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GE FlexEfficiency 50 CCGT Facilities and Wind Turbine Facilities

Historically, electric grids have experienced varying electric demands during a day and varied the output of their generating plants to serve that demand and, at the same time, regulate frequency. Increased wind energy penetration will present additional challenges to the management of the energy on the New England Electric Grid, NEEG. 

 

Because wind energy is variable and intermittent, additional spinning and backup plants, such as a mix of open cycle gas turbines, OCGTs, and combined cycle gas turbines, CCGTs, must be kept in 24/7/365 operation to supply and withdraw energy as required. The plants must respond to changes of:

 

– demand of millions of users during a day.

– supply, such as from unscheduled plant outages.

– supply due to weather events, such as lightning, icing and winds knocking out power lines.

– supply from wind turbine facilities. 

 

If these changes, especially those due to wind energy, are of high megawatt/minute, the CCGTs may have to temporarily operate as OCGTs, because their heat recovery steam generators, HRSGs, would be damaged by rapid cycling; HRSGs have lower ramp rates than OCGTs. This increased OCGT mode of operation increases fuel consumption, NOX and CO2 emissions per kWh.

 

New GE CCGT Plant

 

GE is marketing a new CCGT plant and has sold a few of them. The new “GE FlexEfficiency 50” plant has a capacity of 510 MW and a 61% efficiency at rated output. Its design is based on a unit that has performed utility-scale power generation for decades. The plant fits on about a 10-acre site. 

 

It is quick-starting: from a cold start, it reaches its rated output in about one hour. Various options are available to reduce the start up times to as little as 30 minutes. 

 

Its average efficiency is about 60% from rated output to 87% of rated output (444 MW) and about 58% from 87% to 40% of rated output (204 MW). It can be ramped at 50 MW/minute. 

 

Without wind, the GE unit is designed to efficiently produce electric energy in base-loaded mode and daily-demand-following mode. 

 

With wind, its high ramp rate enables it to also function as a cycling plant to accommodate the variable energy from wind turbine and solar facilities, albeit at reduced efficiency. Below 40% of rated output its efficiency decreases rapidly, as with all gas turbines. This means its economic ramping range is limited.

 

It would be a travesty to misuse and abuse such an advanced CCGT for wind and solar energy balancing.

 

http://www.ge-energy.com/content/multimedia/_files/downloads/FlexEfficie...

 

Selected Levelized Energy Costs 

 

The US Energy Information Administration projects levelized production costs (national averages, excluding subsidies) of NEW plants coming on line in 2016 as follows (2009$) :

 

Offshore wind $0.243/kWh, PV solar $0.211/kWh (higher in marginal solar areas, such as New England), Onshore wind $0.096/kWh (higher in marginal wind areas with greater capital and O&M costs, such as on ridge lines in New England), Conventional coal (base-loaded) $0.095/kWh, Advanced CCGT (base-loaded) $0.0631/kWh.  http://www.energytransition.msu.edu/documents/ipu_eia_electricity_genera...

 

SUMMARY OF STUDY RESULTS

 

Various aspects of wind energy on the NEEG, including capital costs, fuel requirements and CO2 emissions reduction were studied. A comparison of the two alternatives was made. In this section are summarized the main results of the study. 

 

Wind Turbine Facility Plus Cycling Facility

 

Capital cost of CCGT + Wind = $637,500,000 + $500,000,000 = $1,137,500,000

Net NEEG CO2 emission reduction = 802,571 metric ton of CO2/yr

CO2 emission reduction cost = $1,417/metric ton of CO2/yr

Fuel cost = 92,374,140/yr

 

CCGT Facility Only

 

Capital cost of CCGT = $637,500,000 

Net NEEG CO2 emission reduction = 701,363 metric ton of CO2/yr

CO2 emission reduction cost = $909/metric ton of CO2/yr

Fuel cost = $99,986,353/yr

 

Comparison of CCGT + Wind versus CCGT Only

Cost of CO2 emissions reduction: CCGT + Wind is 55.9% greater than CCGT Only

Cost of Owning (excluding subsidies): CCGT + Wind is about 78.4% greater than CCGT Only

