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Giving Up Alternating Current
An anonymous reader writes: Yesterday we discussed Soylent, the artificial food substitute created by Rob Rhinehart and his team. As it turns out, this isn't Rhinehart's only unusual sustainability project. In a new post, he explains how he gave up on alternating current — a tough proposition for anyone living in the U.S. and still interested in using all sorts of modern technology. Rhinehart says, "Most power in the US is generated by burning coal, immediately squandering 67% of its energy, then run through a steam turbine, losing another 50%, then sent across transmission lines, losing another 5%, then to charge a DC device like a cell phone another 50% is lost in conversion. This means for 100 watts of coal or oil burned my phone gets a mere 16."
The biggest hindrance was the kitchen. As you might expect for the creator of Soylent, he doesn't cook, and was able to get rid of almost all kitchen appliances because of that. He uses a butane stove for hot beverages. He powers a small computer off batteries, which get their energy from solar panels. For intensive tasks, he remotes to more powerful machines. He re-wired his apartment's LED lighting to run off direct current. Have any of you made similar changes? How much of an effect does this really have?
The biggest hindrance was the kitchen. As you might expect for the creator of Soylent, he doesn't cook, and was able to get rid of almost all kitchen appliances because of that. He uses a butane stove for hot beverages. He powers a small computer off batteries, which get their energy from solar panels. For intensive tasks, he remotes to more powerful machines. He re-wired his apartment's LED lighting to run off direct current. Have any of you made similar changes? How much of an effect does this really have?
It's the new outdoor trend anyway. All the lighting is obviously LED, so no problem there, the gadgets all transform their AC to DC anyway, so no problem there as well, you just need a decent lab trafo.
Washers and dryers that use solar heated water are no problem either, they mix warm and cold as they need it.
Even the small 12 Volt Camping washing machines work very well nowadays.
You cook by gas and use a gas refrigeration unit as well.
There's a German project the 'direct current house' (in German obviously)
http://www.dasgleichstromhaus....
They have solved many problems.
"For intensive tasks, he remotes to more powerful machines".
So he can't survive without it....
The typical deep-cycle battery does NOT need to be retired in 24 to 26 months lead acid deep-cycle batteries are more like 4 to 8 years longer if you treat them well. If you want to double that spend a little more (ok a lot) and get surrette deep cycle batteries, typical lifespan range is 7 to 15 years.
Sorry, teleporters just kill you and then make a copy. A perfect, soul-less copy.
No where near 50% is lost these days in modern AC/DC or DC/AC conversion devices.
Solar panel DC/AC inverters run at 95% to 98% conversion efficiency.
Likewise modern AC/DC converters can easily achieve 90 to 95% conversion efficiency.
Unless he uses very bulky low voltage, high current cables, he could easily be losing 3-5% of transmitted DC power in those.
He would be better off keeping his residence on AC and covering his roof with as many solar panels as he can fit.
Yeah, your right. The low efficiency of a DC power supply is in the 80% range. http://www.xppower.com/pdfs/TA...
Tucson, AZ, where 4 months out of the year the temperature is above 100F and the humidity above 40% so if you don't have an air-conditioner using direct-expansion gas (not a "swamp-cooler" or "mister") you will bake. They don't make any that run on DC. Even if they did, that would be a LOT of solar cells!
Actually they do make one with an AC/DC dual voltage motor. Lennox sells one. It's ridiculously expensive without even including the panels, but it was an option that we looked into a couple of years ago when we had to relace a 2.5 ton unit that had failed. The replacement alternating current model has a 30A circuit breaker on a 240VAC circuit, so it can draw a max of 7200 Watts. This 8000W system would be enough to power that air conditioner and have some to spare.
I have enough roof space for probably 40,000W of panels. The thing causing me to hold back is the electric utility. I want grid-tie with intentional islanding and battery storage if the grid loses power, and I don't want to get hammered with utility company fees like they're trying to get out of us if we go that route. I'd also like to get reimbursed a fair rate for the power I'd supply back to the grid during peak usage, but they're not interested in doing that either. I'm hoping that Solar City wins their lawsuit against the utility so that I can feel comfortable proceeding at some point down the road with this.
Do not look into laser with remaining eye.
