Nuclear power won't fix the energy problem

[GTrax]

Thanks Ivan
(I didn't know much about the algae)

That is just about all that algae does. It absorbs CO2 and water to make a high quality fuel, using the energy from sunlight. It can be used to make ethanol, biodiesel, or hydrogen, but for now biodiesel is the best option.

The key thing there is that at some stage, the algae receives energy from sunlight., and does something convenient.

So OK, we can expose algae farms to sunlight to do something convenient (take up CO2 put out by all the worlds naughty furnace burners and power stations and transport, and leave stuff that can be changed to fuel.). That is admirably logical, but I cannot shake off my emotional attachment to trees, and grasses, and crops, and teeming bio-diversity of pests and insects and little animals all presumably unfeasible in our brave new world of "let's grow our fuel"

 

[mheslep]

I know solar cells aren't a battery. I meant to ask which was more efficient at converting solar energy to a useable form (electricity/chemical), which you answered anyways. (Has an actual comparison been done though?)

Yes. Maximum possible efficiency of chemical energy capture via photosynthesis is 20-25%, I suspect Algae is the only player that can come anywhere close to that. Then note that energy is conveniently stored chemically until you need it, though when you do use the energy it will be via some heat engine and you will waste half at that time. Photovoltaic efficiency has been at ~12% for many years, and is just now commonly commercially available at 22%. Much more expensive (6 figures for a couple M^2) multi-band PVs such as the ones used on the Mars rovers pull >40%. And, there is research ongoing now using quantum dots that should achieve 60%. Solar is not 'stored', as has been stated many times here, unless its fed into a battery or other such device. However, if you do store the power in a battery you'll only waste 10-15% when using it later in a battery-electric motor system such as for a vehicle, vs 50% when burning fuel in a combustion engine.

 

[vanesch]

Yes. Maximum possible efficiency of chemical energy capture via photosynthesis is 20-25%, I suspect Algae is the only player that can come anywhere close to that.

I have no clue, but I'm amazed by that figure. So I googled a bit and I found this:
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VRV-4S9R4K5-2&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=d5765c1c54a03be6b821c39433029323

Abstract:

Photosynthesis is the source of our food and fiber. Increasing world population, economic development, and diminishing land resources forecast that a doubling of productivity is critical in meeting agricultural demand before the end of this century. A starting point for evaluating the global potential to meet this goal is establishing the maximum efficiency of photosynthetic solar energy conversion. The potential efficiency of each step of the photosynthetic process from light capture to carbohydrate synthesis is examined. This reveals the maximum conversion efficiency of solar energy to biomass is 4.6% for C3 photosynthesis at 30 °C and today's 380 ppm atmospheric [CO2], but 6% for C4 photosynthesis. This advantage over C3 will disappear as atmospheric [CO2] nears 700 ppm.

and:

http://www.fao.org/docrep/w7241e/w7241e05.htm#1.2.1 photosynthetic efficiency

The net result being an overall photosynthetic efficiency of between 3 and 6% of total solar radiation.

Adding a factor of about 1/3 for the Rankine cycle (steam cycle), we obtain finally of the order of 1 - 2 % solar efficiency. (1/2 is very optimistic, it is only reached in combined gas turbine - steam cycle plants)

 

[B. Elliott]

Hopefully I have explained my thinking in the post above. We don't have to have additional CO2 [beyond ambient] to grow algae, but it may help to get the industry started by making it more economical. Ultimately, if we can produce cost competitive fuels from algae using only ambient CO2, the fuel becomes carbon neutral - we only release into the atmosphere the carbon that was absorbed from it in order to grow the algae. So at that point we are not releasing any "new" CO2.

How much algae would be required, acreage-wise, to be a sufficient amount which could be used to produce power for cities and automobiles to drive off of? How quick is the return? ie; can the algae grow quick enough to maintain a steady supply considering the new found demand?

 

[vanesch]

That is admirably logical, but I cannot shake off my emotional attachment to trees, and grasses, and crops, and teeming bio-diversity of pests and insects and little animals all presumably unfeasible in our brave new world of "let's grow our fuel"

For sure I hope they will do this off-shore !

 

[NeoDevin]

So a solution to energy problems, through strictly solar power, could be to have PV, with an algae-oil backup. The oil is produced in relatively small quantities at all times, but only burned when the PV cannot keep up with demand. Combine this with spreading PV across large areas to minimize fluctuations (has the entirety of north america ever been completely cloud covered?) and it could be feasible.

