Seemingly trivial things that intrigue you
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Is that you over there? Oi, stop staring.
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There used to be a forestry guy on here. IIRC he asserted that the forest floor locked up far more carbon than the trunks of commercially farmed softwood. If we want to lock up CO2 for longer than the lifespan of commercial and converting it into coal is not really viable, Construction timber is as good as anything. If looked after it will easily last 200-300 years.
1985 Mercian King of Mercia - work in progress (Hah! Who am I kidding?)
Pinnacle Monzonite
Part of the anti-growth coalition0 -
I think he's right. I also mentioned bogs above. Peat is another one.
Thing is about our forests, as I understand it, is that in absolute terms the amount of carbon locked up is fairly small, and sooner or later reaches equilibrium, except on geological timescales (therein lies the problem).
The main carbon benefit of wood as a building material is therefore not what's locked up in it, but what it is replacing.
Think concrete, steel, bricks (and glass, which isn't replaced obvs) - all use huge amounts of heat energy to make, almost entirely fossil fuel derived at this point, and concrete liberates a good amount of CO2 when it cures. So much so that despite all of the metals used to make a nuclear power station, the concrete required is still the biggest CO2 contribution.
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Concrete sequesters carbon as it cures. The CaO reacts with CO2 to make CaCO3, reverting back to the limestone from whence it came. But you are right that most cement kilns are coal oil or gas fired. It's possible to make these electric or hydrogen fueled (there are hydrogen fired bricks already available but it's always going to need a lot of heat to change raw materials into something else. Partly because of that fact, there is a movement to bring cut stone back, using steel tendons to make pre-tensioned lintels or just straightforward brick-sized stone blocks.
1985 Mercian King of Mercia - work in progress (Hah! Who am I kidding?)
Pinnacle Monzonite
Part of the anti-growth coalition0 -
I read something recently that cement manufacture produces 8% of global human CO2 emissions. I was staggered it was so high and even double checked as I thought it might have been purely 8% of the construction sectors emissions.
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I've finally looked it up,.rather than rely on a 25 year old memory. We are both wrong. It's a hydration reaction. The CO2 is released on production.
There is non hydraulic cement that has a CO2 driven curing reaction, but it's not suitable for construction as far as I can tell, unless it's in the Atacama.
The sequestration is a mineralisation reaction of other calcium salts typically present in the cement. My suspicion is that this is very slow and the benefits over stated by the concrete industry.
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The curing reaction is creation of various quite complex hydroxy alimino silicates. So complex, I am now reminded, that considerable effort goes in to investigate what mineral phases are generated in which conditions, based on different starting blends. Presumably next step is determining how those phases interact and how that relates to mechanical properties.
Bloke I researched with is still dedicating his life to studying cement.
It is actually interesting. Just not interesting enough for me to have carried on doing.
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Yes, it's amazing stuff considering Portland cement was invented in the early 19th century and we still haven't entirely understood out how it works. I don't for a moment think that the carbon absorbed in the curing process offsets more than a token amount of the tonnes of the stuff emitted in heating the raw materials over 1000°C.
1985 Mercian King of Mercia - work in progress (Hah! Who am I kidding?)
Pinnacle Monzonite
Part of the anti-growth coalition0 -
Drax uses sustainable sources, is that a piss take. There’s been a documentary on how they are using primeval Canadian forrest for their wood pallets and I’m sure it’s been written about else where.
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You missed the word "apparently", but it reenforces the point that the source of the wood is what determines whether it is carbon neutral.
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There’s no fucking apparently about it. It’s an absolute scandal that they get away with and get money from the government for carbon neutral.
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On the cement alternatives, someone at Edinburgh University managed to get bacteria to...excrete (?)...CaCO3 and produce usable building blocks from it. Given that limestone is essentially compressed shells and shells are grown, that would seem to be a good avenue to explore further.
1985 Mercian King of Mercia - work in progress (Hah! Who am I kidding?)
Pinnacle Monzonite
Part of the anti-growth coalition0 -
All the major players are investigating/promoting cement alternatives, especially as ggbs gets harder to come by as cement replacement in mixes.
Calcined clay is being pushed by our current supplier, although I've not really had time to engage with much of the bumf.
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Pfft. Scalability.
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Well sure, but the first Portland cement was made in a domestic oven (so the legend goes) and now look where we are.
1985 Mercian King of Mercia - work in progress (Hah! Who am I kidding?)
Pinnacle Monzonite
Part of the anti-growth coalition0 -
Sorry, missed your ground-breaking experiment @masjer . Well, I assume you broke the ground to extract half a carrot.
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Another one Private Eye has been banging on about for ages... basically Drax seems to be a massive, very expensive con, if PE is to be believed.
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It's always easy to use the benefit of hindsight to criticise. Many biomass generators have gone bust due to the cost of the wood pellets. Drax is surviving by importing pellets. With hindsight, should the uk have subsidised biomass? Probably not, but the winners are not always immediately obvious and climate change is a subject that requires all possibilities to be tried.
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It’s the fact that they are lying about where they are sourcing the pallets from and that they are claiming to be a green alternative. That’s not hindsight.
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Why is it, when you have incidents like in Hainault yesterday, the police say they will be increasing their presence in the area? It’s a one off incident where the perpetrator has been caught.
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Isn't that the same as saying "We don't have enough police to maintain that presence."?
Not a newsflash, I know.
The above may be fact, or fiction, I may be serious, I may be jesting.
I am not sure. You have no chance.Veronese68 wrote:PB is the most sensible person on here.0 -
Why would anyone feel safer though? If the person hasn't already been detained or if it is something like terrorist or gang related that may result in similar incidents in the area I can understand that but if someone has been randomly stabbed in my street and the person responsible has been caught I'm not going to feel any less safe than I was before that incident. I guess it comes down to people being bad at assessing risk.
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Probably a community support role to manage questions etc. and protect the crime scene.
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Passed a few milestones swimming wise but struggling to find a useful benchmark to know how good or bad it is. I suspect the latter, but I can't seem to find out.
Sub 2 minute 100m, and sub 9 minute 400m.
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Only thing that really matters is whether you are (a) getting a benefit from it and perhaps (b) improving. Actual time is not that significant.
Open One+ BMC TE29 Seven 622SL On One Scandal Cervelo RS0 -
Not sure how much it helps but looking on Strava and one friend who started swimming about 10 years ago and now ranks fairly highly in his age group in Ironman average around 1.5 minutes per 100m for 2.4k in a race. Someone I run with who is a fairly regular swimmer is around the 2 minute pace when training over a distance of around a mile (I don't know his background but his son has won medals at world and european levels as an U23 in aquathlon and the daughter was also a competitive swimmer). Another person I run with has been having lessons recently and is a little bit slower than you. I'm thinking of starting in the next block of lessons. I suspecty the answer is you're doing well for a learner / improver but you aren't going to be competing any time soon.
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You would fail to qualify for the county championships for 10/11 year olds by quite a margin by the look of it, that is not a judgement by the way - I'd probably struggle to keep up with a competent 7 year old. In fact, I bet i was a lot faster aged 10/11 than I am now 😄
Wheelspinner is right in my opinion, just measure against yourself a month ago
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