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Mixing Coal and Solar To Produce Cheaper Energy
Al writes "It might not please many environmentalists, but a major energy company is adding solar-thermal power to a coal plant and says this could be the cost-effective way to produce energy while lowering CO2 emissions. Abengoa Solar and Xcel Energy, Colorado's largest electrical utility, have begun modifying the coal plant, which is based near Grand Junction, Colorado. Under the design, parabolic troughs will be used to preheat water that will be fed into the coal plant's boilers, where coal is burned to turn the water into steam. Cost savings comes from using existing turbines and generators and from operating at higher efficiencies, since the turbines and generators in solar-thermal plants are normally optimized to run at the lower temperatures generated by parabolic mirrors."
Do you suppose the technology from the article can be combined with one of these?
Promote proofreading. Don't mod up sloppy posts.
sounds good to me, donno any environmentalists who would object to burning less coal...
Why would it not please them...if they are rational?
But maybe the answer is contained within the question....
...the future crusty old bastards are already drinking the Kool-Aid.
It turns out that you can turn CO2 into fuel by exposing it to a titanium oxide catalyst in the presence of sunlight. In a closed cycle, this would be a carbon-neutral way to go. http://dsc.discovery.com/news/2009/03/23/carbon-dioxide-fuel.html
What part of "A well regulated militia" do you not understand?
Why wouldn't environmentalists be happy with this? I consider myself one and think this is great news. Too many people focus on 100% solutions. You don't need to eliminate 100% of coal in the short term. Reducing coal consumption by 80% or so by having solar provide heat during peak hours (daytime) would still be a huge benefit.
Get out, or I'll have vice-president Agnew's headless body throw you out!"
I'm investing in a solar mine in Africa. If it all pans out I'll be rolling in more solar than I know what to do with. The only kinks left are how to transport all the solar I'm expecting to mine.
Coalar energy, let's hope it has the efficiency of coal with the environmental impact of solar, and not the other way around.
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
It turns out that you can turn CO2 into fuel by exposing it to a titanium oxide catalyst in the presence of sunlight.
That's just another form of solar power, it's just you're using the sunlight to produce fuel rather than electricity. If it's more efficient than solar electrical generation (very possible) then it's a good idea, it's bound to be more efficient than biofuels, but whether it's more efficient than solar water heating, I don't know.
You'd probably need a concentrated source of CO2 for that, so it would either reduce efficiency, by using some energy to concentrate CO2, or would use existing power plants outputs, meaning it's not carbon neutral.
Everyone should read this http://www.withouthotair.com/
The solution is nuclear freaking power. Even China realizes this now.
We've been in the Atomic age for 60 years now and still don't have a majority of our energy from nuclear energy. It's such a disgrace.
A coker-coalar? You should be burned at the stake, or something similar.
Sometimes insisting on that last 20% means sacrificing the other 80%.
We can get the 20% later. In time these plants will be phased out, and by then, we should have a better long-distance transmission grid and cheaper power storage. And, in fact, that 80%-ish reduction in coal that this tech could bring about is actually a bigger difference than it may seem, because by reducing coal demand, we'll begin phasing out subbitumenous coal and lignite (the dirtier kinds). In 15-20 years, I hope to see fossil fuels mainly taking up a "reserve" power role, making up for shortfalls in renewables, rather than being a primary generation mechanism in their own right.
And, FYI, IMHO, hydroelectric power is anything but green (moreso in some places than others, mind you). It's utterly devastated the Colorado River ecosystem. Tidal can also be really problematic. I am a fan of solar, wind, and geo, though.
Get out, or I'll have vice-president Agnew's headless body throw you out!"
Don't forget nuclear. Be a fan of nuclear power if you want to be green. We need to start building new feeder/breeder reactors. They can use the waste of the previous generation of plants as fuel with a much reduced waste footprint. Combine that with the small area and resistance to adverse climate and it makes a good compliment for other "green" energy.
Wind IMO is not that great for large scale deployment, to unreliable. Though it would be quite acceptable over time for tasks that don't require constant power, such as water purification or hydrogen electrolysis.
If it displeases environmentalists, it will be because it's still really bad for the environment. Using solar to preheat the water instead of more coal to preheat it just admits that solar is a more effective tech for generating energy than coal is. Any coal still burned is still polluting the Greenhouse, creating huge and unmanageable costs just a little down the road (and downwind, the typical "coal is clean" illusion).
They should just convert the entire plant to solar. But coal is too subsidized for them to abandon it, and its lobbyists have too tight a chokehold on the government for solar to have an equal shot at economic efficiency.
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make install -not war
There have been many attempts of late to greenwash coal, this solar project and the "clean coal" concepts being the most recent incarnation. Even if 100% of coal plants can be made 100% carbon neutral, where do they get the coal from?
in December 2008, a 40 acre ash pond in tennessee broke through its walls and flooded millions of gallons of coal ash, potentially far worse than the Exxon Valdez. This is one of the largest environmental disasters that has happened in the US, and there has been little to no national coverage about this accident.
There are a lot of heavy hitters in the coal industry that want to put the best possible face on coal (e.g. Montana), and it is alarming that 'mountaintop removal', the laziest way to get coal, is frequently not discussed when considering how green a coal plant can be.
