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Technology / Re: Can we construct this?

« on: 26/11/2015 17:53:56 »

Posting under multiple names is against forum policy...

 [ Invalid Attachment ]

Please only post as Hoggart from now on, or you may risk being banned.

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New Theories / Re: The real theory of everything!

« on: 03/04/2015 12:57:02 »

I'm locking this thread.
I have removed the last few posts. Personal attack is uncalled for.

Whatever level of coherent argument this thread may (if ever) have once had, seems to have long vanished anyway.

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The Environment / Re: What role did climate change play in California's droughts?

« on: 04/11/2014 23:25:37 »

Forest growth should reduce the CO2 level in summer.

The 'annual cycle' data shown fits perfectly with that assertion. Drop off starts in May and continues until September.

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The Environment / Re: What role did climate change play in California's droughts?

« on: 03/11/2014 13:19:14 »

As in this: Mauna Loa Carbon Dioxide... ?

The fluctuations are explained by forest 'breathing' - ie. growth through the summer (most forest is concentrated in the Northern Hemisphere).

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The Environment / Re: What role did climate change play in California's droughts?

« on: 01/11/2014 14:18:16 »

It doesn't explain why the prehistoric CO2 curve follows rather than leads the temperature curve.

"CO2 causes warming AND rising temperature causes CO2 rise [most notably] when the Earth comes out of an ice age.
Here, the warming is not initiated by CO2 but by changes in the Earth's orbit. "

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The Environment / Re: What role did climate change play in California's droughts?

« on: 22/10/2014 13:45:42 »

Water vapour, as you say, is a great contributor to global warming. Remember that the production of CO2 from burning fossil fuel is accompanied by a proportionate production of water vapour.

Which makes coal the least climate-change-inducing fuel of all!

It says 'ere...
Water vapour feedback loop amplifies the temperature change caused by CO2.

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The Environment / Re: How can we harness wind and wave power?

« on: 13/10/2014 11:36:48 »

Interesting. Are you thinking of creating ammonia for use as a fuel/energy storage medium, or as a useful product to make when there is excess electrical energy available, and then finding some other source of energy when there is a deficit?

The second. The ammonia produced would be "a useful product to make when there is excess electrical energy available".  There's plenty of it needed for making fertilizers for a start, and the hydrogen needed to industrially produce NH3 comes predominately from natural gas; itself a (fossil!) fuel.   And, in addition, on the occasions when a heavily renewable reliant grid falls short, the option to use natural gas can still be there; whilst the CO2 from said gas is being effectively offset from another sector - ie. agriculture.

I know of a company that pays industrial electro-refineries to up- and down-shift their electricity demand as the grid energy balance fluctuates--they never sell any electricity back to the grid, but because the operation is so energy intensive, and would otherwise be going 24/7, a reduction is consumption is equivalent to increasing the available energy for the grid.

I imagine this company could be an aluminium smelter, for example.
Though clearly it's a little more tricky to turn a large smelter on or off, I suggest that it might be possible to throttle them to a point.
I expect this type of very large demand-side planning would get less practical with a grid heavily reliant on renewables, because of the loss of predictability involved.   However, if we have a future situation where thousands of electric vehicles are plugged in to charge/discharge as needed across the grid then some of the stability (and therefore, predictability) could return.

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The Environment / Re: How can we harness wind and wave power?

« on: 13/10/2014 11:36:30 »

The problem with capacity factors is that they are arbitrary. If I put a 100 kW blade on a 150 kW alternator I can put a 50 kW rating plate on it and claim 20% capacity factor even though it only produces 10 kW.

I am unclear, following your logic, how you get a nameplate rating would be 50kW in your example. It could conceivably be 100kW, based on the size of the generator installed.

And I would question why such a turbine would use a 50% larger generator anyway. Any increasing in size and weight of electrical machinery in a nacelle, a couple of hundred metres in air must also scale up everything else up as well (tower rigidity etc); there will an additional increase in maintenance costs and, off-shore, this is obviously a serious overhead - thus, a generator, say, 10-15% larger than the blade's continuous rating seems somewhat more realistic.

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The Environment / Re: How can we harness wind and wave power?

« on: 10/10/2014 16:16:15 »

Real world capacity factors
UK Wind average (2007-2012): 27.5%

"...best capacity factor of any offshore wind farm - 46.7%, having produced 1,278 GWh over 1.5 years".

I think making ammonia efficiently could be an alternative (better) use of excess electricity from intermittent renewables, instead of producing hydrogen.

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Technology / Re: How large accumulator pack to power a household whole year round?

