It's The Efficiency, Stupid: New York Times Gets It Right This Time

Excellent. So they do read Treehugger.

The Times got it wrong and I hope they get plenty of letters to set them right. The Laws of Thermodynamics do not limit the efficiency to 50%.

While fundamentals limit the shaft work (and the amount of electricity) you get out of the cycle, there is nothing that says you can't use the heat generated by the process. In fact the 1st Law of Thermodynamics says energy is neither created nor destroyed. Most of those "conversion losses" are outside of the smokestack and available for use.

Cogeneration plants use the electricity and heat, and so their overall efficiency can be 80 to 90%. That's a huge increase, a leap in efficiency available with present technology now.

They at least can handle reporting politics objectively (joke).

It may not be limited to 50%, but the new technologies mentioned in the stories may improve conversion efficiency to that level. And that's a good thing in a world where consumers can only do so much to limit waste. Will the producers improve things from there? I imagine they will, but retrofitting every plant in the nation with the newest technology available isn't affordable or even a good idea right now. It should be faster than it has been, but the newest technology will be improved upon soon enough, some of the retrofitted plants will be replaced entirely (a cheaper solution in some instances,) and not every power plant is sitting on a pile of "What do we do with this?" money.

The issue with co-generation of course is that the excess of conversation is just heat. So you need something that actually utilizes a lot of heat (but below boiling) in it's process.

The ideal purposes of this would be city heating, but the issue there is that the smaller the turbine the less efficient the electrical generation. Also heating is a seasonal need where the benefit of captuing waste energy to heat building will likely be canceled out by lower efficeies in the summer months when everyone uses AC, and as a country we are experiencing a southern migration.

100 % of the wind energy blowing by transmission towers is lost. Adding a small wind machine to the top of each tower and eclectic transmission pole on the grid would provide a significant amount of power.

With an oversupply of renewable sourced energy, we could convert coal oil and gas generating facilities to Hydrogen, then make the hydrogen when wind and solar were over producing, and use it during wind and solar shortages.

Good thoughts, all. Still, efficiency is efficiency and it just doesn't cut it when we look the beast in the face. Dr. James Hansen seems to think that the step of eliminating coal power proceeds wind development in urgency, and if we're going to not only stop emissions of CO2 but actually sequester carbon (Hansen says we need to sequester enough carbon to reduce the atmospheric concentration from 385 to 350 ppm), it's going to involve drastic measures beyond entropy losses and transmission efficiency.

The internal combustion engine wastes nearly 3 quarters of every gallon of gas. The fact is that heat can be captured and used to run "rankine cycle" engines that use freon or butane to spin generators. Google "solar ponds" to see how the sun us being used to heat salt water in ponds that is then used to run such generators. This isn't theoretical future stuff. It's here now and working.

In regards to John's comment, there are a few problems. Usually transmission lines are very high voltage, too high to just simply hook a turbine to. Each one would need a little substation (with its loss in efficiency, thanks NYT).

On the other hand, there are a few forward thinkers that are looking at hydrogen pipelines instead of high-tension lines to move energy. Wherever there's wind, you could set up a very simple hydrogen generating DC turbine. To attach to the pipeline, you would just need some water, a little pump and check valve. The water isn't even that much of an issue because you'd only be "borrowing" it. When you recombine the hydrogen in the city, the water would "reappear". The energy storage capability of 1000 miles of pipe filled with hydrogen can also give you a little buffer for when the wind ain't blowin. Look up "hydrogen pipeline" and "North Dakota" on google for some intriguing ideas.

The idea of cogeneration sounds good, but in theory you can do much better. First of all, if the gases you're expelling into the atmosphere don't match the ambient pressure and temperature you're not at peak thermodynamic efficiency. See, the simple way to tell if you're operating at maximum thermodynamic efficiency is to answer the question, "Can I run this process in reverse using the same steps as when I'm running it forward?" Naturally, the only way you could answer "yes" concerning the step of expelling the waste gas is if the gas has the same temperature and pressure as the air around us - because air doesn't spontaneously go up in pressure and temperature just because you're trying to run an engine backwards. The process still isn't reversible then, because you can't unmix the waste gases, or unburn the fuel for that matter, but you're closer than otherwise. Point being that if you're doing it right there isn't any waste heat that you can tap - it's all being expelled at the same or very nearly the same temperature as the surroundings and you can only tap into a stream of heat energy if there's a temperature difference.

Secondly, just because 100% of the energy released is doing something you want doesn't mean you can't do better. In the example of heating a home, say, normally we just burn the fuel and let that produce our heat, and even lose some in the exhaust. We could do much better if instead of just moving the heat around the house we used some of that energy to power a heat pump (think an air conditioner in reverse).

The last thing you need to do is ask the question - what happens if the gas coming out of the smokestack isn't hotter than the surrounding air? Well, the carbon dioxide and a lot of the other things in the exhaust are heavier than air, so unless they're hotter than the surrounding air they'll sink down. I'll grant that there may be some justice in the crud from the power plant being dumped on the populace responsible for creating it, it isn't realistic to expect people to put up with it. That heat going out the smokestack does do useful work for us in lofting the pollutants upward and thus encouraging their dilution before any population gets exposed to it. I don't know how much heat out of the smokestack is optimal for that, but it isn't zero. If you're going to do something with those gases, however, like putting the CO2 into a greenhouse and/or algae farm then having it cool like that is ideal.

Mike Z., the waste heat from a power plant does not have to be low-grade or below the boiling point. But even if it is low-pressure steam, that can run absorption chillers to provide A/C in summer, and/or process cooling.

But first . . . there are a QUADRILLION uses for that waste heat, most industrial plants burn fossil fuel for heat to . . . bake bread, dry paint, cure adhesives, shrink plastic, ferment yogurt, wash all sorts of stuff (including the factories themselves), etc . . .

The energy is right there, and right now it's being thrown away. A potential revenue stream, efficiency increase, or cost savings, it depends how you look at it. Figure it out first, the smart ones will.

Whether it is heat or electricity or any other fuel we have to transport the energy to the user or the user has to get closer to the supply.

So using 'waste' heat from central generating stations means that industries or houses have to be built nearby - along with roads and other utilities.

Then what happens when the plant shuts down for maintenance? Well you have to build a stand-by plant to generate heat. It always sounds easy 'til you start thinking about the customers' needs - economic, security of supply and environmental (non economic). Who will pay?

If this problem was easy to solve we would have done it by now. Little by little we will improve our energy efficiency but there are no easy answers

My view - bring on local efficient solar for electricity and very well insulated homes for heat.

If this problem was easy to solve we would have done it by now. Little by little we will improve our energy efficiency but there are no easy answers

My view - bring on local efficient solarfor electricity and very well insulated homes for heat.

OK it doesn't seem like some of you are getting it.

There is energy lost in transmission lines but that's only 3%.

The bulk is lost in conversion, 64%, but only a small portion of that goes up the smokestack. This is where that graphic is technically wrong. Most of the heat is wasted because the steam has gone through the turbine and is still steam with lots of energy left. Steam has to be condensed into water to feed the boilers, it's a closed system.

PS Cogen is simple but not easy. You can bring the big process loads to the big power plants, or make smaller plants and bring them to the loads. Google "Honda cogen".