The Remarkable Progress of Renewable Energy

[lpetrich]

I see a LOT of headlines about great progress from Wind and Solar; But what is NOT seen is actual reductions in CO₂.

Renewables successfully driving down carbon emissions in Europe — European Environment Agency

Without the deployment of renewable energy since 2005, greenhouse gas emissions in 2012 could have been 7% higher than actual emissions, according to the EEA report 'Renewable energy in Europe – approximated recent growth and knock-on effects'.

Wind Energy Reduces Greenhouse Gas Emissions -- 9% of electricity-generation CO2, not sure whether world or US.
Renewables can reduce CO2 emissions by 70% by 2050 - Climate Action Programme

 

[lpetrich]

Benefits of Renewable Energy Use | Union of Concerned Scientists

Burning natural gas for electricity releases between 0.6 and 2 pounds of carbon dioxide equivalent per kilowatt-hour (CO2E/kWh); coal emits between 1.4 and 3.6 pounds of CO2E/kWh. Wind, on the other hand, is responsible for only 0.02 to 0.04 pounds of CO2E/kWh on a life-cycle basis; solar 0.07 to 0.2; geothermal 0.1 to 0.2; and hydroelectric between 0.1 and 0.5.

I'll make that metric, kg CO2 per kWh, and I'll compare to the numbers for heat of combustion. The renewable ones are lifecycle costs assuming fossil-fuel-powered manufacture.

• Natural gas: (0.18) 0.3 - 0.9
• Oil: (0.24)
• Coal: (0.44) 0.6 - 1.6
• Wind: 0.01 - 0.02
• Solar: 0.03 - 0.09
• Geothermal: 0.05 - 0.09
• Hydroelectric: 0.05 - 0.2

The hydroelectric one may include methane released by decomposing vegetation in hydroelectric-dam lakes.

 

[bilby]

I see a LOT of headlines about great progress from Wind and Solar; But what is NOT seen is actual reductions in CO₂.

Renewables successfully driving down carbon emissions in Europe — European Environment Agency

Without the deployment of renewable energy since 2005, greenhouse gas emissions in 2012 could have been 7% higher than actual emissions, according to the EEA report 'Renewable energy in Europe – approximated recent growth and knock-on effects'.

Without the deployment of nuclear power in France, CO₂ emissions could have been 90% higher.

Wind Energy Reduces Greenhouse Gas Emissions -- 9% of electricity-generation CO2, not sure whether world or US.
Renewables can reduce CO2 emissions by 70% by 2050 - Climate Action Programme

That figure is total fantasy and depends upon storage solutions that don't, and likely can't, exist - and that would cause massive environmental damage if we attempted to implement them.

Wind and Solar would be better than nothing, if there was no other option.

But nuclear is better in every possible way. If we care about the environment, we cannot afford to ignore it; and we shouldn't be wasting resources on these half-baked 'solutions' whose main benefit is to replace coal with gas. That's only doing half of the job - and doing it badly at that.

 

[steve_bank]

The best solution is to decentralize energy down to the individual home where practical. Decentralizing reduces effects of weather and today terrorism.

Nukes represent maintaing the current paradaigm. Centralized power nodes allow control and increase suscepeptibility to failure of the grid.

A friend's brother who has a house on Lake Washington in Seqttle just installed solar voltaics. During the day it supplies all the needs and he sells surplus to the utility. Where appropriate use the grid when needed and limt demand for more capacity.

 

[bilby]

The best solution is to decentralize energy down to the individual home where practical.

No, it isn't.

Decentralizing reduces effects of weather and today terrorism.

No, it doesn't. And terrorism is a non-issue, regardless of the BS Fox News tries to sell.

Nukes represent maintaing the current paradaigm.

I wish.

Centralized power nodes allow control

Good.

and increase suscepeptibility to failure of the grid.

No, they dont.