So we don't need enough oil production to cover our entire energy needs at all times, just enough to cover the times when PV cannot keep up.

 

[vanesch]

So we don't need enough oil production to cover our entire energy needs at all times, just enough to cover the times when PV cannot keep up.

Which is more than half of the time: at night, and in winter, solar is way below average production.

This is the question I ask then: if you have in any case to foresee more than 50% of provision with another technology, why bother with PV ?

 

[GTrax]

100,000 tons of Algae!
Arrived in late May and covers 13,000 sq km.

Pictures can be had http://news.bbc.co.uk/1/hi/world/asia-pacific/7482791.stm"

On the news, it was said the algae growth was driven by "pollution". There are 10,000 Chinese put to dispose of this stuff in time for a sporting event. Thats lots of carbon locked up in 100,000 tons of plant that got there by doing its biology thing with sunlight over an impressive area of ocean!

For sure I hope they will do this off-shore !

We did not have to ask it to do this. It did not require technology investment, capital growth or shareholder payoff. No matter the efficiency of the medium does not match the best we put on a Mars rover, it makes up for it It by using 5000 sq miles. We could burn it, and feel smug about being carbon neutral, or ferment it and make something smelling much sweeter to run our cars on, or we can leave it out there to make its contribution to undoing our damage. Is anyone allowed to be "Carbon Non-Neutral" ?

EDIT: Sorry - the 100,000 tons was what had already been removed. It seems the total is much more!

 

[Ivan Seeking]

For sure I hope they will do this off-shore !

Yes, and when one factors in the number of Hs needed to make a fatty acid, the logic of using salt-water algae is apparent.

Consider for example one common unsaturated fatty acid found in algae oil, Linoleic acid:
CH3(CH2)4CH=CHCH2CH=CH(CH2)7COOH

This is one of the acids that is transesterified to make biodiesel.

In order for the alga to make each molecule of the fatty acid, we need, what, 32 hydrogens, so 16 water molecules.

I don't think this rules out land-based or fresh-water systems altogether as there as places that have plenty of water, but we certainly don't want algae competing with humans, livestock, and food farming, for clean water. So it seems that some land-based systems makes sense, but in the end, we want to use salt-water.

 

[Ivan Seeking]

100,000 tons of Algae!
Arrived in late May and covers 13,000 sq km.

Pictures can be had http://news.bbc.co.uk/1/hi/world/asia-pacific/7482791.stm"

On the news, it was said the algae growth was driven by "pollution". There are 10,000 Chinese put to dispose of this stuff in time for a sporting event. Thats lots of carbon locked up in 100,000 tons of plant that got there by doing its biology thing with sunlight over an impressive area of ocean!


We did not have to ask it to do this. It did not require technology investment, capital growth or shareholder payoff. No matter the efficiency of the medium does not match the best we put on a Mars rover, it makes up for it It by using 5000 sq miles. We could burn it, and feel smug about being carbon neutral, or ferment it and make something smelling much sweeter to run our cars on, or we can leave it out there to make its contribution to undoing our damage. Is anyone allowed to be "Carbon Non-Neutral" ?

EDIT: Sorry - the 100,000 tons was what had already been removed. It seems the total is much more!

We need to be careful about the energy spend to collect the algae, but yes, if we just burn the biomass we are way ahead of the game. Algae has been doing precisely what we need since long before we humans ever arrived on the scene with our campfires.

 

[Ivan Seeking]

In summary, if it takes you 10 years to switch everything (electricity + transport) to algae biofuel, then go ahead.

Clean and highly efficient diesel cars are already popular in Europe, and with the ultra-low sulfur fuels now required in the US, we can run diesel cars here. [note that biodiesel contains no sulfur]. In fact we are now seeing diesel pumps at most filling stations, which is new. We already have a large demand from the transportation industry for biodiesel, and even some of the more reserved claims by people working to solve specific problems with algae, are landing in the 5 years range. So it appears that everything is already in place. Meanwhile, some experts are predicting that crude will hit $200 by July, next year.

If it takes you 40-50 years, then I'd give preference to algae for transport, and nuclear for electricity, because otherwise we will still have 3 or 4 decades of coal ahead.

