Solar power plants using the rivers in Manipur

Prof I Tomba Singh *

Imphal Turel (River) in Sept 2012 : Pix - Jinendra Maibam

With the rapid depletion of fossil fuel reserves, it is feared that the world will soon run out of its energy resources. Energy has an established positive correlation with human population and economic growth. Primary energy requirements are expected to increase manifolds in the years to come. Providing adequate, affordable and clean energy is a prerequisite for eradicating poverty and improving productivity.

The inevitable increase in the use of fossil fuels alongside a country’s economic growth presents associated side effects of threat to the Nation’s energy security as well as environmental degradation through climate change. A feasible alternative to the indiscriminate burning of fossil fuels lies in the accelerated use of renewable energy.

Major types of renewable energy sources include solar, wind, hydro and biomass, all of which have huge potential to meet future energy challenges. Solar Photovoltaic (PV) technology is one of the first among several renewable energy technologies that have been adopted world-wide for meeting the basic needs of electricity particularly in remote areas. In tropical countries, which have sunshine almost throughout the year in most parts, solar energy is one of the most viable options.

This form of renewable energy occupies less space compared to the space occupied by hydropower projects. The amount of solar energy incident on the earth’s surface has been estimated approximately 1.5x10x18 KWH/year which is about 10,000 times the current annual energy consumption of the entire world. In fact, a standalone solar photovoltaic system does not provide a continuous supply of energy due to reasonable and periodic variations.

Therefore in order to satisfy the load demand, grid connected energy systems are now becoming promising options that combine solar and conventional energy systems.

A solar cell is a device which converts photons in solar rays to direct-current (DC) and voltage. A typical silicon photovoltaic (PV) cell is thin wafer consisting of a very thin layer of phosphorous doped (N-type) silicon on top of a ticker layer of boron doped (P-typed) silicon. An electrical field is created near the top surface of the cell where there two materials are in contact (the P-N junction).

When the sunlight hits the semiconductor surface, an electron springs up and is attracted towards the N-type semiconductor materials. These will create more negatives in the N-type and more positives in the P-type semiconductors generating a higher flow of electricity. The Sun is the fundamental driving force for energy in the Earth’s climate system.

It is of crucial importance to understand fully the conditions of its arrival at the top of the atmosphere and its transformation through the earth. The amount of solar power available per unit area is known as irradiance. Irradiance is the radiometric term for the power of electromagnetic radiation at a surface, per unit area. It is used when electromagnetic radiation is incident on the surface.

Irradiance fluctuates according to the weather and Sun’s location in the sky. The solar constant is the amount of incoming solar electromagnetic radiation, measured on the outer surface of Earth’s atmosphere on the plane perpendicular to the rays. Solar constant does not remain fixed over long periods of time. The average value cited 1.366S W/m2 is equivalent to 1.96 calories per minute per square centimetre or 1.96 Langleys (Ly) per minute.

In thin-film solar technology, a very thin layer of chosen semiconductors material is deposited on to either coated glass or stainless steel or a polymer substrate. Various thin-film technologies are being developed to reduce the amount of light-absorbing materials required to construct the solar cell which results in reduction of processing cost.

However, conversion efficiencies are also lower in these cases, as the modules are of lesser efficiency for some level of energy requirement, longer collection area is required and consequently more requirement of land. This technology is, therefore, applied in non-productive land particularly in deserts. This technology became popular compared to wafer silicon due to lower cost, flexibility, lighter weights and ease of integration.

In Manipur, sufficient non-agricultural areas are hardly available, particularly in the valley portion, as such application of thin-film technology cannot be adopted. However, rivers in the valley area like the Imphal river and the Nambul river flowing north to south direction can be utilised for installing solar panels. The areas of Mongsangei in the proximity of Nambul River and Ningomthongjao and Kyamgeiin the proximity of Imphal River can be utilized for installation of such power plants based on photovoltaic modules.

The state of Tripura had been benefited with the commissioning of gas based power plants utilizing the gas resources available in the State. The combined Cycle Project is located at Monarchak, Sonamura in Sepahijala District around 60 KM away from Agartala, the Capital of Tripura.

The project runs on Combined Cycle Mode and consists of one Gas Turbine of 65.42MW and one Steam Turbine of 35.58 MW each of BHEL supplied, operating an natural gas obtained from the gas fields of Oil & Natural Gas Commission (ONGC). The gas turbine started commercial operation in 2015 and the Steam Turbine in 2017.

Recently the Asian Development Bank (ADB) sanctioned Rs. 1925 crore to the Tripura State Electricity Corporation under the initiative of the Government of Tripura for upgradation of power generation and distribution in Tripura.

The project has been sanctioned for upgrading 63 MW capacity Rokhia Project to 120 MW at an estimated cost of Rs. 699.80 crore and modernising Gumti Hydro Electric Project at an estimated cost of Rs. 1225.88 crore.

National Thermal Power Corporation (NTPC) is the largest power generating company in the Country. It has 18 coal-based power stations having the installed capacity of 33,985 MW. Coal based power stations in Vindhyachal, Madhya Pradesh (4,7760 MW), Rihand, Uttar Pradesh (3,000 MW).

Tatcher Kaniha, Odisha (3,000 MW), Sipal, Chattisgarh (2980 MW) Kobra, Chattisgarh (2,600 MW), Ramagundam, Telangana (2,600 MW) can be mentioned as Super Thermal power plants of NTPC. The installed capacity of NTPC is 45,993 MW (including 6,196 MW through joint venture projects) comprising 41 NTPC stations (18 coal-based stations, 7 combined cycle gas/liquid fuel based stations, 1 Hydro-based station) 8 joint ventured stations (7 coal-based and one gas based) and 8 renewable energy projects.

In Manipur, Loktak Hydro-electric power plant of National Hydro-electric Power Corporation (NHPC) has an estalled capacity of 105 MW with 3 turbines of 35 MW capacities each. The State share of energy is very meagre and therefore the entire demand for power is being procured from other states. NTPC has discouraged the setting up of fossil fuel based power plants where there are no local resources.

As such Manipur State Power Corporation, under the initiative of the State Government may take up steps for setting up grid connected solar plants using the rivers flowing north to south direction. The rivers in Manipur valley such as the Imphal River, the Nambul River has the width ranging from 100 ft. to 150 ft. on the average.

PV Solar panels can be installed over the rivers since non-agricultural areas are not available sufficiently. The requirement of space for installing solar panels for a 10 MW grid connected Photovoltaic (PV) solar project is around 10,00,000 sq.ft. The area needed over the river will be around 6700 ft. or 220 metres long for the river having the width of 150 ft.

Such projects can be taken up as joint venture projects with NTPC. Design and feasibility studies for setting up such 10 MW solar projects can be taken up by the State Administration for seeking financial assistance from the funding agencies.

The Manipur State Power Corporation Company limited and the Manipur State Power Distribution Company limited will be benefitted with the implementation of such 10 MW grid connected PV solar projects, using the rivers flowing from north to south direction in the valley areas of the State.