Is 85% the highest efficiency we can achieve with PV technology?

[mheslep]

would this be along the same lines as electric plasma rockets? I read that in one of the Sci America mags? Not sure if that was just an application for space but i do remember something along the lines of using electriicty to shoot plasma out for propulsion?!

Completely unrelated, other than they're both electric.

 

[russ_watters]

Jumping in here - allright, but your prior post was a plan that only sanctioned fossil fuels. Perhaps you were referring only to transportation needs, but it seems your proposal for transportation energy would still have us indefinitely importing oil from maniacs, and would dismiss harm from emissions? I don't buy into the latter entirely, but neither do I recommend indefinitely dumping the yearly emissions from a cubic mile of petroleum into the atmosphere.

First, my "plan" has been sticky'd at the top of this forum for just short of five years*. That post above is in response to a single, specific point someone else made and doesn't have much to do with how I think we should proceed overall. It is nothing more than a reality check about how the world works and an objection to an inflammatory post.

No one in here is naive about what drives buying decisions for consumers. We all saw how SUV sales plummeted after hurricane Katrina doubled gas prices and then went right back up again (over a year and a half) as they fell again. That happened in the 1970s during the gas crises there as well. This is how the world works and this is what is going to continue to drive buying decisions. Scaremongering about the inevitable, near collapse of civilization is unhelpful and wrongminded. Whether we act prudently to fix the problem or not, it just isn't going to happen.

But now that we're on it, I do think that we will eventually need to get off gasoline to power cars. I think it would be nice if we could hasten the demise of gasoline, but I don't see any evidence that there are any real ways to do that. Right now, people are banking on research: they're lying under that tree that was mentioned before and hoping that eventually plug-in hybrids or electrics or synthetic methane or fuel cell vehicles will some day be viable. But while they are doing that, they are ignoring the low hanging fruit that not only could they pick now, but they must pick now in order for any of those gasoline alternatives to become viable! What I'm talking about is what I harp on over and over in energy threads: the fact that half of our electric power comes from coal. Until that issue is addressed, we're just trading one fossil fuel for another, making fancy looking cars that really are nothing more than 150 year old coal fired steam locomotives.

Please understand: I'm not saying we shouldn't research these ideas. I'm sayinig that researching these ideas is only part of what is needed and isn't even the biggest piece. The biggest piece is modernizing the power grid to generate more power using less coal. And there is only really one viable way to do that: we need to start building nuclear plants, by the hundreds, now. Talk of wind power and even worse solar power are worse than doing nothing because they pay lip service to the problem while guaranteeing that it won't be fixed. So what's going to happen? In 20 years, we'll have 10 times as much wind power as we do today and we'll still have more coal power than we do today. Wind power growth will be stagnating and then people will realize that they sqaundered the last 20 years building wind plants when they should have been building nuclear plants. We're following the path that Germany is already far along on (though Germany is proving the poing faster by shutting down nuclear plants and building lots more coal plants to cover what their wind plants can't do).

The US will eventually be an mostly nuclear country like France, but it will be at least 50 years until that happens and we're going to see a lot of needless failure and pain before that happens. Assuming the daydreaming bears fruit, in 20 years, France will be sitting pretty with their electric or fuel cell (or whatever) cars, having the electrical infrastructure needed to power them. We won't. That's not what should happen, that's my prediction about what will happen.

*Probably time to update it...

 

[russ_watters]

Why the hell is everyone always against wind and solar? Wind I can understand as it can be expensive but solar holds some serious promise.

You actually kinda have that backwards: wind isn't substantially more expensive than conventional power sources and as things like coal and oil get more expensive, the economics of wind will improve somewhat. The problem with wind is twofold:
1. Scaleability: It would take millions of turbines to put even a small dent in our power situation. They require land and power lines to serve them.
2. Availability: Because wind is not continuous, it requires more nameplate capacity to get the same generation as other sources and requires a back-up.

The US will not be more than 20% wind within the next 50 years.

There have been some major advancements in solar technology in the past three years and I see no reason why it can not be our major source of energy.

Can you point to some of these advancements? Browsing solar panel sales sites today doesn't look much different from when I browsed them 5 years ago. Where are these advancements?

