<![CDATA[Grist - Comment Feed for Examining the IPCC’s ‘portfolio of technologies’]]> Grist Comment Feed en Comment #1 by bigTom http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 02:53:34 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/1 Beware of renewable nameplate capacity.

  Too often I see nameplate capacity of intermittent renewables used in place of capacity time capacity factor*. For instance in your 14 wedges you state that the 20GW of current wind displaces 20GW of fossil fueled power. It doesn't if the capacity factor is 35% (generous by the way), then it only displaces on average .35*20GW = 7GW. Similar computations apply to solar as well.

    Not all wedges are likely to have the same width -but perhaps I missed the your definition of a wedge.

   Some political horse trading is required. Liberals must trade off some things they find distasteful such as some nuclear wedges, in order to get more renewable, sequestration and conservation wedges.

* Capcity factor is the fraction of the named output capacity a plant averages over a period of time. For example a wind turbine which runs a quarter of the time at full power and otherwise is off would have a capacity factor of only 25%.

]]> Beware of renewable nameplate capacity.

  Too often I see nameplate capacity of intermittent renewables used in place of capacity time capacity factor*. For instance in your 14 wedges you state that the 20GW of current wind displaces 20GW of fossil fueled power. It doesn't if the capacity factor is 35% (generous by the way), then it only displaces on average .35*20GW = 7GW. Similar computations apply to solar as well.

    Not all wedges are likely to have the same width -but perhaps I missed the your definition of a wedge.

   Some political horse trading is required. Liberals must trade off some things they find distasteful such as some nuclear wedges, in order to get more renewable, sequestration and conservation wedges.

* Capcity factor is the fraction of the named output capacity a plant averages over a period of time. For example a wind turbine which runs a quarter of the time at full power and otherwise is off would have a capacity factor of only 25%.

]]> Comment #2 by Karen Street http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 03:45:52 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/2 IPCC pessimism

Note that none of the 177 analyses accepted by IPCC aims to keep the temperature increase below 2 C, only 6 aim for below 2.5 C,and that business as usual has worsened since the analyses were accepted.

Why do you say that liberals find nuclear wedges distasteful? Some liberals, yes, but a decreasing number. It does seem to be true that organizations considered liberal by themselves, such as environmental groups, oppose nuclear power.

I second the point on the difference between capacity and effective capacity--in the US, the capacity factor of rooftop solar is about 19-20%, in Europe it's going to be less. If CA achieves 3 GW in photovoltaics by 2017, the added reductions in greenhouse gases will be much less than if they built one 1.1 or 1.5 GW nuclear power plant. That is not to oppose new solar, it's just that some mistake 3 GW in solar as equivalent to two large nuclear power plants, when it's closer to half a smaller one.

Not every approach can be a wedge. I read increasing pessimism in scientific literature about the ability of trees planted today to sequester as much carbon as was thought a decade ago. Some approaches can supply more than one wedge, notably efficiency and nuclear power.

A Musing Environment

Karen Street

]]> IPCC pessimism

Note that none of the 177 analyses accepted by IPCC aims to keep the temperature increase below 2 C, only 6 aim for below 2.5 C,and that business as usual has worsened since the analyses were accepted.

Why do you say that liberals find nuclear wedges distasteful? Some liberals, yes, but a decreasing number. It does seem to be true that organizations considered liberal by themselves, such as environmental groups, oppose nuclear power.

I second the point on the difference between capacity and effective capacity--in the US, the capacity factor of rooftop solar is about 19-20%, in Europe it's going to be less. If CA achieves 3 GW in photovoltaics by 2017, the added reductions in greenhouse gases will be much less than if they built one 1.1 or 1.5 GW nuclear power plant. That is not to oppose new solar, it's just that some mistake 3 GW in solar as equivalent to two large nuclear power plants, when it's closer to half a smaller one.

Not every approach can be a wedge. I read increasing pessimism in scientific literature about the ability of trees planted today to sequester as much carbon as was thought a decade ago. Some approaches can supply more than one wedge, notably efficiency and nuclear power.

A Musing Environment

Karen Street

]]> Comment #3 by Rico http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 04:39:40 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/3 Capacity

In addition to making distinctions between "nameplate capacity" and "capacity factor" (which I agree is an important distinction), there is also the need to consider how much of the "capacity factor" meaningfully contributes to the grid load at any point in time. For lack of a better term, that's what I would call "effective capacity". For example, though a nuclear (or hydroelectric) plant can operate at near capacity essentially all the time, load requirements are variable over time. So either you have another source of dispatchable power and use the nuclear or hydroelectric plant to satisfy base load only, or its "effective capacity" will be lower than its "capacity factor". On the other hand, since solar capacity follows load requirements pretty well (and in the case of solar thermal, even better if it has heat storage), its "effective capacity" remains close to its "capacity factor".

