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GE's New Gas Turbines Are State of the Art, But Are We Getting Too Cozy With the Fuel?

9HA gas turbine in validation test stand

9HA gas turbine in validation test stand. Photo credit: GE

The first natural gas-fired turbine for US power generation and one of today’s state-of-the-art designs currently live a couple hundred yards apart on GE’s massive 413-acre Greenville, South Carolina campus. The fact that both machines convert natural gas into electricity is pretty much where the similarities end.

The first gas turbine used for electric utility power generation in the US was manufactured by GE and shipped to Oklahoma Gas & Electric in 1949. It represented the transformation from early aviation turbines that rarely ran for more than ten consecutive hours to long-life power generation applications. The unit operated at OG&E’s Belle Isle power station from 1949 to 1980 and helped prove the technology.

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National Historic Mechanical Engineering Landmark: First gas turbine for US utility power generation. Photo credit: Breaking Energy/Jared Anderson

Fast forward over fifty years and natural gas-fired generation has grown to account for roughly 30 percent of US power generation capacity. GE’s Power & Water division has invested heavily developing its next generation of combined-cycle natural gas-fired turbines, the 9HA/7HA series. According to the company, the “H Class” is the world’s most efficient gas turbine, which is helping it quickly gain market share.

The H class turbines have an efficiency rating over 61 percent, meaning 61 percent of the energy contained in the natural gas used as fuel is converted to electricity. “It’s a good machine they put together,” Richard Dennis, Technology Manager for the National Energy Technology Lab told Breaking Energy. The NETL is an organizing national lab within the DOE’s Office of Fossil Energy. “Quick startup and good load following are some of its hallmarks,” he said.

9HA gas turbine going into test stand

9HA gas turbine going into test stand. Photo credit: GE

“There are other companies that also have very highly efficient machines in the 61 percent target range,” said Dennis, who cited Siemens and Mitsubishi Heavy Industries – now in partnership with Hitachi – as examples.

The degree of efficiency at which a turbine operates depends on numerous exogenous factors including altitude, temperature and humidity levels. “The parameter people look to is turbine firing temperature or turbine intake temperature… To get ultra-high efficiencies it takes a coordinated approach to pursue several parameters including firing temperature, optimal pressure ratios, advanced cooling technology and new components,” said Dennis. All these parameters need to be incorporated into a new design in order to increase total efficiency.

“Our target is 65 percent and the commercial developers are all pursuing similar goals. It’s a very technology-intensive endeavor to reach these higher firing temperatures, particularly with such mature technology,” Dennis added.

And GE is working hard at finding the innovations needed to move the dial toward even more efficient gas-fired turbines. Part of this effort is directed at advanced coatings for turbine blades, which allow the metals to reliably operate at higher temperatures. “Coating processing is probably one of the biggest problems they [turbine manufacturers] have… The coating business is very competitive, very secretive and very profitable,” Bruce Pint, a research staff member at the DOE’s Oak Ridge National Laboratory told Breaking Energy.

In addition to coating technology, GE is focusing on fuel and combustion advancements that allow their machines to run on fuels ranging from crude oil – common in Saudi Arabia – to natural gas liquids that are currently abundant in the US due to the proliferation of shale gas development.

Gas Turbine Markets and Environmental Regulations

There is strong appetite on behalf of independent power producers in the US and internationally for natural gas generating capacity as pressure to reduce greenhouse gas emissions in an effort to combat climate change increases. Power plant operators in regions of the world with access to comparatively inexpensive natural gas supplies are also motivated by economic incentives.

GE’s biggest markets for its gas turbines are the US, Middle East and Asia. “One thing we know for sure is that in 10 years people will want cheaper and more reliable power,” Guy DeLeonardo, GE Power & Water’s Power Generation Products Manager told reporters during a recent media tour of the company’s Greenville operations.

The high efficiency H Class turbines offer decreased emissions and increased reliability. Over the past 20 years, fuel combustion technology has decreased power plant emissions 90 percent, said Combustion Engineering Manager Joseph Citeno.

“What GE seems to be bringing to the table is very fast startup and low NOx emissions,” Dennis said.

