## 8 Discussion
### Economic Limitations  
Still, there are limitations which should be overcome in order to utilize very shallow geothermal potentials. The municipality of Ub, as well as its population, are not the wealthiest in the Republic of Serbia and therefore a public or private investment would be necessary. Furthermore, there must be organized maintenance of a potential heating network. Consequently, it makes funding possibilities and sources limited, at least on a local level. Therefore, economic limitations are coming to the fore. Building insulation is crucial factor for effective geothermal heating systems. As our survey showed, our respondents are not completely satisfied with the insulation quality of their houses and apartments. More than half of respondents are interested in renovating their wall insulation as well as doors and windows, and around 90% of them would welcome subsidies for that purpose. Swedish experience showed what happens when fossil fuel got more expensive: district heating developed in urban areas, and heat pumps appeared as a solution in suburban and rural areas [103]. The Swedish state played a very important role in the development of district heating systems based on renewable sources by introducing high taxes on fossil fuels [103]. The question is if it could be a solution for Ub or Serbia in general. There are some limitations for such development. It is already mentioned that average net salaries in Serbia and Ub are just over 500 and 450, respectively. Those incomes are significantly lower than in Western countries (such as Sweden) where such policy brought a positive result. Rising energy prices in Serbia would mean significant upset for household's budget, and certainly would trigger social issues. According to the data of Eurostat [104], prices of natural gas (including taxes) for household consumers in the first half of 2019 were almost twice so expensive in EU-28 than in Serbia. Serbian prices were still on the similar level of some EU members such as Romania and Hungary. Prices of electricity in Serbia compared to prices in EU-28 for the same period were on around three times lower level [105]. Coal is also playing an important role in Serbian energy balance. All energy prices are in responsibility of Serbian governments and government-owned companies [64] (pp. 69-70). Governmental subsides in this sector are instruments for keeping social peace and it is unlikely that such policy can be sustainable in the frames functioning in the EU [106]. Figure 8: Low temperature district heating (very) shallow geothermal system with horizontal collectors and heat pumps [101] (p. 19). District heating systems and heating prices in Serbia are in the jurisdiction of municipalities [64] (p. 69). That is a chance for local authorities to proactively act on the energy market. Community owned district heating systems can be also found in the United Kingdom for instance [107]. This is particularly true for smaller communities such as Ub, which do not yet have already built and inherited supply systems that they need to maintain in order to ensure continuity and ultimately social peace. A small low temperature district heating network could be also built as a result of private investment. It is hardly to be expected that low-income households, like most households in Ub, could invest in the development of such a system. There is a chance for local authorities to act. Numerous subsidies on a republic level in fossil fuels could be turned to local subsidies in renewable sources on a local level. If such local initiatives tend to become successful, there is still an important issue to be overwhelmed--the power of central political elites in Serbia which dispute (in most cases) local authorities to act without restriction and centralized control [108] (p. 93). Low temperature district heating network needs heat pumps beside collectors and network grid. Geothermal heat pumps bring also economic benefits in the cases of low prices of electricity [40].