Forty years ago, when I was a kid, it was all but a foregone conclusion that by now we would have practical electric cars running on fusion power; and flying cars for that matter! But the point is that we can't count on any future technology to save us from the plight of oil. And even if we eventually see an electric battery that makes electric cars practical [we have no gaurantee that will EVER happen] we still don't know that it will ever be possible to fly planes and power trucks on electric power. The only other option for this would be to burn hydrogen produced using nuclear power, but this will not be possible for decades because we don't have the power or the infrastructure for hydrogen. However, jet aircraft have already been flown, and many commercial trucks are now running on biodiesel.

This is what I hadn't figured out.

Yes, I realized that I getting ahead of myself a bit and not mentioning critical details.

 

[Ivan Seeking]

Oh yes, but for closed systems - for power generation and not fuel production - we reclaim the water from the exhaust stream of the burning algae biomass, so in principle we don't need water beyond the initial charge of the system. We [in principle] have nothing but sunlight going in, and electric power coming out.

...So if we compare this to PV, I think it utimately comes down to the cost per square mile for solar cells, as opposed to the cost per square mile for algae bioreactors, the efficiencies, the maintenance costs, the lifespan, and the ability to recycle the components of the systems. As for cost, we see numbers ranging from ~ $2 to $200 per sq. foot for bioreactors.

 

[vanesch]

Clean and highly efficient diesel cars are already popular in Europe, and with the ultra-low sulfur fuels now required in the US, we can run diesel cars here. [note that biodiesel contains no sulfur]. In fact we are now seeing diesel pumps at most filling stations, which is new.

I wasn't talking about the distribution or the cars: that's one of the evident advantages of biodiesel, that it will require few if any modifications to the current way of using fuel for transport. (btw, I'm surprised: I have seen diesel pumps in filling stations, and diesel cars since I was a kid). This is THE big advantage of the biofuel approach. No, the time scale I was talking about was to set up such an amount of practical and economical production of biofuel that it can essentially replace about all oil consumption (which is indeed essentially for transport, and also for heating, which can also be done transparently), and that on top of that there is sufficient economical growth to start replacing electricity production on large scale. Because, promising as it may seem, I still want to see it done on such a large scale.

I was saying that if there is an "upper limit" on the practice of making biofuel for everything in 10-15 years time, and if the horizon of practical large scale electricity production by biofuel, after already having replaced mineral oil about everywhere, is more on the 40 years time scale, or if there are more fundamental problems to going to such large scales which put this to an undefined time horizon then it might still be useful to switch from coal to nuclear in the mean time.

Forty years ago, when I was a kid, it was all but a foregone conclusion that by now we would have practical electric cars running on fusion power; and flying cars for that matter! But the point is that we can't count on any future technology to save us from the plight of oil. And even if we eventually see an electric battery that makes electric cars practical [we have no gaurantee that will EVER happen] we still don't know that it will ever be possible to fly planes and power trucks on electric power. The only other option for this would be to burn hydrogen produced using nuclear power, but this will not be possible for decades because we don't have the power. However, jet aircraft have already been flown, and many commercial trucks are now running on biodiesel.

I agree. But again, let's see the speed and the growth potential: we're still talking about a technology in its infancy ; hopefully the biofuel will not be the new fusion power of 40 years ago, which didn't keep its promises. As I said, if we can go to this biofuel for transportation and other uses of oil, that would be great, but it is a challenge of scale. I'm absolutely not arguing for electric cars, it would be a major change and it also has a lot of technological challenges. The electric car, however, has had another problem, which might now be undone: the very cheap and reliable car on petrol. There was simply no market incentive. Expensive oil might change this. But if biofuel comes along, then that can solve the issue also.

I've always been against biofuels because I always saw them competing for the same resources as other human needs, like water and agriculture. I found this an extremely dangerous path to walk. But given that this problem isn't the case with this algae thing, I really like it. But again, one still has to show how it will work out on large scale. Nuclear is to me the proven technology that can help us out with electricity ; I don't think that there is much promise in the hyped PV or wind at this point, for which to me the main difficulty which remains unsolved is the intermittency - even apart from its price. Maybe biofuels can also be a competing technology for electricity production, and if in the near enough future they prove to be a better technology, then I'm all for it, and I'm willing to put nuclear aside. But first, replace oil already. We'll see after that. At least, biofuels don't seem to have a fundamental difficulty such as intermittency, and CAN be seen as a real solution to electricity production. I have to say it is the FIRST time I see another potentially realistic solution, apart from nuclear, to produce electricity without restriction, in large quantities, when demanded. It is time to stop harassing people to "economize" electricity: it should flow in large and cheap quantities. Nuclear can do that, and if bio fuel can do that, then it is the first worthy competitor of nuclear in that respect, which might win the competition. Future will tell. Maybe one should seriously rethink the current fashion for PV and wind turbines, which have in any case not the potential to bring a serious solution in the next decades.

