Various indicators show that there is still a commitment to subsidize fossil fuels at the expense of renewable energy and energy efficiency projects, as shown in the results of the Madrid Summit [1
]. In the case of micro grids, the lack of specific regulation and the fact that it is still a budding technology renders it a rather costly option as a source of energy, not so much because of technical barriers—even though this aspect could be improved but due to regulatory, legislative, and economic vacuums [5
Given today’s increasing demand for energy, a response that deals with a sustainable energy framework is essential. Many articles raise the question of identifying the actual barriers to the introduction of renewable energies all over the world. These barriers, however, are expected to differ according to different types of renewable energy, environment, and sector of activity. As far as geothermal energy is concerned, despite its all-year-round availability and its independence from external climatological factors, it is scarcely used both on its own and as an energy mix. Hence, there is a need to elaborate more specific studies on the barriers that affect it and the actions that need to be taken to take full advantage of its potential.
One of the main challenges that geothermal energy faces, both for thermal and for electrical uses, is the ignorance of the general public [6
]. In the case of geothermal power generation, the absence of a favorable regulatory framework results in the complete lack of power plants in Spain despite isolated entrepreneurial endeavors to establish them [6
]. On the other hand, and excluding the barrier of the initial investment and the regulations required of high-enthalpy geothermal projects, we would like to point out that there has been certain improvements regarding knowledge and research of the subsoil in areas considered potentially favorable in Spain, besides, a greater involvement in the development of this sector will lead to an increase in projects of this kind [6
]. In the case of low-enthalpy geothermal energy, non-compliance in recent years derives from the fact that it requires a higher initial investment than that of a conventional plant, and the climate of economic downturn over the last decade has not helped. However, in the current, more favorable, context in Spain, there are numerous private initiatives being carried out, especially as far as building renovations are concerned [6
Considering the substantial technical barriers in the case of micro grids, an implementation of changes in meters, safety, ground and linking with the existing electricity grid as well as management of production and consumption and aggregation of new energy sources are seen as necessary at a local level [5
]. As far as geothermal energy in Spain is concerned, working towards not only the introduction of regulatory actions but also on demonstration programs, knowledge management on geothermal potentiality, technology development programs aimed at reducing production costs, and increasing efficiency and developing a training and certification model are viewed as a must [6
There are numerous references that confirm that the main disadvantage of using renewable energies stems from adverse climatological factors—rain, sun, wind [7
]. By contrast, the main advantage of geothermal energy, both in its isolated form and in the form of an energy mix lies in its complete year-round availability and the fact that it does not need to oversize the capacity of the system to compensate for lack of energy. Furthermore, solar and wind energy have a negative impact on the landscape and farming land. This is not the case of geothermal systems due to its concealed nature [7
]. Many articles mention the need to implement renewable energies and improve energy efficiency in remote areas, such as islands not only from an environmental point of view (CO2
and greenhouse gases emissions reduction) but also because they have proven to be more profitable than conventional polluting energy sources, where part of the cost of the bill is often subsidized [1
It is worth noting that the contribution of renewable resources to the sustainability of energy is ever more relevant in remote and insular areas [9
]. Therefore, the Canary Islands were handpicked for this study. One of the most recurrent topics in a variety of articles is the importance of implementing renewable energies at a local level. Unfortunately, European policies show little support on this matter [10
]. There are examples in insular areas, such as the Spanish island of Menorca, of potential energy self-sufficiency through photovoltaic solar energy, where a geothermal study would be desirable [2
]. In other European islands like Mykonos in Greece, there have been studies on solar and wind energy production [7
]. They are all similar case studies: tourist islands with high electricity and water consumption in which fuel produced electricity is shared with agriculture and industry [2
]. Some studies propose the desalination of sea water through renewable energies in insular areas, again making use of solar and wind resources [8
] but with a need to oversize installations in the absence of such resources. An interesting option would be installing a geothermal line that could guarantee year-round energy resources without needing to oversize the systems. In fact, in some studios, the use of geothermal energy for thermal desalination can be justified only in the presence of cheap geothermal reservoirs or in decentralized applications that focus on small-scale water supplies in coastal regions, provided that society is able and willing to pay for desalting [11
The proposal of desalination plants using energy mix is an interesting option for coastal, insular, or desert areas where water resources are scarce since it would benefit both drinking water consumption and water destined to irrigation areas, thus helping to develop the agricultural sector in a sustainable way. Besides, the coupling solar-geothermal in regions with a lot of radiation is a very interesting option for cogeneration plant based on an Organic Rankine Cycle (ORC), powered by a medium-enthalpy geothermal resource and a Parabolic Trough Collector solar field [12
]. Some studies show the importance of land management (planning, agriculture, conservation) and geographic studies to implement energy strategies [13
]. Geothermal energy can be put into a myriad of uses and many have already been studied, though most of them are still in pilot stage—from electricity production to urban heating or agricultural applications, such as greenhouse and stockbreeding facilities heating, besides industrial applications through the use of underground infrastructures, heating for residential and official buildings and swimming pools, just to name a few.
