon farm contributed to the intensification of fish breeding by shortening the rearing cycle and reducing the mortality rate of the whole stock. This was due to the properties of the Jurassic water, which increased the fish’s resistance to various diseases and infections and reduced the large-scale use of antibiotics. Currently, weekly fish production has stabilized at around 12–15 tons, with a target technological potential of up to 20 tons per week. The farm currently employs 21 people, and during the implementation of the investment, in addition to specialists and construction contractors from Poland, experts from Denmark, Chile, Indonesia, Norway, France, and Iceland were involved in the project. Jurassic Salmon was the first company in the country to be internationally certified by the Aquaculture Stewardship Council (ACS) for sustainable fish farming based on geothermal water resources [54].

4. Discussion

The implementation of modern fish farming technology, facilitated by the involvement of scientists and experts, has yielded favorable outcomes for the Jurassic Salmon enterprise. This contributes to new directions in aquaculture development and the efficient use of extracted geothermal water both nationally and internationally. This is an example of an innovative bioculture in the 21st century. The idea of a controlled fish farming environment, which has been transferred from rural to urban areas, fits into the formula of urban agriculture in its broadest sense, including integrated city aquaculture or aquaponics. The urban absorption of geothermal resources, particularly the efficient use of thermal water, will contribute to an innovative economy and a different understanding of nature by city dwellers than at present [51].

4.1. Aquaculture Based on Geothermal Resources as Part of the Energy-Water-Food Nexus from an Urban Planning Perspective

Personal involvement in the design and collaboration on the construction of the Jurassic Salmon farm in Janowo inspires reflection on the future of geothermal energy projects integrated with aquaculture development. The design and technological principles adopted there have helped the start-up of the world’s first indoor salmon farm equipped with autonomous systems for recirculating and re-purifying water extracted from geothermal sources [56]. Land-based fish farming is considered the fastest-growing food production sector globally. Undoubtedly, it should be included in sustainable Blue Economy development strategies. It is based on innovative technologies for creating artificial habitats and the efficient use of water resources, supported by extensive research programs and the interest of international investment capital. In particular, the integration of aquaculture development and geothermal projects deserves attention because of the sharing of a fundamental resource in these areas: water.

Globally, aquaculture fish farming has grown by 7% per year since 2000, and the current consumption of fish and seafood from controlled farms is around 50% of the global production [61]. For example, the consumption of popular fish species, such as salmon, has shown an exponential increase on a worldwide scale. In 2015, global salmon consumption was 1.2 million tons, and it is expected to increase by more than 400% to 5 million tons per year by 2050 [54]. Scientists warn that 48% of marine fish resources are suffering from overfishing and the loss of capacity to regenerate and rebuild vital stocks in the European Union’s fishing zone [62]. Promoting environmentally friendly aquaculture models is, therefore, a key element of the EU’s Common Fisheries Policy. For instance, land-based fish farms with RAS significantly reduce water consumption compared to traditional open-water farms, such as those in Norwegian fjords. Such land-based fish farms eliminate pollution and eutrophication of natural water reservoirs, especially sensitive marine areas, such as the semi-enclosed Baltic Sea [61,63]. Building innovative, controllable fish farms is part of a sustainable Blue Economy and a challenge for current and future generations of designers and architects to bring nature indoors. Planned fish farms under a single roof guarantee a stable breeding environment. This artificial ecosystem, which reduces the risk of diseases, parasites, or predators (such as cormorants) devastating the breeding stock, is easy to control and maintains a high level of biosecurity. RAS technologies provide a constant level of production throughout the year. The closed and controllable environment of this type of farm reduces the risk of escape or theft of fish, which is typical for open-water farms. In the future, economically viable scales for RAS will be mostly indoor, autonomous large-scale farms based on local feed processors, and aquaponics development in combination with hydroponic gardening and integrated processing [64].

Striving to achieve the efficiency of investment scale will lead to the creation of Giga agro-machines—environmentally friendly production and logistics systems, which in the form of integrated hubs will use the effect of synergy, the principles of the sustainable supply chain, and cascading use of energy and resources within the framework of circular economy or nature-based solutions. The RAS systems described in the case study or the exploitation of geothermal waters as a valuable resource and not only as a carrier of thermal energy perfectly fit into this formula. It seems that urban locations for projects such as controlled fish farms integrated with urban agriculture can contribute perfectly to the revitalization of brownfield sites and would be the subject of interdisciplinary scientific research, analysis, and feasibility studies. The sustainable technologies used at the salmon farm in Janowo are a positive example of the use of geothermal water to produce healthy local food. The efficiency of the use of geothermal water resources obtained there is becoming an inspiration for the implementation of this type of project in urban areas, which are characterized by a greater intensification of infrastructure, a denser network of functional links, and growing demand for healthy food (Figure 8).