A friend's brother who has a house on Lake Washington in Seqttle just installed solar voltaics. During the day it supplies all the needs and he sells surplus to the utility. Where appropriate use the grid when needed and limt demand for more capacity.

Cool story, bro.

 

[steve_bank]

No, it isn't.

No, it doesn't. And terrorism is a non-issue, regardless of the BS Fox News tries to sell.

Nukes represent maintaing the current paradaigm.

I wish.

Centralized power nodes allow control

Good.

and increase suscepeptibility to failure of the grid.

No, they dont.

A friend's brother who has a house on Lake Washington in Seqttle just installed solar voltaics. During the day it supplies all the needs and he sells surplus to the utility. Where appropriate use the grid when needed and limt demand for more capacity.

Cool story, bro.

I ain't your bro dude. Get my drift?

Explain why national grids and centalized nodes are prefered.

I was a reen in the 60s in the NYC metro area during the Northeast blackout that darkened NYC for a few days. A fault in the grid propagated faster than the system could keep up creating a cascade failure. I blieve it started with a lighning strike.

To argue that centralized power with thousands of miles of lines is better than decentralization is beyond trying to reason with.

 

[bilby]

No, it isn't.

No, it doesn't. And terrorism is a non-issue, regardless of the BS Fox News tries to sell.

I wish.

Good.

and increase suscepeptibility to failure of the grid.

No, they dont.

A friend's brother who has a house on Lake Washington in Seqttle just installed solar voltaics. During the day it supplies all the needs and he sells surplus to the utility. Where appropriate use the grid when needed and limt demand for more capacity.

Cool story, bro.

I ain't your bro dude. Get my drift?

Explain why national grids and centalized nodes are prefered

Why should I?

I provided EXACTLY as much detail in my rebuttal as you used to support your assertion.

I was a reen in the 60s in the NYC metro area during the Northeast blackout that darkened NYC for a few days. A fault in the grid propagated faster than the system could keep up creating a cascade failure. I blieve it started with a lighning strike.

To argue that centralized power with thousands of miles of lines is better than decentralization is beyond trying to reason with.

Is that your excuse for making unreasoned and unsupported claims?

That's sad.

Pointless anecdotes and bald assertions are not an argument nor a useful contribution to discussion.

 

[bigfield]

A friend's brother who has a house on Lake Washington in Seqttle just installed solar voltaics. During the day it supplies all the needs and he sells surplus to the utility. Where appropriate use the grid when needed and limt demand for more capacity.

You've claimed that decentralisation is better than a grid with thousands of miles of wires, but you give us an story about a guy who is utterly reliant on a centralised energy grid in two ways. Firstly, he needs to be connected to the grid so that he can sell his excess energy to someone during the day; secondly, he needs to buy energy produced by centralised generators at night.

Generation and storage can only be distributed to a limited extent: many commercial properties cannot possibly generate or store their own energy on-site; they are dependent on access to the grid. Many homes are also unsuitable for rooftop PV due to lack of direct sunlight and lack of usable roof space. And if you live in a region where sunlight a scarce for half of the year, you'll be reliant on the grid all day throughout winter.

With current technology, the grid requires specialised installations for generating (and storing) energy that cannot be replaced by rooftop PV (and on-site batteries). And even if we add virtual power plants and lots of wind turbines to the grid, the grid still has to be organised into a network of nodes (i.e. substations).

Explain why national grids and centalized nodes are prefered.

Simple: there is no alternative. Only a small minority of residents have the means to take their property off the grid, and it rarely makes economic sense for them to do so.

 

[James Brown]

I spoke to a lineman who cautioned me about the notion of people selling their excess home-generated electricity back to the electric company.

By design, grids are built to be 'fat' at the central plants, thin out as they spread across an area, and be the thinnest at the last few feet until entering a customer's home or business. The flow of electricity is one-way, from the plant to the customer, much like city-provided water supply.

