The Hindu Business Line : Power: Tap the benign sources

Several countries are orienting themselves towards the environmentally-‘benign’ perennial sources that can be tapped for generating electricity that is clean and potentially inexhaustible. S. K. N. NAIR looks at the resource and technology constraints to these choices and the ways to overcome them.

Is the country doing enough to tap the energy sources from the wind, the sun and the perennial streams? This point has come into focus, thanks to the controversy over the nuclear deal.

Production of coal-based electricity — our current mainstay — damages the environment.

Coal is also a depleting resource. Nuclear energy, the other serious candidate for supplying ‘base-load’ electricity, is environmentally clean, but carries huge safety-related risks. In contrast, the ‘benign’ sources can all be tapped for generating electricity that is clean and potentially inexhaustible.

Several countries — developed and some developing — are orienting themselves towards these environmentally-‘benign’ perennial sources and we would do well to catch up. National consensus on this issue is not wanting. The Prime Minister, Dr Manmohan Singh, has committed to according priority to this area and finding the needed resources. What, then, are the constraints?

Wind energy generation

In fact, we have more than overcome the resource and technology constraints at least in the case of wind energy. From an installed capacity of about 1,600 MW in 2002-03, wind-based power has raced up to account for nearly 8,000 MW by March 2008.

But reliability is a problem — an important concern in electricity supply. Tamil Nadu — the leading State accounting for nearly half the country’s total installed wind power capacity — provides a handy illustration.

“During the last few days, availability of wind power has reduced by almost 1,500 MW”, so read a sentence in an urgent ‘appeal’ put out by the Tamil Nadu Government on August 30, seeking public co-operation in the face of impending power cuts. Drop of 1,500 MW represents about 15 per cent of the State’s current total demand.

The wind power generators are, of course, not to blame for this; wind energy is inherently infirm — it comes and goes as wind speeds pick up and drop — and this limitation will remain until viable cost-effective means are found to store this type of power.

The ‘cuf’ impact

Wind of the required speed to activate the turbines blows only for a few hours of the day, lowering the ‘capacity utilisation factor’ (cuf) which, in India, averages just 15 per cent.

Also, there are sharp seasonal variations that impact the ‘cuf’; wind-speeds across most of India drop below the needed threshold during the autumn winter months. So, even if the unseasonal dip in Tamil Nadu corrects itself in a few days, wind energy generation will hit another trough very soon. Low utilisation factor and infirmity of supply rule out wind energy substituting mainstream power, especially the bulk power needed for ‘base-load’ round the clock supply. But it can be a splendid component in a ‘balanced’ electricity system.

By this, we mean a power system that has enough redundancy to cater to shifting demand, including a reasonable ‘spinning reserve’. Our system is too far removed from that ideal. We just do not have the needed flexibility; hence the sudden emergency in Tamil Nadu.

In balanced systems, when wind speeds drop, other sources take over seamlessly and the supply remains unaffected. Here, the true value of wind power is realised: it helps save fossil-fuelled supply or storeable energy such as hydro and brings large environmental benefits in the process.

The lack of flexibility of our system could be at least part reason for actually lowering the utilisation factor.

System inflexibility induces rigidity in load management leading to sub-optimal wind power utilisation. This is my surmise for our very low ‘cuf’ levels; globally, ‘cuf’ of wind farms is in the 25-30 per cent range, which is considered optimal for the current technology.

Other plausible reasons — an unbalanced incentive regime tilted in favour of capital subsidies and inadequate competition for equipment supply — have also been advanced by informed observers.

As for achievable capacity, the ‘theoretical’ potential for wind power in the country (that is, capacity calculated from estimated — not actually measured — wind patterns and assumptions regarding land area for ‘siting’ wind-farms) is officially placed at 45,195 MW and the ‘technical’ capacity is put at 13,000 MW.

A ‘national wind atlas’ is currently under preparation with expert guidance and firm numbers on the total achievable potential and should be ready next year.

The ‘technical’ capacity (reckoned with reference to the global utilisation levels) could also get revised upwards as designs that capture more wind through increased hub-heights and altered rotor blade specifications are developed.

To exploit the true benefits from this rich potential, we need to speed up, not slow down, our efforts to bridge the demand-supply gap by the mainstream power sources.

Informed public opinion should be cautious not to confuse the short and medium-term priorities with desirable objectives that can be realised only over the longer term.

If carried into policy, this could jeopardise our pressing priority of catching up with soaring demand; we did precisely that in the 1990s based on hyped expectations from private power which took time to fructify.

The solar incentive

Compared to wind, solar energy is certainly a more promising and flexible option for the country over the long term — long term, because grid-connected solar power is at an incipient stage in India. At present, it is a miniscule 3 MW.

To promote units of grid-interactive solar capability, the Ministry of New and Renewable Energy (MNRE) is offering hefty generation-based incentives.

The incentive rates themselves, recently notified — Rs 12 per unit (KwH) of power based on photovoltaic technology and Rs 10 per unit for solar-thermal, the latter involving conversion of solar energy into heat for moving steam turbines — indicate the financial implications of supporting a large programme at the present stage of technology.

Apparently for this reason, the incentive scheme is currently limited to a total of 50 MW, nationally.

Several small-medium size solar ‘pilot’ units are functioning in the US and Europe and there is frenetic research activity to bring down the costs and make this source commercially viable.

But even allowing for an early break-through, solar energy cannot, in any significant measure, meet the urgent purpose of a 140,000 MW system that is projected to double within the next decade, to keep pace with demand.

Large government-subsidised investments are going into silicon wafer and semi-conductor manufacture in India (obviously eyeing the fast-growing European market too), but benefits in the capital costs that could result are unclear. Further, both the solar technologies — photovoltaic and solar thermal — need acres of land for putting up the reflectors that capture solar energy, a factor that could slow down, even hold up, large projects.

Futuristically, there is a ray of hope on this last point. A daring concept put forth recently envisages tapping of solar energy by reflector-equipped orbiting satellites and transmitting it down to earth through radio waves. So the bulk of India’s power needs could yet be met by solar power some time in the (hopefully not too distant) future, without provoking land-related protests.

Down to earth

Coming down to earth, the total estimated potential of the third ‘benign’ source — small hydro projects — is a modest 15,000 MW, of which about just one-fifth is now tapped or being developed. The bulk of the remaining potential is along the Northern, Central and far North-Eastern hilly regions.

They include both run-of-the-river sources and units based on small storage dams. Depending on the location, these can cater to purely localised supply — very valuable for remote communities — or wholly/partially grid-connected ones.

State electricity regulators are authorised to set the subsidised tariffs for this form of power, which will again, (like wind energy) have added value for a balanced power system in the future.

(The author is a former Member of the Central Electricity Authority and a former Consultant to the National Council of Applied Economic Research, New Delhi. blfeedback@thehindu.co.in)

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