 

[Ivan Seeking]

I wasn't talking about the distribution or the cars: that's one of the evident advantages of biodiesel, that it will require few if any modifications to the current way of using fuel for transport. (btw, I'm surprised: I have seen diesel pumps in filling stations, and diesel cars since I was a kid). This is THE big advantage of the biofuel approach. No, the time scale I was talking about was to set up such an amount of practical and economical production of biofuel that it can essentially replace about all oil consumption (which is indeed essentially for transport, and also for heating, which can also be done transparently), and that on top of that there is sufficient economical growth to start replacing electricity production on large scale. Because, promising as it may seem, I still want to see it done on such a large scale.

No doubt, until we see the application at scale, we can't know with absolute certainty that it can work; or really how long it will take to be competitive. Obviously I am greatly inclined to think it can be competitive soon if we are smart and practical about things, but there is one big difference between this and many failed options: The fuel is there. This is not a problem of fundamentals or energy density, it is merely a matter of solving practical problems. For this reason I stongly urge that this is where we should put our greatest efforts.

As for the motivation and the ability to do this quickly, I am counting on the over 1/2 trillion dollars that will be added to our economy annually by displacing foreign oil. If you want to get something done quickly, offer Americans lots of money.

Btw, my avatar is a picture of a couple of algae cells with the pockets of oil stained red.

I must go to bed now.

 

[Ivan Seeking]

Damn, okay, one more thing: If the Chinese would just burn all of that algae for steam powered generators, I think we would have our first crude example operation at scale, for power.

 

[Dale]

In return they hoped to get carbon credits.

No, in return they hoped to sell carbon credits.

By the way, I grabbed the newest popular science magazine because it had an interesting "eco-tropolis" story. It mentioned an interesting idea I had not considered. Use nuclear power and air to synthesize liquid fuels. No estimates on price per barrel where it would be competitive using existing technologies, but I thought it was an interesting idea.

Anyway, Ivan, what do you consider "the energy problem"? Are you principally concerned about the environmental or economic impact. I am personally more concerned about the economic impact, but I think that nuclear power helps on both fronts.

 

[Ivan Seeking]

No, in return they hoped to sell carbon credits.

You can't sell what you don't have.

By the way, I grabbed the newest popular science magazine because it had an interesting "eco-tropolis" story. It mentioned an interesting idea I had not considered. Use nuclear power and air to synthesize liquid fuels. No estimates on price per barrel where it would be competitive using existing technologies, but I thought it was an interesting idea.

Perhaps, but I have seen no evidence that this can be practical.

Anyway, Ivan, what do you consider "the energy problem"? Are you principally concerned about the environmental or economic impact. I am personally more concerned about the economic impact, but I think that nuclear power helps on both fronts.

I am concerned about the environment and the economy, but I am most concerned about the oil supply. Already the impact of the current price of crude ripples through, the economy, and through society generally - from the price of food to reduced air travel, from riots and protests globally to the closing of 600 Starbucks in the US. Not only is the supply of oil critical to our way of life, our standard of living also depends on the price of oil. Long before peak oil poses problems through shortages, the price of oil could not only change our lives forever, but it may well lead to global conflicts, as well as civil unrest.

The need for oil is far more dangerous than religious radicals because every country in the world needs oil.

Even going way back: The attack on Pearl Harbor was rooted in oil.

 

[Ivan Seeking]

I have to wince every time McCain et al tries to link nuclear power to the oil problem. It shows a fundamental lack of understanding of the problem.

 

[rewebster]

hey, Ivan---what's the biggest algae/oil project so far in the way of an ongoing production per day?

 

[Ivan Seeking]

I don't know. Almost all work being done is proprietary, and most people are working on specific aspects of production problems. It is fairly easy to produce mass quantities of algae, but the challenge is to develop economical and practical solutions for production at scale.

 

[rewebster]

well, they (we) need to find the best algae for oil production, a bacteria that feeds off of the dead algae that also produces oil (at night), another bacteria that feeds off of both of those that produces hydrogen, then a solar cell on the bottom of the algae/bacteria tank that uses the rest of the sunlight that the algae doesn't use.

did I miss anything?