Unfortunately, I don't know of any source of "effective capacity" statistics. But this paper discusses the issue with respect to solar thermal. Another point is that when (let's hope it's not "if") smart grid technology is meaningfully deployed, our current conceptions of "peak" and "off-peak" load distributions are likely to change dramatically. It seems to me that smart grid deployment is the very first rate-limiting step in our quest to make "unreliable" renewable power sources optimal.

]]> Capacity

In addition to making distinctions between "nameplate capacity" and "capacity factor" (which I agree is an important distinction), there is also the need to consider how much of the "capacity factor" meaningfully contributes to the grid load at any point in time. For lack of a better term, that's what I would call "effective capacity". For example, though a nuclear (or hydroelectric) plant can operate at near capacity essentially all the time, load requirements are variable over time. So either you have another source of dispatchable power and use the nuclear or hydroelectric plant to satisfy base load only, or its "effective capacity" will be lower than its "capacity factor". On the other hand, since solar capacity follows load requirements pretty well (and in the case of solar thermal, even better if it has heat storage), its "effective capacity" remains close to its "capacity factor".

Unfortunately, I don't know of any source of "effective capacity" statistics. But this paper discusses the issue with respect to solar thermal. Another point is that when (let's hope it's not "if") smart grid technology is meaningfully deployed, our current conceptions of "peak" and "off-peak" load distributions are likely to change dramatically. It seems to me that smart grid deployment is the very first rate-limiting step in our quest to make "unreliable" renewable power sources optimal.

]]> Comment #4 by sunflower http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 05:34:42 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/4 Solar not in the image of nuclear.

A square meter of solar concentrator is worth the same as burning a barrel of oil per year in sunny climates, and half that in cloudy climates.  The concentrator cost is $100-150/m^2 and lasts for 30 years.  The application is to displace fossil fuels for everything, including making power.  That is a very thick wedge.

]]> Solar not in the image of nuclear.

A square meter of solar concentrator is worth the same as burning a barrel of oil per year in sunny climates, and half that in cloudy climates.  The concentrator cost is $100-150/m^2 and lasts for 30 years.  The application is to displace fossil fuels for everything, including making power.  That is a very thick wedge.

]]> Comment #5 by bigTom http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 06:01:58 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/5 were still a minority

  I also consider myself to be a pronuclear liberal. But I don't feel like a fully accepted member of the club because of the high concentration of antinuclear people in the club. We still have a lot of "selling" to do among our choosen (political) tribe.

]]> were still a minority

  I also consider myself to be a pronuclear liberal. But I don't feel like a fully accepted member of the club because of the high concentration of antinuclear people in the club. We still have a lot of "selling" to do among our choosen (political) tribe.

]]> Comment #6 by Rico http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 06:27:43 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/6 Nuclear?

bigTom, I'm ambivalent to nuclear. Other than the obvious (the waste and security issues) part of the reason is the cost and the availability of critical components, like containment vessels. Those variables have to be projected over very long construction times. Meanwhile, have you looked into the potential of geothermal? In particular I mean "hot rock" (EGS) geothermal, or variants on the theme more applicable to "traditional" sites. Granted, hot rock geothermal is one of those technologies that require more R&D. But the level of R&D funding has thus far been pretty pathetic, so it's hard to tell how well better funding would pay off. But according to this study, the potential bang for the buck could be enormous.

I honestly don't understand why EGS is not more discussed and/or pushed more aggressively. Am I missing something? Can anyone help?

]]> Nuclear?

bigTom, I'm ambivalent to nuclear. Other than the obvious (the waste and security issues) part of the reason is the cost and the availability of critical components, like containment vessels. Those variables have to be projected over very long construction times. Meanwhile, have you looked into the potential of geothermal? In particular I mean "hot rock" (EGS) geothermal, or variants on the theme more applicable to "traditional" sites. Granted, hot rock geothermal is one of those technologies that require more R&D. But the level of R&D funding has thus far been pretty pathetic, so it's hard to tell how well better funding would pay off. But according to this study, the potential bang for the buck could be enormous.

I honestly don't understand why EGS is not more discussed and/or pushed more aggressively. Am I missing something? Can anyone help?

]]> Comment #7 by Jon Rynn http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 06:49:54 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/7 Rico, I don't understand it either...