When a homeowner establishes his own electricity supply and sells the surplus, now the flow of electricity must switch to the opposite direction, sometimes multiple times a day. We're pushing a "fluid" up a thin pipe toward the central plant, which is more difficult. It puts added stress on an already stressed system.

Except now those customers aren't paying for 24x7 service from the electric company. They're only paying for partial service because they're generating their own product. So the electric company, which has to be in business to cover the down periods, now has increased maintenance expenses paid for by decreased revenues. It might be a shock for those homeowners who can generate half-a-day's electricity to discover that their down period provided by the electric company costs more than when they were fully provided for.

Furthermore, since electric companies are so tightly-regulated, they can't easily pass cost increases to the customers, so logically they simply cut back on maintenance and manpower, jeopardizing the quality of the grid for everyone.

I know I'm not using the right terminology, so that was the concept he explained to me.

 

[steve_bank]

That sounds like an uninformed commentary.

I worked in power conversion and DC to AC systems. Commercial off the shelf systems for home use that feed excess to the grid have to meet certain requirements. It requires electric circuits to understand, but it is simple. Match voltage and frequency of the grid and the home system acts like a parallel power supply.

Same wirth a commercial wind turbine farm feeding into the grid.

 

[bilby]

I spoke to a lineman who cautioned me about the notion of people selling their excess home-generated electricity back to the electric company.

By design, grids are built to be 'fat' at the central plants, thin out as they spread across an area, and be the thinnest at the last few feet until entering a customer's home or business. The flow of electricity is one-way, from the plant to the customer, much like city-provided water supply.

When a homeowner establishes his own electricity supply and sells the surplus, now the flow of electricity must switch to the opposite direction, sometimes multiple times a day. We're pushing a "fluid" up a thin pipe toward the central plant, which is more difficult. It puts added stress on an already stressed system.

Except now those customers aren't paying for 24x7 service from the electric company. They're only paying for partial service because they're generating their own product. So the electric company, which has to be in business to cover the down periods, now has increased maintenance expenses paid for by decreased revenues. It might be a shock for those homeowners who can generate half-a-day's electricity to discover that their down period provided by the electric company costs more than when they were fully provided for.

Furthermore, since electric companies are so tightly-regulated, they can't easily pass cost increases to the customers, so logically they simply cut back on maintenance and manpower, jeopardizing the quality of the grid for everyone.

I know I'm not using the right terminology, so that was the concept he explained to me.

It works OK as long as only a handful of households do it, and the extra power is all used in the immediate area. The problems arise when trying to push the low voltage local power up to the high voltage distribution network - Those transformers are designed to be efficient and durable for step down, not step up.

The other problem is that the power being generated is largely valueless; Everyone is generating at once, nobody is consuming, and prices go through the floor - you get a government mandated price for power the utility company has to buy from you, but then has to pay to get rid of (negative wholesale prices are becoming a frequent occurrence). Of course that's a major cost to the power companies - which goes on to people's power bills. So those without solar panels are subsidising those who have them, which typically means that the poor are subsidising the middle class.

It's far more complicated than most people realise, both from a technical and a market perspective. And the upshot is that above about 10-15% of supply, rooftop solar becomes unviable without government intervention - intervention that costs taxpayers and/or electricity customers big time.

That's why despite all the new solar power coming online, Californians are seeing sharply rising electricity bills.

The only thing that's preventing disaster is that gas is very cheap, due to fracking.

All this environmental activism is causing more fossil fuels to be burned, and is the direct cause of all the fracking that the people at fault are so upset about. Unintended consequences are a bitch; It would be funny, if it wasn't destroying my environment as well as theirs.

 

[steve_bank]

50-60hz power transformers work equally well in both directions. When operating in parralel power source have one master supply and the rest act like current sources.

Yes pricng for a utlity can become a problem. A few years back utilities in Hawaii and California had a moratorium on new solar instalations. Laws required utilities to buy excess power as a way for homeowners to pay for the systems.

