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Could mechanical trees save the world?

Tom Feilden | 08:07 UK time, Thursday, 27 August 2009

"Artificial trees" along the motorway

If you thought geo-engineering was the stuff of science fiction - all giant sun shades in space - think again.

The Institution of Mechanical Engineers has produced a report focusing on practical geo-engineering solutions that are either available now, or soon will be.

The report lays out a 100-year road map to "de-carbonise" the global economy and the vision includes forests of artificial trees built along motorways, shiny silver roofs that reflect sunlight, and algal bio-reactors running up the sides of buildings.

Some climate scientists say we may only have a few decades left to avoid dangerous climate change, but geo-engineering - the idea of redressing the balance of the atmosphere by blocking the suns rays, or siphoning off harmful greenhouse gases, could buy us more time.

Artificial trees do pretty much the same job as real trees, absorbing CO2 from the atmosphere, but up to a thousand times more efficiently.

The Institution's Dr Tim Fox claims a single artificial tree could remove as much as ten tonnes of carbon a day, and just 100 000 units would be enough to capture the UK's entire transport emissions.

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"After decades of failed mitigation, geo-engineering may give us those extra few years to transition to a low carbon world and prevent any one of the future climate change scenarios we all fear".

Algae unitsBut perhaps the most eye-catching proposal in the report would be to incorporate algal photo bioreactors in the built environment.

At its most basic that means tubes of vivid green algae running up the sides of buildings, although in time the bioreactors could be incorporated into the fabric of the buildings themselves.

Like trees, algae use sunlight to convert carbon dioxide from the air into plant matter using photosynthesis, with the added benefit that the bio-char produced could be siphoned off and used as an organic fertiliser.

The Institution's report is unlikely to be the last word on geo-engineering. Next week the Royal Society will publish a much broader study that reviews all the options - including the most outlandish, science fiction ideas like sun shades in space - and focussing on the ethical and political problems posed by tampering with the planet's climate systems.

Watch this space.


  • Comment number 1.

    good descent realistic solutions, unlike the current crazies that currently camp in London.

  • Comment number 2.

    Not in isolation surely? Wouldn't using LESS fossil fuel, in the meantime, be the most appropriate course?

    How do we know that 100,000 such trees would be enough? What if it dawned on us that we'd need more like 2 million? (Initial estimates are always out by miles) and the appearance of such a grid of trees might just persuade people that it's OK to guzzle gas, as the trees would scrub out the CO2 problem.

  • Comment number 3.

    I hope these "artificial trees" can be made to resemble real tree, rather than giant fly swatters!

  • Comment number 4.

    Or, how about more real trees, and a lot less people?

    Nature may be slow its wonders to perform, but the latest panic about influenza shows how fragile our wonderful civilisation is. Science has long advocated that the simplest solutions are usually the most effective.

  • Comment number 5.

    All these ideas are great but it's hard to see what doing this in the UK will do globally. Fair enough if we start a trend and every other nation follows. This sort of thing needs to be developed for the US as they are one of the least green countries. And as a "super-power" they should be setting the example for the rest of the world.

  • Comment number 6.

    I am sat here reading whilst drinking a can of fizzy drink.If co2 is such a big problem, why are millions of cans full of co2 being opened every day?

  • Comment number 7.

    The artificial trees are old news.
    From 2003:

    Note the comment...

    "Massachusetts Institute of Technology engineer Howard Herzog thinks Dr Lackner's design will not hold together on the scale he proposes. He said you would expend more energy in capturing the CO2 - in keeping the slats coated in absorbent and disposing of it - than you would save. "Once the solvent captures the CO2, it holds it on tight," said Dr Herzog, "and it's going to take a lot of energy to break those bonds." He said that much more research was needed on the technology. "The idea of air capture is seductive and would really be great to have," said Dr Herzog, "but it's important to separate out the concept from the technical details."

    The original story suggested the 'trees' would turn limewater into limestone rock (a bit like the limescale that forms in pipes), while the latest story suggests that the CO2 the 'trees' capture could be stored in old oil wells. I think there's a bit of journalistic obfuscation going on there.

    I love the line, "...he [Dr Lackner] predicts that one synthetic tree could remove 90,000 tonnes of CO2 in a year...". I find that beyond belief, as it means each tree will collect 246 tonnes each day. Does it sound possible that each of those trees along that highway will be able to hold that weight of limestone in its 'branches'? And can you imagine what sort of massive manpower, machinery and fleet of trucks the council would need to remove all that limestone. I'd love to hear a bit more of a scientific explanation -- and know whether the 2003 sketch for the artificial tree is meant to be using the same technology as the 2009 version, which in the artist's impression looks exactly the same.

