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Bikes

I've done some calculations and testing between AC and swamp coolers, and here are some results.
For a standard H12 hexayurt, Figjam cooler is insufficient (Figjan is more than sufficient for a quarter-size yurt that is 4' per side, it will get shivering cold inside even if the temperature outside is over 100). You need at least 1000 CFM swamp cooler. The 1300 CFM Hessair MC18M is more than adequate. A 5000 BTU AC is also more than adequate. I don't believe a lower BTU AC is commonly available and tends to be more expensive than a 5000 BTU AC, but if anyone has tried it, please let us know.
I have heard that 1300 CFM evap cooler or 5000 BTU AC is also adequate for a standard size Shiftpod under a shade or a canvas tent under a shade - can someone confirm, since I haven't tried in either. I can confirm that 3000 CFM cooler is adequate (barely) for a Costco carport, at least if it's not super hot.
The 1300 CFM cooler and 5000 BTU AC works roughly equally well.* They're also about the same price in terms of upfront purchase price.

But... you can run the swamp cooler with 85 watts and no surge capacity while that AC will pull about 500 watts and when it starts it can pull up to 1000 watts. So you will need much larger generator.

One gallon of gasoline gives about 5,000 watt-hours of power, so a gallon will give you 10 hours of runtime for that AC. Assuming 5 hours per day of use and assuming 7 days on the playa, that's 3.5 gal of gasoline. At $4.00 per gallon, that's about $14 for the gas (unless you're having gas delivered by Hell Station in which case the cost will be double. If you're using an inverter AC, your consumption of AC will drop by as much 1/3 but... you still have to have the generator capacity so I'm not sure that actually saves you money.

On top of that, if we assume you spent $1000 for a 5000 watt genny and gas tanks, and that it lasts 5 years, then that's $200 per year, and you are using 10% of that capacity for you AC (here I'm assuming you're sharing the genny with rest of the camp. If not, you need extra idle capacity for the starting watts unless you have a soft start on your AC, so that's going to increases the costs), so that's an additional $20. If you take good care of your genny then it may go max 10 years, and the cost will drop in half.

So cost of running a 5000 BTU AC using a gasoline genny = about $35 for the week

(If you use propane, you get about 20,000 watt hours from a 20 lb tank, and if it costs $20 to exchange a tank, it will be about $2.50 to run the genny for 5 hours. So about $17.50 to run the AC for the week, plus $20 for the amortization = about $40 for the week. If you're getting propane refilled instead exchanging it then you would save $10. If you're using Blue Rhino then add $7 since they only fill 15 lbs into 20lb tanks).
The swamp cooler on the other hand, uses about 1.2 gal of water per hour, which works out to 6 gal a day or 42 gal for 7 days. If you buy your water at Wal-mart in Reno, or have it delivered on playa, it costs about $1.50 so that's $60. If you bring your own water tank and get it filled in Gerlach, it is as low as $0.50 per gallon so that's $20. But that's a lot of water to haul. (I'm ignoring the cost of electricity here).
So the cost of running a 1300 CFM swamp cooler = $20 to $60 for the week.
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*It's very hard to make direct head to head comparison between AC and swamp cooler. The latent heat of boiling, for water, is 2260 kJoules/kg. There are about 4 liters per gallon so 1.2 gallon evaporated is about 5L or 11,000 BTU (1 KJ is about 1 BTU). So a 1300 CFM cooler above is theoretically twice as powerful as the 5000 BTU AC.
However, there are a lot differences. Air is being pushed out of the space at a rapid clip when you use a cooler, while it's being recirculated by the AC. So you're losing energy there. And the cooler is cooling the air outside while the AC is cooling the air inside, so if the temperature inside is higher than the temperature outside then cooler will work better. On the flip side, higher temp outside lowers the efficiency of the AC and the generator.
In my experience, a swamp cooler works better in tents than AC, because loss of air doesn't affect swamp coolers that much - in fact you need that for it to work properly.

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