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http://www.autoblog.com/2009/04/15/report-bill-gates-files-patent-for-electromagnetic-generator-p/


Best comment of this article:

So he's patented the Diesel Generator?

Diesel generators don't have spark plugs.

Right?  Neither does this.

Right, the speculation of the writer is something I should put a lot of credence in.  Sentences that start with the word 'Ostensibly' generally aren't worth very much when it comes to deciphering the ramblings of tech writers.

Herf blerf. (http://en.wikipedia.org/wiki/Glow_plug)

God I hate patents. Its the usual "I have a harebrained semi-formed idea that I came up with while stoned the other night, and I'm going to have my lawyer write it up in such a way as it describes nothing but includes everything so that I can sue anybody who does anything remotely related, and I'll spend more money on lawyers so that unclaimed prior art is discarded". It may or may not involve a spark plug or any other form of making the contents of the barrels ignite, etc. Its rubbish. I have more formed ideas while stoned myself, but I don't have the wealth to file nonsense patent claims for them all.

And a glow plug is not a spark plug and is not used to ignite the diesel fuel. It warms it so that normal cylinder pressures can ignite it.

Yeah, the actual quote is that the 'plasma injector' helps start the reaction, it says nothing about being used for continuous combustion.  If anything it sounds like it pre-heats the fuel rather than the cylinder walls the way a glow plug would.

It's still a meaningless patent, it does absolutely nothing that a diesel generator doesn't already do AND it has the bonus aspect of not even existing yet.  Sounds wonderful.

The only, slightly, news worthy element is the name on the patent and even that doesn't mean anything.

Completely unrelated: If you have a generator system attached to your home is there any viable means to store energy beyond chemical batteries?

Flywheels are used for large scale storage, maybe outside the scope of a single house.

Comparatively easy way to store energy: Take a concrete cube, dig a pit at least twice as deep as the cube is tall, line with concrete (leave a little clearance around each side, and for practical engineering you'll need some guide wheels and rails).  Lower the cube into the pit.  Use surplus electrical energy to raise the cube, use this stored gravitational energy to power the generator when your primary is unavailable. If your original power source is Solar Stirling, you can increase efficiency and simplify your power train considerably with a direct mechanical linkage between the Stirling engine and the weight.

--Dave

Im not sure if you are fucking with me or not. How efficient could a mechanism be to use a concert block and gravity as a means to store an appreciable amount of energy?

Each cubic yard of concrete weighs about 3000 pounds, so for each foot you raise a 3-foot cube, you've stored 3000 foot-pounds of energy.  0.73 foot pound/second can produce 2.77 kW (at 100% efficiency).  Typical residential load is 5000 watts, so for each day you'd need 120 kW/H, or roughly 125,000 foot pounds.  So if you raise a 9-foot cube 1.5 feet, that's a 24 hour electrical supply.

Efficiency wouldn't be 100%, of course, you'd lose at least 50% in the conversion from mechanical energy to electricity.  On the other hand, if you increase the size of the cube by 1 yard, you've more than doubled its weight and therefore the stored energy (and of course you could always dig a deeper hole or raise the block above ground level).  So it's all a matter of making the chunk of concrete big enough, and engineering the gearing to raise and lower it.  It's certainly more efficient than fuel cells and batteries, and requires a hell of lot less maintenance.  Some hydro-electric plants do something effectively similar (pump water up to a holding reservoir when load is low, drain it back down to generate electricity when it's high).

As long as you can avoid or minimize friction losses, storing mechanical energy is always going to be far more efficient than storing electricity directly.  This is all back of the envelope math, and it's possible I screwed up one of the conversion rates, but I don't think it's that far off.

--Dave

That is extremely interesting. When i responded last night i was a little intoxicated and was thinking on the scale of a cinder block. I never even considered that as a means to store power. good stuff

I'm sober and still think Dave is messing with us.

It's all basic physics in the sense that it takes a lot of energy to lift a heavy object! (Now you know why climbing mountains is so damn hard)

How are you (roughly) calculating the efficiency Dave?

I was not dubious of the physics involved. I just figured the efficiency would make it impractical.

Most of our modern devices have terrible efficiency.  Even the ones which harness natural resources.  Those just benefit from being "free" by tapping into natural processes so the wasted energy doesn't matter.

To get good efficiencies when you're storing electricity, you need something that doesn't have too much of a charging overhead, doesn't lose the stored energy, and isn't that hard to pull the power back out of.  On the scales of a single residence, most of the methods used in power grids either aren't efficient, won't hold the energy long term, or they're horribly expensive.  If you're operating on the scale of megawatts, thermal or pressure storage is fine, if you're only looking for minutes worth of power batteries (like NiCad cells) can work, but if you want to power your home through a week of overcast when your primary energy source is solar, and you don't want to spend 10 times as much on your power system as you do on the house, you need simple.  It doesn't get much simpler than a giant rock.  The 50% efficiency is just a rule of thumb for kilowatt scale dynamos, I'm assuming that friction and thermal losses will be fairly minimal since speeds for most of the system are going to be measured in inches per hour.

--Dave

http://www.halfbakery.com/idea/energy_20storage_20gravity

If you want to store mechanical energy, a giant flywheel in a concrete pit is the way to go.

I think you can buy them right now but I have never looked. High upfront cost but they are actually quite efficient.