Science is Cool....

[Fish]

This is a repository for all cool scientific discussion and fascination. Scientific facts, theories, and overall cool scientific stuff that you'd like to share with others. Stuff that makes you smile and wonder at the amazing shit going on around us, that most people don't notice.

Post pictures, vidoes, stories, or links. Ask questions. Share science.

Why should I care?:

[Donger]

Originally Posted by alnorth

The problem is that we transmit power through Alternating Current instead of DC, the power companies have very specific requirements on the properties of that alternating current, and if this mysterious unexpected current that some random dude dumps into their lines does not precisely match what they are sending, it screws things up.

If you want to use solar panels without a surcharge, then you should really cut yourself off the grid, or at least segregate whatever those panels are powering so that those devices you choose to hook up to solar are only solar powered and not connected at all to the utility.

And Edison rolls over in his grave cursing Tesla...

If folks are getting a bunch of crap being off the grid and using solar, I'd call bullshit on that but absolutely not to net metering.

[alnorth]

Originally Posted by Donger

And Edison rolls over in his grave cursing Tesla...

If folks are getting a bunch of crap being off the grid and using solar, I'd call bullshit on that but absolutely not to net metering.

Well, its a "problem" only for the goal of using solar without getting surcharged by the power company. AC is absolutely the correct choice for transmission.

[Baby Lee]

Further, you have the same issue you have with electric cars, they don't consume gas, but they still travel public roads. And public roads are maintained through taxes on gas. So basically, electric cars and solar feeders use the infrastructure without paying in to it's upkeep.

[Beef Supreme]

Originally Posted by alnorth

The problem is that we transmit power through Alternating Current instead of DC, the power companies have very specific requirements on the properties of that alternating current, and if this mysterious unexpected current that some random dude dumps into their lines does not precisely match what they are sending, it screws things up.

If you want to use solar panels without a surcharge, then you should really cut yourself off the grid, or at least segregate whatever those panels are powering so that those devices you choose to hook up to solar are only solar powered and not connected at all to the utility.

Well thanks for letting me know that the power companies don't transmit direct current. :roll eyes:

[Baby Lee]

Originally Posted by BigChiefTablet

Well thanks for letting me know that the power companies don't transmit direct current. :roll eyes:

What level of discourse should we start at when someone scoffs at the concept of clean power transmission?

[MagicHef]

Originally Posted by Rain Man

So do the red squares need to be bigger? I'm fine with that. It looks like Algeria has plenty of room.

Yeah, if we figure 20% total efficiency, it would have to be 5 times as large, each side of the square would be about 2.36x as long. Then there'd be all the batteries and transmission and stuff.

[Rain Man]

Originally Posted by MagicHef

Yeah, if we figure 20% total efficiency, it would have to be 5 times as large, each side of the square would be about 2.36x as long. Then there'd be all the batteries and transmission and stuff.

I have to think that they wouldn't mind the extra shade.

[Baby Lee]

Originally Posted by MagicHef

Yeah, if we figure 20% total efficiency, it would have to be 5 times as large, each side of the square would be about 2.36x as long. Then there'd be all the batteries and transmission and stuff.

And the losses in storage, flywheels, compressors, reservoirs, batteries, heat accumulators, etc.

[Fish]

Originally Posted by Baby Lee

Are you seriously in the dark, or trolling, because the explanation exists, but is cumbersome to assemble for lay persons.

In the shortest possible snippet, power companies put a great deal of effort into transmitting a clean sine wave at a reliable magnitude and frequency. Solar and Wind collects DC power and ancillary devices rectify that power into an AC sine wave of, ideally, identical magnitude, frequency, and phase angle. To the extent their devices fall short, they are wasting their power and destroying a portion of the power the generation plant created.

Think double dutch coupled with Frogger, with the solar power being the rope jumper/frog.

They've done plenty of testing and modeling to determine what the electrical grid can handle with regards to input from solar/wind/etc. And there aren't really any problems until you get to over 30% penetration. Wind power is what causes the most invariability. Solar is fairly consistent. Here's a study done on WestConnect Energy:

http://www.nrel.gov/docs/fy11osti/50057.pdf

Operations with 35% Wind and Solar Energy

The power system is designed to handle variability in load. With wind and solar, the power system is called on to handle variability in the net load (load minus wind minus solar), which can be considerable during certain periods of the year. Figure 2 shows the load (purple line along top edge), wind (green), solar (PV in orange and CSP in yellow), and net load profiles for the 30% case during two selected weeks in July and April. In the July week, (left plot), the net load (blue line along bottom edge) is not significantly impacted by wind and solar variation. However, in the April week (right plot), the high, variable wind output dominates the net load, especially during low load hours, leading to several hours of negative net load during the week. This week in April was the worst week in terms of operational challenges of the three years modeled.



How much wind and solar generation can the system handle? No significant adverse impacts were observed up to the 20% case in WestConnect, given balancing area cooperation. Increased wind/solar generation in the rest of WECC (20/20% case) led to increased stress on system operations within WestConnect, with some instances of insufficient reserves due to wind and solar forecast error. These can be addressed, but the system has to work harder to absorb the wind/solar. Operations become more challenging for the 30% case in which load and contingency reserves are met only if the wind/solar forecasts are perfect.

Infrastructure balancing would be necessary, but feasible. Their results show some decent cost savings.