And this presents an interesting engineering challenge because higher temperature hydrocarbon combustion generates higher levels of nitrogen oxide emissions, but decreases carbon dioxide emissions. So now there is a push toward what’s known as “lean combustion,” which requires additional air to be injected into the reaction.

Combustion System Fundamentals

“Modern gas turbines that utilize a wide variety of gaseous and liquid fuels must operate within a series of constraints, with NOx and CO emissions being the most recognizable. The formation of NOx compounds is dependent on the temperature of the reaction in the combustor. If fuel and air are allowed to mix in a stoichiometric proportion (a balanced chemical reaction), they will burn in a diffusion flame, similar to the flame of a candle, near the highest possible temperature of the reaction. A consequence of burning fuel at a high flame temperature is the production of a large amount of NOx. However, if extra air is introduced into the reaction, the resulting lean mixture will burn with a lower flame temperature and the reaction will generate significantly less NOx. This is known as lean combustion.” – GE Power & Water  

Fuel Costs and the Need for Reliability

“The driving need here is lower cost of electricity to serve a growing world,” DeLeonardo said. The company estimates $5 trillion will be spent on new power plants globally over the next 10 years. And whenever those capital-intensive plants are down for maintenance or service, the owner is usually losing money. That’s why “there is a huge focus on reliability,” said DeLeonardo.

And modern gas-fired turbines are increasingly durable, with intervals between scheduled service growing larger as technology advances. It’s like driving car 1.2 million miles before servicing, Citeno explained. GE’s latest F class turbines currently operate for 24,000 hours before combustion system inspections, he added. And the goal for the H class is to reach 25,000 hours.

With regard to power generation installed costs, GE’s new turbines are within the $500 to $700 per kilowatt range, said DeLeonardo, while renewables are around $1,500 per kW and nuclear can be $5,000 per kW. Indeed, according to the “2013 Wind Technologies Market Report” published last year by the DOE’s Lawrence Berkley National Lab, the capacity-weighted average installed project cost was $1,630/kW in 2013. Of course once wind turbines – or solar installations – are constructed and connected to the grid, the fuel is free.

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GE’s gas turbine manufacturing plant in Greenville, South Carolina, which is reportedly the world’s largest. Photo credit: Breaking Energy/Jared Anderson

Whereas fuel for gas-fired power generation is anywhere from two-thirds to 80 percent of the cost of producing electricity. In the US at current natural gas prices, the fuel cost component of generation is about two-thirds, while Asian markets that rely on imported LNG, face fuel costs that account for roughly 80 percent of the capital spent by a utility to produce power, DeLeonardo explained.

GE has already been technically selected for 45 HA units globally, with 19 of these coming from US customers, seven each from buyers in Japan and the UK, and six in Brazil. Power producers in South Korea, Russia, France, Germany and Turkey have also placed orders for the new machines.

Traveling a Dangerous Path?

Here is where the story gets more complicated. Natural gas is a clear winner today given its commodity price advantage in the US and its emissions advantages over coal. But are we making our infrastructure too reliant on natural gas?

Some contend that piling too heavily into natural gas as a power generation source exposes consumers to disproportionate risk if commodity prices increase as a result of demand growth. Utilities are some of the first to bemoan over-reliance on any single power generation source and always seek balanced feedstock portfolios. However, given public and political resistance to coal in what’s becoming an increasingly carbon-constrained world, natural gas has a leg up in the current environment.

“It’s a dangerous path we are going down,” said Oak Ridge Lab’s Bruce Pint. “I see the benefit and I see the reason why we are doing it, but the fact is not investing in nuclear, not investing as much in coal is probably going to come back to bite us at some point,” he said.

Should the EPA’s Clean Power Plan move forward with resultant coal plant closures, it will be difficult to replace that lost power generation capacity with anything but gas in the short term. Renewable sources can help, but still need baseload backup until utility-scale storage options can be economically and reliably integrated. This is why natural gas is often referred to as a bridge to a more renewable-energy-intensive future.

chart“To me it’s [natural gas] more like a crutch. What I worry about is that it’s not just going to be a bridge. It’s going to be full force with everyone going natural gas,” Pint said.

