The demand for towers, which are a vital component of the transmission system, is set to grow as the country’s network continues to expand to meet the rising power demand and increasing renewable capacity. In 2021-22, the power equipment industry witnessed a V-shaped recovery post-Covid, registering a growth of over 17 per cent over the previous year, according to IEEMA. The transmission line towers segment recorded a growth of 0.9 per cent during this period, primarily supported by exports. With ample line length addition planned in the country over the next few years to enable the evacuation of renewable capacity, the growth rate of towers is expected to increase sharply. Power Line takes a look at the key trends, growth drivers, and issues and challenges in this segment…
Size and growth
As of September 2022, the total transmission line length (at the 220 kV level and above) stood at 463,377 ckt km, the total AC substation capacity stood at 1,104 GVA and the HVDC substation capacity stood at 33,500 MW. Between 2015-16 and 2021-22, the line length has grown at a compound annual growth rate (CAGR) of nearly 5 per cent while AC and HVDC substation capacities have grown at 8.8 per cent and 14.3 per cent respectively. The interregional transfer capacity has also grown considerably from 58,050 MW in 2015-16 to 112,250 MW in 2021-22, recording a CAGR of 15 per cent.
Private participation has also increased in the sector, mainly at the interstate level. As of August 2022, 63 interstate transmission system projects have been bid out to public and private players since 2009. This excludes four projects that have been cancelled or are under litigation. Of the total, while 21 projects were secured by Power Grid Corporation of India (Powergrid), 42 have been won by private players. Key private players in the segment include Sterlite Power (16 projects) and Adani Transmission Limited (14 projects). At the intra-state level, Odisha Power Transmission Corporation Limited recently evinced interest in awarding projects to private players via tariff-based competitive bidding.
Transmission is an enabler of energy transition, and as the country races to meet its climate change goals, rapid expansion and advance planning of the transmission network are required. To recall, India committed, at COP26 in Glasgow in November 2021, to achieve a non-fossil energy capacity of 500 GW and to meet 50 per cent of its energy requirement through renewable energy, by 2030. A significant renewable energy capacity is already under development in the country. Therefore, matching transmission infrastructure needs to be developed in a planned manner to ensure smooth integration with the grid and reliable power supply to load centres.
As per Central Transmission Utility of India Limited’s Interstate Transmission System (ISTS) Rolling Plan 2027-28 (interim report September 2022), the all-India installed capacity is expected to increase from 404 GW (including 114.4 GW of renewable energy and 47 GW of hydro) as on March 2022 to about 594 GW (including about 254 GW of renewable energy and 71 GW of hydro) by 2027-28. Further, the peak demand is projected to increase by over 55 per cent, from 203 GW to 316 GW, during this period. The transmission system for integrating this capacity into the grid has already been planned, and is currently under various stages of implementation. Cumulatively, by 2027-28, transmission schemes comprising 33,019 ckt km of transmission lines and a transformation capacity of 2,42,940 MVA, at an estimated cost of Rs 1,107.44 billion, are expected to be executed. The inter-regional capacity is expected to reach 130,340 MW by 2027-28.
The growing impetus on regional energy collaboration among South Asian nations is also a driving factor for transmission system expansion through cross-border interconnections. Today, electricity trade is taking place between India and Nepal, Bhutan and Bangladesh through existing transmission interconnections, with many more planned. Cross-border interconnections help in meeting the growing power demand and sharing varied energy resources, while reducing operational costs through better resource management, better utilisation of renewable energy resources and deferment of investment in new generation technology by optimising spinning reserves.
Several transmission interconnections between India and its neighbouring countries are under construction or planning. These include the planned link with Bangladesh, the Katihar (Bihar)-Parbotipur (Bangladesh)-Barnagar (Assam) 765 kV double circuit (D/C) line. Some interconnections under discussion with Myanmar are the Imphal (India)-Tamu (Myanmar) high capacity AC line along with a 1×500 MW HVDC back-to-back link; the Nampong (Arunachal Pradesh)-Pansong (Myanmar) 11 kV single circuit (S/C) radial line; the Behiang (Manipur)-Cikha (Myanmar) 11 kV S/C radial line; the Zokhawthar (Mizoram)-Rikhawdar (Myanmar) 11 kV S/C radial line; and 11 kV S/C lines from Nagaland to Myanmar.
From Nepal, an additional 1,800 MW can be transferred to India through the following under-construction links: the Sitamarhi (Powergrid)-Dhalkebar (Nepal) 400 kV D/C (Quad) line (which is associated with the Arun-3 hydroelectric project in Nepal and is expected to be ready by April 2023 to transfer 800 MW); the Gorakhpur (India)-New Butwal (Nepal) 400 kV D/C (Quad) line (which is awaiting the grant of requisite approvals and will enable the transfer of 1,000 MW); and the second circuit of the Kataiya (India)-Kusaha (Nepal) 132kV S/C on D/C line (which is currently undergoing stringing). In addition, more lines are under discussion with Nepal such as the New Purnea (India)-New Duhabi (Nepal) 400 kV (Quad) D/C line (1,500 MW); the Bareilly New (India)-Lumki (Nepal) 400 kV (Quad) D/C line (1,500 MW); the Lucknow (India)-Kohalpur (Nepal) 400 kV (Quad) D/C line (1,500 MW); stringing of the second circuit of the Raxaul (India)-Parwanipur (Nepal) 132 kV S/C on D/C line (50 MW); the Nanpara (India)-Kohlapur (Nepal) 132 kV D/C line (35 MW); and the New Nautanwa (India)-Mainhiya (Nepal) 132 kV D/C line (35 MW).
With Sri Lanka, the New Madurai-New Habarana 1,000 MW HVDC bipole line is under discussion. Meanwhile, with Bhutan, new links are under construction to increase the power transfer capacity to about 4,168 MW by 2027-28 from 1,948 MW at present.
The demand for transmission equipment will also come from the renovation and modernisation of sub-transmission networks. As per a Ministry of Power order in 2021, all 33 kV systems currently maintained by state distribution companies will be brought under state transmission utilities in a phased manner for better planning and loss reduction, and increased supply reliability.
The transmission segment is at the forefront of adopting the latest technology. The design of transmission towers has also evolved over the years. Utilities are deploying towers that require minimum Right of Way (RoW) approvals, can be installed faster and provide cost benefits. As such, utilities are opting for double-circuit towers, multi-circuit towers, compact guy towers, transmission cum telecom towers, and winged circuit towers in place of conventional lattice-type towers. For instance, the country’s largest power transmission utility, Powergrid, has developed and tested monopole structures for the 400 kV and 765 kV voltage levels to address RoW problems in densely populated urban areas, conserve forests and allay aesthetic concerns. Further, post insulators have been used for jumpers to reduce the cross-arm projections and thereby the RoW requirements. The use of direct current transmission can also help optimise RoW. Transcos are also deploying emergency restoration system towers following natural disasters. Project developers are also deploying LiDAR technology, drones and air cranes for the construction of transmission lines, and thermovision cameras and Android-based applications for operations and maintenance. In order to enhance the availability of the transmission network, utilities are deploying online asset monitoring tools. State utilities are also making arrangements for remote inspection and maintenance.
Issues and the way forward
A key issue hampering the pace of transmission expansion is the time required to obtain permits and clearances, which can take up to 12-15 months if forest clearances are involved. In addition, route surveys, obtaining RoW and acquiring land lead to project implementation delays. As a result, the commissioning of transmission projects takes nearly two to three years, while associated renewable energy projects can be completed within a couple of months. Therefore, there is a need to streamline the process of obtaining approvals to ensure transmission projects are completed in time.