It is well known that all five Central Asian countries are divided, among other things, into upstream countries (Tajikistan and Kyrgyzstan) and downstream countries (Kazakhstan, Uzbekistan and Turkmenistan), when upstream countries are primarily interested in the energy use of water resources, and downstream countries rich in hydrocarbons focus on their irrigation potential.. Therefore, we will analyze the hydropower potential of sovereign Tajikistan, located in the head of the region's rivers.

Currently, four strategic objectives are being implemented in the country (energy independence, food security, getting out of communication isolation and accelerated industrialization), when the government pays special attention to the first of them, which has huge untapped resources and opportunities.

Mountainous Tajikistan has ­enormous reserves of hydropower resources, which are estimated at 527 billion kWh per year, and technically, they have good prospects for development and consist of 317 billion kWh per year, of which only 4-5% (16.5 billion kWh) have been used so far. According to this potential, Tajikistan ranks eighth in the world (after China, Russia, the USA, Brazil, Zaire, India and Canada) and first in Central Asia. More than 95% of Tajikistan's energy is based on hydropower.

This (hydropower) potential of Tajikistan is three times higher than the current electricity consumption throughout Central Asia. With the efficient use of these resources, the region can be provided with inexpensive and environmentally friendly ("green") energy. The main hydropower potential is concentrated in the basins of the Panj, Vakhsh, Kafernigan and Zeravshan rivers. At the same time, there is currently an imbalance of energy consumption in the country, when the excess of electricity in summer is 3-5 billion kWh, and the shortage of electricity in winter is 2.5 billion kWh.

Currently, there are 11 large and medium-sized hydroelectric power plants operating in the RT, as well as about 300 small ones, with a total capacity of 132 MW. In 2009, an updated program for the construction of small hydroelectric power plants was adopted. According to this program, the construction of 189 sHPP with a total capacity of 103.6 MW is envisaged. In 2010-2011, more than 60 small hydroelectric power plants with a total capacity of 47 MW were built. And this trend continues. Preliminary estimates show that it is technically possible and economically feasible to build more than 900 sHPP with a capacity of 100 to 3000 kW on the tributaries of rivers in the mountainous regions of the country. According to experts, the use of energy fr om small rivers can satisfy the electricity demand of about 500-600 thousand people living in remote regions of the country by 50-70%, and in some cases – by 100%.

In 2011, a unified energy system of the country was created, connecting the southern energy system of the country with the northern one (after the completion of the South–North transmission line). All this has significantly increased the possibilities of physical access of the entire population of Tajikistan to the generated electricity. Today, electricity tariffs for the population in the Republic of Tajikistan are socially oriented and equal to 2.32 US cents/1 kWh.

The electric power system of Tajikistan operates as a single system and connects four separate regions by geographical location (Sughd (North), Khatlon (South), Dushanbe and nearby districts, as well as regions of republican subordination (RRP)).

The electricity sector is managed by the open joint-stock holding company "Barki Tojik", which is state-owned. The company controls power plants and the generation, transmission and distribution of electricity in the country, except for Gorno-Badakhshan Autonomous Region (GBAO). Since December 2002, GBAO's electricity supply network has been transferred fr om the company "Barki Tojik" to the private company "Pamir Energy" on the basis of a Concession agreement for a period of 25 years. Currently, the GBAO power supply system operates in isolation, i.e, it has no connection with the main power plant of the RT. Pamir Energy operates 11 small and mini-hydroelectric power plants with a total installed capacity of 44.16 MW and 35/10/0.4 kV transmission lines with a total length of 2,609 km.

In order to achieve full energy independence in the country, the Rogun HPP occupies a privileged place — a hydroelectric power plant under construction on the Vakhsh River with an installed capacity of 3,600 MW, being the largest HPP in Central Asia. Six hydroelectric units with a capacity of 600 MW each with radial-axial turbines will be installed in the HPP building. The average annual electricity generation at the Rogun HPP will amount to more than 17 billion kWh per year. In other words, this giant hydroelectric plant doubles the country's electricity generation twice at once (from 16.5 billion to almost 34 billion kWh).

The hydroelectric dam with a height of 335 m will become the highest rock-fill dam in the world. It forms the Rogun reservoir with a total volume of 13.3 cubic km and a useful volume of 10.3 cubic km. The Rogun HPP is planned to be used as a multi-purpose hydroelectric facility, including for generating electricity, regulating water, reducing the risk of floods and mitigating droughts. The uniqueness of this giant hydroelectric facility lies in the placement of its key components (the hydroelectric power station building and the transformer room) in the underground, in the heart of the mountain range surrounding the future reservoir, and the total length of underground tunnels is about 75 km.