Economic and environmental analysis of different District Heating systems aided by geothermal energy were analyzed in a set of buildings located in the province of León in the north of Spain. Real data comparison of the different scenarios studied revealed the most suitable option from an economic and environmental point of view was the assumption of a district heating system totally supplied by geothermal energy clearly stands out from the rest of options [14
Most case studies around the word relate to domestic and residential uses that use geothermal heat pumps, although there are endless applications and sectors still to be developed and improved. In the agricultural sector, for example, the use of geothermal energy in Greece for fruit drying or in Iceland for cod drying are of interest [13
]. In the case of Spain, studies on central heating and sanitary hot water have been carried out in Madrid, greenhouse heating in Cartagena, Murcia and in the sandy fields of Dallas in Almeria [15
]. Residential examples elsewhere, like the one in Okotoks, Canada [16
] or Crailsheim in Germany, are also worth noting [17
], both cases consisting on the hybridization of solar thermal energy with geothermal energy through a geothermal storage. In a similar way, an innovative space-conditioning system is proposed, and a life-cycle assessment is presented for an industrial building. A ground-source heat pump system and an upstream thermal storage are analyzed to reduce the size of the geothermal installation [18
Based on the above-mentioned references, it is reasonable to conclude that geothermal energy has an enormous potential both for small-scale projects like home heating and for greenhouse or large district heating projects with subsoil thermal energy accumulation capable of supplying thermal energy to an entire city [19
Unfortunately, market parameters, such as acceptance from investors, regulatory framework, planning restrictions, and environmental impact, need to be addressed for this kind of technology to achieve effective development [19
Nevertheless, specific studies exploring barriers to the introduction of geothermal energy and/or geothermal energy mix have not been found, although in some cases they are mentioned as an objective for exploration [2
]. Most of the references consulted are on wind and solar energies [2
]. There are some theoretical references in Turkey, where different types of renewable energy were contrasted with five criteria to be taken into consideration: technical, economic, political, social and environmental. According to this, geothermal energy gets the highest score [21
]. Likewise, six production plants in that country are analyzed based on a series of criteria: technology and sustainability, economy, quality of life and socio-economic aspects. Here, geothermal plants rank in the third position.
There exist some investigations that focus on the main barriers and actions needed regarding the introduction of renewable energies in different uses, contexts, regions, and countries [18
]. However, the novelty of this study resides in the scrutiny of barriers and steps to be taken to introduce an energy with such a strong potentiality and as little known as geothermal energy.
In other non-detailed studies on renewable energies where northern European countries (from now on N) are compared with southern European countries (from now on S), it seems like financial barriers are more significant in the latter due to, among other reasons, little tradition of financial support for this type of project from legally established cooperatives. It is also due to a lack of local or municipal initiatives aimed at electricity production, or difficulty to access credits and incentives. As far as social and cultural barriers are concerned, it seems that lack of environmental awareness in southern Europe against a history of energy activism in the N has enabled the creation of bioenergy towns in countries like Germany, thus contributing towards lowering barriers to the introduction of renewable energies to a greater extent than their southern counterparts [22
]. Other studies show that oil prices and the initial investment needed are significant financial barriers [23
In a study of a hybrid project comprising solar, geothermal and wind energies for a greenhouse in Turkey [24
], initial investment as opposed to established heating systems for agriculture and buildings, appears to be the most relevant barrier”.
However, this study concludes that with enough wind this system is preferable to conventional ones.
Similarly, other studies show that, in some cases, institutions contribute significantly to the energy mix and energy policies, proving that institutional quality and income resources are of great importance in the development of renewable energies in any country [25
]. As far as cultural and social barriers are concerned, it is worth noting that in all cases a lack of social acceptance may be a great deterrent to the achievement of desired targets in Europe [26
More generic studies on renewable energies [13
] consider promotion as a key measure for development, along with the establishment of national regulations concerning licenses, permits, and procedures. Renewable energy strategies at the local level based on knowledge, training, and monitoring are also necessary. Some studies suggest that once the use of a technology is explained, the intention to use it increases [27
]. This is directly linked to the importance of promotion as part of the effort to introduce new technologies. In articles that analyze the situation of Dutch industrial companies in terms of implementation of energy efficiency, public investment is also highlighted as a key element [27
]. In Michalena and Hills’ studio, security and diversification of electricity supply are mentioned as elements to take into consideration due to, on the one hand, the high dependency of fossil fuels in many regions and, on the other hand, the high cost of oil [13
]. Lin and Omoju’s article underlines that in the short run, oil price increase affects the development of renewables, but in the long term, financing plays an important role and therefore only adequate planning can help promote the change towards energy transition [28
After the initial introductory section, the second section explores materials and methods and presents the methodology applied on this article for national (Spain) and European contexts, as well as focusing at a local level (the Canary Islands) and in the specific sector of agriculture. In section three, the results obtained will be examined and discussed. In the final section, we present conclusions reached as a result of the research carried out in the article. All sections are complemented with a series of Appendix A
, Appendix B
, Appendix C
and Appendix D
containing relevant extra information. Appendix A
includes the forms that were sent to various experts in the field; Appendix B
contains graphic information and questions asked to experts in the field; Appendix C
gives graphic information on the most relevant advantages stemming from implementing this kind of technology; Appendix D
contains an additional questionnaire of eight closed-ended questions with graphic representations relevant to the above mentioned questionnaire.