(oh, yeah, it uses coal furnace gas, all of it is edible and safe to drink)

 

[mheslep]

I have to wince every time McCain et al tries to link nuclear power to the oil problem. It shows a fundamental lack of understanding of the problem.

In what sense? There's plenty of evidence that considerable oil usage can be displaced by electric power. Just a 10-20% reduction in US oil usage would relieve the price pressure.

 

[Ivan Seeking]

...we...

MIT is working on algae based hydrogen. So it would appear that algae allows us to not only solve the immediate problem, but also to take the next step to a hydrogen economy.

But you are correct in pointing out that algae may only be a part of the equation. There is promising work going on in many areas, including work with bacteria. Biocrude looks very promising.

 

[Ivan Seeking]

In what sense? There's plenty of evidence that considerable oil usage can be displaced by electric power.

How?

 

[rewebster]

OK--most (maybe) of the oil is from algae--------I wonder what percentage of coal is (may be) algae?

 

[Ivan Seeking]

Even if we ignore the projections for supply, we can see what happens to demand.

http://wwotext.blogspot.com/2007/05/world-oil-supply-and-demand-projections.html

 

[rewebster]

Even if we ignore the projections for supply, we can see what happens to demand.

http://wwotext.blogspot.com/2007/05/world-oil-supply-and-demand-projections.html

if that's even halfway close guess from 2005, and you look at 2008 (a shortfall already projected then) and the prices now at 2008---then look around 2012 to 15 for the 'shortfall' dropping off even more--I wonder what the price of oil is going to be then?

 

[Dale]

I am concerned about the environment and the economy, but I am most concerned about the oil supply. Already the impact of the current price of crude ripples through, the economy, and through society generally

Then you cannot ignore or dismiss nuclear power. The solution to the oil crisis is not dependency on another single fuel, but diversification of our transportation sector energy needs. We need to have fossil fuels, biofuels, nuclear, and other energy sources all competing with each other for at least a portion of the transportation sector. Even if each alternative technology is only a small niche and petroleum still dominates it will still greatly impact the marginal elasticity of demand.

 

[Ivan Seeking]

Then you cannot ignore or dismiss nuclear power. The solution to the oil crisis is not dependency on another single fuel, but diversification of our transportation sector energy needs. We need to have fossil fuels, biofuels, nuclear, and other energy sources all competing with each other for at least a portion of the transportation sector. Even if each alternative technology is only a small niche and petroleum still dominates it will still greatly impact the marginal elasticity of demand.

You are missing the essential point: We have no alternative to oil because we have no battery to make electric cars practical. I have been waiting for the promise of an effective battery, which has been just beyond the horizon, for forty years now. We have no more time to wait.

 

[Dale]

You are missing the essential point: We have no alternative to oil because we have no battery to make electric cars practical.

Sure we do. Plug-in hybrids already exist. Commuter transportation could be entirely serviced by electricity with existing battery technology.

I would encourage widespread adoption of existing flex-fuel and plug-in technology to diversify our energy options.

 

[Ivan Seeking]

Sure we do. Plug-in hybrids already exist. Commuter transportation could be entirely serviced by electricity with existing battery technology.

Not even close. Some commuters who only need a small amount of energy for commuting could use electric from hybrids, but battery technology is far too limited for most commuters. That is precisely why, in his misguided attempt to improve the situation, McCain is calling for a 300 million dollar prize for an effective battery. Of course this makes no sense because the market would more than reward any company that could make an effective battery for electric cars. Or are you arguing that McCain is completely fabricating the need for such technology? What's more, anyone who only needs the little bit of energy stored in batteries should use public transportation, rather than running a hybrid.

And we have yet to consider the cradle to grave energy costs of hybrids and all of those dirty batteries, which have a short lifespan. Standard lead-acid batteries ars good for about 1000 charge cycles if we only discharge to about 60% of capacity with each cycle.

 

[Ivan Seeking]

I recently did a project where we needed to store enough energy in batteries to produce about 7HP for 20 minutes. It took 8 large truck batteries.

Most cars can produce at least 100 HP.

The electric grid is already facing problems in both supply, and infrastructure.