« on: 25/06/2014 14:11:07 »

Simple first step: where possible do the most useful things possible with electricity.
Electricity is far too valuable to be squandered on (low-level) heat production if any decent alternative exists!

Maybe you should look into building an an accumulator of the thermal kind first... a large pit full of packed stones, or something.  Look where you can make the most of solar gain on your property in the summer (even improve the thermal store capabilities of the building itself), and consider a ground source heat pump (which can 'pump' in both directions).

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That CAN'T be true! / Re: Could a cooling microwave be possible?

« on: 22/04/2014 17:26:48 »

This is the trouble when one journalist comes up with a tagline and other articles simply parrot the same 'message' (I expect it's a lot more prevalent in the age of online media).

From another site describing the product:
"a new 'microwave cooler' based on Rankine vortices instead of microwaves to chill multiple items in record time"
- This appears to have nothing to do with microwave energy from what I've seen.  I expect the comparison to a microwave is simply because the device uses a rotating plate which changes direction, a bit like in a microwave oven.

“It pays to keep an open mind, but not so open your brains fall out.” ― Carl Sagan

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Technology / Re: Could you power an electric car with an on-board generator

« on: 22/04/2014 16:30:09 »

I find it interesting that a question 4 years old still has not received anything other than a bunch of knee jerk reactions.

Can you explain why you think these reactions are 'knee jerk'.  In general the comments have sort to test the assumptions on which the question is based; which seems perfectly reasonable for a science forum IMO.

You are correct to point out that the Chevy Volt is not solely a series-hybrid vehicle. As mentioned, it has both series- and power-split- modes of operation.  But to understand why such a complex drivetrain was chosen, it useful to think a bit about the typical driving cycle which these vehicles will face in their lifetime (and more specifically about the driving cycles on which the MPG will be calculated by the State).

For instance, if every journey made by road involved driving pretty much straight on to the motorway and sitting at 70 mph for an hour, before reaching the destination, then no one would have any use for hybrids - but how many journeys work out like that?

In fact any highway intensive journey, currently, almost certainly suits a well-geared diesel with good aero, better than any other solution out there.  As BEVs continue to improve (and get cheaper) this is almost certain to change, but choosing any hybrid would be a waste of fuel and be pointlessly over complex.

  [...a hydraulics hybrid] that could carry 4 people, accelerate from 0-60 in less than 6 seconds, and got 75mpg. It used a 5hp engine running at three quarters throttle all the time to charge a hydraulic accumulator...

Do you have a link to this Hydraulic Hybrid?  I immediately wonder about the vehicle's top speed ... with a 5hp engine.  That is, it takes about 7-8hp to hold around 60 mph continuously on the flat for all but the most slippery saloons, all else being equal.   Also, the way that MPG is measured today is based on a more complete driving cycle, whereas previously it was simply a car's consumption at a near-ideal fixed speed, say 55.

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Technology / Re: Will GPS be up to the job in the Driver-less car?

« on: 30/01/2014 12:51:55 »

I wonder what has driven the US State of Missouri to implement this network? And are similar schemes likely to be rolled out across other states or countries?

What about light aircraft? Can they also make use of these ground based 'beacons'?

There must be a whole host of devices in the 'internet of things' age which could take advantage of knowing their precise position (especially in 3D), I would think.

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Technology / Will GPS be up to the job in the Driver-less car?

« on: 29/01/2014 16:09:04 »

GPS can be patchy - or just plain wrong on occasion.

When the commercial self driving cars do come along, is it likely that they will need an alternative or 'double checking' ground based system in place to remain safe and reliable?

Is it fundamentally important that such systems will need to know their exact position (and velocity) at all times? The present Go*gle car system needs to have the route driven out first but is then safe to navigate even a long trip 'alone'. Problems occur in heavy rain and with snow hiding the landscape.

This seems relevant

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Technology / Re: GPS Toll roads

« on: 06/01/2014 15:07:56 »

Putting aside intentional efforts to circumvent this kind of system, isn't GPS still prone to the occasional hiccup or two, from time to time?  What happens then?

If you are simply relying on it to get you to your destination then it is annoying enough when there are poor satellite signals and you drive 'blind' for a while.  A system that says I've entered a toll road when I haven't sounds a lot worse!

Incidentally, I've heard there is a ground based tracking system that some lorries use - i think in parallel with GPS - for similar reasons.  Don't recall what it is called though.

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The Environment / Re: How much CO2 does a tree consume per year?