The construction of the Rogun HPP was started back in the 1970s, but for some reason it was suspended in the early 1990s. In 2007, the Government of the Republic of Tajikistan applied to the World Bank for an international examination of the project, taking into account modern requirements and safety standards. All interim and final evaluation reports for the Rogun HPP were published on September 1, 2014, which marked the completion of the evaluation process. According to these estimates, the Rogun HPP construction project was recognized as technically feasible, economically feasible and compliant with international safety standards both from a technical point of view and from an environmental point of view.

The research also served as a basis for decision-making and dialogue between the countries of the river basin. Over the course of four years, five consultative meetings were held with the participation of officials of government bodies of the river basin countries, representatives of diplomatic circles and international organizations and hundreds of civil society organizations.

The first and second hydroelectric units of the Rogun HPP were commissioned in 2018 and 2019, respectively, and the third and other units are planned to be commissioned in the near future.

Construction and installation works at the Rogun HPP are carried out with the involvement of 70 organizations and institutions, well-known domestic and foreign contractors, 22 thousand specialists and workers, more than 90% of whom are citizens of Tajikistan, as well as using 3,600 machines and mechanisms.

Electricity from the Rogun HPP is already being supplied to the electric power system of Tajikistan by the 500 kV Rogun-Dushanbe transmission line, which was put into operation on the day of the launch of the first unit of the station – November 16, 2018.

The next largest energy project of the region along the route "Central Asia – South Asia" CASA-1000 is closely connected with this giant. This project involves the construction of a cross-border high-voltage power transmission line (HVTL), which will connect the energy systems of Kyrgyzstan and Tajikistan with Afghanistan and Pakistan. The implementation of the project will allow the countries to organize a single electricity market and trade all year round. Kyrgyzstan and Tajikistan will be able to supply 1,300 MW of excess electricity to southern Asian countries every summer.

To implement the CASA-1000 project, it will be necessary to build:

·        Transmission line-500 kV AC from Datka substation (Kyrgyzstan) to Sugd-500 substation (Tajikistan) with a length of 477 km;

·        converter substation with a capacity of 1300 MW in Sangtud (Tajikistan);

·        high-voltage DC transmission line with a length of 750 km from Sangtuda (Tajikistan) to Nowshera (Pakistan);

·        converter substation with a capacity of 1300 MW in Nowshera (Pakistan).

It should be emphasized that the project is supported by a number of global financial institutions and international cooperation institutions, the World Bank Group, the Islamic Development Bank, the European Bank for Reconstruction and Development, the European Investment Bank, the US Agency for International Development (USAID), the US Department of State, the UK Department for International Cooperation (DFID), as well as a number of other donor organizations.

The official start of construction work within the framework of the CASA-1000 project was on May 12, 2016 in Tursunzad (Tajikistan) with the participation of the President of the Republic of Tajikistan, Prime Ministers of the Kyrgyz Republic, the Islamic Republic of Pakistan and the Islamic Republic of Afghanistan.

In September 2018, in Almaty, after signing a number of other contract agreements between energy companies and contractors, the project moved fully to the construction stage in accordance with all legal requirements.

After the Taliban came to power in neighboring Afghanistan in August last year, it was officially confirmed that this project (CASA-1000), along with other major projects in our region, such as TAPI (Turkmenistan–Afghanistan–Pakistan–India gas pipeline) and the Termez–Mazar-I-Sharif railway – Kabul – Peshawar", is a priority.

Despite these obvious prospects in Tajikistan's hydropower sector, which forms the basis of the country's "green" economy, its government is making a number of efforts to create regulatory legal acts on renewable energy sources (RES). These measures are primarily related to global climate change, which in our mountainous republic is projected through the disappearance or reduction of glaciers – the main sources of hydropower. Therefore, the government of the country and the relevant ministry also began to pay attention to alternative electricity, primarily renewable energy sources such as solar and wind energy.

The climate of Tajikistan is particularly favorable for the use of solar energy. Having 280-330 sunny days a year and the intensity of total solar radiation, which, according to experts, varies throughout the year from 280 to 925 MJ/sq.m in the foothill areas, as well as from 360 to 1120 MJ / sq. m in a mountainous area. The use of available solar energy in Tajikistan can cover 10-20% of energy demand in the future. According to estimates, the potential of solar energy in Tajikistan is about 25 billion kWh per year (one and a half times more than the potential of the giant – Rogun HPP). This potential is practically not used, if you do not take into account some of its use for heating water.

