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Feature | June 2017

Energy-efficient power plants crucial to tackle emissions

Ashok Ganesan, Managing Director, GE Power India Ltd, talks about how equipping India's power plants with energy efficient technologies can go a long way in contributing to the countries carbon reduction goals.

India's power generation capacity has nearly tripled in the last 15 years from 105 GW in 2002 to 315 GW in 2017 as demand for electrical energy surged in a rapidly expanding economy. During this time, 140 GW of coal and gas power generation installed base were set-up. Across the world, there is roughly 2,000 GW of coal-based capacity and is here to stay for the foreseeable future.

Coal-based generation accounts for roughly 40 per cent of the world's electricity generation (over 70 per cent in India & China) but also accounts for over 70 per cent of the world's carbon/emissions (from power generation). While this has helped bring electricity to more and more citizens -improving the standard of living, this also has resulted in a significant increase in carbon footprint.

As per International Energy Agency's (IEA) India Energy Outlook-World energy Outlook Special Report-2015, fuelled by an affluent population and industrialisation, electricity consumption in India will increase by 4.9 per cent per year till 2040.

Today, India has 315 GW of installed capacity (Feb 2017); with energy mix dominated by coal (60 per cent), gas (8 per cent); renewables (including hydro) (at 32 per cent). By 2022, the installed power capacity in India is expected to reach 430 GW, and while renewables will be added at an increasing rate, actual power generation will still rely largely on coal (due to energy security issues and affordability). However, the overall efficiency of power generation in India is very low (primarily from coal). This then sets up the need for driving improvements to the install base for coal and driving up the efficiency.

Mitigating emissions - the efficient way
The size of clean market related to coal-based power generation in India is $3 billion for efficiency and $6 billion for emissions. As on Feb-2017, thermal sources (coal, oil and gas) based power generation accounts for 68 per cent of total installed capacity while hydro, renewable and nuclear makeup for the rest.

To control emissions of greenhouse gases and their impact on climate patterns, it's imperative to usher in energy efficient technologies for coal power generation, especially for old plants to control emissions of gases, dust and fumes. Energy-efficiency can be the pivot for India to attain its sustainable energy goals and improving air quality.

The global average efficiency of coal-fired power plants currently hovers around 33 per cent, significantly lower than the 45 per cent efficiency possible for units that run on ultra-supercritical technology. It is estimated that if these plants are upgraded to operate at an average efficiency of 1pt, annual CO2 emissions would fall by more than 2-3 pt.

India is a perfect case in point, where the need for a massive upgrade and introduction of new technologies to raise the efficiency of coal-based power generation is an absolute necessity. To meet its growing demand for electricity, India needs a comprehensive review of its subcritical technology dominated coal-based power plants.

Solutions & way forward
In India, 20 per cent of the installed coal-fired capacity is more than 25 years old and as per a study 52 per cent of the plants are operating at a net Plant High Rate which is over 15 per cent higher than their design levels.

Such plants operating with poor efficiency levels are best suited to deploy renovation and modernisation (R&M) intervention solutions. Depending upon the age of the plant and the efficiency levels, one can adopt and deploy various R&M solutions. These could be targeted efficiency improvement solutions for individual major equipment's like steam turbine, boiler, and mills etc., or could be comprehensive R&M solutions for the plant covering all equipment together. Our global experience indicates an integrated solution approach gives the best results and leads to lowest impact on tariff.

As per a study, 1 per cent efficiency improvement in power generation would typically result in 2-3 per cent reduction in the GHG emissions. A typical R&M solution would improve the efficiency level by minimum 10 per cent. If one assumes 40 GW of coal capacity currently operating at poor efficiency levels deploys R&M solutions improving their operating efficiencies by say 10 per cent. The GHG emissions from them would get reduced by 42 Million Tonne/year from their current levels. This is equivalent to having 32.4 million motor vehicles off the Indian roads. R&M of even 1 unit of 210 MW would reduce GHG emissions equivalent to sending 1.7 lakh motor vehicles off the road and a 500 MW unit R&M would reduce emissions equivalent to sending 4 lakh motor vehicles off the road.

India unlike most of the places in the world is committed to solving the emission problem on multipole problem in same time (Cox, Nox, Mercury). Given the need for efficiency improvement, the real innovation needed is to tackle emissions while minimising the loss of power.

What this all means?
A typical 500-MW pit head plant with a net heat rate of around 2,700 can tackle its NOx and PM problems and at the same time improve its efficiency to 2,300 with a payback of four years on investment.

The latest technology like NID addresses sulphur oxide emission in an efficient manner. Similarly, the selective catalytic reactor (SCR) is the most traditional technology to tackle NOx emissions but SCR is huge to install and takes a lot of space. Here too, adoption of new technology like selective non-catalytic reduction system, allows for in-boiler modification, results in a reduction of NOx emissions by 30-50 per cent. While modifications and retrofits can drive efficiencies and curb emissions, switching to new technologies like carbon capture and storage (CCS) are needed to ensure a sharper reduction in carbon dioxide. Many steam turbines have untapped capacity and capabilities due to the conservative nature of their original design. Here too, solutions are available to improve efficiency, output and boost operational flexibility and reliability by capitalising on the sources of latent potential. Such upgrades address part obsolescence, performance deterioration and reduce carbon dioxide emissions.

The assets, which are typically directly responsible for production at the plants, can be managed in a superb fashion by harvesting sensors, data analytics and industrial internet. This dramatic innovation in software and services solutions for operational technology is referred to as Asset Performance Management (APM). APM is a big leap in terms of automating asset life-cycle management, remote monitoring, condition-based and predictive maintenance, as well as real-time operator intelligence. These software and sensors in the gas turbines helped reduce fuel consumption and production costs at the plant. It helped boost output by more than 3 per cent and reduce consumption by more than 1 per cent. APM is a progression that starts with machines, moves through operations, then transforms the entire industrial systems. Globally, the awareness level to reduce emissions and use technology-driven sustainable models is at an all-time high. It is, thus, important that nations must come together and adopt a common programme to improve the performance of their existing power generating plants in a time-bound manner through retrofitting and upgrades. This one step will go a long way in ensuring a sizeable cut in the emission of harmful gases.
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