Cost of O&M fuel component: CCGT + Wind is $7,612,213/yr, or 7.6% less than CCGT Only

Cost of Other O&M (as a % of capital cost): CCGT + Wind is 78.4% greater than CCGT Only

Useful service life of wind facility is about 25 years versus 35 – 40 years for the CCGT facility

 

Some of the advantages of gas-fired CCGT are: 

 

– No grid modifications would be required

– No inefficient operation of gas-fired wind energy balancing facilities would be required

– Impacts on quality of life (noise, visual, psychological and health), property values and the environment would be minimal

– The facility would take up only a few acres

– The electrical energy would be low-cost, steady 24/7/365, reliable and dispatchable

– Low CO2 emissions/kWh; about 1/3 the CO2 emissions/kWh of coal plants 

– No particulate emissions

– Domestic energy supply, good for energy independence, national security

 

Conclusions and Recommendations

 

Whereas the CCGT facility will improve the economics and reduce the operational difficulties of accommodating wind energy to the grid, the combination of this high-efficiency CCGT facility with a moderate-efficiency wind turbine facility will be less efficient than the CCGT facility in base-loaded mode and daily-demand-following mode.

 

The wind turbine facility contributes just 543,120/4,467,600 x 100% = 12.2% to the total electrical production, but adds 500,000,000/1,137,500,000 x 100% = 44% to the capital cost and adds 1,417/909 x 100% = 55.9% to the cost of reducing CO2 emissions. 

 

The 2.5 MW and 3 MW units are about 390 to 415 ft tall to the tip of the blade, respectively, which would appear very large if the ridge line is at 2,000 ft elevation and a person’s house is at 1,000 ft elevation and within a mile of a row of wind turbines; at night there would be an unsteady beat of whoosh sounds. Wind turbines are often made to look small on distant ridge lines using Adobe’s Photoshop software. Quality of life (noise, visuals, sociatal unrest/opposition), property value and environment are negatively impacted over a large area.

 

CCGT facilities are significantly more effective than wind turbine facilities for reducing CO2 per invested dollar and for reducing the cost of electricity per kWh. The production of energy by the GE FlexEfficiency 50 CCGT facility has a levelized cost less than $0.0631/kWh, whereas energy by a wind turbine facility in New England has a levelized cost greater than $0.096/kWh, i.e., at least 52% greater.

 

Instead of subsidizing poorly performing wind turbine facilities, the subsidies should be for advanced CCGT facilities to accelerate their installation throughout the USA in large numbers and to replace aging, inflexible, polluting coal-fired plants that emit at least 2.15 lb of CO2/kWh versus 0.655 lb of CO2/kWh emitted by advanced CCGT facilities, i.e., 3.28 times less.

 

Those subsidies would be similarly effective if used for increasing energy efficiency that would use mostly US materials and US labor and create jobs all over New England, instead of in Denmark (wind turbines), Spain (wind turbines), Germany (PV inverters) and China (PV panels).

 

Global Warming and Wind Politics 

 

The PR message for wind turbine facilities is for vendors, developers and financiers to get as much federal and state subsidies as possible and have that money, plus private investment, course through a state’s economy to create jobs, make the US energy independent and combat global warming. What is not to love?

 

The hitch is the money is invested in subsidized, uneconomic projects that will ultimately make a state’s economy less efficient for the production of goods and services and thereby lower standards of living; it is similar to shooting oneself in the foot when running to keep up with other nations.

 

Another hitch is we live in a world distorted by coalitions of legislators and special interests in which renewable energy is treated as an end in itself and given preferences, such as renewable portfolio standards, must-take provisions, accelerated depreciation, tax credits, cash grants, low-interest loans and, in some jurisdictions, generous feed-in tariffs.

 

Accordingly, the grids will likely have to continue the complicated and costly efforts of accommodating increasing quantities of expensive, variable, intermittent renewable energy, regardless of whether more capable technologies, such as advanced CCGT facilities, that require:

 

– no such complicated and costly efforts

– generate electricity at a significantly lower cost per kWh

– reduce CO2 emissions at a significantly lower cost per metric ton. 