...it just seems to fall between the cracks somehow, I don't know why.  I did a post on the potential of geothermal heat pumps, but that's a different technology.

]]> Rico, I don't understand it either...

...it just seems to fall between the cracks somehow, I don't know why.  I did a post on the potential of geothermal heat pumps, but that's a different technology.

]]> Comment #8 by amazingdrx http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 08:06:59 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/8 Left out the best

Yep Jon, they left out geo heat exchange heating and cooling of buildings (36% of GHG goes to heat and cool buildings), solar cogeneration (heat/electricty), smart grid and smart grid storage, and a few more.  Yikes.

These alone could cancel half of GHG emissions.

This needs serious ammendment!  Make ammends, step 13.  get on this IPCC.  Get radical.

http://amazngdrx.blogharbor.com/blog

]]> Left out the best

Yep Jon, they left out geo heat exchange heating and cooling of buildings (36% of GHG goes to heat and cool buildings), solar cogeneration (heat/electricty), smart grid and smart grid storage, and a few more.  Yikes.

These alone could cancel half of GHG emissions.

This needs serious ammendment!  Make ammends, step 13.  get on this IPCC.  Get radical.

http://amazngdrx.blogharbor.com/blog

]]> Comment #9 by Jon Rynn http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 08:38:18 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/9 My nominations for wedges

if you look at Joe's simpler description of wedges (which I'll use since I'm just a simple guy), there are many wedges that look like nonstarters -- the ccs ones, in particular, but also biofuels.  But there are several that look good to me:

cutting vehicle miles in half with mass transit/walkable communities

cutting building emissions by 25%.  Let's count 3 wedges here; I think you could make most buildings almost emissions free

I'm not sure what to make of the wind wedge, maybe you could get more than one, let's say one;

Same with solar

stop deforestation is one

improve soil is one

So, if we get 3 wedges out of buildings, that's actually eight wedges, and we need 7, if  I understand this properly.  Quite doable!

]]> My nominations for wedges

if you look at Joe's simpler description of wedges (which I'll use since I'm just a simple guy), there are many wedges that look like nonstarters -- the ccs ones, in particular, but also biofuels.  But there are several that look good to me:

cutting vehicle miles in half with mass transit/walkable communities

cutting building emissions by 25%.  Let's count 3 wedges here; I think you could make most buildings almost emissions free

I'm not sure what to make of the wind wedge, maybe you could get more than one, let's say one;

Same with solar

stop deforestation is one

improve soil is one

So, if we get 3 wedges out of buildings, that's actually eight wedges, and we need 7, if  I understand this properly.  Quite doable!

]]> Comment #10 by Rico http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 10:15:26 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/10 Color me confused

jromm: Confused commenters

While I'm sure all of us commenters appreciate how busy your schedule is. And while I'm also sure that at least many of us, to one extent or another, defer to your superior knowledge and/or experience, I'm equally sure that calling all of us "confused" with no attempt at subtlety or distinction doesn't help your cause much.

I'm trying hard to get in your camp, and probably will end up there (more or less), but you're not making it any easier. There's no sense in pissing people off for no reason, is there? I'm just saying.

]]> Color me confused

jromm: Confused commenters

While I'm sure all of us commenters appreciate how busy your schedule is. And while I'm also sure that at least many of us, to one extent or another, defer to your superior knowledge and/or experience, I'm equally sure that calling all of us "confused" with no attempt at subtlety or distinction doesn't help your cause much.

I'm trying hard to get in your camp, and probably will end up there (more or less), but you're not making it any easier. There's no sense in pissing people off for no reason, is there? I'm just saying.

]]> Comment #11 by Karen Street http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 10:18:46 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/11 But why hasn't any analysis shown it to be easy?

Jon,

You produced wedges that IPCC might not consider doable, not for an entire wedge.

The bottom line is that no peer-reviewed analysis accepted by IPCC gets us to a temperature increase of less than 2 C, even with earlier and more optimistic business-as-usual assumptions. None. Not any of them.

So we may not yet be at the point where we can reject solutions, if our goal is to keep temperature increase below 2 C.

There is non-peer reviewed analysis galore. But do we want to base our future on it?

Karen Street

]]> But why hasn't any analysis shown it to be easy?

Jon,

You produced wedges that IPCC might not consider doable, not for an entire wedge.

The bottom line is that no peer-reviewed analysis accepted by IPCC gets us to a temperature increase of less than 2 C, even with earlier and more optimistic business-as-usual assumptions. None. Not any of them.

So we may not yet be at the point where we can reject solutions, if our goal is to keep temperature increase below 2 C.

