The Hindu Business Line : Wiring up small grids for mega power

If electricity retailing is opened to private enterprise, it will gradually create space for many suppliers who in turn will compete to provide better products and services.

Network to energise.

IN the field of telecom, technological developments have made the networks extremely simple and easy to create. Before the maturity of cellular technology, the telecom industry suffered the same problems as the energy sector does today. The financial structure of the cellular industry harmonised the telecom network, removing capacity constraints. Today, telecom is a thriving industry both in the private and government sectors.

Without a similar breakthrough in technology, the energy situation in India is unlikely to improve. Happily, technology is at the country's doorsteps, and this can so change the situation that power-cuts could become a thing of the past in the not too distant a future. It is quite likely that over 20,000 MW will be added to the national system through the micro-grids in the next two-three years, and this will completely remove the peak power shortage from the national system.

Standalone renewable generating systems

In the field of generation, the renewable will lead the way. New technologies in biomass, biogas, wind, solar and fuel-cells will create hybrid standalone systems. These systems will be a part of micro-grids connected to the national grid through VSC (Voltage Source Converter)-based HVDC (high voltage direct current) connections.

Research in the field of biomass has already made it a viable source of renewable fuel. It is possible to connect small biomass gassifiers along with turbo-generators mounted on trailers to be installed at the source of biomass. These gassifiers can produce fertilisers and `producer gas to run the turbo-generators.

Bagasse is a well-known source for cogeneration and the new technology to convert bagasse into gas rather than burning it in the boiler will make it environmentally acceptable and economically viable for sugar mills. It is also possible to use forest wastes to generate electricity.

Wind has already proved its point in the some coastal States, especially Tamil Nadu, Maharashtra and Gujrat. However, with the development of better technology and the VSC-based HVDC transmission systems it would be feasible to develop offshore wind farms. It may thus be possible to develop large wind farms off the coast to generate large amounts of electricity.

Solar photovoltaic (PV) systems are a common rooftop sight in most Western countries and are adding their bit to the grid. It is also possible to develop large PV stations with few hundred kilowatts/megawatts of power generating capacity in remote areas where there is a good amount of sun. Solar concentrating (thermal) systems have been technically proven and would be another option for the grid during peak loads. Fuel-cells, though still in future, would offer the best option in terms of clean power.

Technology of Transmission and Distribution

Ever since George Westinghouse developed interest in the alternating current (AC) and acquired a patent on polyphase transmission systems on the invention of Nikola Tesla in 1888, electricity distribution and transmission systems have been running on AC. Westinghouse demonstrated the system for the first time in 1893 in Chicago. By 1895 two induction motors had been installed at the Niagra falls power project The two major inventions that contributed to the growth of alternating currents were the induction motor and the transformer, on which ran most industries the world over.

Alternating current or the AC system, is the livewire of all electricity transmission and distribution in the world. Generators generally operate at 50-60 cycles per second. The electricity generated by an AC generator is transformed to higher voltages (of 400,000 Volts) and despatched to distant places. At the load centres, this is again converted back to lower voltages for domestic and industrial use.

Thus, each city has receiving stations where the voltages are transformed and the lines interconnected. The technology of power transmission has matured and it is now possible to transmit power at voltages as high as 12,00,000 Volts AC. The main advantage of high voltage transmission is the reduced losses and, hence, the higher capacity of wires to carry current. While the transmission of electricity on AC is a standard and common practice, the technology has also evolved to convert electricity into DC (direct current) and for transmission to long distances. DC ransmission has many advantages as it is more stable and offers flexibility to the grid operators. It is now feasible to transmit electricity up to 800,000 Volts DC.

DC has many advantages over AC such as lower losses, possibility of using cables in lieu of overhead transmission lines, and better control on the flow of power. However the technology to convert from DC to AC and back was costly and hence not economical. Continuous research and development in this area has now made it economically feasible where there is a large flow of power to long distances or where two dissimilar systems need to be interconnected or where there is a problem of right of way to construct overhead lines such as across seas.

Developing countries, which need to do a lot in terms of transmission infrastructure, would thus see a grid that will be quite different from the current AC systems. The new grids will be a hybrid of AC and DC transmission lines and would not only connect long transmission lines but also use HVDC to interconnect generators to the grid.

In India there are two grids — one connecting the four Southern States of Kerala, Tamil Nadu, Karnataka and Andhra Pradesh, and the rest of the country linked by Extra High Voltage Transmission lines. Before August 2006 there were quite a few independent grids but these have now been interconnected, and thus the frequency of supply of electricity in the North-Eastern States and Maharashtra will always be the same. It is planned to interconnect by 2008-09 the Southern and the Rest of India grids; that is, the entire country will be fed by one supply network. There are quite a few advantages of having such an interconnected network:

Generators in one part of the country can feed loads elsewhere.

A larger grid is generally more stable and interruptions on various generators do not impact significantly the system.

There are, however, some disadvantages of so large a grid. The main one being disturbances that can affect the whole nation. Anyway, with the introduction of HVDC at various interconnecting points it should be possible to minimise such eventualities.

Distribution of electricity has always been less technology focused. However, the introduction of IT in distribution would definitely improve the commercial viability of the retail industry and thus change the complexion of the aggregate technical and commercial losses in the system.

Market reforms - an essential ingredient

For any technology to become affordable it is necessary that the market forces are allowed to function freely. Once the reforms are introduced and the electricity supply industry is opened to competition, market forces will drive the growth. As with the telecom sector — cellular phones were expensive at the time of introduction but soon enough became affordable with technology becoming cheaper — the power supply industry will follow the same path, once the retail industry is opened up. If electricity retailing is opened to private enterprise, it will gradually create space for many suppliers which, in turn, will compete to provide better products and services. It is suggested that two-three private players are encouraged to serve as retailers in all towns in India. The licencees could either create their own networks or use existing facilities by paying a wheeling charge to the owners.

This will encourage big business houses to invest in the wire industry and create a world-class distribution network. Each town could then have a number of retailers and, in some cases, multiple networks. The current mode of setting the price of electricity by the regulator is very inefficient and must be discarded quickly.

(The author, an energy specialist with extensive consulting experience in the US, Australia and Korea, is Director — Operations — Mahatransco, Mumbai.)