Infinite Underwater Energy

I am always on the lookout for novel energy sources that don’t have obvious knockout factors. I have kept vaguely abreast of developments around tidal energy, and it always seemed like this should be a very attractive option for the energy needs of coastal communities. I was present at an alternative energy presentation last year where I heard that the primary problem is that the tides tend to tear the equipment up. It has to be able to withstand the worst conditions it could possibly see, and in the ocean that can be pretty bad.

While this is a serious problem for tidal energy, this morning I spotted a different variation of this concept. I have heard this mentioned before, but this story really goes into detail. I will provide a few excerpts, but the entire article is worth a read:

Oceans Eyed As New Energy Source

DANIA BEACH, Fla. – Just 15 miles off Florida’s coast, the world’s most powerful sustained ocean current – the mighty Gulf Stream – rushes by at nearly 8.5 billion gallons per second. And it never stops.

To scientists, it represents a tantalizing possibility: a new, plentiful and uninterrupted source of clean energy.

Florida Atlantic University researchers say the current could someday be used to drive thousands of underwater turbines, produce as much energy as perhaps 10 nuclear plants and supply one-third of Florida’s electricity. A small test turbine is expected to be installed within months.

From Oregon to Maine, Europe to Australia and beyond, researchers are looking to the sea – currents, tides and waves – for its infinite energy. So far, there are no commercial-scale projects in the U.S. delivering electricity to the grid.

Because the technology is still taking shape, it is too soon to say how much it might cost. But researchers hope to make it as cost-effective as fossil fuels. While the initial investment may be higher, the currents that drive the machinery are free.

Of course there is always an element of hype in these sorts of stories (I can be quite nit picky about the word “infinite”), and until they actually start to install these turbines, it is unclear whether there are serious knockout factors.

There are still many unknowns and risks. One fear is the “Cuisinart effect”: The spinning underwater blades could chop up fish and other creatures.

I would think that could be solved with a grid at the entrance to the turbines. That would increase pressure drop a little, but should be able to keep out the fish.

The field is growing, but there have been growing pains:

The Federal Energy Regulatory Commission has issued 47 preliminary permits for ocean, wave and tidal energy projects, said spokeswoman Celeste Miller. Most such permits grant rights just to study an area’s energy-producing potential, not to build anything.

The field has been dealt some setbacks. An ocean test last year ended in disaster when its $2 million buoy off Oregon’s coast sank to the sea floor. Similarly, a small test project using turbines powered by tidal currents in New York City’s East River ran into trouble last year after turbine blades broke.

One analysis showed that the overall potential is less than 10% of current electricity usage, but different areas are going to want to apply different solutions. Maybe ocean currents in Florida, but perhaps solar in Nevada and Arizona, and wind in Oklahoma.

Roger Bedard of the Electric Power Research Institute said an analysis by his organization found that wave- and tide-generated energy could supply only about 6.5 percent of today’s electricity needs.

I asked a colleague who has expertise in this area what he thought, and he replied:

Had not seen, but have seen similar before.

Issues:

– Power density goes with v^3, may need very big kit if velocities low (the ever reliable web says 1-2 m/s for Gulf Stream whereas tidal can be somewhat higher (2.5m/s) at peaks BUT is not constant, while Gulf Stream is, hence better load factor, no need for off design point operation)

– Power is force x velocity, need lots of mooring force to restrain if velocities low – obviously you would go for high velocity areas

– Conversion of big forces going slowly to little forces going fast is pricey (x100 gearboxes are expensive) but there are good solutions around, including hydraulics and lower speed up combined with non synchronous generation (Multibrid are doing this for wind).

– Near surface, you cannot do more than about 1MW per unit without getting into blade tip cavitation, likely not a problem in Gulf Stream (just go deeper)

– None of this is impossible, just needs smart people, good engineering and time – energy payback is likely to be good (wind turbines pay back in less than one year) since electric power is the other side of the Carnot efficiency – every kWh is displacing at least 2kWh of gas, more like 3 of coal (but you knew that).

There are lots of tidal devices around – speeds tend to be a bit higher and resource is near coasts. The Gulf Stream near US seems to be the highest speed ocean current, likely a good place to start development.

It will be interesting to watch this technology develop.

42 thoughts on “Infinite Underwater Energy”

  1. Yeah, the word the reporter should have used is “inexhaustible”.

    Allow me to play Environmentalist Devils’ Advocate for a moment.

