Merits of gas-based power

India’s power sector has embarked on a high growth trajectory, particularly in the last five years. The capacity addition during the 11th Five Year Plan has been in excess of 55,000 MW, more than double of the performance of the 10th Plan. In spite of such impressive growth, the demand for electricity outstrips supply in most parts of the country. Also, shortage of fuel, in particular coal, is not helping matters, as several generation plants are running well below capacity, while questions are being raised about new ones in the absence of firm coal linkages.

A leading newspaper recently cited the absence of coal linkage as the main reason for more than 36,000 MW of new generation capacity, mostly with private investments, becoming unviable. The power shortage is exacerbated by low utilisation of thermal power plants, starved of coal supplies. The shortage is manifesting itself in many different ways — the sale of domestic and commercial generators, and invertors has been growing at a fast pace, with power outages in the heat having become an order of the day.

Given that most generators run on diesel, their incessant use increases the cost of power (at about two to three times than normal electricity tariff), apart from causing sound and air pollution. The recent announcement of the UP Government to shut down commercial activities and establishments after 7 p.m. everyday does not come as a surprise. The announcement, though hastily withdrawn days after it was criticised, brings to the fore the challenge that policymakers face in meeting the demand for electricity.

The UP Government’s order, seen dispassionately, is part of a time-honoured method of cutting off power when demand outstrips supply. The public outrage that followed would have made policymakers realise that this method will not be accepted. Innovative solutions to balance the growing demand of consumers with the available resources at command of the utility need to be evolved and implemented.

‘TRIGEN’ POTENTIAL

The recent pilot demonstration of the trigeneration plant in Delhi holds promise in this regard for power-starved utilities. The Trigeneration (TG) project, commissioned in the All India Institute of Medical Sciences (AIIMS) on June 5, could serve as a model that could be replicated in cities where availability of gas is not an issue.

The TG project, born out of a collaborative effort of Government of India and Germany through their respective agencies, Bureau of Energy Efficiency and GIZ (which is the nodal agency of German Government), is a decentralised and cleaner form of generation of electricity for captive uses.

As the name suggests, TG technologies could simultaneously supply electricity, heating and cooling requirements from the same fuel source and are best suited for establishments that need all the three applications. Common examples of such establishments are hospitals, hotels, shopping malls, airports, etc.

To intuitively understand why TG is a cleaner and reliable option, before dwelling into further details, it would be useful to look at conventional methods of meeting the three applications, namely electricity, heating and cooling. Undeniably, it is electricity that is used for heating and cooling, apart from it being used for lighting and other applications, barring a minority that uses solar energy for hot water applications. These establishments put a huge burden on the electricity grid. Therefore, it is not very difficult to comprehend why the UP order targeted some of these establishments, in particular the shopping malls.

TG technology, simply put, uses natural gas as a fuel for generating electricity. The high temperature steam that usually is emitted in the process is captured to provide cooling by heat transfer. The low temperature heat, which is another by-product, is used for heating water. Thus, TG, by using one single fuel, is able to cater to the three applications.

The overall efficiency of the conversion of gas into other forms of energy, namely electricity, heating and cooling, is around 2 times than that of conventional systems.

The accompanying diagram summarises the processes and the outcomes in such a system.

Thus, TG technologies substitute the use of electricity for air-conditioning and heating as compared with a conventional system. The overall efficiency of the TG system is therefore two times as compared to the conventional system. To elaborate this further, for every 100 units of coal used by a power plant, only 35 units of electricity is produced, which is reduced further by the transmission and distribution network resulting in use of only about 20-25 units on the demand side. In case of TG, being at the load centre, and having the capacity to use waste heat, in addition to almost 40 units of electricity generated from 100 units of gas input, electricity substitution for air-conditioning and heating enhances the efficiency to 65 per cent.

TG being closer to the application, has minimal distribution losses, thereby increasing the overall system efficiency to almost two times that traditional coal based system. The recently commissioned TG plant commissioned in AIIMS will generate 2.9 million kWh of electrical energy annually and will help save the hospital Rs 1.2 crore annually due to higher efficiency.

The payback on investments made in setting up the plant is a little over 3 years. In addition, TG will also considerably improve reliability of supply. The emissions of greenhouse gases from its usage will be a fraction, compared with coal-based electricity. Scaling up the use of TG could be a viable option in realising India’s objective of low carbon growth of the energy sector.

POLICY IMPLICATIONS

There are some isolated examples of TG being successfully used – some estimates indicate that the total capacity installation at present could be around 300 MW. The assessed potential of TG in India, looking at the availability of gas and the GAIL’s distribution network, is estimated to be anywhere between at least 10,000 MW and growing according to a GIZ study of 2010.

Promoting the use of this technology in establishments that are major users of electricity in urban areas, could provide the leverage to utilities in meeting the rising power demand.

There are some regulatory issues related to gas as well as power sector that may need ironing to scale up this technology. The present gas regulatory regime puts commercial gas distribution in cities, which could provide gas for TG, at a priority level after fertiliser, LPG and power. The pricing of gas for commercial use is also an issue that could impact the commercial viability of TG, and the regulators need to address this to promote gas-based decentralised systems.

On the electricity distribution side, aggregations of establishments best suited for TG could enhance its attractiveness. However, the vexed issue of open access and surcharge needs to be settled in a manner that it balances the genuine commercial concerns of utilities with that of ensuring reliable and cleaner electricity for large commercial consumers.

TG technology has demonstrated its efficacy in meeting the growing demand for electricity in an efficient and clean manner. Regulatory and policy incentives could scale up its applications in cities where gas distribution has commenced.

(The author is Programme Officer, OzonAction Programme, UN Environment Programme, Bangkok. The views are personal.)

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