From an organizational perspective, implementing a complex investment in a salmon farm that uses geothermal water appears easier in a rural area than in a densely built-up urban area, where conflicting interests among various parties pose greater challenges. Local authorities in small municipalities are seeking environmentally friendly projects that generate new jobs. Local authorities support the implementation of such investments by creating various incentive systems and simplifying procedures. However, in relation to greenfield investments, doubts arise concerning low ecological effectiveness and the risk of capital dispersion and loss of synergy effect in comparison to similar investments in urban areas. The advantages and disadvantages of investing in urbanized and rural areas are presented in

Table 2. The use of geothermal water for fish farms investment in rural and urban areas—pros and cons.

Rural Areas Investment	Urban Areas Investment
PROS	CONS
Less bureaucracy and more friendly investment support from local authorities	More bureaucracy and routine support of the investment process by local authorities
Rapid decision-making at administrative level	Risk of increased decision-making time at administrative level
Less complicated investment process	A more complicated investment process
Low cost of land	High cost of land
More attractive investment for small municipalities in terms of tax revenue and employment	Mostly business as usual
Higher level of biosecurity as isolation is easier due to distance	Lower level of biosecurity due to density of settlement and lack of isolation due to shorter distance
CONS	PROS
Lack or weakness of local economic activity	Diversity and richness of local economic activities
Longer transports to logistics hubs or directly accessible local markets	Shorter transports to logistics hubs or directly accessible local markets
Mainly greenfield investments	Potential for development of brownfield, post-industrial sites as part of space recycling and urban regeneration
Lower potential for cascading use of geothermal waters due to lack of existing activation of the local economy and low entrepreneurial dynamism, where the need for new investments requires time and capital	Higher potential for cascading use of geothermal water due to existing activation of the local economy and business dynamics
Not easy access to specialized services	Easy access to specialized services
Longer distance to business and universities	Shorter distance to business and academia
Lack of traffic jams	Risk of traffic jams
Accommodation problems for skilled workers	No accommodation problems for skilled workers
Due to the location in not very densely populated areas, limited public access and less potential to build awareness of the use of geothermal waters and promote fish farming.	Due to the location in densely populated areas, easier public access and potential to build awareness of the use of geothermal waters and promote fish farming
Low potential for synergies in the use and effectiveness of geothermal water	High potential for synergies in the use and effectiveness of geothermal water

[51,56].

The high potential of recognized geothermal resources in Poland and Central Europe means the expansion of this type of development both in the country and in the land of Geothermalia [34], resulting in the increased exploitation of geothermal fluid and intensification of its use in the future. At the same time, geothermal water (not only energy) may become an increasingly valuable resource, urgently needed and appreciated in ecologically inspired design and architecture, and urban and regional land use planning. Therefore, resource productivity and water footprint are recognized as fundamental factors for a sustainable Blue Economy and water-sensitive planning.

With the global migration of people from the countryside to expanding metropolises, there are ideas of transferring agricultural production to densely populated cities [65,66]. The development of urban agriculture based on geothermal water resources will naturally include the spread of urban aquaculture and aquaponics [67,68]. Undoubtedly, the development of this sector depends on economic profitability and the coordination of initiatives undertaken by various actors in economic life. There is untapped potential for local government action and ample scope for interdisciplinary research and feasibility studies. In the near future, it will become clear whether shifts toward intensive, water-dependent agricultural production will materialize in urbanized areas in the 21st century and whether they are economically justified. However, the dissemination of urban agriculture based on renewable energy and resource efficiency will indicate the development of urban inhabitants’ bioculture and their interaction with nature, including sophisticated Nature 4.0 [56]. Recognizing geothermal waters as a valuable resource in a sustainable Blue Economy requires promoting best practices for their rational use, disseminating water-sensitive design principles, and developing architectural solutions that incorporate natural aquatic ecosystems indoors [69]. Feasibility studies for geothermal projects must include plans for managing geothermal water resources in potential locations where alternative water management can be considered for successful water-based economic development initiatives. The cascade model of geothermal resource utilization and its potential should be considered for implementation within the Atlas of Geothermal Water Use Scenarios or in the form of a Good Practice Catalogue of Realised Geothermal Investments. Such documentation would present and promote various cascade models planned or realized based on industrial ecology principles, nature-based solutions, or regenerative design, with emphasis on the importance of the circular economy, breaking the linear approach. The effective use of geothermal resources, water efficiency, and available technological and logistical solutions make it possible to transfer the experience of the Jurassic Salmon farm to urban areas on a larger scale (Figure 9).