Despite the objective fact that there is twice as much solar energy in Tajikistan as in Europe, however, solar energy in our small country is expensive compared to hydropower from the point of view of saving. For example, according to experts, today the unit cost of construction of hydroelectric power plants in Tajikistan is $1000/kW, the tariff is less than 2 cents per 1 kWh. At the same time, the unit cost of solar PP with a capacity of 1000 MW, being built today in China, in the Ordos steppe with huge solar radiation is $2500/kW, and the planned tariff is more than 18.8–20 cents per 1 kWh.

Therefore, the first projects on the introduction of a new (expensive) type of energy – solar electricity – in the republic are implemented within the framework of not purely economic or commercial projects, but social ones aimed at improving the standard of living in remote and mountainous regions of the country. The pioneer in this direction is a new (220 kW) solar power plant commissioned in the autumn of 2019 in the mountainous Murghab district, located on the border with China. This largest solar power plant in Tajikistan, built with the support of USAID, also acts as the tallest solar power plant in the world. This first solar power plant is a direct result of successful cooperation between the Government of Tajikistan, USAID and Pamir Energy. At the request of the Ministry of Energy and Water Resources of Tajikistan, USAID supported a project for installation of solar power plant in Murghab to supplement the nearby Tajikistan hydroelectric power plant (formerly Aksu) with a capacity of 1.5 MW and add clean renewable energy to the local power grid. Murghab settlement (the center of similar name district) in the Pamirs is one of the highest mountain settlements in the world. More than 6,000 people were isolated from Pamir Energy's power supply sources and the national grid due to uneven topography at an altitude of 3,600 m. A new solar power plant in Murghab will increase the available daytime electricity by 50%. This will not only significantly improve the quality of life of residents, but will also contribute to the overall economic development in the region. This pilot solar power plant project demonstrates how the national Government, international donor organizations and the private sector can jointly address development challenges even in the most remote and isolated areas of the world.

The next one of the alternative energy sources in Tajikistan is wind energy. The wind energy potential of the country has not been studied well enough. According to various estimates of experts, it varies from 30 to 100 billion kWh per year, which indicates that when clarifying this potential, which can be commensurate with the technical potential of the country's hydropower, it will also act as another colossal untapped energy resource.

Its use as a complement to the main hydropower is justified in some regions of the country. The strongest winds in the country blow in mountainous areas, wh ere the landscape of the country contributes to convergence of air flows, as well as in the Sughd region and in the Rasht Valley. The average annual wind speed in these regions is about 5-6 m/s. In the annual flow, the highest wind speed is usually observed in spring or winter with increased cyclonic activity, the lowest in summer and autumn. Observations show that the wind with a speed of 1-5 m/s (70-90%) has the greatest repeatability in most areas. The wind speed of more than 10 m/s is rare, and the repeatability does not exceed 10%. In the valleys and hollows, there is an average of 5-15 days a year with strong winds (Dushanbe and Istaravshan). In some forms of relief at high altitude and in places of narrowing valleys, the number of days with strong winds reaches 40-60 ( Khujand, Shakhristan district, Anzob pass, Fedchenko glacier, etc.).

The use of wind energy is promising in certain regions of the republic, wh ere the wind speed is quite high (more than 5-6 m/s at an altitude of 10 m from the surface level – Khujand, Kayrakkum, Faizabad, Khoburobad, Shahristan, Anzob passes, other areas) and wind power plants (wind turbines) can be used to generate electricity, raise water, grinding of grain, etc.

Usually turbines of wind power plants (wind turbines) have a capacity of 250-750 kW. The cost of generating electricity at wind turbines directly depends on the average annual wind speed and local conditions and ranges from $0.03 (10 m/s) – $0.12 (5 m/s) per 1 kWh, which is acceptable for the country. According to experts, the conducted technical and economic estimates of the cost of wind turbines give a value of $ 1000-1500 per 1 kW of design capacity. With the predominant use of hydropower, the use of wind energy is justified in certain areas as autonomous or additional energy sources of small capacity. Not having a large industrial value, wind energy can at the same time solve important social problems, providing energy to remote areas, farms, pasture and beekeeping cooperatives, etc.

Thus, the hydropower industry of Tajikistan, while remaining the core type of energy generation, is gradually losing ground to the generation of electric power in the country, when interest in other renewable energy sources is gradually increasing. In this process, there is an interesting trend when the fragmentation of types of electricity generation does not lead to the disconnection of the country's energy system, but, on the contrary, to their complement, when centralized hydropower is supplemented with alternative solar electricity, which fills the "bottlenecks", therebу ensuring uninterrupted generation and providing the population with affordable electricity.

The completion of the giant Rogun hydroelectric complex and the introduction of large solar and wind power plants contribute not only to achieving genuine energy security of sovereign Tajikistan, but also can help turn the country into one of the leading exporters of electricity in the Central Asian region.