What most people don't know about energy is about to flood the planet. Energy is not something you use up. There is no shortage of it, but it must be captured and concentrated to be useful. This requires spending money to design and build machines that will do so. Such machines need not wear out quickly, and they can capture all the energy we need every day, but they are expensive and not yet designed.

The important thing is that enough people must become aware of the possibility of building machines that move slowly and ponderously and very gently with no wear and tear, all the while producing large amounts of energy in the form of compressed air. The energy comes from the sun, and eventually all of it goes back out into space. It was merely detoured for a few days into the position of some water, or the motion of some molecules of air. I say "no wear and tear" because this means the machines last many many years. Every day they put energy out, but nothing need be put in except for routine maintenance.

Even among those who should know better, it is widely believed there is no free lunch. The sun is our free lunch. We don't need to (and shouldn't) duplicate the sun by developing fusion power on earth. We should just design and build efficient heat engines which every day produce vast quantities of compressed air. This can be converted to electricity or used directly to power all kinds of machinery, or used to extract carbon dioxide from the atmosphere.

One such machine is described at http://www.halfbakery.com/idea/buyairlowsellhigh. There are many similar possibilities.

Please help by reading the questions at halfbakery, and help me to write answers that ordinary people can understand, in order to build support for spending the money to design and build these machines. Making them work is not the problem. Getting people to believe they are possible -- and to get together to fund them -- is the problem. You can help.

Very informative.
But is compressed air necessarily the best way to store energy?
Then again, I guess it just seems strange because it's a new idea.

I totally disagree. When you compress air, it creates heat. The heat energy will be dispersed, resulting in wasted energy. Also, to compress that air, you'd need a motor with lots of power (Joules/Second) (after compressing it a little) to put more air into the tank.
Power=Joules/Second=Watts.
To compress it, you'd need a motor with a huge watt consumption.

To sum it up, energy is energy. There's loss when it turns into heat, but it's still energy. Basically, your "heat engine" is another form of a solar panel, because it takes heat/solar energy and converts it into potential engergy.

Another idea is to get Solar panels everywhere, since the average amount of sun shining on the earth is about constant. Then, during the daytime, excess energy could be converted by electrolysis into Hydrogen. During the nighttime, the hydrogen could be converted back into electricity using fuel cells.

Because Solar cells are proven technology, the second idea is probably better. (feel free to disagree)

Ok, first I'll explain in technical terms. Unfortunately probably not what an average untrained person can understand. Please keep asking questions and telling me I am wrong so that I can see what you don't understand.

"When you compress air, it creates heat"

Yes, as pressure rises without input of heat (adiabatic compression), the temperature rises. Temperature is the average kinetic energy of one degree of freedom of motion of the particles of the gas. So the above reflects the fact that work done compressing the gas has increased the average velocity of the particles.

My heat engine goes to quite a lot of trouble to remove this heat as it is created, so that the working gas does not become harder to compress. The higher the temperature, the higher the average kinetic energy of the gas particles, the harder they push on the moving surface which is compressing the gas. The whole secret to a heat engine is the fact that it is easier to compress cold gas than hot gas.

"The heat energy will be dispersed, resulted in wasted energy"

Yes, a heat engine operating between 273K and 303K will disperse 90% of the energy passing through it as heat. This is absolutely unavoidable, as proved by Carnot in 1824. So one might call it "wasted", but I would call it "used."

"To compress that air, you'd need a motor with lots of power (Joules/Second) (after compressing it a little) to put more air into the tank."

One could compress air using a motor. However, that is not how I do it. I use water in silos above the compression tank. At the beginning of a cycle, the tank is completely full of water. Air at atmospheric pressure flows into the top of the tank as water drains out the bottom to the lowest reservoir. Then, those two valves are closed, and another is opened, connecting the bottom of the tank to a higher silo of water. Water flows out the bottom of the silo, down below the tank, through the valve, and up into the tank, compressing the air. There are no motors involved anywhere. This machine has no solid moving parts aside from valves.

