GM Gasoline-Electric Car

[adciv]

[quote="Captain Pink";p="713435"]@advic: These collectors are suitable to heat a home. I am talking mor about things like this. I have to admid, that is says nothing about the temperatures, but in the german wiki, you can find temperatures of thousands of °C Also you can read, that you only need about 500°C for the generators. sounds good, does it not?![/quote]

500C would only give you low pressure steam. It would provide power, but I think sterling engines would be better due to the higher efficiency.

[JudgeMental]

You guys are looking for the wrong thing; you're looking for a solar furnace.

Check it out.

Posted Thu Jan 25, 2007 6:45 pm:

Oh, and check out the solar updraft tower. The proposed thing is HUGE!

[adciv]

http://en.wikipedia.org/wiki/Sterling_engine

50% to 80% efficiency.

[Captain Pink]

@JM: Also nice. Works fine.
@Advic: For the temperatures: The german wiki says so. I do not have other infos at hand right now, but may it be so, that you need more heat. The solar heat collectors prposed here by JM and me cover those temperatures easily. For the sterling engines: Quite low I think. It would be better to build many small devices for this and put them together in a virtual power plant. those have an effiency of over 90%.
@Tower: I also saw on the stuff about diffusion and osmosis that they only work util a certain presure is reached. Like you know, when you put highly concentrated salt water in one side of an U-Tube and on the other side destilated water, the water will not come complettly through the semipermeable membran. Is this also the case with gases?

[Dr. Tower]

Yes. However, this is because the partial pressure of the water on each side has become the same. The pressure on each side of a U-tube is rho*g*h. Let us assume that side 1 of the U-tube (with a semiperimable membrane at the bottom) is the side with disolved salt, and side 2 is the one with no salt. At steady state, side 1 will be higher than side 2 by some dh, so that.

P1[total] - P2[[total] = rho*g*(h1-h2)=rho*g*h

Assume that rho does not appreciable change due to the addition of solute (so we don't have to keep track of 2 different ones). And the pressures are taken right next to the semipermiable membrane. P2[total] is obviously just the pressure due to water, so we can call it P2[water], or just P2.

P1[total] - P2 is the osmotic pressure, and is the pressure at which there is no more change in the water levels. Osmotic pressure can also be calculated by the molarity of stuff in the water. This is found as

P[osm] = M*R*T = (n/V)*R*T

where M is the total molarity of particles (so for NaCl, it would be 2* M[NaCl]), R is the universal gas constant, and T is the temperature in kelvin. You might notice it looks a lot like the ideal gas law (in fact, is identical). We can essentially think of the solutes as a gas within a container (the liquid). The solute molecules spread out to fill the entire container and have little interaction with each other. Thus, the P[osm] is the pressure exerted within the solution by the solute.

We can thus separate the pressure on the side 1 into the pressure due to the solvent (water) and the pressure due to the solute (M*R*T). We have that

P1[total] = P1[water] + P[osm]

from before we have

P1[total] - P2 = rho*g*dh = P[osm]

so

P1[water] + P[osm] - P2 = P[osm] => P1[water] = P2 = P2[water]

So the partial pressure of water on side 1 is the same as the partial pressure of water on side 2. As we can see, it is the same case as it is with the gasses, but you have to remember that eventually the side 1 for hydrogen (in the case described earlier) will be the atmosphere which has a very low partial pressure of hydrogen that will be essentially constant no matter how much leaks through.

[LQDMTL]

[quote="JudgeMental";p="713520"]Oh, and check out the solar updraft tower. The proposed thing is HUGE![/quote]
You mean this thing... the future of power generation, imo.
Also more infoz here at the company website.

[Martin Blank]

The solar updraft tower has been nearly done with pre-construction steps for about four or five years now. If it gets started, it will be interesting to see the results.

[JudgeMental]

Yeah, my dad found stuff about the solar updraft tower a few years ago. I've been waiting quite eagerly to find out how it goes.

Personally, I'm thinking that regional power generation is going to become a bigger thing, with each area generating power based on the kinds of resources it has.

[Captain Pink]

@JM: I do hope so. It would be just fine, if every nation produces all teh enrgy it needs from their own regenerable ressorces. But when I see how energy is wasted in the nations of the so called first world and with USA on top of them, I do not think it is possible. The first step to save the worlds climate is to save energy. One mayor step is in my view the shutdown of all those oversized powerplants and replacing them with many small engines to created energy, because they are far more efficent than those industrial powerplants ( about 45%-80% vs. 90+%). I am planing to install at my home a mix out of photo electric cells and MicroCHP with Calorific value technology right now. I would be even happier if I could run it on biogas instead of natural gas.

[adciv]

[quote="Captain Pink";p="714209"]One mayor step is in my view the shutdown of all those oversized powerplants and replacing them with many small engines to created energy, because they are far more efficent than those industrial powerplants ( about 45%-80% vs. 90+%).[/quote]

Um.. What? If the smaller engines were that much more efficient then power companies would already be using them. After all, the more efficient the generators, the less fuel they need and the more money they can make.

Or is your 90% including the heat generated by the plant supplying heat to your home? Which would go unused in most places in the summer.

[JudgeMental]

SEMANTICS WARNING!! There's several ways that efficient could be meant here. Remember, energy companies are still driven by the bottom line; many smaller engines might not be financially efficient for them.