The fact of being able to discriminate in this study according to the different uses of geothermal energy (thermal or electrical or mix) depending on the region examined (island, country, or continent) or even including a specific activity sector, in this case agricultural, though it could be any other, allows us to focus attention where it is really needed and to identify the actions more fit for each case.
This work contemplates four big blocks, namely the degree of implementation, barriers, measures and advantages for the three technologies and the four scenarios mentioned in it, thus moving from a global approach to a more specific one and analyzing its results.
The main conclusions of this study are as follows. First, regarding level of implementation of this energy, a lower degree in Spain than in the EU has been identified for all the examined scenarios except for low-enthalpy geothermal energy. It is even lower in the Canary Islands than in the main land in all scenarios except for the geothermal energy mix. On a general level, the degree of development turned out to be two for underdevelopment on a 1 to 5 scale (from lowest to highest), the situation being poorer as far as high-enthalpy geothermal energy is concerned as well as geothermal energy on the agricultural sector.
Second, regarding barriers, when discriminating renewable energies by type and thus separating geothermal from the rest and even its thermal or electrical end uses as in the research that concerns us, we find that economic barriers to low-enthalpy geothermal energy in Spain are not as significant as might be expected and that, in fact, this score is lower than its European counterparts. On the other hand, in the case of high-enthalpy geothermal energy production, economic barriers are high both in Spain and in the rest of Europe. On a global scale, the study concludes that the main barriers to the introduction of electrical uses for geothermal energy are economic/financial, while for thermal uses, they are cultural or social. At a regional level, in the EU economic/financial barriers are still the most important, both for low and high-enthalpy geothermal. This is also true in Spain, although in the latter case to a lesser extent. In the case of the Canary Islands, the main barriers are cultural/social along with regulatory/institutional for low-enthalpy geothermal energy and economic/financial for high-enthalpy geothermal energy.
As stated previously, one of the most commonly cited topics in a variety of articles [35
] is the importance of implementation of renewable energies at a local level, although European policies (and not only in Europe) give minimal support to this issue.
According to the findings of the research carried out here, the institutional or regulatory barriers rank third on the general scale for both high and low enthalpy, being more important in the EU than in Spain especially for electrical uses. As indicated above, the importance of the Canary Islands is also worth mentioning in this case.
In the third place, the measures to be taken, this study concludes that at the regional level, the EU considers that the actions to be taken are private investment in the case of high-enthalpy geothermal energy and promotion for low-enthalpy geothermal energy. In the case of Spain, for the high-enthalpy geothermal energy, it would be public investment and, again, promotion for thermal uses. In the case of the Canary Islands, public investment for low and high-enthalpy, training, and promotion for low-enthalpy. In the agricultural sector, training and promotion would be the most significant measures both for renewable energy in general as well as for geothermal energy in particular. Regarding global actions, depending on whether it is low-enthalpy geothermal, high-enthalpy geothermal or energy mix, public investment, promotion, and regulatory change in this order.
The figures show that when examining barriers to the introduction of renewable energies by focusing on geothermal energy in particular and its energy mix, it is not only promotion and regulatory that change rank on the first positions but also private and public investment, being of more or less importance depending on the region case study and the type of geothermal technology.
Lastly, as far as advantages are concerned, energy security does not seem to be the main concern of experts since this is covered by other sources of energy in the short term (renewable and non-renewable). This is more relevant in the Canary Islands due to its isolated and insular nature. Nonetheless, our study does share with others the crucial importance of energy independence from external sources [37
]. The case of the Canary Islands is not different from the rest of the insular areas in Europe and worldwide, where distributed generation and micro-grids become a fundamental issue. For all three technologies that have been studied here—low-enthalpy, high-enthalpy, and energy mix—the EU scenario is the most positive. This circumstance is repeated in all questionnaires.
A study with more subject matter experts in the field would be desirable in the future when this technology will be well known, to evaluate its differences to the current one. In the same way, it is expected that future research in the line proposed here include new technologies such as dry hot rock, stimulated geothermal systems, or supercritical deposits.