4.2. Benefits of Using Geothermal Water in Indoor Fish Farm

The design and implementation of the salmon farm needed rapid and efficient management, given the strict timeframe for the payment of EU funds. To improve project implementation, the design process and reporting of functional, technological, and installation changes based on a modified 3D model were moved to a virtual cloud. This fast-tracked decision-making and the phasing of construction operations. Such actions made it possible to build the salmon hatchery earlier and conditionally start breeding, along with the acceleration of research work based on Industry 4.0 principles during construction. Following earlier tests, the Jurassic geothermal water, which underwent treatment and iron removal processes, proved to be an excellent environment for rearing Atlantic salmon. Due to the hermetic nature of the deep underground deposits, the extracted thermal water is free of chemical contaminants or parasites dangerous to fish. This increases the level of biosafety compared to conventional open-water fish farming. In addition, RAS working in enclosed, land-based farms essentially become a sort of filter for mineralized geothermal water when it is released back into the environment. In the treatment plant, salt thermal water is mixed with potable water to provide the right living conditions for growing salmon. The water from the breeding pools is successively purified using mechanical filters and biological beds. After passing through sewage treatment plants, the treated water from the farm is pumped into a collective drainage canal and feeds brackish lake Liwia Łuża, which is connected to the saline water reservoir of the Baltic Sea [51]. The water at the farm’s downstream outlet is subjected to treatment and dilution with a minor addition of salt and is subsequently discharged into a drainage canal. Over several decades, the canal has accumulated surface water from neighboring cultivated fields, which contain pollutants from fertilizers and chemical plant protection products. Consequently, the water from the farm dilutes the pollutants emanating from the fields, a phenomenon that is particularly pronounced during periods of drought and scarce rainfall. Concurrently, the influx of water from the canal into the lake stimulates movement, enhances oxygenation and mitigates lake drainage.

Accordingly, it was determined that the consistent provision of treated water from the fish farm to the lake and the drainage canal has a predominantly beneficial effect on the environment in comparison to the pre-investment period, particularly during periods of rainfall deficit. Repeated field environmental surveys have substantiated this assertion.

4.3. Lessons Learned from the Demonstration Project

The case study shows a wider application of geothermal water than just for energy generation purposes. The model incorporating the direct use of thermal water for fish farming has cut a costly second well that reinjects the extracted geothermal water back into the ground. At the same time, a situation where the temperature of the extracted geothermal water is too low does not necessarily lead to the abandonment of further investment activities. In the case described, the determination of the investor, with the support of the academic community and local authorities, made it possible to put Jurassic thermal water to practical use. The path to launching an innovative project in the 21st-century food production sector has been paved, thereby reducing the risks associated with drilling for geothermal wells. The ability to utilize water with a low thermal energy potential as a water-sensitive design element in the framework of a sustainable Blue Economy has been proven [70]. The implementation of the industrial ecology formula [71] and its principles of resource effectiveness or cascading energy and material consumption indicate that there are new development perspectives for linking modern aquaculture with the extraction of geothermal waters. According to McDonough and Braungart: “We don’t have an energy problem. We have a materials-in-the-wrong-place problem. Likewise, we don’t have a toxins problem; we have a materials-in-the-wrong-place problem” [25] (p. 211).

As demonstrated in this process-oriented case study, the potential consequences are illustrated, and the study concludes with recommendations for conducting more extensive and generalized research in a new context. Particularly relevant here are urbanized areas with a large flow of materials and energy, with an extensive consumer market, which, with an appropriate infrastructure network and fast connections to research centers, logistics hubs, or processing plants, become a desirable location for this type of investment referred to as technical-ecological symbiosis [51,72]. In order to obtain a complete picture of the environmental impact of this type of investment and the scale of its profitability, as recommended by Kaczmarczyk, Tomaszewska, and Operacz: “It is also necessary to conduct an economic viability analysis and the environmental impact of the installation, e.g., using an environmental life cycle assessment” [73] (p. 18). However, these analyses and assessments are expected to cover not only the isolated geothermal installation, but also the associated infrastructure and facilities that utilize the extracted geothermal resources. A separate aspect is the application of Social Life Cycle Assessment in the context of broadly defined geothermal investments. It seems that social aspects are often omitted in too narrowly understood subjects of energy investments, especially when it comes to renewable energy sources. However, the issue of social participation is quite commonly developed in the procedures of regional spatial planning, urban planning, or the creation of participatory architecture.

