Solar Is Starting To Replace The Largest Coal Plant In The Western U.S.

On Navajo land in Arizona, a coal plant and coal mine that have devastated the environment are being replaced by solar–with both enormous benefits and local drawbacks that can serve as a lesson for how the rest of the country will need to manage the transition to renewables. In the desert near Arizona’s border with Utah on the Navajo Nation, a massive solar array built in 2017 now provides power for around 18,000 Navajo homes. Nearby, construction will begin later this year on a second solar plant. And on another corner of Navajo land, the largest coal plant west of the Mississippi River is preparing to close 25 years ahead of schedule, despite some last-minute attempts to save it. The coal plant, called the Navajo Generating Station, was built in the 1970s to provide power to growing populations in Southern California, Arizona, and Nevada. A nearby coal mine supplies the power plant with coal. As recently as 2014, the coal plant wasn’t expected to close until 2044–a date negotiated with the EPA to reduce air pollution. But reduced demand for coal, driven both by economics and climate action, means that the plant is scheduled to close in 2019 instead. The coal mine, run by Peabody Energy, will be forced to follow.

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Coal plant has a capacity of 2400 MW and can run 24/7. Solar plant has a capacity of 27 MW, but only at noon on cloudless days.

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Navajo Generating Station is 2250 MW, solar is 27.3 MW, with another 27.3 MW in the future. Someone call this a replacement?

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8 minutes ago, Petar said:

Coal plant has a capacity of 2400 MW and can run 24/7. Solar plant has a capacity of 27 MW, but only at noon on cloudless days.

Works when cloudy and can be in more angles than previous panels. You get sunburnt on cloudy days right?.. tracking panels even more... they wouldn't install them if they weren't cost effective... same as turbines... And, most people use hydro in the daytime.

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Breathing clean air and drinking clean water..It's easy choice for me..

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100%

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Newer solar products on the market horizon, are much more efficient layered and can catch power till dusk , ambient light and even indoors, its just the numbers

everything  counts in small amounts

 

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As is typical of these threads, the original poster overlooked/was completely unaware of/ a few basic points. The problem with American coal-powered generators has never been renewables but gas due to the fracking boom. Obama-era regulations about coal plant efficiency pushed things along, but the basic problem was that gas prices have fallen to the point where gas generators can seriously undercut coal plants. There is no way the solar array mentioned could possibly even begin to substitute for a 2250 MW power station. One poster mentioned an eventual installed capacity of 50 MW or so.. a plaything - barely worth mentioning. The capacity factor (effective output) of PV projects is usually around 20 per cent, so 10 MW is closer. You'll find that gas plants somewhere are making up the power deficit.

The American coal, incidentally, is doing much better now due to exports, I'm sure you'll be happy to know.    

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Three of those utilities—SRP, Arizona Public Service Company, and Tucson Electric—told the Arizona Corporation Commission in late April that they no longer require electricity from the generating station because they have access to cheaper gas-fired generation. The Central Arizona Project (CAP), the largest customer for NGS power, wants out as well; CAP managers say the agency could had acquired power in 2016 for $38.5 million less than it paid for power from the plant had it bought that power somewhere else. Both CAP and Salt River Project, which operates the plant, expect power from NGS will become even more expensive than market power in coming years. 

Sounds like the coal is being replaced by natural gas, not solar.  Economics strikes again.

 

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Sure, solar will replace everything because it's cheaper than everything and still getting cheaper. Fossil fuels are already obsolete for power generation.

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3 hours ago, JunoTen said:

Sure, solar will replace everything because it's cheaper than everything and still getting cheaper. Fossil fuels are already obsolete for power generation.

Sorry, completely wrong. Solar is only cheaper on a per output basis - those are the figures you see enthusiastically quoted. On a grid - the only place that matters - it is more expensive than conventional power and always will be. Solar plants have to be either duplicated by fossil fuel plants or backed by an expensive storage facility. Despite all the enthusiastic stories cheap large-scale storage of power, apart from existing hydro plants, is still a dream. As the bulk of the cost is in depreciation of the plant, and all solar plants have to be duplicated by conventional plant, even if we leave aside all the additional transmission lines required,  solar is a straight cost to the grid. Whether that cost is worth whatever emissions offset is another matter. 

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On 6/28/2018 at 9:21 PM, markslawson said:

Sorry, completely wrong. Solar is only cheaper on a per output basis - those are the figures you see enthusiastically quoted. On a grid - the only place that matters - it is more expensive than conventional power and always will be. Solar plants have to be either duplicated by fossil fuel plants or backed by an expensive storage facility. Despite all the enthusiastic stories cheap large-scale storage of power, apart from existing hydro plants, is still a dream. As the bulk of the cost is in depreciation of the plant, and all solar plants have to be duplicated by conventional plant, even if we leave aside all the additional transmission lines required,  solar is a straight cost to the grid. Whether that cost is worth whatever emissions offset is another matter. 