When I make a cup of tea in the microwave, I can put in a cup of cold water and set the timer for 3 minutes, or I can fill from the "hot" tap, put in a cup of warm water, and set the timer for 2 minutes. Using solar to preheat the water means less coal burned for unit power. Even if you weren't trying to reduce your "carbon footprint", this is still an excellent thing to do.
Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.
A coal plant has scads of waste heat
Let me fix that for you:
A coal plant has scads of low quality waste heat
Don't forget, your waste heat is what's necessary to condense the steam on the other side of the turbines. You *must* have some waste heat, otherwise there's no heat differential, thus no mechanical work can be extracted.
I wouldn't have thought that would be a problem. I hear it's nice and light.
When our name is on the back of your car, we're behind you all the way!
There's no single energy resource that is going to meet the needs of the power grid. Coal and nuclear are too slow to follow load, wind and solar are intermittent, hydro, geothermal and biomass are limited locationally. Natural gas is subject to price volatility.
The grid's energy requirements are too big and complicated to be handled by any one source of energy. Using baseload resources to provide the bulk of the energy with intermittent resources to provide cheaper or more timely energy with hydro and natural gas to fill in the gaps is what it is necessary now.
If absolute power corrupts absolutely, what does this say about renewable power?
I was the post above that said I have been trying for nearly 4 years to get Colorado to do this approach. Lets talk economics of this. Many cities have 1-4 SMALL coal plants (typically about 100 MW) that are located in there. Because they were built in the 50-70, they are much older and not as efficient. Many companies want to get rid of them and bring in GW size plants. These monster would be located on the outer fringe and would then have to transport lots of electricity for a long haul. That is wasteful, but it turns out not terribly expensive. With that approach, easterners can get electricity at about .07-.15/kw.. Now, would can AE do? Well, Solar thermal only works when the sun shines. When it does, the price of electricity is about .09-.14/KW. The problem is that solar thermal requires energy storage to go all night. Also you would have to build out a much larger field of collectors (the original group was collecting for the daytime). If you do storage, then the price is jacked up to .16-.25/kwh. Simply put, you can not compete with the .07-15 price. BUT, if we take CURRENT COAL plants, and add these collectors to them, there will be no need for storage. More importantly, it will lower the use of coal. Basically, you can think of the collectors doing the real work during the day time. During the day time, the collectors have the potential to replace 60-80% of coal. That is HUGE. So, why should this be used? Because we need to get manufacturing going. As you increase manufacturing, the price goes down. Today, the price of the collectors is .09-.14kw. If we push strongly on this, the price of the collectors will drop within 5-10 years so that they are below .03KW (for the west; the east will still be higher priced). That will lead to all fo the small coal plants being converted to holding storage as well.
This is the intelligent start of converting our economy to AE. Solar PV has to be one of the most foolish ideas going. In addition, Wind is cheap, but it can not work 24x7. The solar Thermal can replace coal/natural gas and with cheap cheap storage, it can replace the coal plants. The only other intelligent choice is geo-thermal power. That is coming with potter drilling success
I prefer the "u" in honour as it seems to be missing these days.
The waste heat is currently lost to the atmosphere in the cooling towers. There is no reason not to be running the cold input water through a heat exchanger to recapture some of that waste heat. This is how efficiency works.
The mechanical work comes from superheating the water and letting the steam turn turbines. In other words, you ADD heat - it makes no difference what the exhaust is used for as the work has already been done. There is no useful work being done by having the steam condense back to water other than helping to draw the steam into the turbine. By recapturing some of that waste heat you make the system more efficient. The process does not rely on having ice cold water as an input, just water in a liquid phase. You seem to be confusing a steam turbine with a closed system steam engine, where you need to condense to create a vacuum that actually works on the piston.
To be honest your last statement doesn't make sense anyway. You don't "*need*" waste heat to condense the steam, it is the very thing you are trying to get rid of. In fact you want as little heat as possible to make the phase change quicker. Whether the "waste" heat is lost to the atmosphere or to the incoming cold water makes no difference to the process. In an ideal system you would be getting water out of the exhaust not steam, but as that doesn't work, you need to let the steam condense, but only when you have extracted all the energy you can from it. This is why they reheat steam and admit it to several subsequent turbines before they cut their losses and send it to the cooling towers. Notice that they reheat the steam. It is more efficient to reheat than to heat from cold. The closer the input water is to phase change, then the less energy you need to make that phase change happen. Otherwise there would be no point to this article.
These traditional coal plants...seems to me they could be repurposed to burn dried wood, which is carbon neutral at least. You look at out west, every season, it never skips, we get all these news reports of one buhzillion acres going up in smoke, a total waste. No matter *what* we do, it seems this stuff is gonna burn up anyway, so we might as well create-back a lot of logging jobs and make use of it and improve the forests by managing them better. We don't have to scrap the coal burning infrastructure then, at least not right away, and can turn a liability-drought ravaged forests and now all those pines being killed by the pine beetle-into an energy production asset. Some of them anyway, I am also in favor of some really large biochar facilities, and again, perhaps some coal plants could be re-engineered into production of biochar along with the electricity. So we'd have solar thermal, perhaps a windfarm in the same area to take advantage of the transmission lines, the coal, the wood scraps, and biochar, all at the same complex, with the goal of eventually phasing out the coal. Maybe, just a thought..