 

[Ivan Seeking]

North America's world-class electric system is facing several serious challenges. Major questions exist about its ability to continue providing citizens and businesses with relatively clean, reliable, and affordable energy services. The recent downturn in the economy masks areas of grid congestion in numerous locations across America. These bottlenecks could interfere with regional economic development. The "information economy" requires a reliable, secure, and affordable electric system to grow and prosper. Unless substantial amounts of capital are invested over the next several decades in new generation, transmission, and distribution facilities, service quality will degrade and costs will go up. These investments will involve new technologies that improve the existing electric system and possibly advanced technologies that could revolutionize the electric grid.

http://www.energetics.com/gridworks/grid.html

Climate change and rolling blackouts may be a package deal. More frequent and intense heat waves expected in California over the next 100 years could overburden the state’s electric utility grid, according to a study led by scientists in the U.S. Department of Energy’s Lawrence Berkeley National Laboratory.[continued]

http://www.physorg.com/news6593.html

And then there is the issue of water

California Looks to Desalination for Water Woes
by Amy Standen

Listen Now add to playlist

All Things Considered, August 25, 2007 · Desalination plants used to be found only in oil-rich countries like Saudi Arabia. Now, as water becomes an ever more precious resource in California, proposals for 18 desalination plants are being studied by local officials from San Diego to Marin County. The largest would be in the Bay Area. [continued]

http://www.npr.org/templates/story/story.php?storyId=13950883

So, what is sillier than piping water 1000 miles to keep the fountains at Disneyland flowing? Well, desalination, of course… Desalination uses even more energy than piping water from Northern to Southern California, 4,000 kWh/Acre-foot (3.24 Wh/liter). This is because desalination either uses reverse-osmosis filtration, essentially filtering ocean water by pumping water, at high pressure, through a membrane, or distillation, where water is evaporated and condensed. Both of these methods require a lot of energy for pumping and/or heating the water.[continued]

http://www.triplepundit.com/pages/askpablo-desalination-and-the--002579.php

 

[Dale]

Some commuters who only need a small amount of energy for commuting could use electric from hybrids

I think you are missing the economic point here. These "some commuters", even if they represent only a small portion of the total market, will have a great impact on the marginal price elasticity of demand. The only way the economic problem is solved is through diversification, and it doesn't take a lot to make a large impact.

the market would more than reward any company that could make an effective battery for electric cars.

That has only become true in the last few months. You, of all people, should know how economically unbeatable cheap oil has been for decades.

 

[mheslep]

Not even close. Some commuters who only need a small amount of energy for commuting could use electric from hybrids, but battery technology is far too limited for most commuters. ... What's more, anyone who only needs the little bit of energy stored in batteries should use public transportation, rather than running a hybrid.

And we have yet to consider the cradle to grave energy costs of hybrids and all of those dirty batteries, which have a short lifespan. Standard lead-acid batteries ars good for about 1000 charge cycles if we only discharge to about 60% of capacity with each cycle.

I recently did a project where we needed to store enough energy in batteries to produce about 7HP for 20 minutes. It took 8 large truck batteries.

Most cars can produce at least 100 HP.

The electric grid is already facing problems in both supply, and infrastructure.

We've been through all this.
https://www.physicsforums.com/showpost.php?p=1584293&postcount=12
Electric hybrid plug in vehicles are indeed very close; half a dozen models will come out in the next two years. They will be using Li Ion batteries. They have the energy density and the lifecycle. Nobody is proposing to use old tech lead acid batteries for electric cars. Edison tried and failed to make that work early in the last century. Li Ion has 5 to 8x the energy density of lead acid.
http://en.wikipedia.org/wiki/Energy_density and that's only comparing ones you can buy off the shelf right now. Lithium is not a heavy metal and is not near the threat to the environment (as lead acid). The issue at the moment is cost, as batteries are at the margin of economic viability. The US electric grid has plenty of spare capacity at night (day load ~100GW > night load) to charge a substantial commuter fleet, in fact the electric utilities are very interested in selling that currently unloaded night capacity.

Article on A123 - supplier for the Chevy Volt
https://www.technologyreview.com/read_article.aspx?ch=specialsections&sc=batteries&id=20570
"Plug-In Hybrids: Tailpipes vs. Smokestacks"
http://www.technologyreview.com/read_article.aspx?ch=specialsections&sc=transportation&id=20213

Since utilities have built enough power plants to provide electricity when people are operating their air conditioners at full blast, they have excess generating capacity during off-peak hours. As a result, according to an upcoming report from the Pacific Northwestern National Laboratory (PNNL), a Department of Energy lab, there is enough excess generating capacity during the night and morning to allow more than 80 percent of today's vehicles to make the average daily commute solely using this electricity. If plug-in-hybrid or all-electric-car owners charge their vehicles at these times, the power needed for about 180 million cars could be provided simply by running these plants at full capacity.