Q&A: The evolving role of the turbine

GE’s Gas Power Systems and Steam Power Systems talk about trends in gas and steam turbines and how they are seeing technologies and markets develop

In today’s world 1.2 billion people still don’t have access to electricity and 2.4 billion people in the world don’t have access to reliable power.

What exactly is required to meet this need varies country by country, but what we know is that an energy mix is required. This includes gas, coal, renewables and nuclear.

We asked GE Power’s Gas Power Systems and Steam Power Systems to talk to us about trends in both markets.

Bouchain 9HA combined-cycle plant
Bouchain 9HA combined-cycle plant
Credit: GE

Q: What are the latest trends you are seeing in the industry?

A: Gas Power Systems: In the gas business, we are focusing on two main areas – efficiency and enhancing our plants’ digital capabilities.

Digital is the single biggest disruptor and opportunity in the entire power space. Digital starts with data, and the power industry has more data than any other industry in the world, but only 2 per cent of the data is being used today. That’s the opportunity as it relates to higher generator reliability and profitability.

Efficiency is an area where we continue to invest significantly. Last year, our first 9HA power plant achieved the world record combined-cycle efficiency of 62.22 per cent – and that’s net efficiency. But we aren’t standing still. The team is on a path to achieve 65 per cent combined-cycle efficiency with HA systems, and we’re already offering customers new HA technology that can deliver greater than 63 per cent efficiency.

One fundamental shift you’ll continue to see from our business is evolving from a heavy-duty gas turbine business to a power island business along with strategic turnkey projects.

A: Steam Power Systems: When it comes to steam technology, customers are driven by low operating costs and long-term stability. The price levels for main fuels (coal, lignite, HFO) are relatively stable, which is why more and more countries want to introduce steam plants in their mix. The trend in the last year has clearly been towards higher efficiency plants, supercritical, ultra-supercritical (USC) and now advanced USC, and there is a variety of reasons for that.

First, economic reasons – higher efficiency plants now have a better lifecycle cost than older technologies. Secondly, the most advanced technologies such as USC are now proven and have demonstrated their capability to operate reliably, with improved load flexibility. Finally, due to the focus to reduce carbon emissions, it is now becoming part of the ‘social license to operate’ to use the lowest emitting technologies.

One of the key developments allowing us to achieve record level efficiencies are new materials, for example nickel iron-based alloys. They are easier for fabrication than just nickel-based alloys and have excellent steam oxidation and flue gas corrosion resistance. This means that steam cycle conditions – pressure and temperature – can increase, having a positive impact on efficiency. Interestingly, many of these new innovations have originally been developed in research labs with public funding and they are now becoming commercial products, helping to improve efficiencies and reliability, driving the cost of electricity down.

Another development that we are seeing is the price of coal-fired power plants, which has been going down in recent years. The plant prices have reduced by about 10 per cent since 2014 on average and by 25 per cent since 2010, driven by lower engineering, procurement and construction prices.

In addition to these trends, we are also seeing an increased demand for smaller steam power plants – especially in Asia Pacific – between 110 and 130 MW.

Q: What developments are you seeing in terms of efficiency?

A: GPS: It’s an exciting time because we have HA class turbines coming online and changing the way power is delivered around the world, with examples in the US, Pakistan and Japan. The team is on a path to reach 65 per cent combined-cycle efficiency that drive both capital and operating expense productivity for customers.

And it’s happening on more than just across our HA products. We are investing significantly in performance and fuels improvements across our portfolio with breakthroughs in advanced metals, coatings, fluid dynamics and additive-enabled cooling technologies, all of which will push higher operating temperatures and enable future record-setting efficiencies.

No matter if it’s a 30 MW trailer-mounted unit or 1.6 GW utility block – our sustained commitment to technology and product development will continue to advance cost-effective, reliable and sustainable power around the world.

A: SPS: From the perspective of our steam business, COP21 and climate targets are driving even more focus on operational efficiencies and we respond to that need by developing our USC technology further. The newest coal plants being built are using GE’s USC technology that can deliver an efficiency rate of up to 47.5 per cent, which is significantly higher than the global average of 34 per cent. We have improved this technology even further and are the first to market with advanced ultra-supercritical, or AUSC, the next phase of evolution in steam power technology.

AUSC has higher steam parameters coupled with efficiency rates and can deliver an additional 1.6 percentage points of efficiency beyond the best technology in operation today.

This will drive steam power facilities towards the 50 per cent efficiency mark. In addition to improving the environment, AUSC delivers financial benefits of $80 million in additional value to operators if we use a 1000 MW base plant in Asia as the base case assumption.

The most efficient USC power plant currently in operation is RDK8 in Germany and we are in the process of building new USC plants across Asia and the MENAT region, for example in Malaysia and in Turkey. We can see how customers in many of these fast growing countries are looking for the latest, most efficient and most advanced technologies to meet their growing energy needs.

Q: How has materials’ development enabled efficiency improvements?

A: GPS: Advanced metals, coatings, fluid dynamics and additive-enabled cooling technologies are all helping to push efficiency even further.

