Solar Power: Can we send less CO2 in the atmosphere?

[Arthur Denton]

As a warning, first, I will check this thread later, very likely only next weekend, so discuss as you will. Second, I'd like to ask you guys for your patience if something obvious and stupid has passed by when I thought about this.

With energy prices going low again, this may not be a concern, but I gave it some considerable thought when the oil prices were high. Well, energy is something we all depend on. Electric energy mostly. Homes get warm, we get safer because we have light everywhere at night when we come and go, and mostly, electricity is safe, considering you're smart enough not to put your finger into the wires, and you're also smart enough to use a decent technician when you're about to make new electric connections.

Now, this must have been thought over and over, and I want your thoughts together over this. I thought about using a space that is "lost". Every house has a roof, but most of them are just not used, they serve only to gather dust and to protect from rain (which is not bad). We could use the roofs better. I don't know about the amounts of energy that could be raised by a measure as such as picking up a whole district and adding solar panels to every roof. If every home would produce and use (or release the excess) into the energy matrix, say, half of the energy needed in the house during the day, the traditional power plants could be used to supply the same homes at night. Batteries could be installed to raise the amount of energy the system can produce for the night, and lots of fuel would be saved.

I have separated three pros and three cons:

Pros

1. Could use a space that is lost, can be installed in places without power plant infra structure
2. Do not pollute as much as the other kinds of energy
3. Can remove the pressure over the production of energy on power plants reaching their production limits

Cons

1. Depends on clouds and sun, and ammount of light that is beamed on its panels
2. It is an expensive infra structure, or at least, it is very likely to be
3. It may need expert maintenance, and that may become expensive.

So, that's the tip of the iceberg. Anyone has opinions? Ideas? Thoughts on how to do so? And reasons to believe that I'm actually wrong?

 

[Spud1k]

That pretty much sums it up. Although I predict energy prices won't stay low for very long; as soon as things look like stabilising, OPEC will start cutting back production in earnest.

While on the face of it, a solar panel on every roof would cut energy consumption (or allow us to use more), there are not insignificant costs in money, energy and raw materials associated with manufacturing and maintaining these things. Whether it is worth the investment varies according to the local climate. This sort of thing is more than feasible near the tropics, but isn't common as it could be because in a lot of cases, people lack the money for the initial outlay. While more people further north can afford it, the return on energy savings isn't enough for most to justify coughing up the money.

The hope is (at least in the solar panel industry) that as energy becomes more expensive, government incentives (e.g. loans and tax breaks) become more forthcoming and the technology improves (improving the efficiency of the product while driving down production costs), it may become more common. However, if the UK is anything to go by, they're a long way off reaching critical mass. Most people here usually go down the windmill route if they are getting into home energy production.

 

[soylent]

The rate at which we know we can expand new nuclear generation is much higher than that at which we know we can build solar panels; we know this because we've done it before(e.g. see France, Sweden).

Solar power does peak-loads quite well where the climate is good, but copes badly with base-load. Nuclear copes well with base-load but poorly with peak-load(fuel is a small part of the cost so it doesn't make much sense to ever throttle back on the power output even if the kind of large ~1GW LWRs we have today could be made to do so). Nuclear replaces coal power, solar replaces natural gas and hydro; replacing coal reduces CO2 emissions per unit of energy more but it does not save nearly as much money per unit of energy as replacing natural gas. Nuclear and solar do no compete directly unless you have either a magical storage or magical transmission that's essentially unlimited, efficient and cheap to build.

(wind by the way is terrible at both peak-load or base-load and relies heavily on expensive natural gas or limited hydro peaking capabillity to provide dispatchable electricity. "Raw" wind energy is only useful for things like irrigation where you don't care about intermittency in the least and transmission costs are essentially zero.)

 

[technoextreme]

Solar power does peak-loads quite well where the climate is good, but copes badly with base-load.

Not a problem.

 

[Cainkane1]

Here in the USA I've often wondered why hugh solar power plants are not being built in say Death Valley and other such desert like places.

 

[Spud1k]

Here in the USA I've often wondered why hugh solar power plants are not being built in say Death Valley and other such desert like places.

There's a few in existence and some more in the pipeline. link

ETA: Having clicked around a bit, this is possibly a more relevant link.