    Any energy taken out of the Gulf Stream necessarily diminishes, if not disrupts, the current. The Gulf Stream has been identified by some as a major factor in the climatic system. Tapping that energy in any big way is an intolerable climatic risk, and cannot be allowed.

    You know someone will raise this objection, before any major such project gets approved.

    By the way, has anyone made any progress on ocean thermal? I haven’t heard anything about that for years.

  2. Maintenance, and “bottom cleaning” is the killer.

    In no other alt-energy system do you such a range of tenacious organisms ready to colonize the working surfaces of your machine.

    People sometimes wave that with a glib “so clean it” … but I don’t think those people have seen the beards that boats or buoys can grow in a month or two.

  3. I don’t think those people have seen the beards that boats or buoys can grow
    Bah! Thats not a problem, barnacles are carbon sequestion! Where can I invest? 🙂

    I spent a lot of time researching OTEC and other off-shore ideas. OTEC has a common-sense flaw. With low gradient temperatures, the distance between the warm and cold points and the energy expended to transfer the working media become the obstacle. The gradient is too low and the cold/warm water too far apart for OTEC to generate significant power. The pilot plant built in the ’80’s in Hawaii has never been able to be energy positive, but they have created a bunch of cottage industries around the deep nutrient rich sea water.

    Apparently Titan has a mess of hydrocarbons. IMO keeping current turbines running in the Gulf Stream or pumping cold water 3000′ in an OTEC system with a 30 degree temp gradient have less technical difficulties than harvesting LNG from Titan.

  4. I’ve never been a fan of this. Solar seems much easier to deploy and scale. How large an area/volume of ocean would we have to fill up to generate 1 MW of power? What impact would this have on the marine biosphere? How could we possibly maintain it? How would we get the power back to where we need it?

  5. Odograph – I have a LOT of recent professional experience with big energy projects and fish, and dealing with NOAA. You are right about the environment. To keep stuff from growing on our intakes we had to dose every 8 hours with sodium hypochlorite. The deeper the water the more expensive to clean. The biggest problem would be fish impingement on the screens. Intake velociies must be less than 1 1/2 times the length of the fish per second in order for the fish to swim away. This sort of precludes fast turbines unless you back pulse to clean the fish off.

    On my project we had the science on our side (even internal NOAA memos agreed with us) but the NGOs made a big deal out of killing fish eggs and larvae and they got key people within NOAA to stonewall. If you have time I can show you a few thousand letters demonstrating how silly people can be.

    BTW – in my research I found that about 30% of the fish who go through power turbines in a hydro damn survive. What kills them is not the mechanical crushing so much but the change in pressure blows up their air bladder.

  6. larryd has got it right — taking large amounts of energy out of the Gulf Stream will have large environmental consequences.

    Here is what I can’t understand:

    One of the predictions from followers of the One True Faith of anthropogenic global warming is that melting of Arctic ice will interfer with ocean conveyor belts such as the Gulf Stream — therefore, the little people must be forced to live in poverty to prevent such a bad thing happening.

    Them someone comes out with an idea to interfer with those ocean currents directly — and the same people clap their hands & forget all about ocean conveyors.

    How can human beings be so intellectually inconsistent?

  7. I think a key question – and I don’t know the answer – is how much impact could you have on it? The amount of energy you pulled out might affect it far less than normal daily variations. Again, I don’t know, but it is also something I had thought about. (Just like a lot of wind turbines in an area have the potential to affect wind speed and increase local ground temperatures).

  8. Well obviously you’d stop building before you stopped the stream. Otherwise what’s the point?

    So what you are really asking is how many turbines would it take to hit declining returns?

    I’d guess a lot. Of course if you think “green jobs” for 100,000 scuba divers are a good idea … you can get them down there scrub, scrub, scrubbing turbine blades.

    King, in a river system wouldn’t the environmental question be how critical the “bottleneck” is to eggs & larvae?

    I drank 1Tsp of sodium hypochlorite per 5Gallons of water as a kid (on a long trip through mexico) so I’m not too afraid of that chemical itself … though for due diligence I suppose you had to look at the chlorinated hydrocarbons generated as it did its work.

    (Kinuachdrach, definitely work “the One True Faith of anthropogenic global warming” into every conversation. It makes you seem like so much less of a crank.)

  9. You know Robert you could spice things up a bit by grabbing a public domain image to head each story.

    Yeah, but that would probably increase my average 10 minute time to write an article by 30%. Who has that kind of time?