Benefits of 35% Wind and Solar

Wind and solar generation primarily displace gas resources nearly all hours of the year, given the fuel prices and carbon tax assumed for this study. Across WECC, operating costs drop by $20 billion/yr ($17 billion/yr in 2009$) from approximately $50 billion/yr ($43 billion/yr in 2009$), resulting in a 40% savings due to offset fuel and emissions. Figure 4 (left plot) shows the overall impact on the operating costs of WECC for the various penetration levels under the In-Area Scenario with a state-of-the-art (SOA) forecast. The 30% case shows WECC operating cost savings of $20 billion/yr ($17 billion/yr in 2009$) due to the wind and solar generation resources.

Figure 4 (right plot) divides these values by the corresponding amount of renewable energy provided. In the 30% case, this equates to $80/MWh ($60/MWh in 2009$) of wind and solar energy produced. These operating cost savings would be applied toward the costs of wind and solar energy, and depending on the magnitude of these costs, may or may not be sufficient to cover them. At a $3.50/MBTU gas price, wind and solar primarily displace coal generation. With lower gas price assumptions, operating cost savings are about 40% or $46/MWh ($39/MWh in 2009$).

Key Conclusion:

No need to commit additional reserves to cover increased variability – In addition to contingency reserves, utilities are required to hold variability or load following reserves to cover 10-minute load variability 95% of the time. With wind and solar, the net load variability increases and in the 30% case, the average variability reserve requirement doubles. However, when wind and solar are added to the system, thermal units are backed down because it is sometimes more economical to back down a unit rather than to decommit it. This results in more up- reserves available than in the case when there is no wind and solar. Regulating reserves are a subset of the fast variability requirement, but are held separately from the 10-minute variability reserves. While WWSIS did not evaluate which units were on AGC, the minute-to-minute analysis showed that sufficient regulating reserve capability was available. Down reserves can be handled through wind curtailment when other resources are depleted. A wind plant can reduce its output very quickly in response to a command signal. Simulations in this study show that down reserves can be implemented through command signals (ACE signals) from system operators.

[alnorth]

Originally Posted by BigChiefTablet

Well thanks for letting me know that the power companies don't transmit direct current. :roll eyes:

I was not trying to be condescending, I was being serious.

You may have gotten a bit of a harsh response to your initial questions, but that wasn't me.

[alnorth]

Originally Posted by Fish

They've done plenty of testing and modeling to determine what the electrical grid can handle with regards to input from solar/wind/etc. And there aren't really any problems until you get to over 30% penetration. Wind power is what causes the most invariability. Solar is fairly consistent. Here's a study done on WestConnect Energy:

The problem is not the amount of power produced or the variability. Its the quality of the power thats being put into the system. Your articles are talking about demand and the mix between base load and variable power, but thats not what we're talking about.

It costs money to make sure that the solar power being provided by random homeowners, however much is produced or whenever it is produced, is fully compliant (or is adjusted to be fully complicant) with that utility's specifications for AC.

[Baby Lee]

Originally Posted by Fish

They've done plenty of testing and modeling to determine what the electrical grid can handle with regards to input from solar/wind/etc. And there aren't really any problems until you get to over 30% penetration. Wind power is what causes the most invariability. Solar is fairly consistent. Here's a study done on WestConnect Energy:

http://www.nrel.gov/docs/fy11osti/50057.pdf



Infrastructure balancing would be necessary, but feasible. Their results show some decent cost savings.



Key Conclusion:

Those all address variations in the power on the line, instantaneous demand [load] and storage capabilities, once all the other problems I was addressing are sorted out.

EDIT: Or, what al said above.

[Baby Lee]

Another thing you have to fund as a power supplier is inspection, upkeep and compliance of automatic shutoff devices in the instance of power outages or maintenance. The last thing power companies need is to send technicians into the field to repair outages and downed lines while your solar panel or turbine [and/or battery reserves] are energizing what should be dead lines.

[alnorth]

Yeah, even if power quality was not an issue, some kind of connection fee should still be paid unless you truly and completely cut yourself off the grid, physically disconnecting your house from the utility's power. Most solar power homes do not produce enough to meet their own needs and still rely on the utility to give them power, so they still need to help pay to maintain the grid, repair downed power lines, etc.

[hometeam]

uh ohhhhhhhhh

http://www.independent.co.uk/news/sc...e-9563136.html

breakthrough in the production of solar cells will make the next generation of solar panels cheaper and safer, and promises to accelerate the development of solar energy over the next decade, scientists said.






A technical advance based on an edible salt used in the manufacture of tofu could revolutionize the production of future solar panels to make them less expensive, more flexible and easier to use than the current models seen on millions of roofs across Britain.

Researchers believe they have found a way of overcoming one of the most serious limitations of the next generation of solar panels, which are based on toxic cadmium chloride, by simply adding magnesium chloride, an abundant salt found in seawater.

A study has shown that the solar cells produced with magnesium chloride – which is also found in bath salts as well as used to coagulate soya milk into tofu – work just as efficiently as conventional cadmium cells but at a fraction of the cost and with much lower toxicity.

“We certainly believe it’s going to make a big change to the costs of these devices. The cost of solar is going to match fossil fuels eventually but this is going to get us there quicker,” said Jon Major of the University of Liverpool, who led the research.

“Magnesium chloride is incredibly low-cost and it’s simply recovered from seawater. It’s used to de-ice roads in winter and it’s completely harmless and non-toxic. We’ve managed to replace a highly expensive, toxic material with one that’s completely benign and low cost,” Dr Major said.

About 90 per cent of the solar panels currently in use are made of photovoltaic cells composed of silicon semiconductors, which convert sunlight directly into electricity. However, silicon is not good at absorbing sunlight which is why the next generation of PV cells will be based on a thin coating of cadmium telluride, which absorbs sunlight so well that it only needs to be about one hundredth of the thickness of silicon.