 

[G-K-4]

Electric energy mostly. Homes get warm...

Actually, where I live my residence is heated with oil. When I assessed my carbon dioxide emissions in 2007, heating was a much larger proportion than electricity. For my situation, electricity is an easier part. I hope to switch to geothermal in the near future.

If every home would produce and use (or release the excess) into the energy matrix, say, half of the energy needed in the house during the day, the traditional power plants could be used to supply the same homes at night. Batteries could be installed to raise the amount of energy the system can produce for the night, and lots of fuel would be saved.

There are other approaches as well. You can compress air in underground caverns during the day, and release the pressure at night to generate electricity then. You can also simply transfer electricity from a sunny part of the world to a night-time part of the world with high-voltage DC power lines.
http://www.nytimes.com/2008/08/26/nyregion/26wind.html
http://www.economist.com/science/displaystory.cfm?story_id=9539765

I think that either of these would work for wind or solar. And that's a good thing, since you can't put wind turbines in areas with lots of turbulence, such as over your house.

I have separated three pros and three cons:
Pros
1. Could use a space that is lost, can be installed in places without power plant infra structure

You can even make it look more like part of your roof, instead of an add-on.
http://www.technologyreview.com/Energy/21365/?nlid=1334&a=f
http://www.thisoldhouse.com/toh/article/0,,1205726,00.html

Assuming, of course, that you aren't using your roof for a garden.

2. Do not pollute as much as the other kinds of energy

You can also use solar thermal plants for purposes other than electricity generation. One such purpose is water desalinization, which is very expensive when done by fossil fuels.
http://www.guardian.co.uk/environme...energy.renewableenergy?gusrc=rss&feed=science

3. Can remove the pressure over the production of energy on power plants reaching their production limits

Solar and wind can also replace fossil-fuel facilities when they need to be shut down because of their age or high CO2 pollution.

Cons
1. Depends on clouds and sun, and amount of light that is beamed on its panels

Maybe in some parts of the U.S., but certainly not everywhere. And even though Germany (and Denmark?) have less insolation than Seattle, they're still using solar a lot more than we are. (See the graphic at this commentary.)
http://www.forbes.com/opinions/2008/07/08/opec-oil-congress-oped-cx_mc_0709energy.html

2. It is an expensive infra structure, or at least, it is very likely to be

It's getting cheaper. Several new companies have recently started up in the U.S. to build photovoltaic panels and films. And other new companies are building solar thermal plants for electrical generation.
http://www.alternet.org/environment...reading_from_california_to_new_jersey/?page=1
http://blog.wired.com/wiredscience/2008/10/thin-film-solar.html
http://powerelectronics.com/news/konarka-thin-film_solar_panel-1022/
http://www.renewableenergyworld.com/rea/news/story?id=53947
http://www.renewableenergyworld.com/rea/news/story?id=53916
http://news.smh.com.au/world/schwarzenegger-opens-aussie-solar-plant-20081024-57o0.html

Meanwhile, the Japanese government is planning to subsidize up to ten percent of the cost of solar installation in new homes.
http://www.treehugger.com/files/2008/09/japan-will-subsidize-solar.php

3. It may need expert maintenance, and that may become expensive.

Sure, you need skilled workers to upgrade or maintain solar plants and wind turbines. But those are jobs that can't be outsourced (assuming, of course, that we are talking about roofs and fields and waters here in the U.S.) And I'd rather pay a gal here to work on these systems than send my money to build giant skyscrapers on the Middle East.

I think that solar roofs are one part of an overall process of upgrading the world's electric-generation infrastructure.

 

[kleinjahr]

I assume we're talking pv here, rather than water/air heating. Either way I'd be concerned with the weight or static load, especially if it is a retrofit. If it is significantly heavier than the rafters, joists and walls were designed for, then it can get very expensive. Another thing to think about is whether the roof is properly aligned and sloped for optimum insolation. Most aren't. Then, of course, there is the need to allow for penetrations through the roof, vents and chimneys in other words. Can pv panels have holes cut in them? I doubt it. Final concerns are the simple maintenance problems. Can you walk on these panels? If not, how do you remove leaves or snow? How do you check and clean out your chimneys and vents?
Now, assume that these problems have all been solved, what of your neighbours? Are they planting trees or building something which will have an effect on the insolation you receive? Are you willing and able to take them to court to prevent such? Can you take on a developer who wants to build hi-rise apartments?
In rural or semi-rural areas it is much easier,thinking politically, to build as you want. In the cities, towns and suburbs there are often restrictions. For instance, you probably wouldn't be allowed to put up a windmill in your backyard. Someplaces you're not even allowed to put up a clothesline. Quite often, your house must comply with the local aesthetic, fit in with local architecture. No dome homes in Victorian neighbourhoods.