  10. There are a number of “inexhaustible” supplies of energy: Tides, the Sun, ocean currents, river currents, the earth’s magnetic field, atmospheric jetstreams, and geothermal just to name a few.

    The obstacle to all is the practicality and economics of tapping into them, and putting underwater turbines to tap the Gulf Stream would probably have more difficulties than most. How would you even anchor the turbines to the ocean floor several thousand feet below the surface, and how tall would the turbine masts have to be to put the blades in the optimum current of the Gulf Stream? (You could use thrusters to hold the turbines stationary against the current, but they would use more energy than the turbines could capture.)

    While the energy of the Gulf Stream is practically limitless and there to tap, I suspect the EROEI would make it highly impractical.

    Just think of all the water that flows past St Louis, Memphis, or Vicksburg every minute as the Mississippi flows to the Gulf. (12,000,000 to 42,000,000 cubic ft/min depending on season and how far south the measuring point. The Amazon is ten times that.)

    It seems it would cost less in energy invested and money spent to put turbines on the beds of the Mississippi and other great rivers, rather than in the Atlantic under the Gulf Stream.

  11. One analysis showed that the overall potential is less than 10% of current electricity usage, but different areas are going to want to apply different solutions. Maybe ocean currents in Florida, but perhaps solar in Nevada and Arizona, and wind in Oklahoma.

    That right there is absolutely the key to building a civilization that can live off of current solar income. A diversity of solutions will be essential. Unfortunately, the industrial mindset (in which all engineers, including myself, are trained) prefers single, uniform, one-size-fits-all answers.

  12. I wonder if the whole spinning blades thing isn’t just the wrong way to go about this.

    Aeroelastic flutter presumably still happens in water as it does in air (unless it’s a compressibility-related effect, which I don’t think it is). Perhaps an adaptation of the Windbelt (http://www.humdingerwind.com/windbelt.html) would be workable.

    I’m not enough of a fluids guy to really even give this one the giggle test, but I can see a couple of really notable advantages, just based on the form factor:
    1) No blades or major pressure changes, no fish kills.
    2) The ribbon moves constantly, so it hopefully doesn’t grow a beard. The rest of the hardware is at the endpoints, where flow doesn’t matter much, so maybe we don’t care if it gets hairy.
    3) Anchoring is easier, because the energy extraction is perpendicular to the flow. Drag should be low.

    Efficiency per belt is probably poor, so you might have to install lots of them, or multiple belts in series. Again, not a fluids guy, so I don’t know how much each belt would disrupt the flow for the one behind it. My intuition suggests, though, that the disruption would be much less than what you would see with a conventional rotary turbine/prop.

  13. I think a key question – and I don’t know the answer – is how much impact could you have on it? The amount of energy you pulled out might affect it far less than normal daily variations. Again, I don’t know, but it is also something I had thought about. (Just like a lot of wind turbines in an area have the potential to affect wind speed and increase local ground temperatures).

    Any energy take out of the system reduce the energy left in the system. (OK, I’m stating the obvious here, I know.) But the extraction system won’t be 100% efficient, and it will most likely introduce turbulence into the system. Given our state of ignorance, we simply don’t know where the boundary conditions are. I’m sure we could tap megawatts out of the stream down around Florida, with no risk. New York, on the other hand, I’m not so sure about.

    And I’ve seen the teasers for Dirty Jobs Buoy Cleaner episode, so I have a faint conception of what odograph is referring to.

    Calisoca, yes, I saw that article. If Bussard fusion pans out, it could be practical.

  14. If you get a belt fluttering … that might be a design that could be auto-cleaning (picture the belt drawn between blades/squeegees.

    ^
    prior art for anyone who needs to beat a patent later 😉

  15. larryd has got it right — taking large amounts of energy out of the Gulf Stream will have large environmental consequences.
    Good to see you are concerned about the environment, Kinuachdrach.

    But this is a non-issue. We’d do well to capture as much as 0.1% of the available energy, and the environmental impact (of the energy extraction part) would be of the same order.

    Just like a lot of wind turbines in an area have the potential to affect wind speed and increase local ground temperatures.
    Increased local ground temperature -> lower air pressure -> higher wind speeds to that location. A self-correcting system?

    And that’s assuming you can withdraw enough energy from the system to make a noticeable difference in the first place.