 

Legislators need to pay less attention to the PR of renewables vendors, developers and financiers and re-examine the people’s priorities before providing continued subsidies for wind facilities, which are such obviously poor investments and have such an everlasting, undesirable environmental impact on what are now mostly pristene ridge line areas. Wiser minds should prevail and stop this subsidy-driven, mad rush to New England’s ridge lines before it is too late. 

 

STUDY PURPOSE AND APPROACH

 

The purpose and approach of this study is to:

 

– evaluate 2 alternatives: one consists of a 510 MW CCGT facility plus a 200 MW wind turbine facility, the other consists of only the CCGT facility.  An average efficiency of 58% was assumed for the cycling range of 310 MW to 510 MW.

 

– determine the capital cost of the alternatives, the production, MWh/yr, and the emissions, metric tons of CO2/yr, and compare them. 

 

Notes: 

 

If the wind turbine facility capacity were significantly increased beyond 200 MW, the CCGT facility would operate at lesser efficiencies, i.e., increased fuel/kWh and increased pollution/kWh, and the CO2 emissions reduction due to wind would become less and less, until it becomes zero and then becomes positive.

 

CCGT heat rate = 3,413 Btu/kWh/efficiency 0.58 = 5,884 Btu/kWh*

CCGT heat rate = 3,413 Btu/kWh/efficiency 0.61 = 5,595 Btu/kWh; base-loaded

CO2 emission = 117 lb of CO2/(million Btu x 1 kWh/5,884 Btu/kWh) = 0.688 lb of CO2/kWh

CO2 emission = 117 lb of CO2/(million Btu x 1 kWh/5,595 Btu/kWh) = 0.655 lb of CO2/kWh; base-loaded 

Utility long-term contract fuel cost is assumed at $4/1,000,000 Btu

NEPOOL average marginal CO2 emissions about 1.0 lb/kWh

http://www.iso-ne.com/committees/comm_wkgrps/relblty_comm/pwrsuppln_comm...

 

* The 58% stated by GE is for base-load/load-following mode. The CCGT ramps up and down at least 100 times a day to accommodate varying wind energy, whereas in base-load/load-following mode ramping up and down may occur only a few times a day. 

The rapid ramping will increase the heat rate, Btu/kWh, and CO2 emissions, lb of CO2/kWh.

 

For example: a car driven on a level road at a steady speed of 40 mph has a mileage of, say 26 mpg. The same car driven on a level road at irregular and rapidly changing speeds that average 40 mph has a mileage of, say 22 mpg. The mileage degradation due to the speed changes would be (26-22)/26 x 100% = 15%. A car’s best mileage usually is at 55 mph, at a steady speed, on a smooth, level road; it is the oft-quoted EPA highway mileage.

 

A New England average CF = 0.31 was chosen because early installed wind turbine facilities would likely be on ridge lines with higher CFs, such as facilities in western Maine which have an average CF = 0.32, whereas later installed facilities would be on ridge lines with CFs of 0.30 or less.   http://www.coalitionforenergysolutions.org/maine_wind_farms.pdf

 

The New England average CF = 0.31 may prove to be very optimistic, because large geographical areas rarely have capacity factors greater than 0.30. For comparison: Western Ireland (0.323 for the 2002-2009 period, the best in Europe), UK (0.282 for 1998-2004), Texas (0.258 for 2009), Denmark (0.242 for the 2005-2009 period), the Netherlands (0.186), Germany (0.167). It would not be credible to aver onshore wind speeds in New England are comparable to onshore wind speeds in western Ireland, one of the windiest areas of Europe.

 

An installed capital cost of $2,500,000/MW was chosen for this study. It is the same as the average of the capital costs of the recently installed operating and planned wind turbine facilities in Maine and less than the $2,778,000/MW of the Granite Reliable Power Windpark, Coos County, NH, consisting of 33 Vestas units @ 3 MW each.   http://www.coalitionforenergysolutions.org/maine_wind_farms.pdf

 

CAPITAL COSTS 

 

CCGT facility about 510 MW x $1,250,000/MW = $637,500,000

Wind turbine facility, on New England ridge lines, about 200 MW x $2,500,000/MW = $500,000,000

 

PRODUCTION, FUEL COSTS, CO2 EMISSIONS

 

CCGT + Wind

 