So as you can see there are several problems, the worst are probably the political. None are insurmountable, just add more to time and cost. Frankly, if the developers started designing and building their projects, taking into account such things as solar power/heating and cooling it would be easier. Unfortunately they build to minimum code, at best.

 

[Hindmost]

Here in the USA I've often wondered why hugh solar power plants are not being built in say Death Valley and other such desert like places.

Eventually, this may occur...however, right now, the installation, maintenance and transmission costs can't compete with coal and other sources.

The efficiency of reasonably priced solar cells is low when producing electricity...around 12%. They need to be cleaned and also require a direct current transmission system and have a short life span overall. Currently, it takes 10-15 years to recover an investment in solar for one's own home.

Subsidies have kept solar working. If the conversion efficiency can be improved and a few other break throughs, we will have something. A recent article in MIT technology review about using solar for electrolysis of water looks promising if it can be scaled up.

glenn

 

[shadron]

Here in the USA I've often wondered why hugh solar power plants are not being built in say Death Valley and other such desert like places.

In my tender relatively youthful middle age (oh, say 1980) I worked on the 100MW demonstration power plan built by the Dept of Energy and PG&E near Daggett, California (see http://maps.google.com/maps?f=q&hl=...375&spn=0.005378,0.011802&t=h&z=17&iwloc=addr ; you can see other solar demo plants done since in he surrounding area). It was during Jimmy Carter's grand solar experiment; Martin Lockheed (then Martin Marietta) had a large facility in Pueblo, CO building those "heliostats", or huge mobile mirrors you see in the pic. They focused sunlight (Daggett, near Barstow, is on the high desert) onto a tower and particularly on a cavity in the top of the tower outfitted like a steam engine boiler. It worked great, but was sort of expensive to maintain; it was, afterall, a demo plant; it got the first real run of heliostats coming off the assembly line. When Reagan got into the presidency, he killed solar power research dead (a small remnant survived as ESRI), and Martin/McDonnell Douglas and others dropped all their facilities and research like so many hot potatoes.

The reason it's expensive is because it is a technology in its infancy, just as oil drilling was in the 1850s. We had to learn lessons, like, there is no such thing as a "waterproof seal"; put a drain in the bottom of everything, and that plastic computer chips fail in harsh environments after about 6 months, what kind of boiler materials to use, how to avoid zorching airplanes passing overhead and so on. The consortium decommissioned the plant after ten years of running, though it is pretty much all still there in the desert, as you can see.

 

[The Atheist]

Good thread!

But I would say that, I sell this stuff. The short answer is that solar energy is an obvious solution because it's free and infinitely renewable. We just haven't quite the technology right, but drawing a parallel through other advances, I'd say we're only a decade from getting it right.

The problem with houses and roofs is that solar cells work best when the sun is prependicular to them. On some roofs, that situation never occurs, and on most of them, for about 5 minutes a day. To work, we need to use a control and mounting system which follows the sun.

There are two issues with cells - cost & efficiency. Costs are coming down, but far too slowly to be attractive just yet. (I was hoping that $250 a barrel oil would come about, but we're a little way off that now, dammit!)

Efficiency is also an issue as you need a lot of cells to power even one house.

What we need is for cells to be designed into new houses, which would make matters easier, just as kleinjahr points out later in his post.

I assume we're talking pv here, rather than water/air heating. Either way I'd be concerned with the weight or static load, especially if it is a retrofit. If it is significantly heavier than the rafters, joists and walls were designed for, then it can get very expensive.

Weight isn't usually an issue as roofs - especially tiles - are bloody heavy.