How did the water get into the silos above the tank? After the compressed air has absorbed heat and increased in temperature from 273K to 303K (or whatever), the air is allowed to expand in the tank, pushing water out the bottom, through a valve, and up into a silo above. The air gets colder during this process, because the molecules which did work on the water lost kinetic energy and the average kinetic energy of the gas molecules decreased. The heat engine again goes to a lot of trouble to keep the temperature of the expanding gas equal to that of the surrounding air. So heat is absorbed from the air at 303K and goes into the working gas and from there into the position of the raised water.



No, energy is motion and heat is motion. Actually, energy is a scalar whose value depends on the state of motion of the observer. Energy and momentum together form a four-vector which is invariant under a Lorentz transformation. If an observer is moving with the same velocity as a particle, it appears to him that the particle has zero kinetic energy. But to an observer moving with respect to the particle, it has nonzero kinetic energy. (But I guess ordinary people, including people who make the important decisions, don't know this. The fact that they don't is a good part of why we are using fossil fuels unnecessarily.)

In the case of light, energy is equal to the frequency of the photons (converted to joules by multiplying by Planck's constant, which is in joule-seconds, or joules per hertz) times the number of photons.

Light energy = (frequency in hertz) * (joules / hertz) * (number of photons)

The connection between photon reciprocal wavelength and photon frequency is also given by a constant, the speed of light. Just as Planck's constant in joule-seconds is "really" joules per hertz, the speed of light in meters per second is "really" hertz per inverse meter. So any quantity in reciprocal meters can be converted to hertz by multiplying by the speed of light. It's still energy.

(meters/second) = (1/seconds) / (1/meters) = hertz per inverse meter.

1/(wavelength in meters) = (frequency in hertz) / (hertz per inverse meter)

To get from wavelength to frequency, multiply inverse wavelength (in inverse meters) times the speed of light (in hertz per inverse meter).

To get from wavelength to energy, multiply inverse wavelength by speed of light and by Planck's constant. (inverse meters)(hertz per inverse meter)(joules per hertz).

And finally, the connection between temperature and energy is given by a third constant, Boltzmann's constant, in joules per kelvin. The fact that it is a constant reflects the fact that temperature of a gas is 1/2 the average energy of a degree of freedom of a gas particle. In other words, a kelvin is just a funny unit of energy which can be converted to joules by multiplying by Boltzmann's constant. (Or one can express temperature in joules -- it is always a very small number because at ordinary temperatures individual molecules of gas have very small amounts of kinetic energy).

Solar panels require photons with wavelength under 600 nm. Heat engines obtain heat energy from the air, but that energy originally came from photons from the sun with much longer wavelength. There is a lot more energy available at these longer wavelengths. So a heat engine is not just another solar panel. Although it can absorb light, it mainly absorbs energy through collisions with gas molecules from the surrounding air.



Of course I disagree. Hopefully you will too after you understand the principles involved. But in the mean time, please keep trying to explain why I am wrong.

Mynck: compressed air is a bad way to store energy, in that if it gets cold, you can't get as much work out of it. But it has advantages over hydrogen (safety, and hydrogen is very hard to keep inside of a tank). Anyway, this machine naturally produces compressed air, but if you wait for the hottest part of the day and then convert the compressed air to some other form of energy like hydrogen gas, or electricity, or gasoline, it works out the same. Or if your upper reservoir happens to be located at a pumped-storage facility, you can leave excess energy stored as water in the high reservoir, and convert it to electricity very quickly on demand.

[edited to add note about Boltzmann's constant also being a conversion factor to joules, like Planck's constant, and other minor changes]

Archimerged, I like your ideas, and I agree, but most of us on KL just aren't of the age to invest money.
Actually solar panels are a good idea, put them on your house and sell the energy you don't need , over a couple of years you'll easily earn your investment back, and never have to pay for electricity. Just ask Mrs. Town (RJH 8th grade Science teacher), she has something like that I think.