  16. I’m just a dumb engineer and my knowledge atmospheric science is next to nil, but why would raising temperature of a gas _lower_ the pressure?? PV = nRT and all that … seems like they go in the same direction.

  17. But this is a non-issue. We’d do well to capture as much as 0.1% of the available energy, and the environmental impact (of the energy extraction part) would be of the same order.

    Could you not make the same small effect argument about adding small amounts of carbon dioxide to the atmosphere?

  18. Could you not make the same small effect argument about adding small amounts of carbon dioxide to the atmosphere?

    No, and here’s why: The argument as it applies to extracting energy from the GS is a straight-up energy balance. (Ignoring concerns about disruption of habitat, migratory patterns, spawning, or other ecological considerations.) The extraction of a of energy is going to reduce the energy in the system by that amount. If the amount is a small percentage, it will likely have no effect. Energy is flowing in and out of the system continuously (as water movement), so there is no accumulative effect.

    CO2, on the other hand, impacts the planet’s radiation balance. Though that balance will fluctuate, it must average to zero over time or the planet will heat/cool. If you bias that balance consistently in one direction or the other, you’ll get warming or cooling. The difference will accumulate. And the total impact can be large even with a very small bias (e.g. 0.5watts/m^2) because the total area involved is so huge.

    Another way to look at it is this: In terms of mass, the Gulf Stream is an open control volume, while the planet is (essentially) a closed control volume. In the Gulf Stream, the mass from which you are extracting energy moves on, and new mass (with its energy balance recharged) takes its place. Energy moves in and out of the system via flow in amounts vastly greater than the energy extracted. On the planet, no such exchange is happening (at least, not at a relevant scale), and the system is dominated totally by the radiative balance. So if you mess with the balance, it accumulates.

    This is all pretty basic stuff, for an engineer.

  19. I’m just a dumb engineer and my knowledge atmospheric science is next to nil, but why would raising temperature of a gas _lower_ the pressure?? PV = nRT and all that … seems like they go in the same direction.
    Or so it seems. What happens outside is that warm air rises and is replaced by cool air from somewhere else as wind.

    Or, at least, that’s my theory.

  20. “East River Fights Bid to Harness Its Currents for Electricity” by Anthony DePalma in the New York Times on August 13, 2007:

    ***

    North of the bridge, black cables snake out of the churning surface of the East River. …

    Weeks after they were formally dedicated by Mayor Michael R. Bloomberg, six underwater turbines that turn the river’s currents into electricity have been shut down for repairs and a basic redesign. The East River’s powerful tides have been wreaking havoc with the giant turbine blades since the first two were installed in December.

    … Days after the first two turbines were lowered into the water, the East River’s powerful currents sheared off the tips of several blades about a third of the way down. New blades were ordered, made of a cast aluminum that theoretically would hold up better. …

    But the East River tides have proved too formidable even for the stronger blades, putting excessive strain on the bolts that hold them to the turbine hubs. To keep them from coming apart, all six of the 20-foot-tall mechanisms, which resemble ship propellers on masts, have been shut down for repairs and may not be back in operation until November.

    “The only way for us to learn is to get the turbines into the water and start breaking them,” said Trey Taylor, the habitually optimistic founder of Verdant Power.

    ***

  21. I think the lesson here is watch out for the hype. No energy supply system is going to be cheap, and none of them will be without environmental issues.

  22. Green – who would have thought adding a little CO2 to the atmosphere might be a problem? How do you know then that taking a little energy out of the gulfstream might have long term consequences.

  23. Kinuachdrach,
    “larryd has got it right — taking large amounts of energy out of the Gulf Stream will have large environmental consequences.”

    Doesn’t it rather depend on how large the avaliable energy is? Ultimate effency in energy extraction is less of a design goal when the energy source is huge.

    Hawkshaw,

    “How would you even anchor the turbines to the ocean floor several thousand feet below the surface, and how tall would the turbine masts have to be to put the blades in the optimum current of the Gulf Stream?”

    Why not use the same principal they use for drill ships – buoyancy? Multiple anchors on the bottom attached by cables to a buoyant structure far enough below the surface to eliminate most storm effects and navigation conflicts? You could probably do marine life removable and other maintenance at the surface by easing the cables. The working part could be detached and floated to a drydock facility for overhauls, and the anchors and cables can be robust enough to be functionally “set and forget”.