« on: 06/01/2014 14:36:03 »

Or just over 1 kg of CO2 exhaled per day per human. Multiply by 9 x 10^9 and you find that humans contribute a massive 10 megatonnes of carbon dioxide to global warming (or is it climate change these days) every day even if they don't use fossil fuels. Shocking, isn't it? 

But this is not 'new' CO2 is it.  I'm sure that you wouldn't want to give the impression that just through respiration, humans (or any other animals for that matter) cause an inherent increase in the amount of 'free' CO2 in the atmosphere (and ecosystem as whole), would you?

Increased numbers of humans are in no way directly, by breathing, putting any more CO2 into the system. Instead, so far as 'just staying alive' goes, modern agriculture relies on unlocking fossil carbon - by using hydrocarbons to drive the Haber–Bosch process of making fertilizers.

Prior to this process becoming commercialised, there was obviously very little opportunity for stored, fossil carbon to re-enter the system. But, and this may be your pooint, there was no practical way to support the billions of people we have living on the planet today.

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Technology / Re: Britain’s Coal fired power plants facing closure:

« on: 15/12/2013 14:51:27 »

Further the problem of integrating renewables into the grid makes renewable energy more costly than fossil fuel power generation.

It does? Over what time frame?
Our national grid and links to Europe and Scandinavia have developed over decades and continue to be strengthened and will become 'smarter' in the coming years - with or without renewables to a certain extent.  In the short-term sense, yes, it is likely that we will see a rise in infrastructure costs but it should also be noted that the tenancy toward underinvestment in improving the grid was exaggerated by its privatisation back in the 90s - ie, it's not something that we (or the profitable private company responsible) couldn't have foreseen.

Edit: To clarify, the total cost to the consumer (esp. as fuel prices and carbon levies continue to increase) of operating a (European-wide) grid, heavily reliant on renewables, ought to be considerably less than the 'business as usual' approach.

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Chemistry / Re: Why not break down excess carbon dioxide into carbon and oxygen?

« on: 12/12/2013 17:24:40 »

What were the results of the attempt? Also, I believe the melting ice in the south sea releases iron on it's own so it's a natural phenomenon, but so is CO2 release, and we obviously cannot predict what all of the effects can be without testing.

It did result in plumes of algae, but moral questions aside (about how and why this guy did this unilaterally), the 'ocean system' outcome seems anything but clear.  The simplistic concept that dead algae would reliably transport vast amounts of carbon to the seabed, or that if this did happen the sea's PH balance would remain unaffected - has not been verified.

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Chemistry / Re: Why not break down excess carbon dioxide into carbon and oxygen?

« on: 11/12/2013 00:47:17 »

When it comes to the 'market' driving carbon mitigation efforts (all too slowly to be of any use IMO), I have to wonder about how the calculations are arrived at for some of this stuff. ... I can almost see some civil servant hitting on using electricity from wind or solar to 'crack' carbon dioxide indeed!

An example we have at the moment that seems especially lacking in 'full lifecycle analysis' is the import of torrefied (anaerobic 'cooked') wood, shipped from forests in Canada to the ageing Drax power plant here in the UK.  By doing this Drax's operators can merrily continue to burn large amounts of CO2-laiden coal, whilst keeping just inside the EU imposed emissions ceiling on greenhouse gases per MW.

A pragmatic (if still flawed environmentally) alternative it seems, would be to instead take the 'cooked' wood and stick it back in the ground close to where it was grown.  This is known as biochar (historically as Terra Preta) and is by far the oldest form of anthropogenic carbon sequestration.  The char can be produced in such a way that practically all the carbon locked into the wood during growth remains, but the cooked product becomes far more inert biologically than raw biomass ~ a web search on Terra Preta describes that soil and productivity is improved as well as locking in most of the carbon for centuries.

On this analysis, it would appear that ironically continuing to burn coal (the more 'local' the better) - with it's higher energy content than torrefied wood - and burying the very same biomass where it originated would mean less co2 is released. - No ships. - No lorries. - and better soils!

Or maybe I'm missing the obvious -

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Chemistry / Re: Why not break down excess carbon dioxide into carbon and oxygen?

« on: 11/12/2013 00:12:20 »

I am unsure why the Algae doesn't get decomposed by bacteria or other microbes when they sink like usual but it seems like a pretty good plan to try out.

It was tried last year... and apart from wondering what action was taken against this 'business man', I note that we are not all singing his praises and repeating this idea all over the oceans.

Simplicity is often very attractive when it comes to fixing a difficult problem eh!  And apart from the further acidification of the seas that is likely to occur, it seems somewhat premature to suppose that a little added iron is going to be the quick fix humanity wants.