Perhaps more to the point, the cost of the panel is only a portion of the cost of the system - the electronics are just as expensive (for residential, anyway) and that technology is as mature as it is going to get.

But the bigger problem is that the scaleability and availability problems of solar dwarf those of wind. We're talking here about charging our plug-in hybrids at night!

50 years from now, solar will not be more than 10% of our generating capacity - and then only due to rediculous government subsidies.

I do not. I mean thermochemical and photochemical hydrogen production. The produced hydrogen of which can be used for either transportation (PEMFC) or stationary (SOFC, AFC) power generation.

http://www.treehugger.com/files/2008...giant-leap.php

We see announcements like that about once a month. None of them have ever panned out (the best are the Israeli and Chinese plastic solar panel breakthroughs we regularly see). In particular, that one reads like a free energy hoax. Given the source, that shouldn't be surprising. At face value, that invention doesn't do anything at all: it says you can use it plus an input of electricity to split water into hydrogen and oxygen at room temperature. Uh...that's what electrolysis is! But it's claiming a catalyst to assist, which is crackpot code for "this invention violates the first law of thermodynamics".

 

[russ_watters]

I know big oil won't be keen on letting go of oil. In an engineering ethics class we learned of one of the first patents for the electric car battery / motor was bought by big oil and they used that patent to block all research in that area. Led Honda and toyota to investigate other methods of electric car development. If this didn't happen we would have had electric cars commercialized at an earlier sage

Oy vey, are you kidding me?!? It is a sad day when the crackpot/conspiracy theorists have invaded engineering classes.

I don't doubt that oil companies have bought patents and quashed competing technology - every big company that can do that does it. But you can't stop research by buying a patent. Especially for things as widely used as batteries and electric motors! The reason we don't have electric cars today isn't some big oil conspiracy, it is because electric cars are expensive and can't perform. They will only become viable when gas becomes so expensive that electric cars don't look as expensive anymore.

 

[russ_watters]

no, i didn't initiate the thread to point out that H and Li are really sources of energy. My hypothetical question about suddenly having a technology that would make as much electricity needed at any time (beyond base load...whatever) would not right away solve the problem of mass transportation by car (thus the oil issue right away). Hydrogen couldn't just easily be subsituted for gas (transport, volume inefficiency, safety?) and Li was not abundent enough in the world to replace the number of cars that run on gas.

Your point in the OP is absolutely correct and it is what I've said in other places in this thread: cars are going to be powered primarily by gas for the forseeable future, whether people like it or not. Efficiency legislation and stop-gap technologies like plug-in hybrids will help, but they don't change that reality. While we should promote reseach, we should put the bulk of our efforts into solving now the problems that can be solved now. And that means...

It was all dependent on the hypothetical world that we can make enough electricity (not coal,gas or nuclear) to satisfy all our needs - including enough left to do away with oil.

That hypothetical world is not a pipe dream, it is a reality in France today, a nuclear fueled country. Nuclear does satisfy their needs cheaply and cleanly and can satisfy ours if we choose to do it. Sadly, this is only going to happen when the economics overcome the politics for nuclear power here.

 

[vanesch]

But now that we're on it, I do think that we will eventually need to get off gasoline to power cars. I think it would be nice if we could hasten the demise of gasoline, but I don't see any evidence that there are any real ways to do that. Right now, people are banking on research: they're lying under that tree that was mentioned before and hoping that eventually plug-in hybrids or electrics or synthetic methane or fuel cell vehicles will some day be viable. But while they are doing that, they are ignoring the low hanging fruit that not only could they pick now, but they must pick now in order for any of those gasoline alternatives to become viable! What I'm talking about is what I harp on over and over in energy threads: the fact that half of our electric power comes from coal. Until that issue is addressed, we're just trading one fossil fuel for another, making fancy looking cars that really are nothing more than 150 year old coal fired steam locomotives.