Capital cost CCGT + Wind: $637,500,000 + $500,000,000 = $1,137,500,000

 

Wind turbine facility production: 200 MW x 8,760 hr/yr x capacity factor 0.31 = 543,120 MWh/yr

CCGT facility production: (510 – 0.31 x 200) MW x 8,760 hr/yr = 3,924,480 MWh/yr

Total production: 543,120 + 3,924,480 = 4,467,600 MWh/yr

 

Net NEEG CO2 emission reduction = 1.0 x 543,120 x 1,000 x 1/2,200 + (1.0 – 0.688) x 3,924,480 x 1,000 x 1/2,200 = 802,571 metric ton of CO2/yr

 

Fuel cost: 3,924,480 x 1,000 x 5,884 x $4/1,000,000 = $92,374,140/yr, or $0.0207/kWh

 

Capital cost/Net NEEG CO2 emission reduction = 1,137,500,000/802,571 = $1,417/metric ton of CO2 

 

CCGT Only

 

Capital cost of CCGT Only: 200 MW x $2,500,000/MW = $500,000,000 

 

CCGT facility production: 510 MW x 8,760 hr/yr = 4,467,600/yr

 

Net NEEG CO2 emission reduction = (1.0 – 0.655) x  4,467,600 x 1,000 x 1/2,200 = 701,363 metric ton of CO2/yr 

 

Fuel cost: 4,467,600 x 1,000 x 5,595 x $4/1,000,000 Btu = $99,986,353/yr, or $0.0224/kWh

 

Capital cost/Net NEEG CO2 emission reduction = 637,500,000/632,603 = $909/metric ton of CO2

 

INCREASED ENERGY EFFICIENCY

 

The real issue regarding CO2 reduction is energy intensity, Btu/$ of GDP; it must be DECLINING to offset GDP and population growth. To accomplish this energy efficiency needs to be at the top of the list, followed by the most efficient renewables of which hydro power is the best and residential small wind is the worst, in fact, it is atrocious. EE is so good that it should be subsidized before any and all renewables, because it is much more effective per invested dollar. 

 

Effective CO2 emission reduction policy requires that all households eagerly participate. Current subsidies for electric vehicles, residential wind, PV solar and geothermal systems benefit mostly the top 5% of households that pay enough taxes to take advantage of the renewables tax credits, while all other households are required to pay for them by means of fees and taxes or higher electric rates; the net effect is much cynicism and little CO2 reduction. Improved energy efficiency policy will provide much greater opportunities to many more households to significantly reduce their CO2 emissions. 

 

Energy efficiency will have a much bigger role in the near future, as energy system analysts come to realize that tens of trillions of dollars will be required to reduce CO2 from all sources and that energy efficiency will reduce CO2 at a lesser cost and more effectively. Every household can participate.

 

Energy efficiency projects:

 

– will make the US more competitive, increase exports and reduce the trade balance.

 

– usually have simple payback periods of 6 months to 5 years. 

 

– reduce the need for expensive and highly visible transmission and distribution systems.

 

– reduce two to five times the energy consumption and greenhouse gas emissions and create two to three times more jobs than renewables per dollar invested; no studies, research, demonstration and pilot plants will be required. 

 

– have minimal or no pollution, are invisible and quiet, something people really like.

 

– are by far the cleanest energy development anyone can engage in; they often are quick, cheap and easy.

 

– have a capacity factor = 1.0 and are available 24/7/365.

 

– use materials, such as for taping, sealing, caulking, insulation, windows, doors, refrigerators, water heaters, furnaces, fans, air conditioners, etc., that are almost entirely made in the US. They represent about 30% of a project cost, the rest is mostly labor. About 70% of the materials cost of expensive renewables, such as PV solar, is imported (panels from China, inverters from Germany), the rest of the materials cost is miscellaneous electrical items and brackets.

 

– will quickly reduce CO2 at the lowest cost per dollar invested AND make the economy more efficient in many areas which will raise living standards, or prevent them from falling further. 

 

– if done before renewables, will reduce the future capacities and capital costs of renewables. 

 

 

 

 

 

 

 

 

 

Willem Post's picture

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Discussions

Stephen Gloor's picture
Stephen Gloor on June 21, 2011

Willem

First of all I totally agree with you that energy efficiency and conservation should be number one on anyone’s priority list.  It is the no-brainer solution for at least some of the required CO2 reductions.

