Author Topic: Episode #727  (Read 4689 times)

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Offline brilligtove

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Re: Episode #727
« Reply #30 on: June 17, 2019, 10:50:44 AM »
Reactors that can only fail safe have been around a long time. CANDU reactors are physically structured so the reaction has to be forced to happen at all. The more things fail and break down the more the reaction can't even start.

There are certainly ways bad things could happen, especially heavy water leaking or flooding out - but these have been largely mitigated too.

IIRC part of the reason the US went with reactors that can melt down was to generate weapons-grade plutonium. New reactors don't necessarily have that requirement.
"Blyat Igor, what are you suggesting? anything goes wrong you just push the az5 shut down button, the rods drop, and the reaction is killed, there are issues but its all mitigated now".....final design review for the rbmk type reactors.

I suspect similar argumentation in the Fukashima case .."man you just start the generators and pump water into them...the rest is physics, relax "

What about intentional subbotage from the inside? are u saying  it is completely foolproof, because its literally has to be so if we are to rely on nuclear and build thousands all around the world?

Before we shift the goalposts to sabotage, let's finish talking about breakdowns and errors.

The CANDU wiki page describes a bunch of the safety features. Perhaps the most basic is that the fuel is not enriched, so it can't go critical. It can still melt down, but in the process of melting down it quenches the reaction several ways.
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Offline werecow

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Re: Episode #727
« Reply #31 on: June 17, 2019, 01:40:15 PM »
Name that logical fallacy: Steve: “nuclear is safer than solar, is safer than wind”.
(analogy: since more people on earth die for allergic reactions than for gunshots, going to war is safer than eating peanuts)

The statistics Steve cited were in a per megawatt-hour basis, so they were in fact equalized based upon the prevalence of the technology.

IIRC most of the deaths from solar are due to people falling off roofs while installing them (although I could be misremembering) - likewise for wind. If that's the case, it somehow seems a bit dubious to say that nuclear energy is safer than solar. Or at least, that's not really inherent in the technology, more a safety regulations issue. Was trying to find out if there were any big-ish incidents involving solar power plants, but when I google "solar power plant disaster", the only power plant disaster that comes up is, ironically, Chernobyl, which is apparently opening a solar power plant. }|:op

Offline stands2reason

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Re: Episode #727
« Reply #32 on: June 17, 2019, 01:58:08 PM »
IIRC most of the deaths from solar are due to people falling off roofs while installing them (although I could be misremembering) - likewise for wind.

Photovoltaics use semiconductors doped with heavy metals. So the deaths would include: mining & transportation of raw materials, industrial accidents in factories, and estimated deaths resulting from pollution in manufacturing. Plus, depending on where the electricity comes form, the manufacturing also contributes to that.

Offline lonely moa

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Re: Episode #727
« Reply #33 on: June 17, 2019, 02:28:59 PM »
Some people spend a lot of money on a backup gas generator. I won't need that.

Gas and other domestic backup gensets are not that expensive. Certainly a lot cheaper than batteries.

Gensets have the advantage of not being capacity constrained. They have the disadvantage of being mechanical with associated noise and exhaust and require a short interruption to power supply during cutover from the grid.

I will be installing a backup genset with a cut over switch in the future, due to local grid reliability issues.

We have had a portable petrol generator for years.  Works a treat when the power goes off.  Mostly we cope without, but it's nice to power the wifi and water pump. 
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Offline brilligtove

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Re: Episode #727
« Reply #34 on: June 17, 2019, 02:34:59 PM »
Name that logical fallacy: Steve: “nuclear is safer than solar, is safer than wind”.
(analogy: since more people on earth die for allergic reactions than for gunshots, going to war is safer than eating peanuts)

The statistics Steve cited were in a per megawatt-hour basis, so they were in fact equalized based upon the prevalence of the technology.