Please understand: I'm not saying we shouldn't research these ideas. I'm sayinig that researching these ideas is only part of what is needed and isn't even the biggest piece. The biggest piece is modernizing the power grid to generate more power using less coal. And there is only really one viable way to do that: we need to start building nuclear plants, by the hundreds, now. Talk of wind power and even worse solar power are worse than doing nothing because they pay lip service to the problem while guaranteeing that it won't be fixed. So what's going to happen? In 20 years, we'll have 10 times as much wind power as we do today and we'll still have more coal power than we do today. Wind power growth will be stagnating and then people will realize that they sqaundered the last 20 years building wind plants when they should have been building nuclear plants. We're following the path that Germany is already far along on (though Germany is proving the poing faster by shutting down nuclear plants and building lots more coal plants to cover what their wind plants can't do).

I am trying (in vain I fear) to pass the same message to the tree-hugger brigade in my native country - Belgium - where they succeeded voting a nuclear phase-out (from 56% nuclear to 0% in 2015)

... which explains also why I'm not so very present on PF by times - I have only so much time to spend on the internet :shy: ...

They started out by saying I'm "one of those" again ;
then they told me that one "shouldn't look at the problem with numbers, but with ethics" ;
then they said it was going to be too expensive ;
now, after some 260 posts, they said they were going to verify my numbers

silence since about a week

 

[Topher925]

Can you point to some of these advancements? Browsing solar panel sales sites today doesn't look much different from when I browsed them 5 years ago. Where are these advancements?

Where did I mention anything about photovoltaics? I pointed to one of these advancements earlier in the thread but if you want more University of Florida has some good articles. I'm not going to spend my time listing more just so you can blindly disregard them and refer to them as an "energy hoax".
http://www.fsec.ucf.edu/en/research/hydrogen/production.htm

But the bigger problem is that the scaleability and availability problems of solar dwarf those of wind. We're talking here about charging our plug-in hybrids at night!

Scalability becomes less of an issue when photovoltaics are integrated into buildings and roads of urban areas and thermochemical or photochemical methods are used in non-rural areas. And no, were not.

We see announcements like that about once a month.

Ok, show me the greatest "hoax" for this month?

In particular, that one reads like a free energy hoax. Given the source, that shouldn't be surprising.

I'm sorry, your right. Obviously all the chemists that work at MIT are crackpots and all the work they do is just done to feed the minds of nutcases and treehuggers. MIT isn't even a real university anyway and only the dumbest professors on the planet work there.
http://web.mit.edu/newsoffice/2008/oxygen-0731.html

At face value, that invention doesn't do anything at all: it says you can use it plus an input of electricity to split water into hydrogen and oxygen at room temperature. Uh...that's what electrolysis is! But it's claiming a catalyst to assist, which is crackpot code for "this invention violates the first law of thermodynamics".

Every industrial electrolysis process out there that I know of uses a catalyst for splitting water to increase efficiency. I don't know of a single processes that does it at room temperature either. There is nothing that violates any law here, but if you want to see that for yourself you can download the paper that describes the work. And the significants of the process isn't that its just electrolysis, its that performs electrolysis at very high efficiencies at a lower cost and under ambient conditions. Something previously never accomplished before.

The efficacy of electrolysis is increased through the addition of an electrolyte (such as a salt, an acid or a base) and the use of electrocatalysts.

http://en.wikipedia.org/wiki/Electrolysis_of_water

 

[xxChrisxx]

Come on boys let's not have a fight about all this.

 

[mheslep]

... What I'm talking about is what I harp on over and over in energy threads: the fact that half of our electric power comes from coal. Until that issue is addressed, we're just trading one fossil fuel for another, ...

Yes, but: One, we would be trading one fuel (oil) that we don't have much of and little control over for one that we do (coal), and we end up funding maniacs abroad to get the oil. Two, switching to electric transportation is not a joule for joule switch in energy because of the efficiency gains (2 or 3:1), likewise it is not a 1:1 emissions switch either. Three, electric transportation makes the primary energy source inherently flexible in the future - maybe its coal (only half even now), maybe its natural gas, nuclear, whatever. There are also several other lesser points such as eliminating emissions in urban areas, etc.

BTW, US wholesale electric prices have recently dropped to http://online.wsj.com/article/SB125003563550224269.html"(wholesale). Yes that's in part because of the recession, but in that same recession the price of oil is climbing, $71/bbl today.

