Year round renewable energy?

[Scythe13]

Everyone knows about solar and wind power. Solar will be great in the summer and not so great in the winter. Not anything magical about that, there is more daylight hours in summer than winter, so enough said there. Wind will be a very hit and miss power source.

I'm entertaining the ideas of alternative power sources, that can be employed.

I've thought about waterwheels, and ways to harness rainwater (for people like myself whom don't have a stream running through the garden) for power production.

I just thought I'd pop the question out there to see what other ideas everyone else was playing with.

How do you plan to go off grid and have power, year round, if you had to go off grid?

[Mortblanc]

Hook it to an old car alternator and you are good to go.

https://www.youtube.com/watch?v=1VuMdLm0ccU

[bigpaul]

not worrying about power once the grid goes down, going the old fashioned route with hand tools and wind up lanterns and torches.

[Tarrel]

Adapting to low-energy living is a good start. If you think about the "game-changing" electrical applications, lighting has to come out streets ahead of anything else, followed, IMHO, by refrigeration. Both of these are achievable with relatively low levels of energy use. (Especially if you convert a chest freezer to run as a fridge).

Solar and wind are fairly complementary to each other. Solar is stronger in summer and wind in winter. Obviously there are the exceptions, such as a prolonged high pressure spell in the winter, when little wind will be combined with the short days / long nights of winter. However, at that time of year, the more power-hungry of the "game-changer" applications (refrigeration) will be less important. Being frugal with energy use plus a decent battery bank should tide you over any periods of "no wind / no sun".

In emergency there's always a generator, though the OP did frame the question as "year round renewable energy".

I read an article once looking at the idea of capturing rainwater on a roof and then letting it gush down through a pipe, turning a micro turbine on the way. The general critique was that there wouldn't be enough stored energy in the water on the roof to achieve very much.*

Although, having just done a rough calculation:
Say you had 1000 litres up there. That's 1000kg. So, assuming the roof is 5m above ground, the stored energy is 1000 x 5 x 9.81 = 49,050J. Assume you're going to lose half of it in losses due to friction, etc, leaves roughly 25,000J, which is the equivalent of 6.9kWh. That would keep your LED lighting and a very efficient fridge running for a few days.

You could use such a system for pumped storage, so the roof tank is filled by a combination of rainwater falling on the roof and water being pumped up there using surplus solar / wind energy when available. Such a system would also give you additional emergency water storage.

[Skvez]

The first thing you have to ask yourself is “If capturing energy from rainfall on our roof was even vaguely practical, why don’t we hear about people doing it?”

Average *yearly* rainfall in the UK is 855 mm

The Average UK house has 33m^2 of floor space. Assuming two floors to a house this is a roof area of 16.5m^2

This gives a yearly roof capturable volume of rain of 141m^3

Which is 14,100 Litres

Which seems like a lot but is actually on 0.02 Litres / minute

Looking at a home-hydro scheme the smallest system they consider expects about 660 L / min with a static head of 25 ft producing 233W of electricity. (http://www.pumpfundamentals.com/micro-hydro.htm)

You’re going to have to store a lot of water up on the roof (in which case your house will collapse under the extra weight) and only run your turbine very periodically.

Even assuming we could do this we could expect a typical hydro system to provide 233W for 21 minutes using a years worth of water which is 82 Wh (not kWh) a year.

And that’s why people aren’t doing it.

[Scythe13]

Great info. Thanks Skvez

[bigpaul]

the problem with any renewable energy system is not so much the main unit, that may last 25, 30 years-it may last forever, but its the little stuff like connectors and inverters and relays, how are you going to replace or repair them when they fail, can you even repair these things even if you had the skills to do so? or do you need a container full of spare parts to keep it running for the next 30-40 years, if the production line shuts down because of economic failure(or some other reason) getting spare parts may not be easy, sure there might be a s...load of parts lying about post SHTF but you wont be the only one looking for them.

[Steve]

(1 August 2015, 08:29)bigpaul Wrote: the problem with any renewable energy system is not so much the main unit, that may last 25, 30 years-it may last forever, but its the little stuff like connectors and inverters and relays, how are you going to replace or repair them when they fail, can you even repair these things even if you had the skills to do so? or do you need a container full of spare parts to keep it running for the next 30-40 years, if the production line shuts down because of economic failure(or some other reason) getting spare parts may not be easy, sure there might be a s...load of parts lying about post SHTF but you wont be the only one looking for them.

That's a good point Paul. I just did some fag-packet calculations for car alternators.

There will be other factors, but as an example:

Assume a car alternator lasts 100,000 miles, at an average speed of 30mph that is 3333 hours. With 24 hours in a day that's just 140 days.

Car alternators are easily changed, and you might assume they'll be plentiful when people run out of fuel, but in a decline there will be people robbing the scrap metals from the cars; batteries, alternators and catalytic converters would be the first to go.

Most alternator failures I have seen are bearings, which are easily changed if you have them but they won't be easy to source unless you can get them from the scrappies as they rip the copper out. A bit of maintenance might also prolong their lives, I've never seen anyone do any preventative maintenance on an alternator, but I certainly would if my home electricity depended on it.

[bigpaul]

i'm not that worried about electricity, man has lived without electricity for all but the last 80 years, both wife and I have lived without power so its not a biggie for us, mind you I know lots of people who will go mental if they cant get their phones, ipods and Xboxes to work!!

[Steve]

(1 August 2015, 14:17)bigpaul Wrote: i'm not that worried about electricity, man has lived without electricity for all but the last 80 years, both wife and I have lived without power so its not a biggie for us, mind you I know lots of people who will go mental if they cant get their phones, ipods and Xboxes to work!!

It's music and comedy I'd miss.