I don't know either way, I just don't want an argument to break out over something like this when both parties could be right.

[Captain Pink]

K. Iwill tell you in a careful way what I think about it: Smaller machines are in this case more efficent, because they do not give so much energy to the atmosphere like the industrial once that can fill out a facility buildig cmpletely, since they (in simple words) have shorter ways where they can loose their energy to the atmosphere. The down of those smaller machines is that you need several hundreds or even thousands of them to create as much energy as a hughe powerplant, even if they have almost double of the efficiency rate. The problem with such a cascade of energy producing machines is that they are more complecaited to be controlled. At night the amount of electrical energy needed is significantly lower than at day (since most people do not use as much electric energy as they do through the day period). So the problem is to reduce the amount of energy produced at night. If we have one huge powerplant, it is quite easy to lower its output. But we if we are talking about e. g. 10000 single machines, all placed somewhere else (In classical houses, facilities, hospitals...) you are facing a problem. One solution alredy being tested and now starting to be used is the creation of virtuell powerplants. In this way, many thousand of those nergy generators are linked together like PCs in a LAN. They all act as one powerplant and can be controlled like one. if you have a total output of 100% and want to reduce it to 75%, you just type it in your controlls and all the small energy generators rduce their output a bit, depending on complex mathematic formulas, from which you as the controller do not feel anything when they are once installed. To stay with the LAN-picture, you can imagine this like this NASA-Program, wher you can give them some capacity of your home PC for their calculations. By this way, they could build a virtuel supercomputer.

[adciv]

Interesting. From most things I've seen, generators get more efficient with size. Then again, that is usually when they are running at their most efficient rate and not anywhere else as they would have to be with a varying load. After all, the most efficient method of generating heat would probably be to do it all in one place.

By the way, what you mention is similar to something already done. Power companies generate the base load with their plants and then (at times) they will call up some of the customers with backup generators and have them supply power to the grid instead of starting up another generator at the power plant. The customer gets paid for the electricity generated.

One of the things I've wondered is if someone wants to cut CO2/fossil fuel consumption, then they should eliminate anything that burns Natural Gas/heating oil. Use the grid for electricity that can come from cleaner sources for power and/or use solar cells/wind.

[Bigity]

Captain Pink,

Don't take this the wrong way, but punctuation and paragraphs are your friend.

Please some of the same effort into college papers that I'm sure you wrote into your forum posts, and make it easier to read.

[Captain Pink]

[quote="adciv";p="714369"]Interesting. [/quote]
Nice to hear this.

One of the things I've wondered is if someone wants to cut CO2/fossil fuel consumption, then they should eliminate anything that burns Natural Gas/heating oil. Use the grid for electricity that can come from cleaner sources for power and/or use solar cells/wind.

The only problem is that wind, water and sun are not that muc reliable as energy sources. At a given time, you can get more than you need, at another time you get nothing. This is why I thought about storing the energy in H2.

From most things I've seen, generators get more efficient with size. Then again, that is usually when they are running at their most efficient rate and not anywhere else as they would have to be with a varying load.

Trust me. as a mechanic for Cetral heating and airconditioning, I have to deal with this almost everyday.

Don't take this the wrong way

I never do take things wrong way.

Please some of the same effort into college papers that I'm sure you wrote into your forum posts, and make it easier to read.

I will consider this for next posts. Thanx

Edit:
Here is an german article I found on the Web:

Besonders verlustreich ist die Stromerzeugung in Kraftwerken, bei der nur ca. 39 Prozent der Primärenergie genutzt werden. Zwar können moderne Kraftwerke Wirkungsgrade bis zu 53 Prozent erreichen, aber das Problem ist ein grundsätzliches: Strom ist ein hochwertiger Energieträger, dessen Herstellung in Kraftwerken immer mit erheblichen Wärmeverlusten verbunden ist. Um deutliche Steigerungen der Energienutzung zu erzielen, muss daher diese Abwärme genutzt werden (Kraft-Wärme-Koppelung). Dieses lohnt sich aber nur, wenn die Kraftwerke nicht zu weit von den Wärmeverbrauchern entfernt sind. Konsequenz: Große, zentrale Kraftwerke müssen durch kleinere Kraftwerke mit hohem Wirkungsgrad ersetzt werden, bei denen die entstehende Abwärme als Fernwärme zur Hausheizung oder für gewerbliche Zwecke verwendet wird - und dort die Erzeugung von Kohlendioxid durch Heizkessel vermeidet.

Here the translation:

The generation of current is particularly involving heavy losses in power stations, with only approx. 39 per cent of the primary energy to be used. Modern power stations can reach efficiencies up to 53 per cent, but the problem is a fundamental: River is a high-quality source of energy, its production in power stations is connected with substantial calorific losses always.In order to obtain clear increases of the energy use, therefore this waste heat must be used (force heat coupling). This is worthwhile itself however only, if the power stations are not too far distant from the heat consumers. Consequence: Large one, central of power stations must be replaced by smaller power stations with high efficiency, with those the developing waste heat as long-distance heating to the domestic heating or for commercial purposes is used - and there the production of carbon dioxide by boilers avoids.

As you can see on the HP I linked, most of the primary energy is lost in the power plants by leting the heat go out of the cooling chimney. And of cause by wasting of energy by th consumer on the other side. Both problems can be solved with smaller effort than the minus you make by the transport.