 

[russ_watters]

I am trying (in vain I fear) to pass the same message to the tree-hugger brigade in my native country - Belgium - where they succeeded voting a nuclear phase-out (from 56% nuclear to 0% in 2015)

Well gee, vanesch, I'm sure it is possible to phase-out nuclear power in Belgium without resorting to coal. You can just import power from one of your neighbors! (as long as you don't check how they make it...)

... which explains also why I'm not so very present on PF by times - I have only so much time to spend on the internet :shy: ...

They started out by saying I'm "one of those" again ;
then they told me that one "shouldn't look at the problem with numbers, but with ethics" ;
then they said it was going to be too expensive ;
now, after some 260 posts, they said they were going to verify my numbers

silence since about a week

Good luck with that!

 

[russ_watters]

Where did I mention anything about photovoltaics? I pointed to one of these advancements earlier in the thread but if you want more University of Florida has some good articles. I'm not going to spend my time listing more just so you can blindly disregard them and refer to them as an "energy hoax".
http://www.fsec.ucf.edu/en/research/hydrogen/production.htm

Your "treehugger" link said the energy to split the hydrogen came from photovoltaics.

Now that link there has a number of widely different technologies, most of which just appear to be reforming hydrocarboms (which imo isn't very useful). But regardless, they are research projects. Those technologies have not been commercialized yet, as far as I know.

Scalability becomes less of an issue when photovoltaics are integrated into buildings and roads of urban areas and thermochemical or photochemical methods are used in non-rural areas.

No, it doesn't. Making smaller and more distributed generation with poor availability makes scaleability worse, not better. Instead of providing back-up power at the grid level, with distributed production of photovoltaics, you need full conventional redundancy. And that's in addition to the main meaning of "scaleability": economies of scale. Large installations are cheaper than small ones.

And no, were not. [charging at night]

?? When are you going to charge your car after driving home if not at night? In the winter, it is dark when I leave for work and dark when I get home.

Ok, show me the greatest "hoax" for this month?

You just posted it! But from the web, a google for "solar breakthrough" yields plenty of examples. Here's one from July: http://www.topix.com/energy/solar-energy/2009/07/portland-company-makes-breakthrough-in-solar-power

Now perhaps the word "hoax" is too strong - it is possible that some/many of these people are well-meaning inventor types. The important point, though, is that none of these breakthroughs have been successfully commercialized on a reasonable scale.

I'm sorry, your right. Obviously all the chemists that work at MIT are crackpots and all the work they do is just done to feed the minds of nutcases and treehuggers. MIT isn't even a real university anyway and only the dumbest professors on the planet work there.
http://web.mit.edu/newsoffice/2008/oxygen-0731.html

Where are you getting this stuff, Topher? Relax! I didn't say anything about MIT, much less that "all" chemist at MIT are crackpots! I questioned the one example you gave.

Topher, you made a mistake. That story (it's the same as the treehugger article) is not about a solar power breakthrough, it is about an electrolysis breakthrough. But the article (both it and the treehugger article are about the same thing) are both both so terribly written that they fooled you into thinking it was something it wasn't and led me to believe it is a crackpot claim. Might that guy have made an advancement in electrolysis? Sure. But the way he's promoting it - making a connection between it and solar power while trying out his Nobel acceptance speach - is highly questionable.

Every industrial electrolysis process out there that I know of uses a catalyst for splitting water to increase efficiency. I don't know of a single processes that does it at room temperature either. There is nothing that violates any law here, but if you want to see that for yourself you can download the paper that describes the work. And the significants of the process isn't that its just electrolysis, its that performs electrolysis at very high efficiencies at a lower cost and under ambient conditions. Something previously never accomplished before.

That's all well and good, and I'll acknowledge I'm not real up on how electrolysis is done commercially, but when a product hasn't hit the market yet and he's saying things like: "This is a major discovery with enormous implications for the future prosperity of humankind. The importance of [this] discovery cannot be overstated..." that shold make everyone's crackpot detector peg off the scale.

 

[russ_watters]

Yes, but: One, we would be trading one fuel (oil) that we don't have much of and little control over for one that we do (coal), and we end up funding maniacs abroad to get the oil.