    And what's the illustration of 'trees' in the sea all about?
    [ ]
    I understand the point of building wind turbines out at sea: but what's the reason to go to the massive additional expense of building the CO2 collectors offshore? I wonder if it's the link between oil wells and CCS that formed in the artist's mind?

    It's all flights of fancy methinks; the promise of which allows the movers and shakers to delude themselves into thinking that we can carry on with business as usual.

  • Comment number 8.

    Some fascinating ideas, but they certainly raise a number of concerns-

    Aren't we in danger of devaluing real trees by labelling the artificial trees as more efficient carbon sinks? Whilst artificial trees will capture more CO2, they are only a finite solution, as there is limited space for the CO2 to be stored. Furthermore, trees and forests do a lot more in terms of ecosystem services than the artificial ones could ever achieve- oxygenating the atmosphere, preventing soil erosion and leaching of nutrients, stabilizing hydrology in water catchment areas, and providing a source of organisms with other important ecological services such as pollinators for example. I worry that labeling real trees as inefficient carbon sinks could indirectly lead to their devaluation and continued loss.

    Another concern of mine is how these schemes can 'buy us time.' Recent scientific reports from Arctic tundra suggest that the permafrost is melting dues to elevated temperatures, leading to increasing rates of methane release into the atmosphere, which is a far more powerful greenhouse gas than CO2. This is predicted to cause a positive feedback, where higher methane levels cause faster rates of temperature increase and arctic thawing, thus more methane is released..... Given this is already happening, we really need to install artificial forests of trees and algal bloom bioreactors IMMEDIATELY in order to mitigate current warming trends. And given that Network Rail can only manage to plan a UK high-speed network completion date of 2030, can we realistically install these geo-engineering solutions sooner? We need to. Within ten years at the latest, not 20, and we need every major CO2 producing nation to comply. That is a tall order.

  • Comment number 9.

    This is really frightening. Our summers are not getting warmer and already there are boffins trying to interfere with the atmosphere on the basis that they are.

  • Comment number 10.

    What about the by-product methane that algae produce? Does this not negate the CO2 removed as it is a much more potent global warming gas?

    I believe there are already algae bioreactors in Calafornia using huge algae tubes. Maybe not a big step integrating it into the built enviornment if it works.

  • Comment number 11.

    To dualrealitysandwich who wrote:

    "This is really frightening. Our summers are not getting warmer and already there are boffins trying to interfere with the atmosphere on the basis that they are."

    Check the following website and look at the graph which spans over 300 years, which will prove you are wrong about temperature rises:

    You know, it really annoys me when people with no scientific training think they know better than 'boffins'- we scientists (not boffins, scientists) have rigorous training in objective scientific methods, and recognize the importance of taking a long term view when it comes to investigating climate change. You cannot just say climate change is not happening because you have failed to perceive any increase in average summer temperature in only the UK in only your short lifespan. Do you have temperature data to back your comment up? No, probably not. If you want to challenge the idea that temperature is increasing, have a look through the met-office data, and try plotting some graphs :-)

    Why is it that much of the non-scientific public turn down the facts scientists present them, in favour of pub-talk, personal opinion, and output from scientifically naive and subjectively driven journalism?! So don't call scientists 'boffins' and dismiss what they have to say before looking at their science and data, thanks. And for the record, media reports on science do not pass as data or evidence. Bad reporting by the media is almost always to blame for the public's misunderstanding, and sometimes mistrust, of science and scientists. Try reading Ben Goldacres' book if you don't believe me.

  • Comment number 12.

    Your article is incomplete - take a look at a British company Solarbotanic, they currently make/develop a concept of natural looking trees and shrubs that convert light, heat, sound, rain and wind energy into electricity, additionally these trees can filter CO2 out of the air and other pollutants as well. This surely looks better than what you have shown in your picture. Solarbotanic can create thousands of jobs and can save our landscape too, now that's is worth to report on. Our own Green solution.

  • Comment number 13.

    It is sad that a foreign company gets so much attention while We Brit's have our own carbon capturing trees. Solarbotanic is developing artificial natural looking trees that convert light, heat, sound, rain and wind energy into electricity. In addition these trees can capture CO2 and store it for further use. Now this product is multi efficient, looks good and will fit in any British country side. And this development would create thousands of jobs for the UK

  • Comment number 14.

    It is usambara who is proved wrong about temperature rises - even the graph he links to shows that the temperature is currently falling, and the worldwide temperature average has been flat for the last ten years.

    I think JR Woodman is right. The scheme seems ridiculous. Just think about the logistics for a minute. Tons of carbon are somehow stored (Where? How?) in each tree each day. This will all have to be collected from each tree and transported by lorry along the motorway to some site where it is further processed and buried.