Also, if you are building large conventional hydropower plants (not pumped storage) for supporting wind and solar, why not simply save a ton of money and generate electricity from hydro like it does Russia, Canada, Norway, Iceland, Swede, China, Brazil, NewZealand.

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On 6/29/2018 at 5:06 AM, JunoTen said:

Sure, solar will replace everything because it's cheaper than everything and still getting cheaper. Fossil fuels are already obsolete for power generation.

You really will not like this article, which completely disagrees:

Wind and Solar Require Massive Subsidies

... We are constantly treated to disinformation claiming that wind or solar is competitive with fossil fuels. How is it competitive when it can’t replace fossil fuels, but only serves as a supplemental source of power that reduces fuel consumption in the fossil-fuel plants? Since it costs far more to reduce the fuel consumed than it is worth, wind and solar make absolutely no sense. Neither is a cost-effective method of reducing CO2emissions. If you justify the subsidy as an expense to reduce emissions, you find that it costs more than $100 per metric ton of CO2 emissions avoided. There are many ways to reduce emissions for far less than building windmills and solar farms. Many companies sell carbon offsets for around $10 a metric ton. Worry about global warming is fading for good reason. CO2 is very beneficial for agriculture and greens deserts, so why bother worrying about reducing CO2? If you insist on worrying, worry about Asian emissions that are large and increasing fast.

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6 hours ago, Tom Kirkman said:

You really will not like this article, which completely disagrees:

Wind and Solar Require Massive Subsidies

... We are constantly treated to disinformation claiming that wind or solar is competitive with fossil fuels. How is it competitive when it can’t replace fossil fuels, but only serves as a supplemental source of power that reduces fuel consumption in the fossil-fuel plants? Since it costs far more to reduce the fuel consumed than it is worth, wind and solar make absolutely no sense. Neither is a cost-effective method of reducing CO2emissions. If you justify the subsidy as an expense to reduce emissions, you find that it costs more than $100 per metric ton of CO2 emissions avoided. There are many ways to reduce emissions for far less than building windmills and solar farms. Many companies sell carbon offsets for around $10 a metric ton. Worry about global warming is fading for good reason. CO2 is very beneficial for agriculture and greens deserts, so why bother worrying about reducing CO2? If you insist on worrying, worry about Asian emissions that are large and increasing fast.

A problem with that article is that it contains so many mistakes the author doesn't so much shoot himself in the foot but performs a Kalashnikov river dance across the stage.

The claim that renewables are irratic - well no, not the context of bringing conventional plant on or off line. Solar and wind outputs at a national or regional level are predictable to within a few % a couple of hours before the outturn point. 

The claim that extra CO2 and greens deserts is a classic claim that needs to come with further qualification. Yes - CO2 can help providing it is the limiting factor in plant growth. More often than not it isn't - the limiting factor is availability of water, Phosphate or Nitrogen. This of course explains why Co2 fertilisation of air in enclosed greenhouses works if other nutrients are maintained in the natural environment CO2 fertilisation is a short lived effect and once availability of other nutrients is exhausted growth scales back. 

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18 hours ago, Sebastian Meana said:

Also, if you are building large conventional hydropower plants (not pumped storage) for supporting wind and solar, why not simply save a ton of money and generate electricity from hydro like it does Russia, Canada, Norway, Iceland, Swede, China, Brazil, NewZealand.

Sebastian - your response makes no sense. Where Hydro already exists - Norway, New Zealand, etc - then it is good to have, and may work very well with wind. The problem is building more where the topography clearly doesn't suit - Australia, parts of the US. Lots of dams are now being build world wide. Last time I looked India was planning to dam half the Himalayas and the Chinese are building more dams because that's what they do, build dams. (There ae various reasons for this, but none involve the environment.) None of this is anything like enough to offset the problem of more renewables coming on to grids. 

Also, this point in your response to Tom Kirkman "Solar and wind outputs at a national or regional level are predictable to within a few % a couple of hours before the outturn point." That's wrong. No-one has been able to do that. You will find various claims have been made about forecasting systems for wind, and grids may be using them to narrow the gaps but two hours and a few per cent! Sorry, not happening. Tom will no doubt take you to task about other stuff.. 