Ok, I guess - I've just never heard someone claim that trading oil for coal was a good thing!

Two, switching to electric transportation is not a joule for joule switch in energy because of the efficiency gains (2 or 3:1)...

The efficiency gains are probably more on the order of 1.3:1. A gas car is about 30% efficient and a power plant is about 45% efficient. The electrical transportation, storage, and usage is altogether about 85% efficient. Mulitply that out and you get 30:38 or 1.3

...likewise it is not a 1:1 emissions switch either.

A coal plant is worse than a car in emissions.

Three, electric transportation makes the primary energy source inherently flexible in the future - maybe its coal (only half even now), maybe its natural gas, nuclear, whatever.

Once again, I've never heard someone talk about coal as if it were a viable option. Right now, increased power demand is increasing coal electricity and increasing emissions. That's a fact. Adding electric transportation only makes that situation worse, unless we make a change in how we make power.

 

[xxChrisxx]

A coal plant is worse than a car in emissions. Once again, I've never heard someone talk about coal as if it were a viable option. Right now, increased power demand is increasing coal electricity and increasing emissions. That's a fact. Adding electric transportation only makes that situation worse, unless we make a change in how we make power.

The only good thing about centralising power produciton to a coal plant over a car, is that coal plants can more effectively deal with emissions (CO2 scrubbing etc).

 

[Integral]

Ok, I guess - I've just never heard someone claim that trading oil for coal was a good thing!
The efficiency gains are probably more on the order of 1.3:1. A gas car is about 30% efficient and a power plant is about 45% efficient. The electrical transportation, storage, and usage is altogether about 85% efficient. Mulitply that out and you get 30:38 or 1.3 A coal plant is worse than a car in emissions. Once again, I've never heard someone talk about coal as if it were a viable option. Right now, increased power demand is increasing coal electricity and increasing emissions. That's a fact. Adding electric transportation only makes that situation worse, unless we make a change in how we make power.

In all reality coal may be a very viable alternative. But some R&D needs to be done. We need to learn to burn coal cleanly and efficiently. The emission stream can then be used to feed algae beds. The algae then becomes the source of your liquid fuel.

While there are arguments for large centralized power plants, they also have their disadvantages. For one, damage due to either natural disaster or terrorism can create major issues. I see advantages to a more distributed power net with each region contributing what ever the local resources can provide. Perhaps the desert SW could have large photovoltaic fields, coastal ares could provide energy from wave, tide and wind, others areas could grow algae or maybe tap geothermal sources. River turbines are being tested in the Hudson and other rivers. Putting all your eggs in one basket is never a good idea, along with the current coal, nucs and hydro we will need the alternative sources.

 

[vanesch]

In all reality coal may be a very viable alternative. But some R&D needs to be done. We need to learn to burn coal cleanly and efficiently. The emission stream can then be used to feed algae beds. The algae then becomes the source of your liquid fuel.

Yes, but in the end, you DID bring that CO2 in the atmosphere (when you use the fuel), although you used it twice, and so you divided the emissions per KWhr by about two.

Perhaps the desert SW could have large photovoltaic fields, coastal ares could provide energy from wave, tide and wind, others areas could grow algae or maybe tap geothermal sources.

In fact, if you have access to large amounts of direct sunlight such as in hot deserts, CSP is much cheaper and much more efficient than PV, and this will always be so, because mirror will always be cheaper than PV. Also, they can partly solve the problem of storage and of demand-following, at least day/night, because using molten salts, you can store heat during daytime, to use it during night-time. However, you need, eh, water (or you might use huge air heat exchangers, but that's more challenging) - so you may need to be not too far from a coast line. As a by-product, you can get (just as with nuclear) fresh water if you use seawater as cooling.

In fact, CSP in deserts is IMO, the only viable large-scale alternative to nuclear on a longer term. But, beware: it is going to be HUGE.

River turbines are being tested in the Hudson and other rivers. Putting all your eggs in one basket is never a good idea, along with the current coal, nucs and hydro we will need the alternative sources.