At some point it affected rate strucrures and profit. It demonstrates that in some areas of high sunshine solar is cheaper than fossil fuels taking into account generation, grid distrubution, and maintenance.

In the home side the systems is a constant voltage power supply that can supply a maximum current. If the max output of a solar panel is not used, there is no 'excess energy' that has to go somewhere. Like a spigot on a large water tank. The utility does not pay for your excess energy, it pays for energy added to the grid. The power meters can be designed to run backwards dending on current flow.

The major cost issue for solar added to existing homes is the return on investment, as opposed to designing it in at the start. Someone adding solar may not own the home long enough to see a return without being paid for adding to the grid.

 

[Loren Pechtel]

I spoke to a lineman who cautioned me about the notion of people selling their excess home-generated electricity back to the electric company.

By design, grids are built to be 'fat' at the central plants, thin out as they spread across an area, and be the thinnest at the last few feet until entering a customer's home or business. The flow of electricity is one-way, from the plant to the customer, much like city-provided water supply.

When a homeowner establishes his own electricity supply and sells the surplus, now the flow of electricity must switch to the opposite direction, sometimes multiple times a day. We're pushing a "fluid" up a thin pipe toward the central plant, which is more difficult. It puts added stress on an already stressed system.

Except now those customers aren't paying for 24x7 service from the electric company. They're only paying for partial service because they're generating their own product. So the electric company, which has to be in business to cover the down periods, now has increased maintenance expenses paid for by decreased revenues. It might be a shock for those homeowners who can generate half-a-day's electricity to discover that their down period provided by the electric company costs more than when they were fully provided for.

Furthermore, since electric companies are so tightly-regulated, they can't easily pass cost increases to the customers, so logically they simply cut back on maintenance and manpower, jeopardizing the quality of the grid for everyone.

I know I'm not using the right terminology, so that was the concept he explained to me.

Not really a good explanation of the problem, but not that far off, either. There are multiple issues here.

Wires don't give a hoot which way the power flows. Dumping solar power into your local segment of the grid causes no stress on the system. High power transformers, however, do care which way the power flows--the wires still don't give a hoot but all that power creates heat and they were engineered expecting more heat from the primary winding than from the secondary. Try to push power up the chain through a transformer and you have thermal issues--and thermal issues in high power transformers tend to be spectacular. In Hawaii where this has become an actual threat the electric company simply will not permit too many solar installations on a single segment (which has resulted in some hopping-mad homeowners with cells on the roof but no permit to connect them so they're all but useless.)

The second issue which I have never seen discussed is that the normal rule always is you have a circuit breaker between the power source and the use. Said breaker must be no bigger than what the wires after it (but before another breaker) can carry. This model falls down when you have distributed generation, however. A local segment with a bunch of solar on it can overload without tripping a breaker.

Solar also makes life harder on the line crews. Normally, if you open the breaker you know there's no power and can work the wires cold. With a solar setup, however, the inverter is supposed to keep the power from flowing back into a dead feed. Nowhere near the safety of an open breaker, not to mention what could happen if somebody goes the cheap route and simply puts a suicide plug on a panel with an inverter rather than doing a proper installation.

 

[bilby]

It's also worth mentioning that most wind and solar generation is NOT distributed (and that distributed generation cannot possibly replace more than a fraction of domestic power demand, and almost none of commercial or industrial demand, due to a lack of roof space). It takes place at (usually remote) solar or wind 'farms', which have all of the disadvantages of centralized generation, PLUS the extra problem of that generation being sited to optimize wind or sun, and not to minimize distribution distances.

So, for example, in California, you can choose between the Diabolo Canyon nuclear plant, on the coast, not far from the population it serves; Or the Ivanpah solar farm, in the desert, a bloody long way from the customers. Which of these options is more resilient to transmission issues is left as an exercise for the reader.