 

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22 hours ago, markslawson said:

Sebastian - your response makes no sense. Where Hydro already exists - Norway, New Zealand, etc - then it is good to have, and may work very well with wind. The problem is building more where the topography clearly doesn't suit - Australia, parts of the US. Lots of dams are now being build world wide. Last time I looked India was planning to dam half the Himalayas and the Chinese are building more dams because that's what they do, build dams. (There ae various reasons for this, but none involve the environment.) None of this is anything like enough to offset the problem of more renewables coming on to grids. 

Also, this point in your response to Tom Kirkman "Solar and wind outputs at a national or regional level are predictable to within a few % a couple of hours before the outturn point." That's wrong. No-one has been able to do that. You will find various claims have been made about forecasting systems for wind, and grids may be using them to narrow the gaps but two hours and a few per cent! Sorry, not happening. Tom will no doubt take you to task about other stuff.. 

 

Thats probably pushing it other than in very predictable climates - Ex. Solar in the Arabia Gulf. 

A quick Google of Data trawls up some interesting data on wind and solar predictability. 

see attachment for Links

NE Germany

Average deviation for wind 2-4%

Average deviation for PV – 5-7%

UK Solar (National Grid)

<10% forecast variability

US Utilities

Idaho Power (2013) Day ahead accuracy Variability 13 &. Hour Ahead 6.5%

CAISO (2013)  Day ahead forecast variability <10%

 

 

Solar and Wind predictability.docx

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^ that's a better percentage of predictability than I expected.

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1 hour ago, NickW said:

Thats probably pushing it other than in very predictable climates - Ex. Solar in the Arabia Gulf. 

A quick Google of Data trawls up some interesting data on wind and solar predictability. 

see attachment for Links

NE Germany

Average deviation for wind 2-4%

Average deviation for PV – 5-7%

UK Solar (National Grid)

<10% forecast variability

US Utilities

Idaho Power (2013) Day ahead accuracy Variability 13 &. Hour Ahead 6.5%

CAISO (2013)  Day ahead forecast variability <10%

 

 

Solar and Wind predictability.docx

NickW - you've quoted the stuff on wind and PV without understanding what it means, because the figures you quote underline the uselessness of forecasting in this area. Persistence or status quo forecasting (high wind today, so high wind tomorrow) has a high success rate. Getting to 90 per cent plus forecasting success over two hours or even over a day is no problem. The real problem is the remaining 10 per cent - when change occurs. That was what you were claiming before. If people could be persuaded to do without electricity for a few per cent of the time when wind dies and the diesel generators are fired up then no problem. But as far as I know, no-one is claiming sufficient success with wind/solar forecasting to offset that major problem. The 90 per cent plus figures you mention are useless, as are the deviation figures. They simply do not help at all. If you need further illustration of this then put yourself in the shoes of a grid operator and imagine what they have to do to balance demand and supply 24-7, bearing in mind that even small slips will cause the company switch board to be jammed. Also remember that the geographical spread idea - spread the wind farms out so that wind is always blowing somewhere - has probed a complete bust. Now that's it. I only answer a couple of times then move on. If you don't want to listen that's up to you, but wind and solar have major limitations that aren't going away any time soon.

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Fast improvement of energy storage solutions will solve this problem quicker than you think.

 

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15 hours ago, markslawson said:

NickW - you've quoted the stuff on wind and PV without understanding what it means, because the figures you quote underline the uselessness of forecasting in this area. Persistence or status quo forecasting (high wind today, so high wind tomorrow) has a high success rate. Getting to 90 per cent plus forecasting success over two hours or even over a day is no problem. The real problem is the remaining 10 per cent - when change occurs. That was what you were claiming before. If people could be persuaded to do without electricity for a few per cent of the time when wind dies and the diesel generators are fired up then no problem. But as far as I know, no-one is claiming sufficient success with wind/solar forecasting to offset that major problem. The 90 per cent plus figures you mention are useless, as are the deviation figures. They simply do not help at all. If you need further illustration of this then put yourself in the shoes of a grid operator and imagine what they have to do to balance demand and supply 24-7, bearing in mind that even small slips will cause the company switch board to be jammed. Also remember that the geographical spread idea - spread the wind farms out so that wind is always blowing somewhere - has probed a complete bust. Now that's it. I only answer a couple of times then move on. If you don't want to listen that's up to you, but wind and solar have major limitations that aren't going away any time soon.

You really don't understand how modern integrated electricity transmission and distribution grids work do you? 

A little anecdote - my Dads cousin, until recently managed a sizable part of the UK National Grid. His response to claims that the Operators couldn't cope with Solar & Wind sunpredicted variation which typically ran at less than 10MW / Min but in extreme circumstances might hit 30MW / min

How do think we cope with Sizewell B (1.1GW) or another large generator dropping out without any warning in  a couple of seconds? Alternatively when ITV forget to tell us Coronation Street will end a minute early and 5 million 2 KW kettles get switched on. 