You can easily estimate an upper limit to hydro power: take all the rivers that verse their water directly into the ocean or sea. Take the height of their highest source of the drainage bassin, and take it's end flow rate. That will give you an upper bound on the maximum hydro power you could ever hope to extract from the drainage bassin. In fact, it is an overestimation, often by a factor of 2 or more, because not all of the flow rate finds its origin in the highest source, usually you have a gradual build-up.

 

[Integral]

Yes, but in the end, you DID bring that CO2 in the atmosphere (when you use the fuel), although you used it twice, and so you divided the emissions per KWhr by about two.

You are right once the fossil carbon is released the damage is done.

In fact, if you have access to large amounts of direct sunlight such as in hot deserts, CSP is much cheaper and much more efficient than PV, and this will always be so, because mirror will always be cheaper than PV. Also, they can partly solve the problem of storage and of demand-following, at least day/night, because using molten salts, you can store heat during daytime, to use it during night-time. However, you need, eh, water (or you might use huge air heat exchangers, but that's more challenging) - so you may need to be not too far from a coast line. As a by-product, you can get (just as with nuclear) fresh water if you use seawater as cooling.

In fact, CSP in deserts is IMO, the only viable large-scale alternative to nuclear on a longer term. But, beware: it is going to be HUGE.

I guess that is what I meant by R&D in my first sentence.

You can easily estimate an upper limit to hydro power: take all the rivers that verse their water directly into the ocean or sea. Take the height of their highest source of the drainage bassin, and take it's end flow rate. That will give you an upper bound on the maximum hydro power you could ever hope to extract from the drainage bassin. In fact, it is an overestimation, often by a factor of 2 or more, because not all of the flow rate finds its origin in the highest source, usually you have a gradual build-up.

What's your point? Are you implying that hydroelectric is a not meaningful power source?
Maybe you should do the calculation. A large percentage of the power generated in the Western US is hydroelectric. According to this http://hubpages.com/hub/facts-about-hydroelectric-energy" about 20% of the worlds power is hydroelectric.

 

[vanesch]

What's your point? Are you implying that hydroelectric is a not meaningful power source?
Maybe you should do the calculation. A large percentage of the power generated in the Western US is hydroelectric. According to this http://hubpages.com/hub/facts-about-hydroelectric-energy" about 20% of the worlds power is hydroelectric.

Some 20% of world's electric power now is hydro-electric. But if we are talking about electrical replacements of all our fossil-fuel usage, it is smaller. It is one of the finest ways of generating power (very flexible, clean, economical, and all that), but I wanted to say that it is a limited resource, and we used it already to a good extend. It is not much more stretchable (except maybe in countries like China and so) I think.

 

[Integral]

Guess you have not read or understood anything I have said. Never have I claimed anything was a "replacement" for anything. My point is we need to use what is available and not rely solely on the huge centralized power generation. Just for the record, I am not a big fan of large hydroelectric dams they are not nearly as eco friendly as commonly believed.

NYC is currently generating power with a http://www.verdantpower.com/what-initiative/" Many coastal cities may be able to benefit from similar systems.

 

[vanesch]

Guess you have not read or understood anything I have said. Never have I claimed anything was a "replacement" for anything.

Well, the point *is* that we'll need to get off eventually of oil, and we'll need off dirty coal. So we'll need a replacement for that, no ? I thought that was what the thread was about... In how much there is really something like "clean coal", I doubt it. There's maybe "less dirty" coal.

My point is we need to use what is available and not rely solely on the huge centralized power generation.

Of course, in as much as that is realistically and economically available, sure.

 

[vanesch]

NYC is currently generating power with a http://www.verdantpower.com/what-initiative/" Many coastal cities may be able to benefit from similar systems.

Over this two-year period, Verdant Power operated six full-scale turbines in array at the RITE Project, successfully demonstrating the Free Flow System as an efficient source of renewable energy with the following outcomes:
[ ... ]
80 megawatt hours of energy delivered to two end users;
[ ... ]

80 MWhr in 2 years, means 40 MWhr in 1 year means average power 40 MWhr / 8760 hrs = 4.6 KW.

Did I do that right ? We're talking about 4.6 KW average ?

