1. Subscribersonhouse
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    30 Sep '16 09:452 edits
    http://www.sciencealert.com/scientists-just-discovered-a-major-new-source-of-greenhouse-gases

    Dams. The water acting on plant life generates enourmous amounts of methane, almost 40 times greater threat to heating than CO2.

    I think it impossible for climate change deniers to deny this one since before the anthropocine era only beavers made artificial dams. Now we have 30,000 square kilometers of man made dammed water generating methane.
  2. Cape Town
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    30 Sep '16 14:46
    Originally posted by sonhouse
    I think it impossible for climate change deniers to deny this one since before the anthropocine era only beavers made artificial dams. Now we have 30,000 square kilometers of man made dammed water generating methane.
    Actually we have drained large areas of swamp land and lakes. Human created dams tend to be deeper and less full of plants than the drained areas.
    It is also untrue that it is a particularly new discovery.
  3. Subscribersonhouse
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    30 Sep '16 17:45
    Originally posted by twhitehead
    Actually we have drained large areas of swamp land and lakes. Human created dams tend to be deeper and less full of plants than the drained areas.
    It is also untrue that it is a particularly new discovery.
    Here is something annouced as new:

    http://phys.org/news/2016-09-biologist-comments-startling-climate.html

    Melting permafrost we knew did methane but now it seems also to produce CO2.
  4. Cape Town
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    30 Sep '16 18:34
    Originally posted by sonhouse
    Here is something annouced as new:

    http://phys.org/news/2016-09-biologist-comments-startling-climate.html

    Melting permafrost we knew did methane but now it seems also to produce CO2.
    There are always new reports and findings, but it would seem the reporters are a little bit over enthusiastic trying to make out that everything is new when it just plain isn't.

    Lets for example go back to 1989:
    http://link.springer.com/article/10.1007/BF00052826

    I could dig up many more. That permafrost releases carbon is not a new finding.
  5. Subscribersonhouse
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    01 Oct '16 13:43
    Originally posted by twhitehead
    There are always new reports and findings, but it would seem the reporters are a little bit over enthusiastic trying to make out that everything is new when it just plain isn't.

    Lets for example go back to 1989:
    http://link.springer.com/article/10.1007/BF00052826

    I could dig up many more. That permafrost releases carbon is not a new finding.
    Still, people need a kick in the butt every now and again when old reports are just paved over, business as usual.
  6. Cape Town
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    01 Oct '16 15:461 edit
    Originally posted by sonhouse
    Still, people need a kick in the butt every now and again when old reports are just paved over, business as usual.
    Except that when there are over inflated reports every day, people very quickly realise they are over inflated then stop paying attention. A large part of the apathy against global warming is due to less than honest reporting on the subject in both directions. Scare mongering doesn't work.

    Have you installed solar yet, or do you only want everyone else to do something about global warming?
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    02 Oct '16 10:0910 edits
    personally, I am a great fan of run-of-the-river hydroelectricity (ROR)
    https://en.wikipedia.org/wiki/Run-of-the-river_hydroelectricity
    I assert that ROR is generally a currently massively under-exploited renewable (I think this because have personally seen loads of rivers where I can see you could have ROR and yet I have NEVER seen any ROR on a single one of them anywhere along the length of any!) that we should pour much money in for research and development into it to massively increase our exploitation of it.
    Although ROR has the obvious disadvantage that it has little or no energy storage, there are doable ways around that (off-the-grid electric energy storage + supergrid + combine it with other renewables) and ROR has the big advantage that it generally requires comparatively only very small damns which not only helps to greatly reduce the initial setup costs (thus making it more cost effective in the shorter run) but also would surely massively reduce the problem of methane which you would otherwise get from big-damn hydroelectric.
    I say, lets go ROR in a big way!
    -oh, and I say lets also go marine current power in a big way; ( https://en.wikipedia.org/wiki/Marine_current_power ) which is something else I assert is currently massively under-exploited (actually, currently not exploited at all)
  8. Cape Town
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    02 Oct '16 13:02
    Originally posted by humy
    I assert that ROR is generally a currently massively under-exploited renewable

    -oh, and I say lets also go marine current power in a big way;
    There is no shortage of power sources. The issue with renewables is cost effectiveness. Do you have any references showing the cost effectiveness of ROR?

    I believe marine current power is currently not cost effective.
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    03 Oct '16 06:534 edits
    Originally posted by twhitehead
    Do you have any references showing the cost effectiveness of ROR?
    No, and I suppose no such references exist.
    I only guess ROR would be more cost effective compared specifically to non-ROR hydroelectric (and I don't know how to compare cost effectiveness of ROR/non-ROR hydroelectric with non-hydroelectric renewables) in the relative shorter run because ROR desn't require the building of massive and therefore extremely expensive damns but RPR only requires the building of much smaller and therefore cheaper damns; does that seem logical to you?

