Rather than write a long return comment, I'm going to address all of this in a two posts. I want to address two points - the energy use of various preserving methods and the energy use of dishwashing methods.
Claudia wrote that an Energy Star dishwasher is better than handwashing. I agree that it probably is, depending on your circumstances. She also mentioned that her gut feeling is that freezing is better than canning. I'm not so sure about that.
Let's look at dishwashing first.
The ideal situation is that you have an Energy Star dishwasher, do not use the heat drying option, and only run it when full. And you'd have to already own the dishwasher, because this is certainly not taking into account the manufacturing costs. You'd need to consider not just the water used, but also the electricity.
At Off-grid.net, they say this: "Washing dishes by hand can cost a household more than $431 in additional
energy and water bills over the estimated nine-year lifetime of an
Energy-Star certified dishwasher. Energy Star dishwashers use less than
half as much energy as washing dishes by hand and save nearly 5,000
gallons of water a year. They can also save you more than 230 hours of
personal time over the course of a year."
The problem is that the dishwasher (I'm looking at The Brick for prices) starts at about $400 and goes up to $2000. That's a lot to spend to save less than $50/year. Washing dishes isn't really my favourite household job, but 230 hours per year means ... 36 minutes per day, during which time I listen to music on my ipod and relax. In a couple of years, I'll put the kids on the job and teach them cooperation, patience and attention to detail. (And thereby save myself 36 minutes per day!)
When dishwashing methods are compared, they always seem to assume that hand washers run a *lot* of water. The truth is that an experienced hand washer can do a lot of dishes with two basins full of hot water - one soapy and one clear. Do NOT run hot water to rinse everything. If you're not washing in a double sink, then have a basin of hot water for rinsing. And of course it depends on how you're heating your water. Once we're off-grid, I can heat a kettle of water during the cold months with no extra cost because the stove will be already on.
However, I don't think that even the most efficient hand washer can match 4 gallons for a large load of dishes, especially if that includes cooking dishes. And when it comes to using them in graywater systems, they're equal - neither should be used.
Looking at it, I'd say this - IF you already own an energy efficient dishwasher, use it, especially if water supply is an issue. You'd be silly not to, because it's probably going to save you a little bit of money and a little bit of time, and it will certainly use less water. If you don't have one already, I don't think it makes much sense to buy one. By the time you've recouped your investment, you need to buy a new one.
I'm open to being told where I'm wrong. LOL My experience with dishwashers is very minimal and dates from about 25 years ago when my parents briefly had one. They got rid of it because Mom said it was making us lazy!
Tomorrow, I'll talk about preserving costs. :D