Actually, I'm not asking for money. I'm asking for questions and sincere attempts to understand so that I can develop better explainations (and fix any problems that get exposed). If I can communicate effectively enough, the project will get developed. Also, you don't have money now, but you will in 10 years. Ten years is not that long a time.

Seriously, you guys have at least as much science knowledge as most of the general public and unfortunately, probably more than the power elite (who have mostly forgotten what they knew). So if I can't explain it to you, how can I explain it to them?

Maybe someone needs a science fair project? (Or for next year...) A model of this machine built from hoses and plastic soda bottles ought to work just fine, although it would produce only tiny amounts of power. (Discuss the design before trying it).

Drawings and animations would be very useful, if you put them on the renewable energy wikia site. One way to get the project built is to attract the attention of someone who can build it. This is done by attracting the attention of lots of people, until someone who knows the right person draws their attention to it. When I have a good article with illustrations and maybe even a working model I could use some shills to give it diggs... (Which is where I ran accross this site in the first place, fearless leader lappy512 submitted his algebra problem to digg.com).

Regarding solar panels, current costs are several thousand dollars per killwatt of peak output. Large coal-fired power plants cost only $500 to $1000 per kilowatt. Also, you have to store the energy produced. And you can't run a car off it. Cars can be modified to run off compressed air... I don't know how much this machine might cost to build and need to figure it out. Considering that power plants need fuel but this machine (like solar panels) doesn't, it can cost somewhat more per kilowatt.

Correct, current prices for solar panels are around $3,000 for a panel that can produce up to 1kw of energy. I'm not sure of the cost for coal plants, but isn't there also a recurring price, because of the price of coal? I'm assuming you mean that's the price when you first build it.

If solar currently is 3-6x the current cost for coal plants, then solar power (,if methods for creating solar panels are refined,) could be as competitive as coal. You can put it on roofs of houses, and companies can buy excess power to store in hydrogen so during the nighttime they can sell back the power.

Of course, I'm not saying that this is a bad idea. Solar cannot become the one dominant power, either. This idea would work if the earth gets more cloud coverage, and the clouds contribute to the greenhouse effect even more. (Currently they do not, as the coverage is relatively sparse).

But, the potential energy of compressed air is less than the potential energy of a chemical reaction (eg hydrogen converting into oxygen and water). That would result in high psi's, which would make storage of this pressurised air more difficult than storing hydrogen (apart from hydrogen's flamability).

Perhaps I might think of making a model or something about this during the summer, after I understand it a bit better. Have you tried making something like that? After you do, perhaps you can post it on digg like you said.

I am fully supportive of new renewable energy solutions. As many other people, I agree that global warming is a threat. If you ever decide that your current wikia is not enough, and you need more, I can help you develop a website or something. As you can (probably) see, I do have experience in developing websites.

Hopefully you can draft up some diagrams or even CG up some short videos to explain your concept

It all makes sense to me. But I was thinking the same thing about the high-pressure air.

Maybe we figure out how to make antimatter efficiently!

But wait... that'd be even more dangerous.

You are right. I shouldn't be getting side-tracked into a discussion of how to fuel cars. The point is that an adequate supply of energy is flowing past us every day, and if we only build a nearly friction-free machine, we can capture it. Once we do that, we can use some of the captured energy to remove CO_2 from the atmosphere, and some to make whatever fuel we want to use for cars.

I'm currently writing a new proposal in which the energy is all stored as pumped water at an existing pumped storage site, and gets converted to electricity on demand using the existing generator. It has some significant advantages over the previous design, including much more space devoted to heat exchange.

My main question is what are the benefits of this system over using solar panels? I have not seen any significant ones so far, and I haven't seen you really compare this to other energy sources.

There are really only three energy sources, the sun, heat from inside the earth (natural fission), and artificial fusion or fission. The energy in fossil fuels came from the sun.

Solar panels are expensive, they only work during sunlight, and they produce electricity which must be used immediately or else stored. Batteries have a finite life and are expensive too, and sending the electricity into the grid is making use of storage somewhere else.