IIRC most of the deaths from solar are due to people falling off roofs while installing them (although I could be misremembering) - likewise for wind. If that's the case, it somehow seems a bit dubious to say that nuclear energy is safer than solar. Or at least, that's not really inherent in the technology, more a safety regulations issue. Was trying to find out if there were any big-ish incidents involving solar power plants, but when I google "solar power plant disaster", the only power plant disaster that comes up is, ironically, Chernobyl, which is apparently opening a solar power plant. }|:op

Apparently some of the deaths are electrocutions of people who don't handle the batteries properly during installation and maintenance.
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Offline werecow

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Re: Episode #727
« Reply #35 on: June 17, 2019, 03:18:57 PM »
IIRC most of the deaths from solar are due to people falling off roofs while installing them (although I could be misremembering) - likewise for wind.

Photovoltaics use semiconductors doped with heavy metals. So the deaths would include: mining & transportation of raw materials, industrial accidents in factories, and estimated deaths resulting from pollution in manufacturing. Plus, depending on where the electricity comes form, the manufacturing also contributes to that.

Fair enough.

However, I'm curious how those numbers are estimated, and what the uncertainty ranges might look like. It seems like counting up all the externalities would involve an extreme amount of uncertainty and many ways in which to massage the numbers either way. I mean, I'm sure we use (or could use) those metals for other purposes as well, so what percentage of deaths involved in the mining and transport of these materials count as "excess solar power deaths"? For nuclear, do we count studies that claim to show excess leukemia deaths in populations living near reactors or are they too contentious/implausible? For solar, what is the uncertainty range for excess deaths due to heavy metal poisoning or other environmental impacts? Do we also include, say, excess deaths due to exhaust fumes caused by the transport of materials? The uncertainty ranges must be pretty wide for nuclear given that the death toll estimates for even the one major event under discussion alone span 5 orders of magnitude, and I assume they're pretty wide for solar, too, if we include all these factors.

Also, this is a politically contentious issue where we know all too well that the various industries and special interest groups are not shy about peddling antiscience, and it's hard to find actual scientific studies showing direct comparisons that include all the externalities. Combined with those uncertainty ranges that leaves the door wide open for cherry picking.

Don't get me wrong, I'm not saying the (qualitative) conclusions can't be correct, nor would I be especially surprised if they are; I'm just a little skeptical about the confidence with which Steve stated them on the show.
« Last Edit: June 18, 2019, 05:11:03 PM by werecow »
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Offline Zelda McMuffin

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Re: Episode #727
« Reply #36 on: June 17, 2019, 04:42:25 PM »
I don't want to get into another argument about "soft" science vs. "hard" science so I'll just say that I understand why you think the study mentioned in the show was terrible, and I agree. Researchers should understand the theoretical and methodological limits of their work.
However, there's value in studying large scale human behavior, particularly with the huge amount of data available now. It's a mistake, IMO, to dismiss whole areas of study because *some* people/groups are doing bad science or bad PR in that field.


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Offline daniel1948

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Re: Episode #727
« Reply #37 on: June 17, 2019, 04:42:37 PM »
Name that logical fallacy: Steve: “nuclear is safer than solar, is safer than wind”.
(analogy: since more people on earth die for allergic reactions than for gunshots, going to war is safer than eating peanuts)

Just don't eat peanuts in a war zone.  ::)

Some people spend a lot of money on a backup gas generator. I won't need that.

Gas and other domestic backup gensets are not that expensive. Certainly a lot cheaper than batteries.

Gensets have the advantage of not being capacity constrained. They have the disadvantage of being mechanical with associated noise and exhaust and require a short interruption to power supply during cutover from the grid.

I will be installing a backup genset with a cut over switch in the future, due to local grid reliability issues.

Yes, a genset is much cheaper. Having uninterrupted power is just one small added benefit of batteries. Their main function is to store solar for night-time use. And they don't require me to handle gasoline or smell the stink and they won't keep my neighbors awake at night or need special care to stay in working order after a year or two idle. When I lived on the farmstead, I hated having to handle gasoline for the lawn mowers, the rototiller, the chainsaw, and other power equipment.

We may not be able to meet our energy needs with solar & batteries alone, but we could meet much more of our energy needs with solar & batteries than we're doing now. And if we required carbon emitters to pay the full external cost of that carbon, and ended other subsidies to fossil fuels, renewables would be much more competitive and a lot more people would be switching.

