The Ramagundam plant’s operator — the National Thermal Power Corporation — will spend nearly $65 million to update the plant's seven units that were commissioned between 1983 and 2004, as well as its four smokestacks — one of which is India's tallest at 275 meters (900 feet). “This plant doesn’t need any new technology miracles,” says Mike Donohue, chief marketing officer at GE Power’s Power Services unit, the business tapped to do the upgrade. “This is taking our existing technology and applying it to coal plants around the globe. It turns out that if we upgrade coal plants globally with the latest technology available, it will reduce emissions by as much as taking almost all the U.S. cars off the road.” Donohue says that if applied to all of India’s older coal plants, the technology would help India cut its CO2 emissions by roughly 12 percent.
Upgrading Ramagundam is the first job for GE’s new Powering Efficiency Center of Excellence, which aims to slash the global CO2 emissions from the world’s fleet of existing coal plants through hardware upgrades and software. The opportunity is huge — it’s an approach that can reduce CO2 emissions from coal plants globally by 924 metric mega tons. That’s more than the entire carbon footprint of Germany.
Donohue says that India is a great place for clean coal upgrades like the technology that will be deployed in Ramagundam. That’s because the country uses low-quality, domestic coal to produce about 70 percent of its electricity. When burned, this coal releases twice the heat-trapping emissions as natural gas. It also holds about 40 percent more ash content than the average coal lump. In addition to producing grime, ash lowers the coal burning temperature, which means that power plants need to use more coal to make a megawatt. It’s a vicious circle, Donohue says.
The upgrade has four crucial steps. First, technicians will coat the grinding surfaces of the plant’s coal milling machines with an ultra-hard tungsten carbide and cobalt chrome coating applied with a high-velocity air nozzle that can deposit a thick layer of the stuff. The tougher surfaces will allow the mill’s crushers to grind the coal to a finer dust that increases the fuel’s surface area and allows it to burn 10 percent hotter.
The second step involves injecting ammonia into the flue gas leaving the boiler, a towering structure where the burning coal transforms water into steam for the turbine. The ammonia reacts with sulfur in the gas to create ammonium sulfate.
Next, the team will open up the steam turbine and replace its blades with more modern and lighter ones. The steam will be able to spin the blades more efficiently and deliver more momentum into the power generator.
The fourth and crucial step doesn’t involve hardware at all. The team will deploy GE’s Digital Power Plant for Steam software that can analyze data coming from 10,000 sensors on the power plant’s equipment and help the operators gauge precisely the right amount of coal to burn and just the right temperature to maximize efficiency. The software can also predict when the utility should take the plant offline for maintenance and reduce unplanned downtime by as much as 5 percent.
This mix of hardware and software upgrades to the Ramagundam’s three 200MW steam turbines, made by the Italian company Ansaldo Energia and installed in 1982 and 1983, should boost the power plant’s output by 30MW — enough to power an additional 40,000 homes. The upgrades will make the three units 4 percent more efficient — raising their efficiency from 34 percent to 38 percent points. The upgrade also will cut the amount of coal burned by 270,000 tons annually. Donohue says that refurbishing the turbines and boilers will yield 2.5 percent of the efficiency gains, while software and analytics add 1.5 percent.
The upgrades will only take a few months to complete and should extend the life of the turbine by 20 years. Donohue says the investment should pay for itself within 12 to 18 months.
This technology has applications beyond India. It could also help China reduce its coal plant CO2 emissions by 9 percent and the United States’ by 12 percent. Russia, Germany and South Africa also could significantly cut CO2 emissions by upgrading their coal plants. Eastern Europe is doing the same. This is important because coal is expected to remain the world’s largest energy source, especially in developing economies, until renewables overtake it by 2040 as the No. 1 source of electricity.
“Today we live in a world where some of the old trade-offs are becoming a thing of the past,” Donohue says. “With coal plants, it used to be that you had to give up efficiency to get emissions compliance. Now, you can have emissions compliance and increased efficiency. It’s a game changer.”