 

[kleinjahr]

"Weight isn't usually an issue as roofs - especially tiles - are bloody heavy"
Actually it is an issue. A building is designed to carry a specific load, the roof is part of that load, increase the load past those specs and it can and probably will, collapse. A silly example would be to use 2 by 2s for your studs at the standard 16" on center. Now use 2 by 10s for joists and rafters, 5/8 thick plywood for the roof boards, standard shingles to cover. Makes a nice strong roof, just not much holding it up.

 

[shadron]

Certainly you want to be able to make sure your structure will handle the expected loads with ample safety margin. Here in Colorado, roofs and all supporting structures have to be able to support their own dead weight plus a snow loading of 50 lbs/ft^2 (about 2400 pascals), plus wind loading, plus safety margin. Adding solar (electrical, or even water panels, but not, of course, tankage) is relatively minor compared to that. According to code, though, these items add to the roof's dead weight and cannot be taken out of the wind/snow allowance or the safety margin.

The last time we had a large snow here (April of 2002, if I remember right, about 50+") we had a few older houses collapse (roof failures, not the whole house), but mostly it was gas station canopies.

 

[kleinjahr]

I'm Canadian. I think it's fun, going up on the roof to shovel the snow off. Maybe this year I'll try and get the blower up there, ehhhh.

As I understand it, average weight for snow is 50 lbs per cubic foot. So your numbers are probably right, seeing as the codes do tend to err on the side of caution.

I'd be very cautious in retrofitting, especially if it was built by developer. A new building, you design with such loads in mind.

 

[The Atheist]

I'm Canadian.

Is that the problem?

I'd be very cautious in retrofitting, especially if it was built by developer. A new building, you design with such loads in mind.

Why on earth do you keep harping on with this?

You have heard of engineers? A special type of engineer is called a "structural engineer". These blokes do things like work out how much stress buildings can take. Included in their portfolio is little things like "Is the roof designed for/capable of supporting, solar cells and if so, how many?"

People don't usually put up sophisticated arrays of solar panels in the afternoon by themselves.

As I said earlier - in almost all cases of existing buildings, the weight is no issue. That does not equate to "She'll be right, nail her up."

Someone actually goes & checks.

 

[portlandatheist]

I think we should keep in mind that Germany has the most ambitious solar PV program in the world and has for quite sometime. The result of billions spent on PV systems and extremely expensive consumer level electricity is that solar power now provides Germany with roughly half of one percent of her energy consumption (source: http://en.wikipedia.org/wiki/Solar_power_in_Germany ). Even with an extremely ambitious solar power program here in the states with massive government subsidies, I think achieving .5% of our energy from solar is pretty unrealistic.
Solar certainly has its place, but it is not going to meet our transportation needs or our space heating needs for example.

 

[The Atheist]

Solar certainly has its place, but it is not going to meet our transportation needs or our space heating needs for example.

Well, not yet, it isn't, but it might be in the future. We do power satellites & the Mars rover with solar cells, so it does have a few uses.

 

[quarky]

Solar power will look better when we have better technology to go with it. PV is quite hopeless for powering archaic appliances, for instance, many of which were designed during an energy glut. Refrigeration is a good example, as are lighting systems.

 

[kleinjahr]

I keep harping on it because to many do think it is just a case of "nail her up" and hope. So crunch the numbers, add in the safety factors then add a little more for just in case. Then hope you're not a victim of a random "act of God".
There are also the human factors of greed, laziness and ignorance, notably on the part of developers, contractors and sub-contractors. Which can lead to such things as,"just a little extra sand in the concrete". Watch "Holmes on Homes" on HGTV for some examples of when renos go bad.
I've nothing against solar power per se. However, as with all power generation systems, it does have some concerns that need to be addressed. It won't bring in the Age of Aquarious, but it can supplement our needs. In my opinion the best methodology, I've read of, for large scale solar power, is as power generating sattelites. Other methods of power generation are also worthy of development, wind, wave, ocean thermal, wood gas etc. Each having it's own set of problems to be solved.

 

[quarky]

true enough, they are all problematic. Wind power development could alter air flow systems.
Tidal power development could alter the orbit of the moon.
Hydro-electric used to be the 'tits' of the deal, yet its negatives are strong enough to pay for dams to be decommissioned.

(I threw in the moon orbit to be provacative)

Point being this:

The future of energy consumption lies in the technology needed to minimize it.
I have much faith in this, although it will have some awkward moments.