Too many questions remain unanswered at this point to say for sure, but there is substantial evidence that indicates how historically low natural gas prices – coupled with emissions benefits – are motivating numerous businesses to switch fuel sources. Foreign and domestic gas-intensive manufacturers have been expanding operations in the US, shipping companies are looking at LNG instead of bunker fuel, railroads are considering using LNG over diesel and fleet vehicle operators like UPS have already adopted natural gas to varying degrees.

“In general I think that metaphor needs to be carefully considered… if you are going to look at any bridge to the future you need to consider the whole life cycle for GHG emissions for any power source,” Dennis said. And he added that energy storage is part of the destination point for the bridge metaphor, meaning that it’s hard to say how long a natural gas bridge would need to be until there is more clarity around the emergence of affordable and reliable utility-scale energy storage solutions.

So against that backdrop, natural gas is currently very well positioned in the power generation market and so are GE’s gas turbine offerings compared with other generation technologies. The main goals of any energy source are for it to be affordable, reliable and clean. Gas basically beats coal across the board on these measures and while it’s not as clean as renewable sources like wind and solar, gas still takes two out of three, winning on price and reliability.

“What other technology is going to compete with that? To be able to turn on and off whenever you need it. That’s where natural gas has a big grin on its face saying we own the next decade,” Pint said.

Pete Danko contributed to this article.

Editorial note: GE paid Breaking Energy’s media tour travel and accommodation expenses.

Breaking Energy Breaking Energy provides access to news, analysis, thought leadership, reference materials and discussions about the day’s most important energy market trends. Breaking Energy participants stay ahead of breaking news, participate in high-profile events and enjoy access to the central hub of the industry community as it transforms in response to fast-moving changes in energy politics and regulation, deals with financial challenges and leads technological advances.

Content Discussion

Hops Gegangen's picture
Hops Gegangen on April 9, 2015

 

Natural gas output in the Marcellus just continues to grow. But for electricity generation, I don’t know where it would all go.

U.S. total gas production is now 40 billion cubic feet a day, and stll climbing, mostly due to the Marcellus.

http://www.eia.gov/naturalgas/weekly/img/201502-February-monthly.png

 

 

Mark Heslep's picture
Mark Heslep on April 9, 2015

Hops – That chart is for shale gas only.  US total gas production from all sources is over 80 Bcf/day, the highest in the world and pulling away from #2 Russia. 

Josh Nilsen's picture
Josh Nilsen on April 9, 2015

Natural gas plays well with renewable energy.  It can ramp and down efficiently and quickly.  (Florida actually has the world’s first combined natural gas + solar CSP plant, cool stuff).

Natural gas also has plays to make in the transport sector.

Natural gas also covers the primary heating load for much of the midwest and northeast US.

That fossil fuel is going to be sticking around.

Bob Meinetz's picture
Bob Meinetz on April 10, 2015

Jared, it’s amusing to see how cozy renewables advocates on TEC are getting with burning methane as it becomes obvious wind and PV depend on it. Hopefully we’ll able to combine the two in calculations of emissions, for a more accurate picture of renewables’ carbon footprint.

Since Energy Quotes of the Day are in vogue, here’s my nomination:

“…the fact is not investing in nuclear…is probably going to come back to bite us at some point.”

Bob Meinetz's picture
Bob Meinetz on April 10, 2015

Josh, Ivanpah CSP in California has won permission to produce as much as 1/4 of its annual generation by burning natural gas. Renewables play so well with fossil fuels, we’ll soon be able to hang a mirror on a coal plant and call it “renewable”. Cool stuff!

Engineer- Poet's picture
Engineer- Poet on April 10, 2015

In the words of Robert F. Kennedy Jr, “the plants that we’re building, the wind plants and the solar plants, are gas plants“.

Which is what the people truly concerned about climate change have been saying all along… but without taking money from the natural gas lobby.