5. Conclusions

Geothermal water extraction is driven by the demand for inexpensive renewable energy. Beyond its thermal properties, geothermal water is a valuable resource that influences living conditions within the energy-water-food nexus. It can take on different forms and spatial scales. The described example of a salmon farm, where a controllable version of nature and life-support systems has been created, influences the growth of natural and social capital in the local environment. The utilization of geothermal resources, in this case, can be summarized in the following key conclusions. They are only a partial answer to the questions posed at the beginning of this article.

5.1. Key Conclusions

Under favorable hydrogeological conditions, the direct use of clean, sterile geothermal water ensures biosecurity and prevents parasites and pathogens in hermetically sealed fish farms, unlike in traditional open systems. Geothermal water offers stability in production and indoor environmental quality on a closed fish farm through a constant supply of water and heat and independence from seasonal changes in demand or daily peaks in heat and water consumption.

Industry 4.0 and Water 4.0 devices absorb data focused on the fish farm environment to monitor water quality and improve water management (including geothermal management) through the implementation of a digital water shadow. Such technologies have implications for creating a hybrid Nature 4.0 environment that will increase food productivity from water. Land-based fish farms using RAS can radically increase the conservation of water resources. This type of farm acts as a filter when mineralized geothermal water is purified and pumped into open reservoirs after use. This has been demonstrated in the Jurassic Salmon farm, which has been operating for several years. The subject of this study is a land-based farm that has received international accreditation for sustainable fish farming from the Aquaculture Stewardship Council (ASC) on the basis of the use of geothermal water resources. This could serve as a paradigm of best practice, suitable for emulation in the quest for a sustainable Blue Economy. The implementation of efficient, land-based indoor fish farms is expected to have a significant impact on the reduction of traditional overfishing practices and the elimination of unsustainable, cage culture fish farms in marine waters. This will reduce the scale of marine pollution and allow depleted fish stocks to recover in the wild, which is in accordance with the strategy of a sustainable Blue Economy.

Compacted indoor fish farms could fit into a cascade model of energy consumption and water resource use, increasing the resilience of geothermal development and the effectiveness of land use. This cascade model deserves to be promoted within a sample Atlas of Geothermal Resource Utilisation Scenarios or in the form of a Good Practice Catalogue of Realised Geothermal Investments, among others, to prove its potential and enhance synergies in architectural and urban planning.

A holistic and water-wise approach to planning provides local governments with important tools to lower the entropy level of geothermal investments and promote such projects toward a more syntropic development model. Therefore, social involvement in geothermal development is important for establishing local alliances for the effective use of geothermal resources and extensive public acceptance of such sustainable Blue Economy projects.

Urban fish farms located within built-up areas offer a number of advantages over their rural counterparts. Firstly, they are able to make more efficient use of geothermal resources. Secondly, they can intensify the use of existing municipal infrastructure. Thirdly, they have the potential to have a positive impact on the circular economy, as well as on the public perception of the investment.

The implementation of indoor fish farms based on geothermal resources in densely populated urban areas is only a matter of time. Therefore, geothermal development scenarios, with particular emphasis on feasibility studies on the size of underground deposits and the use of geothermal water, should be incorporated into flexible and dynamic urban and regional planning.

5.2. Future Outlook

We must learn to use geothermal water resources efficiently in the long term, rather than treating geothermal fluid as a by-product of energy extraction, especially in times of increasing water scarcity risk. Like architectural design, knowledge acquisition and research are long-term processes that often result in well-integrated hybrids within the sustainable Blue Economy. The architectural engagement in the Jurassic Salmon farm development is an organic process that fosters a deeper connection with nature. This ranges from the rational economic man to the ecologically adaptive man, from mechanistic balance to the dynamic complexity of the animated fish breeding ecosystem, and from creation to its regeneration.

A new context for the use of geothermal water emerges, where the conditions that support aquatic life become evident in this reflection on architectural practice. The biological paradigm of architecture that appeared in the Jurassic Salmon farm project is part of a holistic adaptive strategy aimed at the survival or, in a better sense, the flourishing of novel human ecosystems in harmony with the Blue Planet as constitutive of a sustainable Blue Economy.