  • Comment number 15.

    Samuel Pickwick, your comment FURTHER emphasises the points I made about misunderstandings and misinterpretations of science and scientific output!

    First point- what the graph I referred to is telling you, is that compared to the average temperature across 1961 to 1990, temperature on average right back to 1659 was, on the whole, lower. From 1990 to 2009, temperature has on average, been higher than the 1961-1990 period for this part of the UK. That also means the past 20 years we have seen a trend that temperatures compared the past 300 or so years have been warmer. You can look up "temperature CO2 graph" on any search engine, in any climate science journal until you are blue in the face. The fact is, climate IS warming, and CO2 increases since the industrial revolution are the most plausible explanation for this rise.

    Second point- You make the other error I referred to, which is viewing a short term drop in temperature as evidence that global warming has stopped. This could be short term variability in temperature, but the long term trend again, is upwards (you can actually see that long term trend on the plot I referred to- it is pretty obvious). The met office actually gives a good explanation of this myth, with reference to the low temperature experienced early in 2008.

    Third point- Look at the data if you look up "uk climate data". You can look at trends in max and min temperatures in the UK at various temperature stations over the past 50 years, and you will find in many cases, an increase in monthly minimum and maximum temperatures. These are REAL data! For example, the south coast of sussex has has sustained higher termperatures over the past ten years compared to 1959 to 1969 in June. Braemar has had an increase in minimum temperatures in winter. I don't have time to look at all datasets and all plots, but the trend reported by the met office is irrefutable.

    FINALLY- I provided a link to a graph that shows the increase in temperatures, where is your evidence that temperature is flat over the past ten years????! You have probably read the graph wrong. The met-office site includes a global temperature graph, of temperatures over the past 160 years, compared to mean temperature at the end of the 19th century:

    What are you talking about flattening of temperature? You can see throughout the plot there are 'steps' where termperature increase appears to level off, and then it continues to rise. You CANNOT say the the slow down in current temperature rise will be sustained, or that temperature will continue to fall long term. Given the strong link between rising CO2 (and other greenhouse gases) and temperature, you would be a fool to believe that temperature is not going to continue to rise. Thousands of rigorous climate models show the temperatures WILL continue to rise.

    Back to the blog subject, I think prevent is ultimately better than cure, and we must switch to renwables as soon as possible. Simple as that.

  • Comment number 16.

    "Thousands of rigorous climate models show the temperatures WILL continue to rise." Apologies- "iterations of" preceeds "rigorous", above

  • Comment number 17.

    I've got to say I was not to keen on the BBC News article reporting on this. It stated that the report the story was based on claimed that "without Geo-engineering it will be impossible to avoid dangerousclimate change". I read that report and it said no such thing. If anything it said Geo-engineering should be used as a last resort.

  • Comment number 18.

    Does anybody know how much electrical energy it would take to capture one molecule of carbon dioxide and split it into one molecule of carbon (in the form of graphite) and two molecules of oxygen ?

  • Comment number 19.

    People with crazy ideas such as 'artificial trees' should always remember the Law of Unintended Consequences.
    Can anyone think of unintended consequences in this case?

  • Comment number 20.


    I hope that the mechanical trees; Could save the world; But, I have my doubts...

    =Dennis Junior=

  • Comment number 21.

    The Artificial trees option should be persuded vigoursly and urgently, to determine if it is technically viable.

    Given the key facts of the report"geo-engineering giving us the time to act?" by The Instution of Mechanical Engineers

    key facts
    • Artificial trees would be several thousand times more effective at removing CO2 compared with natural trees
    • Five to ten million ‘trees’ could remove the current global annual non-energy production CO2 emissions
    • Leveraging emerging CCS infrastructure will lead to economies of scale
    • Each tree would cost about $20,000.

    Total cost of the trees required to remove the current global annual non-energy production CO2 emissions is between £100bn

    and $200bn.

    This compare with:
    * Global military expenditure in 2008 that is estimated to have totalled $1464 billion.

    * During the last quarter of 2008, central banks purchased US$2.5 trillion of government debt and troubled private assets from

    * The global currency market was $3,200 billion a day in 2007, or £400,000 billion per annum. A Tobin Tax of 1% would yeild

    £4000 bn per year.
    * In the UK about £5bn per year is paid in bonuses to 'bankers' in the Financial Sector.

    The Artificial trees option is certainly financially viable.

  • Comment number 22.

    Yes i do agree with the Herzog's proclamation. So far the Solarbotanic is considered to be best in my aspect. But Mr. Lackner must reveal the hidden secrets of his technology. Factors that will affect or the detailed description for the consideration should be notified.



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