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Solar power only generates power during the day. At night, either fossil fuels or battery power must be used to keep things going.
Taking solar energy and storing it in a battery is never perfect, some energy will not be transferred to the battery and instead lost as heat. This idea is to use the
waste heat to pre-heat water destined to enter a home's own hot water heater. There'd be a little extra plumbing but only on a local scale.
Ideally the battery needs to be large enough to the neighborhood over 48 hours without recharging, but making it through the night is better than nothing. A fixed central battery rather than a battery in every home means that a battery with higher maintenance needs can be used, rather than an idiot-proof room temperature battery.
For example, one current bettery technology is NiCd, which of course has special recycling needs and is toxic. There are at least two versions of NiCd battery: the idiot proof fully sealed consumer device, which unfortunately is only recycled 20% of the time, or the vented industrial kind, which currently boasts a recycle rate of 80%. Whatever technology is used, the target is the lowest cost for the total lifecycle, including recycling costs.
it will probably mean less waste
http://pubs.usgs.go...c/c1196o/c1196o.pdf
[Madai, Mar 13 2013]
A Solar Grand Plan
http://web.chem.ucs...olar_grand_plan.pdf
a Jan 2007 SciAm article, mentioned in ano. [CraigD, Mar 13 2013]
Clean and environmentally friendly batteries made exactly for this purpose
http://www.aquionenergy.com
High volume production ready in 3rd quarter of 2014 [pashute, Mar 14 2013]
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Well, let's work the numbers: |
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The average household (at least in the US) goes
through about 958 kWhrs/month. In your 48hr
period, you're looking at 64kWhrs. Let's say this
neighborhood is a little gathering of.... 20 houses.
So your 48hr period will need a battery packing
about 1280kWhrs, or 1344kWhrs. Because let's face
it, the inverter is going to loose 5%. |
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NiCd gets about 0.06kWhrs per kg. So, we're
looking at a battery weighing 22352kg. |
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In terms of cost, lead-acid runs about $150 per
kWhr, Li-ion about $400. I can't find it easily, but
like everything NiCd I'd expect it to fall between
the two. So, let's say $200 per kW hr installed.
Which is going to make your battery $266800. |
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NiCd has memory, and also is done after about
2000 cycles. So we're looking at a 5 year
replacement cycle costing $2670 for the battery
per year. |
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Grid electricity is about $0.12/kWhr. About $1370
per year for the equivalent household. |
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So about two fold, just for the battery. Not
including solar/wind/backup.... infrastructure like
the chargers and inverters. Now, if this
neighborhood lived near a mountain, and there
were lakes, pumped storage would be the way to
go. |
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not to mention 22,000 kg of cadmium-contaminated
waste to get rid of every 5 years. If 1% of US
households went this way, 1.14 x10^6*22,000 = about
5 million tonnes per year. |
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I heard an interview on NPR about a company that was building a battery for this exact purpose. Being NPR the interviewer asked exactly /zero/ technical questions about it, so I don't know how it was supposed to work. |
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the 2000 cycle lifespan is based on a sealed cell. |
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with professional management/fixed location, the battery can use vented cell technology. 20+ year lifespan. |
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Also, the materials can be recycled. The neighborhood model should insure that the cadmium DOES get recycled, rather than accidentally thrown away by a careless consumer with a AA NiCd battery. |
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This is proven out in statistics: even now 80% of industrial batteries are recycled, 20% of consumer batteries are. |
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Cadmium losses when actually recycled are 0.1%, the bigger problem is all the consumer cadmium not being recycled at all. |
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The solar power at night problem is an old one,
and while not successfully solved in a commercially
competitive sense, has many well-to-over-baked
solutions. |
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A bunch of experts published a big article in Jan
2008 Scientific American (see link) that proposed
storing photovoltaic energy overnight as
compressed air in big underground caverns at
powerplants next to big consumers (cities). This
design has not, to be best of my ability, had any
large-scale prototypes. |
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Solar updraft towers utilize a design where
sunlight is converted to heat, moving air by
convection to drive air turbines to generate
electricity. These can be managed – “throttled” –
to generate continuously, night and day, matching
day and night demand. Several large ones have
been in operation for some time, notably in Spain
and Australia. The design’s drawback is that it
needs lots of intense direct sunlight and surface
area. |
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Another design is pumped-storage
hydroelectricity, where electric power from any
source is stored by raising water. It has the
drawback of lower efficiency, because water loses
more energy to turbulence than air. |
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Flywheel energy storage is another old one design.
It’s drawback is low energy density, requiring huge
vacuum chambers and flywheels to substantial
amounts of energy, so has found a niche mostly in
meeting short-duration electric generation needs,
such as power-failure backup and grid load-
leveling. |
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Chemical battery storage are usually a design of
last resorts, for reasons of the drawbacks
previously annotated. |
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If the battery had a 1.5V output, it could also be
used to provide power for the neighbourhood watch. |
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//Solar updraft towers ...in Australia//
There was a lot of noise and promotion about this project - not really as an efficient way to economically produce power but as a 'demonstration project'. Nothing ever happened as far as I know. |
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So... the "idea" part is _using_ the waste heat created when the battery is charging. Hot water heating is typically 12-21% of total energy needs depending on climate. |
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I suppose I shouldn't have bothered talking NiCad. The real fix to go with whatever delivers the lowest total yearly cost per installed kWh, with recycling needs folded in. |
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The first plus here is mine! Sorry, but didn't have the
time to find and post the link till now. Anyway the
idea is great if you can use an environmentally
friendly and safe battery. Which is exactly what
Aquion developed. |
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[+] for spelling "dilemna". |
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Per the idea, well it sounds like it may have some strong points, but you might want to proofread that third paragraph a bit for content. |
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Where's your "solar power" coming from: individual rooftop collectors ? in which case the residual radiation (70%) might as well be used to preheat water, as well as battery charge/discharge losses. |
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Okay I did a substantial re-write. |
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to answer the question and talk about residual radiation: |
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Yes, the solar panels will be on the roof, mostly. |
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I suppose if solar heating can be done easily enough, the panels could be dual purpose, getting both electical and heat energy. |
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I was hoping that having a central battery and central heat exchanger would confer advantages over a single home system. But perhaps a large enough array on a single home could provide suplus electricity AND surplus hot water too. |
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I wish there was some way to efficiently, locally, allocate all or most of the surpluses. |
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AFAIK, commercial PV isn't particularly viable,
however, those solar towers, with the molten salt
and the parabolic mirrors are much more up to
scratch. Perhaps, a neighbourhood version of this
could be built? Hell, if you're going to have a big
tower, why not life in the bottom 2/3rds of it?
Then you've got lots of high grade heat to make
steam out of, and low grade heat (from the
turbine condenser) for your washing machine and
so forth. No need for pesky batteries, the whole
thing could be a water tower as well, excess
energy could be used to pump water up and
recover it on the way down. |
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