    I should also point out that 'cost effectiveness' here is a somewhat subjective and arbitrary concept in this context because how 'cost effectiveness' a hydroelectric setup is depends on what sort of time scale you consider it over; is it 'cost effectiveness' over, say, just one year? if so, then it probably isn't cost effective because it would probably take more than a year to pay for itself. Is it 'cost effectiveness' over, say, 10 year? -depends; will it pay for itself in ten years? Is it 'cost effectiveness' over, say, 100 year? -it surely is definitely very cost effective over 100 year because then it has time to pay for itself many times over. But I think we are not willing to wait that long. So when you say 'cost effectiveness', over what period of time and why that period? -because how 'cost effectiveness' it is just depends on and varies with that rather arbitrarily chosen period of time.
  10. Cape Town
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    03 Oct '16 07:101 edit
    Originally posted by humy
    No, and I suppose no such references exist.
    Why? That would suggest it doesn't work.

    does that seem logical to you?
    No it doesn't. Most power technologies are cheaper at scale. The larger you make them the cheaper they get.
    A hydro power dam has the advantage that you build a single large wall an you effectively capture a large river over many kilometres. ROR would need to build many many dams and have much more infrastructure to achieve the same power output or alternatively have long very large pipes over many kilometres.

    Only in rare instances might that not be the case. In my home town of Livingstone we have a ROR power station at the Victoria Falls which is probably significantly more cost effective than a traditional dam, but such perfect locations are rare.
  11. Cape Town
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    03 Oct '16 07:19
    After actually reading the Wikipedia page 🙂
    It would appear ROR, just like standard hydro, requires suitable sites. It has the advantage of usually being less damaging to the environment and the disadvantage of being dependent on consistent river flow (no storage).

    Can you give any examples of places you thought were suitable but have not been exploited?
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    03 Oct '16 07:2315 edits
    Originally posted by twhitehead
    Why? That would suggest it doesn't work.
    that's a big assumption I think.

    No it doesn't. Most power technologies are cheaper at scale. The larger you make them the cheaper they get.

    But why should that apply to hydroelectric? You cannot safely logically make that extrapolation from that premise alone; very risky I think.

    A hydro power dam has the advantage that you build a single large wall an you effectively capture a large river over many kilometres. ROR would need to build many many dams

    -and each being much smaller and, because of the way ROR works, for the vast majority of that length of river over many kilometres would not have to be made to be a reservoir behind a small damn thus this would result in vastly less, not more, infrastructure to achieve the same power output; you appear to not have understood the whole point of ROR and how it works; it trades-off the advantage of energy storage for the advantage of less damn/construction costs.

    And, at least in credible theory, with careful design and construction, you could have effective ROR without any damns at all!
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    03 Oct '16 07:328 edits
    Originally posted by twhitehead
    Can you give any examples of places you thought were suitable but have not been exploited?
    ALL the many reasonably fast moving rivers I have seen in the highlands of Scotland (I don't actually live there, in case you are wondering).
    And I disagree ROR would "dependent on consistent river flow"; although it obviously would be a desirable big advantage to have consistent river flow, we could simply accept the lower/absent electric power when the river has a low flow rate, just like we simply accept the absent electric power from wind turbines when the wind stops blowing; it doesn't necessarily mean it isn't cost effective; just less cost effective because of the greater need for energy storage (which could be almost completely eliminated with a supergrid)
  14. Cape Town
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    03 Oct '16 09:27
    Originally posted by humy
    that's a big assumption I think.
    No, I don't think so. If nobody has ever compared costs then the technology doesn't exist and doesn't work. In reality the technology does exists and people have compared costs.

    But why should that apply to hydroelectric? You cannot safely logically make that extrapolation from that premise alone; very risky I think.
    It is not necessarily true but it is a fairly safe assumption as it applies to almost anything. The premise itself however was wrong as ROR is not necessarily smaller than dams. I did not realise that when I made that comment.

    All hydro requires a drop in height. Whether building a tunnel or a dam to achieve the same drop in height would be cheaper depends on the particular geography. As I mentioned, at the Victoria Falls, there is no need for a dam and ROR has been used.
    There is currently a plan for a dam to be built downstream of the Victoria Falls. I believe that the dam may be cheaper to build than ROR at the same location would be. The same applies to Kariba Dam which is downstream on the same river.

    Taking Kariba as an example. The choice is between a 240km or longer tunnel or diversion of some sort and a single dam wall. I am very sure that the dam is the cheaper option by far. The dam also provides storage, tourism, fisheries and more.
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