Nathan Wilson's picture
Nathan Wilson on April 10, 2015

Surprisingly, the same combined-cycle technology that makes fossil gas so cost effective is proving a big boost to a new nuclear power plant design.  This presentation describes a nuclear concept being explored at UC Berkeley and MIT, built around a molten-salt cooled reactor which uses high-temperature TRISO fuel.  The high temperature-heat would be used to power a Brayton-cycle turbine followed by a steam bottoming cycle.  

This system gets much better energy efficiency than a conventional reactor, plus fossil gas (or biomethane, hydrogen, or ammonia) can be added to boost the output by 140% for essentially no extra plant cost.  Due to the higher combustion temperature, this system would burn the added gas at 66% efficiency.  With the optional thermal energy storage, the reactor could continue to run baseload while avoiding selling electricity in times of low demand (low prices), and could even buy electricity from the grid and store it with electric heaters.

This reactor concept is designed to operate in a zero carbon grid, and function along side renewables.  No doubt the Chinese are watching, and will use the best ideas in their much-better funded salt-cooled reactor program.

Engineer- Poet's picture
Engineer- Poet on April 10, 2015

I’ve been going through the PB-FHR document as time permits, and I’m not impressed.  The 66% marginal efficiency of NG use is barely superior to the best CCGTs and markedly inferior to the 80% for non-adiabatic CAES systems.  The only selling point seems to be near-instantaneous response to fuel addition, which is only needed to cope with wildly-varying wind and PV output.  This fulfills RFK Jr’s claim that “the plants that we’re building, the wind plants and the solar plants, are gas plants.”  If you postulate that politics will force so-called “renewables” onto the grid first and gas must fill in for their unreliability this makes sense, but not in any other scenario/philosophy.

A supercritical CO2 cycle would have better thermal efficiency in the nuclear part, and likely similar water efficiency in the cooling system (exhaust temperature of the recuperator in a recompression cycle is around 175°C, more than hot enough to drive a natural-draft cooling tower).  Surge power requirements could be handled using a “heat battery” of solar salt.  The whole thing could go carbon-free relatively easily, so I must ask… WHY the designed-in reliance on natural gas, except as a sop to the gas lobby?

 

 

Josh Nilsen's picture
Josh Nilsen on April 11, 2015

Do I have to explain the concept of a hybrid car to you?

With your logic a Toyota Prius is just as bad as a vanilla ICE car.

Apparently you have people to just follow you around and upvote your rhetoric.  Well played bro.

Hops Gegangen's picture
Hops Gegangen on April 11, 2015

 

Vanilla ICE? Ice ice baby…

But I agree with the premise. Burning natural gas part time is better than coal full time, that’s for sure.

 

Nathan Wilson's picture
Nathan Wilson on April 11, 2015

Could you provide a source for your information on super-critical CO2 power conversion systems?  This article (by a Sandia labs guy who worked on it) says that the critical point is around 31C, and to get the benefits, the system must span this temperature.  That seems to means water cooling is a must (although the article does mention dry cooling in passing).

Also, I remember reading somewhere that throttling is not very efficient with these system.  Various techniques are possible, but they basically all come down to discarding the power you don’t need (at a not very useful intermediate temperature).  This is a baseload technology, although in a modular plant like the one envisioned by MIT and Berkeley, each of the 12 turbines could be spun up or down independently, which does give a useful control on power output (but response time could be an issue).

 

WHY the designed-in reliance on natural gas…

I think the PB-FHR folks like the air-Brayton combined cycle primarily because it’s available nearly off-the-shelf (the fossil gas boost is just a free-be that comes with it).  Remember that the helium-cooled pebble-bed reactor people dropped the idea of a helium turbine, not because it wouldn’t have worked well, but simply because there were no investors lined up to pay for the development.

Engineer- Poet's picture
Engineer- Poet on April 11, 2015

I found Vaclav Dostal’s doctoral paper on the sCO2 recompression cycle to be highly informative and quite accessible.  There’s piles of data in it if you like to drill down.  Sadly, the free version is not searchable.

http://dspace.mit.edu/handle/1721.1/17746

IIRC, Dostal proposed to throttle using a bypass that routes fluid around the reactor.