There is non-peer reviewed analysis galore. But do we want to base our future on it?

Karen Street

]]> Comment #12 by Sean Casten http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 11:09:14 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/12 Don't assume all options are in those wedges

I love Socolow's wedge concept, if only because it breaks the goal up into manageable slices.  However, their great disadvantage is that they suggest that the universe of our options is to be found within those wedges... which simply isn't true.  Note that none of those wedges capture improved power generation efficiency (which have the potential to lower CO2 emissions by 20%, if all we do is return to 1910 efficiency levels).  

There may be other options as well - but it bears keeping in mind that once we finally get serious about lowering GHG emissions, we'll find a lot of opportunities that we didn't previously know were out there.  Put a price on carbon and markets will respond in unpredictable ways - and one doesn't therefore need to know the universe of possible options to be able to say categorically that there are more options than will be dreamt of in our philosophies... and therefore, the task ahead of us is not as hard as we think.  But for God's sake, let's get started!

]]> Don't assume all options are in those wedges

I love Socolow's wedge concept, if only because it breaks the goal up into manageable slices.  However, their great disadvantage is that they suggest that the universe of our options is to be found within those wedges... which simply isn't true.  Note that none of those wedges capture improved power generation efficiency (which have the potential to lower CO2 emissions by 20%, if all we do is return to 1910 efficiency levels).  

There may be other options as well - but it bears keeping in mind that once we finally get serious about lowering GHG emissions, we'll find a lot of opportunities that we didn't previously know were out there.  Put a price on carbon and markets will respond in unpredictable ways - and one doesn't therefore need to know the universe of possible options to be able to say categorically that there are more options than will be dreamt of in our philosophies... and therefore, the task ahead of us is not as hard as we think.  But for God's sake, let's get started!

]]> Comment #13 by Jon Rynn http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 11:19:12 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/13 Karen, what's up with the journals?

I mean, I don't edit a peer-reviewed journal.  They could have a special issue, many special issues (I once actually edited a special issue of an IEEE social issues journal).  They can do it.  They should do it.

Sean, the more people can propose "wedges", the better.  I agree that the market may come up with some unknown alternatives -- I certainly hope so -- we should also think about policies to implement the known wedges.  And hey, figure out a chp-type wedge!

]]> Karen, what's up with the journals?

I mean, I don't edit a peer-reviewed journal.  They could have a special issue, many special issues (I once actually edited a special issue of an IEEE social issues journal).  They can do it.  They should do it.

Sean, the more people can propose "wedges", the better.  I agree that the market may come up with some unknown alternatives -- I certainly hope so -- we should also think about policies to implement the known wedges.  And hey, figure out a chp-type wedge!

]]> Comment #14 by Sean Casten http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 11:24:44 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/14 Jon

My point is a bit larger - I'm not suggesting that with the addition of one more wedge we'd have it, but rather that no matter how smart the dude, s/he can't come up with all the ideas that a marketplace of dumb actors will come up with on their own.  The "chp wedge" as you put it - but more broadly, just the generation-efficiency wedge - is a good example, but only as a specific example.  Ask Joe-on-the-street what we can do to address AGW, and you'll more or less get all the options in the wedges, in one form or another.  Conservation.  Better fuel economy.  More nuke.  CCS.  But Joe-on-the-street will miss the same thing that the Princeton professors miss: namely, the massive inefficiency of our power sector.  We assume it's ideal, when it's the opposite.  

And yeah, I rant on this all the time only because it's in the little slice of the AGW world that I really get.  Which makes me wonder how much else is out there that we simply haven't thought of.  After all, missing a 20% slice is pretty huge...

]]> Jon

My point is a bit larger - I'm not suggesting that with the addition of one more wedge we'd have it, but rather that no matter how smart the dude, s/he can't come up with all the ideas that a marketplace of dumb actors will come up with on their own.  The "chp wedge" as you put it - but more broadly, just the generation-efficiency wedge - is a good example, but only as a specific example.  Ask Joe-on-the-street what we can do to address AGW, and you'll more or less get all the options in the wedges, in one form or another.  Conservation.  Better fuel economy.  More nuke.  CCS.  But Joe-on-the-street will miss the same thing that the Princeton professors miss: namely, the massive inefficiency of our power sector.  We assume it's ideal, when it's the opposite.  

And yeah, I rant on this all the time only because it's in the little slice of the AGW world that I really get.  Which makes me wonder how much else is out there that we simply haven't thought of.  After all, missing a 20% slice is pretty huge...