 

[Integral]

80 MWhr in 2 years, means 40 MWhr in 1 year means average power 40 MWhr / 8760 hrs = 4.6 KW.

Did I do that right ? We're talking about 4.6 KW average ?

Ya, got to start somewhere!

 

[mheslep]

... Right now, increased power demand is increasing coal electricity and increasing emissions. That's a fact.

Perhaps you mean historically, but electrical demand clearly declined recently, and substantially.
http://online.wsj.com/article/SB125003563550224269.html

...On Friday, the nation's largest wholesale power market serving parts of 13 states east of the Rockies is expected to report that electricity demand fell 4.4% in the first half of the year...
Wholesale electricity -- power furnished to utilities and other big energy users -- cost an average of $40 a megawatt hour in the region, down from $66.40 a year earlier. The price declines in this market, which extends from Delaware to Michigan, come on top of a 2.7% drop in energy use in 2008 over 2007.

Part of that is no doubt due to the recession, but there's also apparently been some large investments in efficiency given the spiking oil prices last year and now the threat of pending carbon taxes.

Adding electric transportation only makes that situation worse, unless we make a change in how we make power.

It could if its done with no planning, but as you probably know some 10% of US electrical generation (~100GW) is idle overnight. Edit: That's enough to charge 200 million sedans w/ a 110 mile (25kWh) capacity ( 5 hours charge @ 5 kw)

 

[mheslep]

Scalability becomes less of an issue when photovoltaics are integrated into buildings and roads of urban areas and thermochemical or photochemical methods are used in non-rural areas.

No, it doesn't. Making smaller and more distributed generation with poor availability makes scaleability worse, not better. Instead of providing back-up power at the grid level, with distributed production of photovoltaics, you need full conventional redundancy. And that's in addition to the main meaning of "scaleability": economies of scale. ...

I'd say you both have a point here, depending on use. If PV's are deployed on roof tops to provide for only peak load, say for grocery store air conditioning in the middle of a sunny day, then Topher is correct, as they lessen the demands on the grid. To the degree PV's are deployed to handle base load without their own long term storage mechanism, then Russ is correct, as then the grid has to be there to match every PV deployment in the event of a four day blizzard.

 

[Ivan Seeking]

Yes, but in the end, you DID bring that CO2 in the atmosphere (when you use the fuel), although you used it twice, and so you divided the emissions per KWhr by about two.

Then we replace the coal with algae biomass: Loop closed.

 

[mheslep]

... A coal plant is worse than a car in emissions.

http://www.epa.gov/otaq/climate/420f05001.htm": 2.095 lbs CO2 from coal/ kWh (year 2000 plants)
http://www.eia.doe.gov/cneaf/electricity/page/co2_report/co2emiss.pdf" : 19.4 lbs CO2 / gallon gasoline

CO2 per mile (28 miles):
EV (4 miles/kWh - battery to wheel): 14.7 lbs. Including charging losses, 16.3 lbs.
ICE vehicle (28mpg): 19.4 lbs

The coal CO2 figures are net over all the old coal plants in the US. I understand the new supercritical coal plants do much better.

 

[mheslep]

Ok, I guess - I've just never heard someone claim that trading oil for coal was a good thing!

Not for the long term, and not all of the oil would replaced with coal of course. Replace just half of the oil with coal, the rest is natural gas, nuke, etc.

The efficiency gains are probably more on the order of 1.3:1. A gas car is about 30% efficient and a power plant is about 45% efficient. The electrical transportation, storage, and usage is altogether about 85% efficient. Multiply that out and you get 30:38 or 1.3 A

Ok, I was talking tank-to-wheel, your figure is the more inclusive well-to-wheel which I agree is the one we want at the moment. However these advocates (Tesla) still show well-to-wheel efficiency of EV's at least 2x or 3x better than even small ICE cars.
http://www.teslamotors.com/efficiency/well_to_wheel.php
They rightly include petroleum well-to-station distribution losses, and using a natural gas 52.5% electric source.

 

[mheslep]

..In fact, if you have access to large amounts of direct sunlight such as in hot deserts, CSP is much cheaper and much more efficient than PV, and this will always be so, because mirror will always be cheaper than PV. ...