    “It seems it would cost less in energy invested and money spent to put turbines on the beds of the Mississippi and other great rivers, rather than in the Atlantic under the Gulf Stream.

    Off the top of my head I’d say erosion might be a problem, given the effort that the Corps of Engineers has maintaining the lower river control structures. I’d suspect there would be potential conflicts with commercial navigation. Rivers have lots of natural trash moving in their flow.

    Not to say these are likely insurmountable, and I’ve liked the in stream idea for a long time. It has lots of potential for scaling in areas where a stand alone mini grid would be appropriate.

    WhiteBeard

  24. “Greenengineer” tried to poo-poo King’s question about comparing adding a minute concentration of CO2 with extracting substantial amounts of energy from the Gulf Stream:
    This is all pretty basic stuff, for an engineer.

    Indeed! Read a few books. Take a few classes. It will certainly open your mind.

    One of the recurring issues in real engineering is the issue of scale.

    Take a little power from the Gulf Stream, and it is irrelevant. Take power on the scale required to be relevant to human needs (TeraWatts) and it will have impacts. The engineering question is — what are those impacts?

    There is an analogy here with the travails that Dr. Keith went through when he looked at the impact of taking relevant scale power (TW) from the wind, instead of just having a few cute windmills in Holland.

    Surprise, surprise! Large scale power extraction from wind will have significant impacts on global distribution of moisture and temperature. But in the modern world of politicized science, that is a message that is not welcome in “peer”-reviewed journals. Seems that common-sense engineering is not politically-correct.


  25. Take a little power from the Gulf Stream, and it is irrelevant. Take power on the scale required to be relevant to human needs (TeraWatts) and it will have impacts. The engineering question is — what are those impacts?

    This was never proposed. Gulf Stream power is a regional partial solution (if at all) not a universal solution.

    Note my previous comment about people who want a single, uniform one-size-fits all answer.

    You do point at (sort of vaguely in the direction of) one true fact, though, which is that the pool of sustainable energy is far from infinite. More precisely, while the energy may be infinite, the power (energy/time) is NOT.

    Sustainable energy must come from current solar income (or geothermal) either directly or indirectly (e.g. wind, waves). And there’s a whole wackload of it out there, but most of it’s already being used for something important to the climate, the ecology, or some other species.

    This is why radical efficient improvements are so critical. They enable a civilization to operate on current solar income.

    In the meantime, though, we’re no where near extracting enough energy to cause a problem (certainly not on par with the impact of fossil energy).

  26. In the meantime, though, we’re no where near extracting enough energy to cause a problem (certainly not on par with the impact of fossil energy).

    Come on, “greenengineer” — live up to your moniker!

    Fossil energy has had tremendous impact on humanity & the world — mainly positive, some negative — and is employed on a huge scale around the globe. If the defence of “Infinite Underwater Energy” is that the power supplied will be trivial compared to human needs, then why are you wasting time talking about it?

    Think like an engineer! The human race needs staggering amounts of power — on the scale of at least tens of TeraWatts. Fossil fuels can provide that — until we approach resource limits. Any reasonable alternative engineering solution has to offer at least the potential of TeraWatt scale.

  27. “Any reasonable alternative engineering solution has to offer at least the potential of TeraWatt scale.”

    And that is why so many of the alternative energy solutions are far from actually mattering. They can’t scale up big enough.

    By the way, the official figure for CO2 is 380 parts per million. That’s 0.038 percent of the atmosphere. And the official measuring site is Mauna Loa Observatory. Observing an active volcano. One location, taken to represent the entire atmosphere.

  28. Kinuachdrach, I can’t tell if you’re being an intentional troll, or you’re just so blinded by your preconceptions that you cannot hear what I am saying.

    Gulf Stream generators could provide a good fraction of, say, Florida’s energy. (Possibly all of it, once you achieve a reasonable level of efficiency.) They’re not going to meet the energy needs of the planet. What part of They are a regional solution. do you fail to comprehend?

    Renewable energy is necessarily specific to region and climate, because it relies on tapping natural resources, which are not uniformly distributed. Some places have sun, some places have wind, some places have moving water, or hot rock, etc, etc. No one single source is sufficient, but taken together, there’s enough energy available to run a civilization, if you’re smart about how you use it.

    If “thinking like an engineer” really does mean confining your solutions to the very simplest and most uniform — as it apparently does to you — then we really are well and truly screwed. Not because the problems are technically intractable, but because we were so blinded and narrow in our vision that we lacked the imagination to see the solutions.

