Can coal turn flexible to spur green energy?

Experts believe the more renewable grows, the more will be the need to put up coal capacity

April 21 was the first ever working day since the Industrial Revolution that Britain generated power without coal. The West Burton power station, the only coal-fired plant up and running, went offline a day earlier. Many see this as a signal to coal producers as well as coal-based power generators to rediscover themselves and shift away from this fossil fuel as an energy source.

With the energy mix changing fast even in countries like India that are yet to provide power for all, there is talk of coal-based power giving space to renewable forms of energy. But can coal-based power move away from being the base load and start playing balancing role when renewables are not available or there is a shortage of power?

Though technical constraints prevent fast ramp-up of coal power plants and, therefore, gas-based power and hydropower are considered best for balancing blip shortages, GE Power India Managing Director Ashok Ganesan says coal power plants are being made flexible. “Our customers tell us that. In the new regulatory environment, plants are being built with heavy demand on flexibility. Countries like Germany went through it. They make coal power flexible,” he says.

So, when GE does renovation and modernisation for coal-based power plants, it tries to make plants flexible to address fast ramp-up and start-up issues. “With digital and hardware changes, you can make a coal plant flexible,” says Ganesan.

Coal-based power is witnessing low or nil capacity addition, besides low utilisation reflected in lower plant load factor (PLF). “The energy mix is shifting to renewables in India like elsewhere. However, we don’t think that it is the death of coal. Even in the shifting mix, coal-based power generation will continue for the foreseeable future to be the mainstay,” Ganesan adds. While its share of the pie will go down, actual generation may not fall.

Why coal matters 

Ashok Ganesan, MD, GE Power India

What gives coal the coveted base load status is the reliability and higher PLF compared to both wind and solar. Even nuclear generation is considered to be part of the base load. For balancing or peaking power, hydropower and natural gas are considered ideal. At the same time, experts believe that the more renewable grows, the more will be the need to put up coal capacity. “India’s demand for energy is growing at 6-7 per cent per annum. Fifty per cent can be met by wind and solar. But the other 50 per cent needs to be met by the base load. If the base load is not increasing, renewable will not grow,” says Suzlon CMD Tulsi Tanti.

PricewaterhouseCoopers Partner Kameshwar Rao says coal can never be replaced as the base load despite technological improvements. “It takes at least 40 minutes to start up a coal plant and back down since it has high pressure steam.” Besides, there is high fluctuation in the generation levels of renewable during production hours. There could be a cloud cover or a storm which could reduce generation of a solar plant,” he says.

As renewables increase, there is a demand which will be created to balance them out. This demand was otherwise non-existent. In India, before the current push for renewables, designing power plants for meeting peak requirements had not caught the attention of industry or the government. Power plants designed as base loads  are now forced to back down when there isn’t enough demand or when a distribution company wants to buy renewable energy to meet its purchase obligation. 

The only policy which came out from the government was in February 2014 when a model agreement for the procurement of peaking power was put out. The Union power ministry laid down that availability of the contracted capacity of a power station should be at least 85 per cent during peak hours of each year in the contract period. The peak hours were defined as two hours up to or before 10 am and four hours from or after 5 pm. The distribution company (discom) must specify the time, with a notice of 30 days, to the generator. The buyer is to pay a fixed charge for 85 per cent capacity but in the event of buying more than the contracted capacity, the fixed charge will not be applicable — only variable or energy (fuel) charge would apply.

In such a contractual arrangement, the per unit (kilowatt per hour) cost of a peak load plant is higher compared to a base load plant and the discoms have to agree to buy power at higher costs to make peak load plants viable. However, since peak load is a smaller percentage, the total power purchase costs are averaged out.

Coal rules

Coal-based power plants can produce 80 per cent and even above 90 per cent of their capacity provided there is enough coal available and the discoms are ready for off-take. Tanti says hybrid of wind and solar will give stability to renewables. They will become more competitive because common infrastructure will be used. Still, coal-based power plant will give at least 60 per cent PLF, on an average, while wind’s PLF will be 35 per cent and  that of solar 20-25 per cent. 

Besides hybrid, reliability can be improved through storage where a lot of research is currently going on globally. Rao, however, avers storage will increase the cost substantially. “It is a matter of economic viability. The cost starts from  Rs 15-18 crore per megawatt.” Currently, most of it is pump storage at hydropower plants. On Britain’s no coal-power day, Rao says such events happen when demand is anyway low and the spring season ensures adequate sunshine and wind to generate green energy.

It is, nonetheless, certain that more investment will move towards renewable than the conventional sources of power. Tanti says today world is building 60 per cent renewable and 40 per cent conventional. Over the past two years, of the total investment of $1.2 trillion in power,  $620 billion was for renewable. This will put coal in a spot where it will be a base load but with enough flexibility to back down and ramp up to balance the fluctuating renewable generation.