Media reports often characterise coal and coal-fired power as a technology of the past: a dirty baseload power source that has no place in today’s cleaner, greener and ultra-flexible power mix. But one company is challenging that perception and helping to bring coal very much into the twenty-first century.
That company is GE. World Coal first reported on what GE was doing in the coal-fired power space back in April, when the company announced it was acquiring NeuCo – a supplier of plant optimisation technologies to the coal power industry. But GE is going further with the launch of the Digital Power Plant for Steam at its Minds + Machines event in Paris.
Digital Power Plant for Steam is a suite of technologies that offer coal-fired power plants the opportunity to improve performance and efficiency, reducing greenhouse gas emissions along the way. It follows on the footsteps of similar solutions for the wind and gas power industries – but as Scott Bolick to World Coal in a recent interview, coal throws up its own unique challenges and opportunities.
The coal challenge
Firstly, the average efficiency of coal-fired power plants around the world is just 33%, which is not helped by the relatively old age of the existing fleet: 50% of coal-fired power plants in Europe, for example, are over 25 yrs old. Coal-fired power plants are also increasingly being asked to operate flexibly to work around more intermittent renewables energy sources – not something that they were originally designed to do. And of course there is the challenge of emissions and climate change regulations – particularly after the COP21 Paris Agreement.
GE’s Digital Power Plant for Steam helps to tackle these challenges – both in new plants and as a retrofit on almost all existing plants commissioned in the past 25 yrs, including non-GE and legacy Alstom plants. It represents GE going “all in” on coal-fired power efficiency, said Bolick. For example, Digital Power Plant for Steam is able to contribute 1.5 percentage points of efficiency over the life of the plant, helping to maintain peak efficiency for longer periods of time. This reduces coal consumption (reducing costs) and carbon emissions.
But what is the technology that lies behind this. As Bolick explained, it all begins with a relatively simple concept – the digital twin – and spirals out from there. So what is the digital twin?
The digital twin
At the heart of GE’s Digital Power Plant solutions – whether for wind turbines, CCGT plants or coal plants – is the digital twin concept. This takes data on the construction, operation, maintenance, thermal performance etc. of the plant and combines them with data from the more-than 10 000 sensor inputs across the plant, weather data, market information etc. to form a complete picture of that equipment.
This allows operators to understand how to run a plant to best meet their operating context. For example, one CCGT plant uses GE’s Digital Power Plant solution to know when and how to take advantage of peak power periods – maximising revenue while minimising costs.
The digital twin concept it made possible by Predix – GE’s cloud platform for the industrial internet. Predix itself is the result of a vision GE’s CEO Jeff Imelt had about five years ago, Bolick explained, to move the company into the Big Data space - transitioning from a traditional industrial company to a “digital industrial” company. It resulted in the creation of GE Digital at San Ramon, California, and ultimately Predix.
A couple more products feed into the Digital Power Plant solution, Bolick continued: GE’s cyber security software and NeuCo’s optimisation software. These three building blocks underpin the solutions offered by Digital Power Plant.
Digital Power Plant for Steam
So what exactly does Digital Power Plant for Steam offer coal-fired power plants operators? According to Bolick, it can be broken down into six major applications
- Asset Performance Management for the Digital Steam Plant: this continuously monitors coal-fired power plants equipment health, informing operations teams’ decisions and, in so doing, helping to reduce unplanned downtime and extend plant life.
- Operations Opimisation for the Digital Steam Plant, which provides customers will plant and fleet-wide visibility of the impact of operations decisions on efficiency, emissions, capacity and production costs. This includes:
- Boiler optimisation – which improves boiler reliability and efficiency, reducing carbon and NOx emissions through optimisation of combustion and soot-cleaning processes.
- Coal analysis – which tunes combustion and exhaust management processes to coal properties.
- Smart start – which reduces inefficiencies that occur on load change by helping the operator improve key parameters, including speed to grid, impact to asset life and fuel consumption.
- Business Optimsation for the Digital Steam Plant: this aggregates information, such as fuel and power price, demand and plant capacity, to enable energy traders to make better buying and selling decision.
Case study: Owensboro Municipal Utilities
An example of what can be achieved by GE’s Digital Steam Plant system comes from the town of Owensboro, Kentucky. Owensboro Municipal Utilities (OMU) has been running the boiler optimisation software, also know as BoilerOpt, at its Elmer Smith coal-fired power plants since 2005 – 2006. GE acquired BoilerOpt with its acquisition of NeuCo earlier this year and it now forms a part of the Digital Steam Plant offering.
The Elmer Smith plant is a pretty old plant, explained Kevin Frizzell, Director of Power Production at OMU to World Coal in a recent interview. It comprises two units: the 151 MW Unit 1, which was built in 1964, and the 285 MW Unit 2 of 1974 vintage. The plant burns about 1.25 million t a year of high-sulfur Illinois Basin coal and was designed to provide baseload power to the city of Owensboro with surplus power sold to the market.
In the early 2000s, OMU – along with the rest of the US power industry – was preparing for new NOX emissions rules. These would require OMU to fit NOX control equipment to its units to maintain regulatory compliance. This driver led the company to look for ways to reduce NOX formation in its boilers, a B&W in Unit 1 and Alstom in Unit 2. After evaluating several options, OMU settled on NeuCo’s BoilerOpt, said Frizzell.
BoilerOpt allowed OMU to reduce its NOX formation by 10 – 15% before any post-combustion control systems were added. But it also provided a benefit after the NOX control systems started to impact steam temperatures in the plant’s boilers. BoilerOpt allowed OMU to balance the need to manage NOX formation with the need to maintain steam temperature – to “hit the sweet spot”, as Frizzell put it – something that human operators would have found much more difficult.
“It helps to keep performance very steady compared to human operators, each of whom has their own way of setting things,” said Frizzell. BoilerOpt is also able to respond to changes in combustion processes much more quickly that human operators, added Frizzell, with the constant monitoring helping to fine tune NOX performance and operations performance.
Although NOX regulation was the primary driver behind fitting BoilerOpt, over the last 4 – 6 years OMU has been challenged by the rise of renewables and natural gas and the resultant need to operate much more flexibly than the Elmer Smith plant was originally designed for, added Frizzell.
The challenge is particularly acute at night. At night demand from Owensboro drops to around 100 MW, while input from wind turbines – of which there are a lot in the US Midwest – peaks. This has resulted in significant load swings impacting the Elmer Smith plant’s performance with the plant sometimes cycling down to 30% of capacity on Unit 2 over night.
In these operating conditions, BoilerOpt is helping OMU to optimise performance at super-low loads, explained Frizzell, allowing it to stay competitive and maintain efficiency in the changed competitive landscape in which it finds itself. This has kept the Elmer Smith plant operating, even as many other plants of its vintage have closed.
Setting the platform for the future
Returning to the big picture: coal is set to remain the world’s second largest energy source through to 2030 – and an even more critical power source for emerging economies. Yet the operating environment in which coal is operating is in almost constant flux at present as renewables disrupt the traditional model of baseload power and regulations make it tougher to operate coal-fired plant – as the Elmer Smith plant has discovered.
In that environment, innovation is key. As Ganesh Bell, Chief Digital Offices at GE Power said, the only way to meet the current challenges “is by applying date science and intelligent software-defined automation to every aspect of the electricity value chain.” Digital Power Plant for Steam “marks another big step on that journey.”
Read the article online at: https://www.worldcoal.com/power/04072016/coals-digital-revolution-2016-1056/