]]> Comment #15 by Jon Rynn http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 11:52:02 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/15 There's a market and then there's markets...

...for instance, if you want denser, multi-use building, you can create incentives for those policies, without building the buildings (although I wouldn't mind some of that too).  Or, if you want buildings to be much more energy efficient and generate some of its own energy, same thing.  So there are rather broad areas, or "wedges", that can be targeted where it can still be left to the market to figure out the details.

By the way, saw an article in the N.Y. Times recently about gas "microturbines", that make sense for buildings with more than 60 people, so the article states.  Seems like a good deal for buildings, no?

]]> There's a market and then there's markets...

...for instance, if you want denser, multi-use building, you can create incentives for those policies, without building the buildings (although I wouldn't mind some of that too).  Or, if you want buildings to be much more energy efficient and generate some of its own energy, same thing.  So there are rather broad areas, or "wedges", that can be targeted where it can still be left to the market to figure out the details.

By the way, saw an article in the N.Y. Times recently about gas "microturbines", that make sense for buildings with more than 60 people, so the article states.  Seems like a good deal for buildings, no?

]]> Comment #16 by amazingdrx http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 13:51:31 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/16 Wrong

"Some political horse trading is required. Liberals must trade off some things they find distasteful such as some nuclear wedges, in order to get more renewable, sequestration and conservation wedges."

You are the ones who must compromise.  Nuclear power is a disaster in it's present state.

No more nukes until you admit the problems exist and redesign and prove the new designs take care of the problems.

We are not devestating the environment with our wedges, as you are.

http://amazngdrx.blogharbor.com/blog


]]> Wrong

"Some political horse trading is required. Liberals must trade off some things they find distasteful such as some nuclear wedges, in order to get more renewable, sequestration and conservation wedges."

You are the ones who must compromise.  Nuclear power is a disaster in it's present state.

No more nukes until you admit the problems exist and redesign and prove the new designs take care of the problems.

We are not devestating the environment with our wedges, as you are.

http://amazngdrx.blogharbor.com/blog


]]> Comment #17 by amazingdrx http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 14:02:02 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/17 Capacity factor?

Was that the confusion you were talking about Joe?

I think so Rico.  Big nuke..er tom made the mistake, as he mistakenly supports nuclear power that is understandable.  Massive confusion of the Brand/Lovelocke variety.

Nuclear advocates can't wait to shuffle through their anti-renewables talking points.

Low capacity factor, intermittent (needing 100% backup),  expensive, dangerous (millions have been killed building wind towers!), and so forth.  It's radioactive exposure that makes them exagerate, hehey.

http://amazngdrx.blogharbor.com/blog

]]> Capacity factor?

Was that the confusion you were talking about Joe?

I think so Rico.  Big nuke..er tom made the mistake, as he mistakenly supports nuclear power that is understandable.  Massive confusion of the Brand/Lovelocke variety.

Nuclear advocates can't wait to shuffle through their anti-renewables talking points.

Low capacity factor, intermittent (needing 100% backup),  expensive, dangerous (millions have been killed building wind towers!), and so forth.  It's radioactive exposure that makes them exagerate, hehey.

http://amazngdrx.blogharbor.com/blog

]]> Comment #18 by Des Emery http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/ Thu, 10 Apr 2008 15:08:02 -0700 http://www.grist.org/article/the-technologies-needed-to-beat-450-ppm-part-1/18 450 ppm

Just a couple of comments --  it's a good thing to have a destination in mind when you plan a trip and you have all the time in the world to think deeply about it.   But when you're running from a fire or a flood, you don't really care which way is the road to the promised land, you just get the hell out.

So instead of arguing about which 'wedge' is the most appropriate, why not just get busy and build them all. Before catastrophe (Global Warming) arrives with a vengeance.

And for electricity,whether wind or solar or nuclear sourced, build a grid that will accept input from all producers and provide output for all users, letting the electrons surge back and forth as required, so there is no 'up' or 'down' time involved.  

Des Emery

]]> 450 ppm

Just a couple of comments --  it's a good thing to have a destination in mind when you plan a trip and you have all the time in the world to think deeply about it.   But when you're running from a fire or a flood, you don't really care which way is the road to the promised land, you just get the hell out.

So instead of arguing about which 'wedge' is the most appropriate, why not just get busy and build them all. Before catastrophe (Global Warming) arrives with a vengeance.

And for electricity,whether wind or solar or nuclear sourced, build a grid that will accept input from all producers and provide output for all users, letting the electrons surge back and forth as required, so there is no 'up' or 'down' time involved.  

Des Emery

]]>