Having to bring the working fluid down to 31 C at the compressor inlet is an issue, but much of the heat rejection is at temperatures upwards of 50 C and a natural-draft cooling tower should get strong convection.  If groundwater is available a geothermal cooling loop could provide a last bit of evaporation-free cooling during the summer months, or a small amount of water spray in the cooling tower could be used for the last increment of chilling.

Joe Deely's picture
Joe Deely on April 12, 2015

Nat Gas has done a good job of replacing Coal in many states and it looks like low prices for fuel over the next few years will accelerate that trend – Bloomberg report.

Georgia is a great example of a state where Nat Gas has been replacing coal and lowering carbon.
 
in 2005 Georgia’s mix was: 
  • 64% Coal
  • 7%  Nat Gas
  • 23% Nuclear
 
in 2014 Georgia’s mix was:
  • 36% Coal
  • 32% Nat Gas
  • 25% Nuclear
 
Over this time period (2005-2015) CO2 from Electricity generation in GA has decreased by more than 30% – see here.
 
By 2020-with Vogtle Nuclear coming on-line and more Coal being replaced by Nat Gas the mix could be:
  • 20% Coal
  • 38% Nat Gas
  • 36% Nuclear
 
This would mean that CO2 levels from Electric Power in GA would have dropped by over 50% from their 2005 levels by 2020. Not bad.  
 
Throw in some wind and a huge solar resource and the remaining coal will be knocked out of the mix.  Then the next wave of nuclear along with increasing Solar can come in and start replacing the Nat Gas. 

 

Bruce McFarling's picture
Bruce McFarling on April 21, 2015

The ellipses there could well goes beyond Energy ellipses of the Day to Energy ellipses of the Month: “… but the fact is not investing in nuclear, [not investing as much in coal] is probably going to come back to bite us at some point.”

Not investing in nuclear could well come back to bite us at some point. Not investing in coal coming back to bite us is like suggesting that in pursuit of a more balanced diet, we ought to add a bit of lead paint.

Bruce McFarling's picture
Bruce McFarling on April 21, 2015

… double post (flaky WiFi onsite in Beijing? No! Never!)

Bruce McFarling's picture
Bruce McFarling on April 21, 2015

We can’t allow it to stick around indefinitely … there’s only a fixed budget of CO2 and equivalent GHG we can emit, and, even worse, we can only approximate what that fixed budget might be.

Indeed, the reliance on natural gas in heating in the midwest is an argument against increasing its use in power generation … since with a fixed budget, the more we use carbon emitting fossil fuels for electricity generation, the less of the budget can be use in heating.

Mark Heslep's picture
Mark Heslep on April 21, 2015

Mark Heslep's picture
Mark Heslep on April 21, 2015

Indeed, the reliance on natural gas in heating in the midwest is an argument againstincreasing its use in power generation”

That depends entirely on what gas replaces in power generation.

Bruce McFarling's picture
Bruce McFarling on April 21, 2015

Links?

Cost over-runs are not always a knock against a technology … given compliant governance in a state (say, under a “pro-business” banner), and a profit-seeking corporation, it can at times make financial sense to take as much advantage as practicable.

And in some cases, cost over-runs are due to exogenous changes imposed on a project that would not be expected to be repeated in a following implementation of the same technology.

… but, OTOH, CSP loses traction in places where it rains a lot, and CSP+NG is only long run sustainable given adequate supplies of biogas or “electrofuel” from sustainable energy sources, and a “bridge” that requires substantial R&D lead time to knock out the kinks does not make a lot of sense, given the time frames we are looking at to get off the “bridge’. 

Bruce McFarling's picture
Bruce McFarling on April 22, 2015

Start with the benefit of whatever fuel or mix of fuels that the natural gas is replacing. Then the argument is made that there is an additional benefit to using natural gas because it is heavily used in heating.

Rather, the use of natural gas in heating implies that whatever the benefit of the fuel or mix of fuels that natural gas is replacing, the benefit of reduction in energy use is greater if the share of the CO2 emission budget available to electricity generation is smaller.