Because wind energy is variable and intermittent, additional spinning and backup plants, such as a mix of open cycle gas turbines, OCGTs, and combined cycle gas turbines, CCGTs, must be kept in 24/7/365 operation to supply and withdraw energy as required.

This statement is not true.  Spinning reserve and backup plants are in place now to cope with intermittent fossil fuel and nuclear plants and to cope with variable demand.  All power plants are intermittant – wind us just more so.  Both the EWITS and NWITS studies concluded that up to 20% wind can be accomodated on grids with no increase in the normal operational reserve.  It is only when you push it beyond this you need extra reserve however a wind is actually quite predictable these can be OCGTs that are off when not required not spinning and consuming fuel.  If the lack of wind does not co-incide with the summer peak then these could well be the generators that are only used a few days a year when summer demand stresses the grid in which case the required generators are already on hand ready to go when the wind drops.

The other problem I have with your analysis is that it is not a realistic scenerio.  You are  modelling a 510MW baseload plant that has 200MW of variable capacity.  So the CCGT cycles from 310MW to 510MW over the year and therefore you conclude that it is cheaper to just build the CCGT and leave off the wind.  Which is probably correct.

However in practice this almost never happens.  If you had modelled the 510MW generator with a realistic demand model where the CCGT was cycling with demand, not just the wind,  then you would find that the 200MW wind farm at time would be supplying more of the current demand than the CCGT.  In this way averaged over a full year the wind farm would actually supply more energy than its proportion in the power mix would suggest especially at a CF of .31.  The point is that there is no place where a 510MW CCGT generator would be working in baseload mode on its own.   If it was isolated then it would be in load-following mode and cycling up and down with demand.  If it was in baseload mode then it would be part of a grid of more than one CCGT in which case some of the CCGTs would be working following the load with the wind forming a part of that.

For example an isolated wind/gas grid:

http://www.horizonpower.com.au/environment/renewable_energy/wind/wind_nine_mile.html

The current power system comprises two wind farms (5.6 MW total capacity) which operate in parallel with the 30 MW Esperance gas-fired power station owned and operated by Esperance Power Station Pty Ltd (a subsidiary of WorleyParsons).  The majority of the electricity on this system comes from these gas turbines.

The wind farm includes a control system based on a Master Controller, which talks directly with the gas turbine control system to manage the wind farm output.  Due to the distance of the wind farms from the power station, the system incorporates sophisticated high reliability communications equipment using digital radio modems and fibre optic within the wind farms.

The wind farms generate about 22% of Esperance’s electricity.  Maximum instantaneous penetration is just over 65%.”

The current power system comprises two wind farms (5.6 MW total capacity) which operate in parallel with the 30 MW Esperance gas-fired power station owned and operated by Esperance Power Station Pty Ltd (a subsidiary of WorleyParsons).  The majority of the electricity on this system comes from these gas turbines.
The wind farm includes a control system based on a Master Controller, which talks directly with the gas turbine control system to manage the wind farm output.  Due to the distance of the wind farms from the power station, the system incorporates sophisticated high reliability communications equipment using digital radio modems and fibre optic within the wind farms.
The wind farms generate about 22% of Esperance’s electricity.  Maximum instantaneous penetration is just over 65%.The current power system comprises two wind farms (5.6 MW total capacity) which operate in parallel with the 30 MW Esperance gas-fired power station owned and operated by Esperance Power Station Pty Ltd (a subsidiary of WorleyParsons).  The majority of the electricity on this system comes from these gas turbines.The wind farm includes a control system based on a Master Controller, which talks directly with the gas turbine control system to manage the wind farm output.  Due to the distance of the wind farms from the power station, the system incorporates sophisticated high reliability communications equipment using digital radio modems and fibre optic within the wind farms.The wind farms generate about 22% of Esperance’s electricity.  Maximum instantaneous penetration is just over 65%.”

The Esperance wind/gas system is almost exactly the scenerio you describe and the wind farms contribute much more than their power proportion.