Fundamentally, it’s about advancing how well we mix air and fuel prior to and during combustion and make cooling air more effective – that’s where additive manufacturing (3D printing) can help.

By improving these subsystems and components, we can lower emissions and increase efficiency without impacting the lifespan of the turbine. We don’t just do additive to be cutting edge, we are doing it to increase performance and drive better customer outcomes and returns. One example of this is the DLN fuel nozzle tip, which enables better mixing of fuel and air, enabling 5 ppm NOx on F-class cycles. We have over 8000 metal additive components running in the field today.

It also helps when bringing new products to market. We couldn’t have done the HA validation testing we did – at the speed in which we did it – without creating prototype parts with additive manufacturing. Instead of fabricating something out of two or three parts, you can print it as one. For things like cooling holes and other small features, you can print those as well. So this removes an entire step out of the manufacturing process.

A: SPS: The prices of new materials – such as the nickel iron-based alloy mentioned earlier, enabling better efficiencies – have come down in recent years. Hence, increase in material cost is lower than the benefit that the higher efficiency brings. Nickel iron-based alloy, for example, has excellent creep properties at the right cost. We have now commercialized advanced ultra-supercritical plants, with cycle conditions of 330 bar/650à‚°C/670à‚°C, using these materials.

RDK8 steam turbine
RDK8 steam turbine
Credit: GE

Q: What about flexibility?

A: GPS: Flexibility is especially key as more renewables come in. Renewable power capacity additions will be twice that of gas additions in the next decade, however gas turbine power plants will play a vital role. They serve as a complement to intermittent renewable generation, offering such valuable features as rapid start, output flexibility and turndown capability.

For example, the HA can achieve simple cycle ramp-up in under 15 minutes and full combined-cycle ramp-up in about 25 minutes. Or our LM6000, which meets various dispatch profiles with five-minute starts and can reach max power in less than ten minutes.

Gas power gives end users several advantages. First is the ability to respond quickly with high efficiency, which lowers the cost of electricity, in a very tight footprint. We can put a gas turbine in about 8 ha of land and generate over a gigawatt of power. That is the best power density that you see in the industry.

A: SPS: We should think about flexibility in terms of both operational flexibility and fuel flexibility. I agree that we are seeing more variety with fuels. Customers have an increasing variety of fuels available and are looking for efficient ways to use them. For example, several new projects have come up using difficult lignite which cannot be easily transported. There is also an increasing interest for using biomass for smaller sized power plants around 100-110 MW.

In terms of operational flexibility, we have implemented solutions which significantly improve the ramp-up and -down times. There has been approximately 30 per cent improvement in the last five years and it now takes about 120 minutes to ramp up to full load. The minimum load that we can operate our plants is around 15 per cent, for smaller sized plants as well as for larger, and more sophisticated 1000 MW USC plants.

As an example, our latest commissioned plants in Germany are operating mostly in peaking mode, and are used to balance the instability of the grid caused by the increase in intermittent power generation.

The need for improved flexibility is often driven by the customer’s objectives to keep fuel consumption as low as possible, to protect the lifetime of critical components, or to answer to additional grid power demands as fast as possible. Improvements in flexibility support the increasing use of renewable energy and coal-based steam power can play a role in this.

Q: How important are digital capabilities in modern power plants?

A: GPS: A monumental shift is taking place in the power generation industry, challenging old models and creating unprecedented opportunities. Software and data analytics are combining with advanced hardware to create new digitally-enhanced power generation that will deliver greater performance, reliability, affordability and sustainability. These new capabilities are helping to lower costs, improve efficiencies, create growth opportunities and reduce carbon footprints.

Fully-customized digital power plant solutions allow power plant owners to optimize the performance and profitability of their systems with better informed short- and long-term decisions to balance revenue, cost and risk. Predictive analytics and control simulations consider past and future scenarios and advanced control capabilities act to achieve desired outcomes. It serves a plant’s full lifecycle, from project planning to startup to servicing.

A: SPS: Digital capabilities are starting to show their full potential on steam plants, helping customers extract more value from their plants by increasing efficiency across the full range of operation modes or supporting more flexible operation while optimizing maintenance costs.

Q: Are there a lot of commonalities between gas and steam power?

A: GPS: Customers are increasingly looking for full solutions, including financing. In a more decentralized environment, there are several customers that are not typical operators, but rather hospitals or factories that want to generate their own energy. These customers are looking for the entire package with total project management. Now we can offer that. On top of that, when it comes to optimizing efficiency, what’s important is how the overall system is designed and operated. Gas Power Systems has expanded its capabilities to cover the entire plant: from gas turbines, steam turbines and generators, to heat recovery steam generators, condensers, other balance of plant equipment and digital solutions that help manage assets and operations more efficiently.

A: SPS: I agree. There is more demand for full project management. Customers – both utilities and other plant operators – know that it takes more than selecting a set of high efficiency components to achieve advanced economic and technical goals. The value of the integrated approach is that the performance of the plant is better optimized, delivering better efficiency throughout the process.

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