Now these events do happen. Last time Sizewell B dropped out they just about managed to keep the lights on in East Anglia. So if they can cope with 1.1GW dropping out suddenly an unpredicted rate change of 10-20MW a minute hardly registers. 

I don't know where you are but Diesel Gensets are not used in Europe for short service response other than in some dire situation where the generator fires up its black start diesels. 

Now in the real World and using the UK as an example what do we have in the Transmission network on top of Spinning reserve / grid capacity (5000kwh) 

  • 2.8GW of Pumped storage that can go from 0-100% in approx 2 minutes
  • 1.8GW of conventional Hydro - Bit slower than PS but still a quick response. 
  • 800MW OCGT - 2-5 minute ramp rates to 100%

Interconnections with France, Ireland and The Netherlands assuming there is some capacity to draw on. 

CCGT plant Ramp rates of 40-50%. 

Coal Plant - ramp rate of approx 17% an hour. 

Biomass plant - not sure on ramp rate but probably somewhere between CCGT and Coal. 

In the Distribution Network

100's of small producers that can bring extra supply onto the network within a minute or two - its all automated by radio signal or through measuring the frequency on the grid. A friend who is an Engineer for a Biogas producer can add about 7MW to the grid in 2 minutes as his CHP engines normally run at 50%. Doesn't have to lift a finger - a radio  signals tells the engines to go 100% 

Batteries are starting to be added which will help. 2nd hand EV batteries have a useful second life in this capacity. 

Demand can be managed too. 

Many users are on interruptible supply where the supply can be cut off for between 20 minutes and an hour to help deal with short term grid imbalances - Examples include large refrigerated warehouses, Aluminium smelters, large Air Systems on big buildings etc

 

Ok beyond a certain penetration level of solar and wind then yes - additional back up or storage will have to be built but not generally  in situations where penetration is in the 15-20% range and the grid is served by a wide variety of energy sources.  

 

 

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On 6/27/2018 at 4:58 PM, Petar said:

Coal plant has a capacity of 2400 MW and can run 24/7. Solar plant has a capacity of 27 MW, but only at noon on cloudless days.

The peak can be spread out over 3-4 hours by orientating the panels in different directions from East to West. 

In regard to a south facing panel it will be producing approx 2/3rds of its peak power at 9am and 3pm. With East and West the same times are a bit earlier and later respectively

You can get all the data off here

http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php

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On 6/27/2018 at 9:58 AM, Petar said:

Coal plant has a capacity of 2400 MW and can run 24/7. Solar plant has a capacity of 27 MW, but only at noon on cloudless days.

NGS has a nameplate capacity of 2400 MW. It has become increasingly uneconomic to run, so the capacity factor for all three units is now in the 60% range. One of the units was set to be retired ever before the current owners decided that keeping the plant open simply was not economically possible. So all of a sudden, the capacity of NGS is down to around 960 MW. 
Power from NGS costs more than $50 per MWh. The Central Arizona Project, which is NGS's biggest customers, just signed a deal for 30 MW of solar for around half that. In Colorado, Xcel Energy plans to retire two units of coal and replace them with 1,100 MW of wind generation, 700 MW of large-scale solar and 275 MW of large-scale battery storage, along with adding about 380 MW of existing natural gas generation - because building new gas is too expensive. In Nevada, the state's largest utility has filed for approval of a contract for 300 MW of solar at $23.76/MWh as part of its plan to add 1 GW of renewables and 100 MW / 400 MWh of energy storage. California is killing new gas plants in favor of large-scale battery arrays because it is more affordable for customers.
One can pretend these facts don't exist, but any sane analyst would - and most already have - recognized the writing on the wall. Something tells me the planners working for these utilities know a bit more about the economics and strong reliability of the massive amounts of clean energy they're bringing online than the people posting on this thread. Coal will soon be gone completely, gas is becoming irrelevant. It won't happen overnight, but eventually, we'll have turned the corner and any fossil fuels will be viewed like typewriters and cassette recorders are now. It is technologically and economically inevitable.

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Rainman said breathing clean and and drinking clean water is a plus. That is what the people of California get now. They export the pollution to Ingin country and enjoy clean air and electric supply. People in NYC do the same they export their electric generation and pollution to northern New York State for them it is a win-win, for us in upstate it is a lose-lose.

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It is night time and it is not windy so Los Angles is shutting down until further notice. Driving is prohibited as stop light are out due to no electric. Cell towers are down due to no electric. Water pumping has stopped. Enjoy your vacation folks.  

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In New York State we are planning to build new nuclear plants upstate where only the dispicables live. Long will the lights of Broadway burn brightly. 

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