Solar panels do not capture energy which has already been spread around into the air. They only capture energy from photons arriving directly from the sun. A heat engine captures energy from the air. If there is someplace to dump the excess heat (like a river), it can capture energy even from cold air. Most of the energy arriving from the sun is not available to solar panels but is available to heat engines. For example, the energy absorbed by clouds cannot be converted to electricity by solar panels, but a heat engine can use it to pump water.

See for example http://science.howstuffworks.com/solar-cell6.htm, which reminds me that photons with too little energy simply pass through the cell, while photons with excess energy produce no more current than photons of the minimum energy.

Of course, heat engines cannot use most of the energy passing through them, but there is so much more energy available for capture that they come out ahead.

So, Archimerged, how would I produce this on a small scale? If I can use it to even power a light or make a buzzer sound using hoses and plastic soda bottles I would like to try it out. It would be a nice science project, and since most of us live in the Seatlle area there is a large chance of it being seen by someone in Boeing/Microsoft, our two big companies.Its a thought and it may work.

My other question is, how long would it take to earn back an investment in an energy creating source?

A solar panel will return you your investmen in >10 years, right? I can see people wanting it if they return their investment in 10 or even 20 years, its like a grant. But if it takes 40 or 50, I can't see an individual taking that kind of leap.

Your best bet is submitting the idea to a science magazine or journaljournal to help it get around. This doess need a few diagrams, because at this point in time I can't see the benefits of making this system, or even How I would make one.

So Archimerged, how would I make my science project?

I'm working on a new version my blog but am still editing the post there, i.e., what you read now will change -- I don't have the connections between the tanks right yet. (as of 16 April 14:20 wordpress is down and the blog is AWOL. See the page at the Renewable Energy Design wikia where I am rewriting what wordpress lost). The hope is to find a system that doesn't need a whole series of reservoirs at closely spaced heights. This one would have two upper water reservoirs (one slightly higher than the other) and many expansion/compression tanks at different heights below the reservoirs. It also has a lower reservoir, and the point is to pump water up from the lower reservoir to the two upper reservoirs.

The fact you need to know about efficient heat engines is they must be nearly reversible. That means when you open a valve, the pressures should be almost the same and the flow will run for a while and then stop. In the system I described on halfbakery, I had one compression/expansion tank and very many reservoirs at different heights. I'm sure that works, but there are advantages to having many tanks and just a few reservoirs. But I don't have it working quite yet and the system for moving air from one tank to the next doesn't stop flowing by itself.

A model probably wouldn't need the heat pipes, but that means the temperature inside the tanks might get too high during compression or low during expansion unless the process moves so slowly it doesn't finish in time. (It is possible to make heat pipes out of copper tubing and propane or some other refrigerant but you would need a lot of them). If you build it with computer controlled valves and sensors and program the machine to watch the weather forecast so it knows when the low and high temperatures are going to be, it ought to pump more water upward than it lets fall down. It would be enough to measure how much water it pumps to demonstrate feasibility, but for the literal minded, you could rig up a water powered generator.

With too many losses (for instance if the pressure tanks leak or the temperature changes inside the tanks too much), the machine would end up lowering more water at low temperature than it raises at high temperature. For machines with solid moving parts, it always turns out that way unless the temperature difference is at lot more than 30K. Because it has always turned out that way, and because until very recently, fossil fuels have been working fine, people have just not tried hard enough to think of a way to eliminate the losses.
If the machine works like I hope (I suppose there might be a gotcha I haven't noticed yet)... a large version costing millions or billions of dollars will pay itself off well under 30 years, and might last a lot longer than 30 years. But I'm afraid to actually do the calculations, because probably it won't turn out that way... Besides you can't really do the calculations without doing some experiments first to see how it actually performs.
Yes, if it comes to that, I can submit it to arXiv.org, but not without sending it in from a .edu email address. I could even submit it to Nature (and in fact I have been co-author on a couple of papers that did get accepted in Science or Nature). However, this is more fun... And yes it does need diagrams. I've been drawing one in pencil. I guess I'm a little old fashioned, but it takes longer to do it in a drawing program. Or it seems to.