Another example is:

http://worldofenergy.com.au/factsheet_wind/07_fact_wind_WA.html#esperance

Denham is now powered by a diesel power station and three wind turbines. These wind turbines contribute approximately 40 per cent of Denham’s electricity requirements and save about 550,000 litres of diesel fuel and 1,700 tonnes of carbon dioxide gas emissions in the town each year.

These are small examples however it indicates that you need to do a lot more work to determine the cost/benefit of wind rather than the simple calculations you have presented.  I am sure it is not beyond the resources of the Coalition for Energy Solutions with all the qualified people there to do a proper analysis.

Stephen Gloor's picture
Stephen Gloor on June 21, 2011

Willem Post – “My article is about utility-scale power generation.”

I noted that in my reply. In that case the small generators will model the load following part of the utility generation which may be all the generation capacity or only the capacity that is capable of load following.  In which case wind, if properly dispatched on short time intervals (as discussed in EWITS), will displace more of the fossil fuel generation over the course of a year.

Your article implies a generator in base load mode with wind contributing a fixed part of that generation capacity depending on the state of the wind varying from 0 to 200MW.   As I have said before the wind would be despatched with the load following part of the capacity not the baseload at least up to 20% to 40% wind penetration which is probably as high as wind will ever go.  Solar thermal and geothermal will make up most of the baseload capacity and fossil fuel or biomass generators will almost certainly be the 10 – 20% peaking capacity required.

Your article IMHO is not a realistic scenerio and therefore is not a valid cost estimation.  

Michael Hogan's picture
Michael Hogan on December 30, 2011

Stephen Gloor’s comments are right on track. There is a virtual cottage industry in back-of-the-envelope calculations of why intermittent renewables can’t work or don’t make any sense. They all focus on the pathway to achieve the next ton of CO2 abatement, or get to a 20% reduction in sector emissions, or any number of other intermediate steps. None of them address the ultimate objective, and all of them lack any sophisticated modelling of the power grid to determine what the answer actually is. if Mr. Post’s initial thesis regarding CO2 abatement is to make any sense, it rests on the science underpinning anthropogenic climate change. That science points to two things – an almost immediate reversal in the trajectory of total emissions, and a full or nearly full decarbonization of the power sector by well before 2050 as a key enabler for the level of abatement required in the rest of the economy. There are a number of credible mainstream analyses that lay out both the imperatives inherent in the scientific premise seemingly accepted by Mr. Post, and the options available to us to meet those imperatives. There are no cost-effective, risk-diversified options that include less than approximately 50% of electricity coming from renewable sources by 2030 (much of that coming from intermittent sources like wind and solar), none that afford us the choice of “doing efficiency now and renewables later” (we can and must do both now), and none of those pathways affords us the option of waiting to commercialize the renewables technologies upon which we will need to rely. Flexible, efficient mid-merit gas-fired generation is absolutely a key enabling technology, but even the most efficienct gas-fired generation emits far too much CO2 to be a major player in the power sector post-2030 (something that could be remedied by carbon capture and storage technology, but there is at least as much risk attached to the likely commercialization of that technology for CCGTs as there is for any of the renewables technologies or for any significant new nuclear construction). So Mr. Post will need to do two things before he is in a position to posit any credible conclusions – (i) consider the full scope of the challenge before us rather than basing his conclusions on ways to reach intermediate milestones, and (ii) conduct a proper dynamic grid analysis that tests the question of whether reliable, cost-effective power supplies are possible with large shares of power produced from wind and solar (hint: the answer has already been provided by several reputable studies, including the one I managed in Europe, “Roadmap 2050: a practical guide to a prosperous, low-carbon Europe”). Either the science behind Mr. Post’s starting point is valid – in which case his prescriptions clearly do not go far enough – or it isn’t – in which case even the steps he promotes constitute a waste of money and resources. And the science is valid, as even Mr. Post would very clearly appear to accept.

Marc Neurer's picture
Marc Neurer on July 6, 2012

Dear Mr. Post!

 

Is there the possibility of getting a look at the whole study of yours talking about

GE FlexEfficiency 50 CCGT Facilities and Wind Turbine Facilities

It would be great to see the whole picture and get a more detailed insight in your findings.

Sincerely Marc Neurer

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