A big advantage of home-based solar & storage is that it cuts out the middleman. This is good for consumers but bad for utility monopolies. For decades they've had guaranteed zero-risk profit. They want to keep energy-generation centralized so that people have to buy it from them. I'm really looking forward to having my own.
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Offline Alex Simmons

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Re: Episode #727
« Reply #38 on: June 17, 2019, 05:32:30 PM »
We may not be able to meet our energy needs with solar & batteries alone, but we could meet much more of our energy needs with solar & batteries than we're doing now. And if we required carbon emitters to pay the full external cost of that carbon, and ended other subsidies to fossil fuels, renewables would be much more competitive and a lot more people would be switching.

I agree re the price on pollution as being the best and most effective market based solution.

As for whether batteries reduce carbon emissions, that's not universally true. In the case where no solar PV export is permitted and your have a largely fossil fuelled grid, then yes that's certainly true as that combination of grid characteristics results in lower demand of fossil fuel and lower carbon emissions.

However domestic batteries typically result in higher emissions in many locations, or have no net benefit. Much depends on the local grid and the energy sources feeding it.

In the case of a location where excess domestic solar PV is exported to a grid which has a high proportion of carbon intensive power production (coal, gas, oil), then domestic batteries result in higher carbon emissions.

Why? Well if excess solar PV is exported then it is immediately used to offset someone else's (typically a neighbour's) energy demand which would have previously been supplied by fossil fuel sources. If it is instead stored for evening use (to offset evening fossil fuel grid energy import) then yes that also offsets fossil fuel use by that household, however the round trip efficiency losses (11-20%) means the carbon offset via the battery is less than it would have been via simply exporting to the grid to offset your neighbour's carbon emissions.

If however the grid is substantially powered by low/zero carbon sources already, then the addition of a battery won't make a difference to carbon emissions, other than the increase associated its manufacture and installation.

There is an in-between scenario where there is a substantial difference between daytime and nighttime sources of grid energy. If daytime grid energy supply is dominated by low/zero carbon sources while nighttime energy supply is dominated by carbon intensive sources, then yes a domestic battery will certainly help reduce carbon emissions overall.

A big advantage of home-based solar & storage is that it cuts out the middleman. This is good for consumers but bad for utility monopolies. For decades they've had guaranteed zero-risk profit. They want to keep energy-generation centralized so that people have to buy it from them. I'm really looking forward to having my own.

All having a battery does is replace the energy supply middleman with a battery supplier middleman. Installing a battery is in effect pre-paying for your energy supply up front to a battery installation company.

As a principle, the concept of democratising energy supply and demand is a good one.

One of the challenges however is managing the impacts on those who cannot access such tech (e.g. they are renters, or live in an apartment or home unsuitable to instal such equipment) or more importantly cannot afford to instal such tech and they are reliant on the grid supply and utility for their energy. It's the most vulnerable with no choice on their energy supply who get left behind dealing with the utilities who need to cover their large fixed operating costs over a smaller demand base.

Offline bachfiend

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Re: Episode #727
« Reply #39 on: June 17, 2019, 05:42:43 PM »
We may not be able to meet our energy needs with solar & batteries alone, but we could meet much more of our energy needs with solar & batteries than we're doing now. And if we required carbon emitters to pay the full external cost of that carbon, and ended other subsidies to fossil fuels, renewables would be much more competitive and a lot more people would be switching.

I agree re the price on pollution as being the best and most effective market based solution.

As for whether batteries reduce carbon emissions, that's not universally true. In the case where no solar PV export is permitted and your have a largely fossil fuelled grid, then yes that's certainly true as that combination of grid characteristics results in lower demand of fossil fuel and lower carbon emissions.

However domestic batteries typically result in higher emissions in many locations, or have no net benefit. Much depends on the local grid and the energy sources feeding it.

In the case of a location where excess domestic solar PV is exported to a grid which has a high proportion of carbon intensive power production (coal, gas, oil), then domestic batteries result in higher carbon emissions.

Why? Well if excess solar PV is exported then it is immediately used to offset someone else's (typically a neighbour's) energy demand which would have previously been supplied by fossil fuel sources. If it is instead stored for evening use (to offset evening fossil fuel grid energy import) then yes that also offsets fossil fuel use by that household, however the round trip efficiency losses (11-20%) means the carbon offset via the battery is less than it would have been via simply exporting to the grid to offset your neighbour's carbon emissions.