Always is a very long time. I think both CSP and PV will win out in combination. You're right of course about the cost of mirrors, but consider:
1. PV's are http://thefraserdomain.typepad.com/energy/solarconcentrating_pv/" , making the use of high efficiency PV's affordable
2. Other work's being done to essentially 'waveguide' bandshifted http://www.technologyreview.com/energy/21066/"
3. Projects like the space based solar power plan for mirrors focused on PVs.
4. The upper limit on PV efficiency is apparently http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V51-3VTFJVJ-16&_user=3938616&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=980826264&_rerunOrigin=google&_acct=C000061828&_version=1&_urlVersion=0&_userid=3938616&md5=2a2c22990ac5eae6adc6c2c8a4a98501", far beyond what any thermal heat cycle can do.

The advantage you mention of overnight heat storage in thermal CSP will hold off PV for awhile, but not forever I suspect.

 

[gloo]

Your point in the OP is absolutely correct and it is what I've said in other places in this thread: cars are going to be powered primarily by gas for the forseeable future, whether people like it or not. Efficiency legislation and stop-gap technologies like plug-in hybrids will help, but they don't change that reality. While we should promote reseach, we should put the bulk of our efforts into solving now the problems that can be solved now. And that means... That hypothetical world is not a pipe dream, it is a reality in France today, a nuclear fueled country. Nuclear does satisfy their needs cheaply and cleanly and can satisfy ours if we choose to do it. Sadly, this is only going to happen when the economics overcome the politics for nuclear power here.

Wait Russ, so you are saying that part of the equation to get off of gas for cars will be the use of Nuclear to create electricity for cars? Did you mean to create electric power to feed into cars at plug in stations? I am pretty sure you don't mean making hydrogen off some kind of electrolysis (not efficient). You think nuclear is abundant enough to significantly replace coal and nat gas? Not challenging you (you are way more of an expert) - just trying to clarify.

 

[Ivan Seeking]

Your point in the OP is absolutely correct and it is what I've said in other places in this thread: cars are going to be powered primarily by gas for the forseeable future, whether people like it or not. Efficiency legislation and stop-gap technologies like plug-in hybrids will help, but they don't change that reality. While we should promote reseach, we should put the bulk of our efforts into solving now the problems that can be solved now. And that means... That hypothetical world is not a pipe dream, it is a reality in France today, a nuclear fueled country. Nuclear does satisfy their needs cheaply and cleanly and can satisfy ours if we choose to do it. Sadly, this is only going to happen when the economics overcome the politics for nuclear power here.

But we'll have better options before that happens.

 

[Ivan Seeking]

I wasn't sure if this was linked or not.
http://www.exxonmobil.com/corporate/files/news_pub_algae_factsheet.pdf

What is described as an exhaustive two-year review of all alternative fuel options landed Exxon on Algae, which I have been pushing for three years now, btw.

 

[mheslep]

Your point in the OP is absolutely correct and it is what I've said in other places in this thread: cars are going to be powered primarily by gas for the forseeable future, whether people like it or not. Efficiency legislation and stop-gap technologies like plug-in hybrids will help, but they don't change that reality. While we should promote reseach, we should put the bulk of our efforts into solving now the problems that can be solved now. And that means... That hypothetical world is not a pipe dream, it is a reality in France today, a nuclear fueled country. Nuclear does satisfy their needs cheaply and cleanly and can satisfy ours if we choose to do it. Sadly, this is only going to happen when the economics overcome the politics for nuclear power here.

Going to all nuclear electrical power in the US would do little by itself to remedy the oil dependency and import problem. Oil primarily goes to transportation in the US.

 

[mheslep]

Following up on CO2 emissions from EVs vs conventional vehicles in https://www.physicsforums.com/showpost.php?p=2309271&postcount=75", page 8.

 

[mheslep]

...
4. The upper limit on PV efficiency is apparently 85%, far beyond what any thermal heat cycle can do...

Working link:
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V51-3VTFJVJ-16&_user=3938616&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1046943350&_rerunOrigin=google&_acct=C000061828&_version=1&_urlVersion=0&_userid=3938616&md5=a8c43418a43c3d5ccadc277290468c9e