  29. Gulf Stream generators could provide a good fraction of, say, Florida’s energy.

    So that’s what “infinite” now means? Enough power to keep Florida going! At some yet-to-be-determined environmental costs, which will mainly affect the EUtopians on the other side of the Atlantic — and who in Florida cares about those people anyway?

    Read Larryd’s 12.30 AM post carefully, “greenengineer”. Some people get the point here, even if you are finding difficulty with it. There are over 6 billion human beings on the planet. Most of them don’t live in Florida. What are they going to do when fossil fuels hit supply limits?

    It is a little irritating when activists make hand-waving general statements about there being enough energy from politically-correct sources, without any quantification. You claim to be an engineer — Where are the numbers to back that assertion? Give us the specifics!

    And once you have provided the numbers, please give a credible explanation for why generations of human beings have been paying heavily for energy instead of harvesting all that free power just lying around the planet. In engineering circles, that’s called “passing the smell test”.

  30. http://en.wikipedia.org/wiki/World_energy_resources_and_consumption

    The estimates of remaining worldwide energy resources vary, with the remaining fossil fuels totaling an estimated 0.4 YJ (1 YJ = 1024J) and the available nuclear fuel such as uranium exceeding 2.5 YJ. Fossil fuels range from 0.6-3 YJ if estimates of reserves of methane clathrates are accurate and become technically extractable. Mostly thanks to the Sun, the world also has a renewable usable energy flux that exceeds 120 PW (8,000 times 2004 total usage), or 3.8 YJ/yr, dwarfing all non-renewable resources.

    We shouldn’t probably try to harness more than 1/10 of 1% of that energy — after all, it’s got to keep the rest of the biosphere going too — but that still leaves us with 8 times our current demand. And we can use a HELL of a lot less energy than we do, here in the “developed” world, while improving our standard of living.

    And now, troll, I am done talking to you.

  31. Oh wow! A link to wikipedia! Well, that settles any argument, doesn’t it.

    “greenengineer”, there is no question that the sun produces an incomprehensible amount of energy, and that the minor portion reaching Planet Earth is orders of magnitude larger than any foreseeable human demand.

    There is a question, though, about how to harness that energy. That is the kind of thing an engineer thinks about.

    Saying that we only need 1/10 of 1% is fatuous — unless you provide a technologically-feasible pathway to do so. A little like saying there are billions of dollars of gold in Forth Knox, and a True Believer needs only 1/10 of 1% of that gold to make a major contribution to Al Gore latest campaign.

    However, you have definitely earned the “green” part of your name, “greenengineer”. You would rather throw ad hominems than present rational physics-based arguments. Definitely “green”!

  32. larryd (February 17, 2008 12:30 AM)

    ”By the way, the official figure for CO2 is 380 parts per million. That’s 0.038 percent of the atmosphere. And the official measuring site is Mauna Loa Observatory. Observing an active volcano. One location, taken to represent the entire atmosphere.”

    So?

    The lethal dose for Botulinum toxin is thought to be about 1 ng/kg. That’s 0.00000009% of your body if you weight 200 lbs (~90 kilos).

    Did you have a constructive point in mind?

    Atmospheric CO2 concentration has been monitored since 1958 at the Mauna Loa Atmospheric Observatory. Since then it has been measured at a number of locations around the world confirming that CO2 is “well-mixed” throughout the atmosphere after a “mixing time” of about six months. Mauna Loa was actually chosen for atmospheric monitoring because of it’s mid Pacific isolation from other sources of emisions. Do you really think no-one realized that the mountian produced gasses, and they needed to control for that?

    US NOAA run sites are at:

    http://esrl.noaa.gov/gmd/obop/

    An inventory of international
    observation sites is at:

    http://gaw.kishou.go.jp/cgi-bin/wdcgg/map_search.cgi?zoom=world_map&category=Stationary&para=CO2&orgn=

  33. Whitebeard wrote:
    So? The lethal dose for Botulinum toxin is thought to be about 1 ng/kg.

    Are you seriously equating essential CO2 to a virulent toxin?

    Atmospheric CO2 is a vital part of the Carbon Cycle — something that in less politically-correct times was taught in high school. If there were no atmospheric CO2, plant life on Planet Earth would die, and animal life which depends on plants for food & oxygen would shortly follow.

    Equating an essential component of the biosphere to a virulent toxin is simply incomprehensible!

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