DC arcs are strongly self-sustaining once ignited, as there's nothing to halt the continuous generation of ions which provide an easy conductive path. In contrast, AC arcs tend to self-extinguish twice a cycle when the voltage drops to zero, and so the AC arc has to re-ignite each cycle once the voltage rises high enough. Even if it does manage to re-ignite, the arc is not usually conducting the full cycle.
This reduced arcing makes AC a significantly lower fire hazard than DC, and the same effect happens to make AC switch contacts last much longer since breaking a circuit rarely arcs for more than a half cycle so contacts don't usually heat up and little metal is carried away from their surfaces.
I've looked at an off grid cabin for weekend vacations. A few portable propane cylinders would cover the fridge (assuming a pound/liter of LP gas a day), and it would also cover a water heater.
Solar wouldn't be cheap, but for a few thousand, I could place a number of solar panels, have them feed in via 1-2 decent MPPT controllers into a set of AGM batteries (so watering the batteries isn't an issue), then have a decent PSW inverter coming off for use. Because lead-acid batteries destroy themselves if they go under 50% SoC, take the expected ampere-hours you plan to use, and double it, at the least. This would easily handle almost anything but heating/cooling and the well pump (which can use 1500-2000 watts each.)
The trick with the well pump and an off-grid cabin, would be to run a generator so the pump can move water into an above ground storage tank 250-2500 gallons, then from there, a much smaller pump that runs from 12 volts can pump water from the tank into the cabin.
Of course, come Texas summers, that is what a generator is for on a weekend basis. I can get 8-20 hours of use from three gallons of gasoline in a 3000 watt Yamaha inverter generator, and for a small cabin, a 10k BTU A/C is more than enough to cool it down, assuming some semblance of insulation [1]. As an added bonus, with a converter (rectifier), it is a way to help keep the batteries topped off if the panels can't keep up with use.
Disclaimer: This is a vacation cabin. For a real house, it would cost over $40,000 for a solar panel setup that can handle the amp draw of the well pump and the A/C.
Of course, there are other items like waste water (I like using a cassette toilet and having cartridges on hand, since those can be dumped down the commode safely and legally once back home, and gray water can be filtered and recycled in a settling tank so it doesn't destroy the ground around it.)
[1]: Ironic thing is that if solar panels are mounted with air space between them and the rest of the roof, they function as shade, doing a decent job at keeping the place cooler, even though the panels are likely at around 150 degrees (66 degrees C) on a hot day.
No, the Prius air conditioner compressor is AC. The Prius inverter electronics converts the HVDC to the correct AC frequency to run the motor. So you'd need both the compressor and inverter assembly, which also includes the inverters for the motor-generators that move the car. And a 200V DC power supply. And all the right computers to get the inverter assembly to do something useful.
You'd wind up with a whole bunch of a Prius just to get a silly air conditioner.
From Special Issue: Inside the Toyota Prius: Part 5 - Inverter/converter is Prius' power broker:
What I find most annoying about all this is less the could of smug, and more the fact that household electricity use is such a small slice of the pie of overall US energy use. From wind power to this DC nonsense, it's obsessing on feelgood measures of little importance to the big picture.
This biggest slice of the pie is industrial energy use where electricity isn't part of the picture: "Primary energy use" by heavy industry for blast furnaces and the like. Industrial electricity use is the next biggest slice, followed by IIRC industrial transportation.
Socialism: a lie told by totalitarians and believed by fools.
I can't say much about your specific situation, but in general if you're far enough from the equator for snow, the ideal solar panel will have a fair bit of tilt to it. At which point you have some options for snow-clearing. One of the popular ones is to use a relatively small amount of electrical heating once the snow stops to make the panel 'too slick' for the snow, at which point it simply slides off. Then the panels make up that energy through the day. Keep in mind that they're considerably 'slicker' that way than an asphalt roof.
Also, if your roof is only worth 1/3rd your electrical use, that may be something that you want to examine, because you could save considerable money for cheaper than installing solar panels fixing whatever is taking so much.
I say this because I can satisfy my electrical needs using about 2/3rds of my south-facing roof, and I'm in Fairbanks, Alaska. Disclaimer: Annual average; I'd have to sell electricity in the summer and buy in the winter.
I don't read AC A human right