 

[steve_bank]

Loren

You are correct on the xfmr. Normaly high voltage on the primary means lower current and less copper, the reason for high voltage grids. Low voltage on the secondary means high current and more copper to keep IR losses down.

I don't think power can simulatneously flow both ways through a xfmr. There would be magnetic core flux problems due to Faraday's Law. Actualy current does not flow, Current in one winding creates a magnetic field which induces a current in other windings.

As to safety I used to have a copy of the National Electric Code at work. There are safety requiremnts taht apply when connecting to the grid, the same as any generator. It includes acess to a discnnect and overload fault protection. Home systems are not generator masters, they slave to grid.

Solar at the local level is distributed, the opposite of centralized power generation.

 

[Loren Pechtel]

Loren

You are correct on the xfmr. Normaly high voltage on the primary means lower current and less copper, the reason for high voltage grids. Low voltage on the secondary means high current and more copper to keep IR losses down.

I don't think power can simulatneously flow both ways through a xfmr. There would be magnetic core flux problems due to Faraday's Law. Actualy current does not flow, Current in one winding creates a magnetic field which induces a current in other windings.

As to safety I used to have a copy of the National Electric Code at work. There are safety requiremnts taht apply when connecting to the grid, the same as any generator. It includes acess to a discnnect and overload fault protection. Home systems are not generator masters, they slave to grid.

Solar at the local level is distributed, the opposite of centralized power generation.

Yeah, it can't flow both ways at once but that's not a problem--power flows from the side with more to the side with less. The problem is overheating the secondary if too much power is flowing up.

 

[steve_bank]

Loren

You are correct on the xfmr. Normaly high voltage on the primary means lower current and less copper, the reason for high voltage grids. Low voltage on the secondary means high current and more copper to keep IR losses down.

I don't think power can simulatneously flow both ways through a xfmr. There would be magnetic core flux problems due to Faraday's Law. Actualy current does not flow, Current in one winding creates a magnetic field which induces a current in other windings.

As to safety I used to have a copy of the National Electric Code at work. There are safety requiremnts taht apply when connecting to the grid, the same as any generator. It includes acess to a discnnect and overload fault protection. Home systems are not generator masters, they slave to grid.

Solar at the local level is distributed, the opposite of centralized power generation.

Yeah, it can't flow both ways at once but that's not a problem--power flows from the side with more to the side with less. The problem is overheating the secondary if too much power is flowing up.

Yje two basic circuit models for sorces is Thevenin and Norton. You can google.

for first order analysis the trasformer is 'thevinized' to a simple resitance in series with a zero resistance generator. Voltage sources are low resistance, Norton current models are high resistance.

Looking from the grid the and all the home systems look like Theveinin sources in parallel. At that point you are right, the highest voltage source woul create current in the other sources, inclusing the trasformer. The only low frequency resitsance is the winding wire.

The home systems slave the amplitude to match grid voltage. It would not be exact but negligible.

Another aspect. In power supplies there are two forms of overload protection, current limiting and current foldback. In current foldback as overload is reached the output voltage drops smoothly. parralel power supplies and the one with the higher voltage will create current in the other supply. As current increases into the limit the output voltage drops until it matches the lower voltage of the other supply. They then share current roughly equal..

Just like paralleling two batteries. To parallel car batteries they have to be diode isloated, they are diode ORed together. Intially the higher voltage supplies the load. As the terminal voltage drops and equals the other battery they begin to share current to the load through diodes.

 

[lpetrich]

Thévenin's and Norton's theorems both assume linear-response components, and those two theorems are mathematically equivalent.

 

[steve_bank]

Thévenin's and Norton's theorems both assume linear-response components, and those two theorems are mathematically equivalent.

Yes, that is correct. It Is not just theoretical, it is a cornerstone of circuit analysis. I would argue the linear part, sources can be non linear.

If I were to actually build a model I would model the transformer and each generator in the homes as a Thevenin or Norton two terminal source with terminals in common.

 

[bilby]