I just had an awesome idea - power company arbitrage!
 

Saw on TV how a hydro power station uses gigantic inverters/UPSs to "bank" power to batteries during off peak times, then feed it back into the grid once peak starts.

So I thought - why couldn't anyone do this? If you have a power connection that will credit you for power you return to the grid (usually for renewable energy setups that sell back generated but unused power) then why not just use an inverter and a big-ass battery bank? Buy cheap off peak power a few hours before it ends to charge your batteries, then feed it back in once peak starts. Even though it sounds shifty you are actually providing a useful service since you're boosting the grid (by a tiny amount) during peak.

Thoughts? :Graucho

Batteries aren't 100% efficient?

what is the projected ROI?

Neither is the process of converting AC to DC, then converting DC to AC...

But the idea is that off peak electricity is CHEAPER than peak. You buy it at a lower price, hold it, then sell it back at a higher price.

Of course the question is whether the inefficiences involved, and capital costs of the equipment, would result in a +ve profit. It's possible the power stations do it (at a small loss) because adding generator capacity would cost significantly more.

Another way to leverage off peak savings might be to charge batteries for your own use. For example, I have 7 computers that are on 24/7, it may actually work out cheaper to charge a bank of batteries (as well as power the computers) during off peak times, then they run off batteries during peak hours. Food for thought. :D

Many many people who run their houses on solar and wind ARE already doing this. There was a green episode of Extreme Makeover or some such show where they built the house with massive solar and other energy generating devices and the set up sent all excess energy back into the grid. The electric company even pays them for the energy they put into the grid.

This idea is similar, but there's no power generator such as solar panels involved. You're simply buying low, selling high.

You will be losing about 35 - 40% of the energy in the battery store/restore process. Add 30% for the equipment costs and maintainance, assuming you are doing it at large enough scale.
This means that the project will be viable only in countries that have at least 70% price difference between peak/offpeak hours.

Other problem is that this must be a long term plan with near 10 - 20 years durability to be economically viable. Nowadays governments and energy companies pay for that power. Are you sure they will pay the same or will even pay at all in 15 years from now?

I watch this show called "world's greenest homes". In most of the houses they sell the power back to the grid and cut their bills by 70% to 90%. Excellent way to cut down costs each quarter.

Maybe this idea isn't so small scale. To store 1 kWh would require five or six 200AH batteries, which would take up a fair bit of space and would also present some safety issues. Feeding that back into the grid might only net you a few cents. To make that a few dollars a day you'd need 600 batteries... and the payback time (profit covers capital) would be measured in decades. The batteries won't last that long.

I think there's a simpler way. Some providers offer smart meters which will separately count kWh in peak and off peak periods, getting one installed and making some small changes to the appliances you use could save you. Since my computers are on 24/7 even a relatively short off peak period (say midnight-6am) could provide a significant saving. One real world example I saw had the off peak rate at about 70% less than the peak rate.

Hmmmmmmm.... :)

You could do that with a perfectly efficient battery. Trouble is, there are numerous forms of generation, and you could do arbitrage between them, but there are only a few forms of storage, all of them lossy. Transport loses as well, so you'd need to move your storage next to the generation. Develop an efficient battery and you won't care about this because to paraphrase the guy in Shallow Hal you'll be wiping your ass with $100s.