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ScienceNostalgia101

Why if at all would solar energy be expensive?

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So last night I threw away some aluminum foil. It was in contact with food I was using it to keep warm, I didn't think I'd have much use for washing it and saving it, and I thought nothing of it until afterwards.

 

I just realized... if there were some program to collect everyone's pre-washed aluminum foil, and/or wash it after collecting it, it could be arranged in an increasing variety/size of concave shapes, be used as a solar collector, and boil water, whether to distribute energy directly as heat, or to turn turbines and generate electricity.

 

So why aren't we doing this? Have the fossil fuel and nuclear industry lobbies bribed politicians into not going for it or something? How expensive can it be to arrange aluminum foil in a concave shape, or find an absorptive, water-storing material to put at the focal point, especially compared to the lengths a nuclear or fossil fuel power plant goes to for the same water-boiling turbine-turning purposes?

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Solar energy isn't expensive. 

https://www.energy.gov/eere/solar/sunshot-2030

 "In 2017, the solar industry achieved SunShot’s original 2020 cost target of $0.06 per kilowatt-hour for utility-scale photovoltaic (PV) solar power three years ahead of schedule"

 

I think your solution isn't utilized because it would not be cost-effective to repurpose used aluminum foil.

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14 minutes ago, ScienceNostalgia101 said:

So why aren't we doing this? Have the fossil fuel and nuclear industry lobbies bribed politicians into not going for it or something? How expensive can it be to arrange aluminum foil in a concave shape, or find an absorptive, water-storing material to put at the focal point, especially compared to the lengths a nuclear or fossil fuel power plant goes to for the same water-boiling turbine-turning purposes?

Aluminium scrap including foil is commonly recycled in Europe.

 

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Even if you could get consumers to stop crumpling the foil before recycling, as swansont mentions, trying to re-purpose thin foil for use as a reflector would be very labor-intensive. Not sure it would be efficient enough to warrant the resource expenditure.

I LOVE re-purposing stuff, but it's just not practical sometimes. I clean the foil I use and re-use it at least once (baked potatoes!), then recycle it (while imagining it's going to be precision made into something insanely fabulous, like a reflective solar collector).

studiot, I had to hunt for a garbage collection company that takes lightly soiled aluminum foil. Not all of them do in the US, so perhaps that's where pressure should be brought to bear (apparently a lot of Americans eat TV dinners and nobody rinses the aluminum trays before trying to recycle them). 

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Posted (edited)

@Phi for All

Aluminium can for beer or other drink 0.5 L has mass ~18 grams. 0.33 L has mass ~15 grams.

So you need to get at least ~56 cans to have 1 kg.

On scrapyard here they pay collectors (usually homeless people) between $0.5 to $0.75 for 1 kg of aluminium cans.

 

Now, measure the mass of the aluminium foil used in the food industry and by restaurants (I imagine it will be a fraction of the mass of the can).

Calculate how much do you need of them to have 1 kg. If it's 10g, you need 100 of them to get $0.5 on scrapyard..

Search the net for "[your country] [region] scrapyard aluminium price" or so.

I tried searching Colorado USA and got these prices:

https://www.scrapmonster.com/scrap-yards/prices/colorado/state/3371

Prices of aluminium cans per city in the USA:

https://www.scrapmonster.com/scrap-yard/price/aluminum-cans-scrap/193

Find your city on the list.

You can find the junkyard on Google Maps.

ps. I see they used "lb" not "kg".. so take the amendment..

Edited by Sensei

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57 minutes ago, Phi for All said:

I LOVE re-purposing stuff, but it's just not practical sometimes. I clean the foil I use and re-use it at least once (baked potatoes!), then recycle it (while imagining it's going to be precision made into something insanely fabulous, like a reflective solar collector).

There is a programme on the BBC called

The Repair Shop.

People take in all sorts of treasured items to be restored

Stief bears, grandfather clocks, leather guncases, bicycles, music boxes, arcade penny slot devices, broken china, stained glass  -   the list is wide and diverse.

The experts there (woodwork, metalwork, painting, leatherwork, etc etc cooperate to effect restoration)

There are some absolutely fascinating projects each programme.

 

As regards the aluminium.

I think we should all remember (unlike the Mafia) that money is not the most important aspect of dealing with waste material.

I say unlike the Mafia because there was a BBC (again) article about organised crime and waste cardboard rackets, which is apparantly fetching big money at the moment.

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I will note that the OP’s suggestion is fairly specific, and does not really fall under the mundane act of recycling aluminum. i.e. it’s not suggesting you melt down the aluminum and then make something new. 

 

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Posted (edited)
On 8/24/2020 at 4:29 PM, ScienceNostalgia101 said:

So why aren't we doing this [collecting aluminum foils and use it for reflective heaters]? Have the fossil fuel and nuclear industry lobbies bribed politicians into not going for it or something? How expensive can it be to arrange aluminum foil in a concave shape, or find an absorptive, water-storing material to put at the focal point, especially compared to the lengths a nuclear or fossil fuel power plant goes to for the same water-boiling turbine-turning purposes?

I am not sure to what extent that is common knowledge: Using reflectors to focus on a point, generate steam and then run a turbine just as in fuel-based power plants is actually done. It's called Solar-Thermal Power (see e.g. https://www.eia.gov/energyexplained/solar/solar-thermal-power-plants.php) or Concentrated Solar Power. As far as I know, for electricity generation this method is more expensive than using Photovoltaic systems, and therefore often not considered. And for generating heat you usually do not reflect+focus but simply absorb (-> Solar Collector). The biggest advantage of Solar-Thermal over Photovoltaics is that Solar-Thermal power plants can store the thermal energy to some extent before using it, so they are somewhat controllable in their generation and can generate electricity at night. In some situations, this can make them the preferred choice (according to a former colleague of mine who did a lot of energy system design for northern Africa).

 

For the system cost I would assume that on the side of steam system, turbine and electrical system it's pretty much the same as for any other coal, gas or nuclear power plant, except that those tend to be larger and therefore perhaps more cost efficient. The difference in cost hence is heater vs. collectors+storage. I have no intuitive feeling for it, except that I expect the hater to be relatively cheap (specifically: a simpler piece of technology than a turbine). From an old Irena publication (https://www.irena.org/documentdownloads/publications/re_technologies_cost_analysis-csp.pdf) it seems that collectors+storage make up roughly 50% of the project cost (Figure 4.2 - there's also lot's of tables with more details if you are interested in those). So my answer to "how expensive can it be" would be "roughly twice the cost of a coal power plant" in terms of construction cost. You obviously don't pay for fuel (coal). End-costs for generated electricity (levelized cost of electricity or LCOE) always depend a lot on local situations and calculation method. On the Wikipedia page https://en.wikipedia.org/wiki/Cost_of_electricity_by_source the listed figures suggest 6.1 ct/kWh for Australian Solar Thermal generation and anything from 3.3 - 15.2 ct/kWh for coal.

 

On a final note: You seem to implicitly assume that main investments into new power infrastructure goes into coal and nuclear power plants. That is not the case. Globally, new installations in renewable technologies have overtaken the non-renewables a few years ago. Even in the US, the only country that left the Paris Climate Agreement, new power installations are either renewable or gas (mostly because energy infrastructure is built private companies, not the federal government): https://www.eia.gov/todayinenergy/detail.php?id=42495 .

 

Edited by timo

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Posted (edited)
1 hour ago, timo said:

I am not sure to what extent that is common knowledge: Using reflectors to focus on a point

Good contribution. +1

The French have a solar furnace capable of smelting metals, that works on this principle.

Edited by studiot

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