The Hydropower Resources of Georgia and Use of their Economical and Ecological Challenges

The paper explains the renewable energy resources of Georgia quantitatively and qualitatively in country and regional contexts. It is mentioned that Georgia is rich in this regard and in some degree it fills the lack of fuel resources (oil, natural gas) in the country. It comes 3.27MMkWh energy of river surface runoffs on each square kilometer of the territory.In this regard, it is a better situation with the use of hydro power resources. However, according to 2016 year data, Georgian HPPs worked out only 11.4% of their technical capacity and 23.6% of their economic potential.There are some measures for improving the use of hydropower resources, in terms of technical and economical and ecological context as well.


Introduction
Georgia, having rivers with high energy potential, is reach with hydropower. This fact is partially compensating the fuel deficit of the country. Georgia has rich hydropower potential due to the mountainous terrain. Caucasus and small Caucasus mountains have specifically high slope and rivers of those mountains can have high hydropower potential due to ability of gaining high pressure in small distances. The statement is especially true for west Georgia [1]. Totally, there are 26 thousand rivers in Georgia, with total length of 60 thousand km. The rivers with total length of 25km and less account for 99.3% of the total amount of the rivers and for 76% of the total length of all rivers. Total volume of water flow is 52.8km 3 , while the total water resources of Georgia reach 61.5km 3 . If we add the amount of fresh water, including the glaciers, lakes, reservoirs, and wetlands, the amount of total water resources will increase up to 96.5km 3 [2].
According to "Hydro Project", 319 out of total amount of rivers have significant hydropower potential, with potential capacity of 15.63mnkW and average annual generation of 135.8 bl. kWh, in total [3]. 208 out of these rivers are small and medium sized rivers with potential capacity of 14.78GWh and 129.5TWh. The other 111 rivers have potential of 851 thousand kW (7% of total capacity of the rivers). The energy of total surface waters of Georgia accounts for 228.5TWh, with corresponding capacity of 26.1GWh. According to the studies of the same institute, if we take into account the theoretical amount of hydropower potential of the main rivers in Georgia, we can calculate the amount of river flows per square meter, accounting for 3.27GWh for the total country; 5.06GWh for eastern Georgia and 1.73GWh for west Georgia [4]. In terms of absolute numbers, we can see that 228.5TWh (72.1%) falls on west Georgia and 63.7TWh (27.9%) -on the eastern Georgia [5].
If we separate the potential of small, medium and large rivers, we can assume that they account for 60% (135.8TWh) of total energy potential of surface waters, with additional 40% (92.7blkWh) falling on the waters from the mountains (see Table 1): Theoretical hydro potential of large and medium rivers is 136TWh, which is 3.4% of the total hydro potential of all rivers on the territory of former soviet republics [6,7]. Technical hydro potential of Georgia is 81blkWh; while economic hydro potential equals 39TWh. Hydro potential per each square meter of current territory of Georgia is 1943ths kWh, one of the highest figures worldwide. Georgia was on third place in USSR countries by per capita hydro potential and was above the average USSR data by 41.7% [8].  Additionally, favorable condition for HPP construction is that 40% of technically possible hydro potential of all 319 rivers is concentrated on eight main rivers (Mtkvari, Rioni, Enguri, Tskhenistskali, Kodori, Bzifi, Khrami and Aragvi). Economic potential for main rivers of Georgia is given in Table 2 [9]. Abovementioned hydro potential of Georgia (135.8TWh) reflects capacity of 319 small and medium rivers. It is well-known, that the seasonal distribution of the potential hydro capacity is theoretically dependent only on the seasonality of the river flaws [10]. Also, the reallocation within the year of within different years is possible by construction of conventional HPPs, this is why the seasonality of water flaw, considering overall energy situation, is the most important for development of country's thermal-electric complex.
Below is given data of annual seasonal distribution of hydropower potential for main rivers of Georgia, given as a percentage from the annual potential (see Table 3): We should hereby note, that the theories revealing, evaluating and calculating potential usage of hydropower is based on the data of the previous century and needs additional evaluation according to modern standards. The works toward this direction are at the very initial stage. Engineering assistance of the hydropower development needs additional funds for the field works and desk study. Annual technically feasible hydro potential of large and medium HPPs is 81TWh, 73% of which is in west Georgia (59TWh) and 27% in east Georgia (22TWh.) The distribution of the technical potential by the main river basins of the country is given in Table 4. The economically feasible hydro potential equals about 39TWh, almost 50% of technically feasible potential. The economically feasible potential of the main river basins of the country is given in Table 4. Hereby, the hydro potential of the country besides the positive effects has also negative ones: it is unequally distributed on the territory of Georgia. West and east Georgia with almost the same area have 70% of energy potential falling on west Georgia.   Table 5 shows that all Georgian rivers Georgia is exceptionally rich with considerably small rivers. Their technically feasible potential is 12.3TWh. In recent years, 300 schemes for deployment of small and medium rivers have been prepared, out of which 229 small HPPs can be located in 47 different districts. Out of them 155 can be located in 28 districts of west Georgia and 73 of them can be located in 19 districts of east Georgia. Total capacity of small HPPs is 2.1GWh; they can generate annual 12.3TWh. 66.7% of capacity and 68.38% of generation falls on west part of Georgia.
Most of Georgian rivers have rough seasonality, which means high water flow in spring-summer period and low water flow in autumn-winter. This is why the effective utilization of the potential can be reached by constructing different types of HPPs, where the impact on natural regimes will be minimal and development of mutual application of natural and artificial systems will take place. For further development of hydro potential, as important energy resource, it is necessary to study and justify the utilization methodologies, definition of locations and parameters of new objects by complex utilization considering the scales and reasonability.
According to Ministry of Energy of Georgia, the international project financed by the grant from Ministry of Foreign affairs of the Kingdom of Netherlands is on-going. The aim of the project is to study the river basins and reveal the list of potential HPPs. The project includes digitalization and justification of existing historic hydrological and meteorological data. As final result we will have the digital map of Georgia in GIS system, where the information on the potential HPPs will appear: coordinates, capacity, generation, amount of investment for construction, etc. Technical-economical parameters of existing and potential HPPs is given in Appendixes.

4.
Construction of hydro hubs, which will create possibility for water flow to be regulated and utilized for irrigation, water supply and electricity.

5.
Creation of the list of actions to be conducted for safety and recovery of black sea coast, from the damages caused due to decrease of sediments from the rivers.
Full utilization of the economically feasible local hydro potential.