If however the grid is substantially powered by low/zero carbon sources already, then the addition of a battery won't make a difference to carbon emissions, other than the increase associated its manufacture and installation.

There is an in-between scenario where there is a substantial difference between daytime and nighttime sources of grid energy. If daytime grid energy supply is dominated by low/zero carbon sources while nighttime energy supply is dominated by carbon intensive sources, then yes a domestic battery will certainly help reduce carbon emissions overall.

A big advantage of home-based solar & storage is that it cuts out the middleman. This is good for consumers but bad for utility monopolies. For decades they've had guaranteed zero-risk profit. They want to keep energy-generation centralized so that people have to buy it from them. I'm really looking forward to having my own.

All having a battery does is replace the energy supply middleman with a battery supplier middleman. Installing a battery is in effect pre-paying for your energy supply up front to a battery installation company.

As a principle, the concept of democratising energy supply and demand is a good one.

One of the challenges however is managing the impacts on those who cannot access such tech (e.g. they are renters, or live in an apartment or home unsuitable to instal such equipment) or more importantly cannot afford to instal such tech and they are reliant on the grid supply and utility for their energy. It's the most vulnerable with no choice on their energy supply who get left behind dealing with the utilities who need to cover their large fixed operating costs over a smaller demand base.

It’s not true that renters can’t access solar.  I have two rental properties, and decided to install 20 solar panels on each.  I did it for two reasons.  I decided it would make it easier to rent the properties during the current soft period for renting (the renters get whatever benefit of the panels without it affecting the rent).  And it’s also my carbon offset when I fly long distance.
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Re: Episode #727
« Reply #40 on: June 17, 2019, 06:50:27 PM »
And it’s also my carbon offset when I fly long distance.

Not saying it isn't nice to install solar wherever it's possible and efficient enough, but are you saying that you're counting the emissions that your renters would've caused with a less ideal energy mix as something that you can subtract from your own emissions?

Offline bachfiend

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Re: Episode #727
« Reply #41 on: June 17, 2019, 08:21:03 PM »
And it’s also my carbon offset when I fly long distance.

Not saying it isn't nice to install solar wherever it's possible and efficient enough, but are you saying that you're counting the emissions that your renters would've caused with a less ideal energy mix as something that you can subtract from your own emissions?

Yes, why not?  One of my tenants uses an incredibly small amount of electricity (5 kW.hr/day, which is well below the average for a household of their size), and the 20 panels I installed generates around 40 kW.hr/day in summer and 10 in winter, so why can’t I count the excess as an offset?  And my CO2 emissions are pretty low too.  I draw around 3-4 kW.hr/day from the grid, I generate a similar amount from my panels and my car usage is less than 10 km a month.

In the absence of a government that takes global warming seriously (the Australian government gives only lip service), individual action is the only response.

The point is: landlords can install solar panels on their rental properties just as much as they can install air conditioning or heating if they think it adds to the properties’ value.

The CO2 emissions for when I fly long distance is only hypothetical.  The airline is going to fly that plane regardless of whether I’m on it or not.  My last flight, Frankfurt to Perth, was virtually empty on the first leg to Dubai.  Now, if I was using a chartered private plane...
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Re: Episode #727
« Reply #42 on: June 17, 2019, 08:49:17 PM »
I interpreted the closest planet question differently from the whole world, it seems like. I interpreted it as asking which planet's orbit is closest to the Earth's orbit. So the answer would be Venus.

What metric are you using to define the distance between two orbits?

I don't understand the question. The orbit of Mars averages 227.9 million km from the sun. The orbit of Earth averages 149.6 million km. The orbit of Venus averages 108.2 million km. And then simple subtraction. Venus' orbit is 41.4 million km from Earth's, and Earth's orbit is 78.3 million km from Mars'. Venus' orbit is closer to Earth's than Mars' is.

If that's not what you mean by "the metric I'm using", I suppose I could re-do the calculation in miles.

I was just asking how you were assigning a single number for distance to two trajectories in space. For example, one possible metric is:
d(orbitA, orbitB)= |rA-rB|, where rA is the minimum distance between a point on orbit A from the sun and rB is the minimum distance between a point on orbit B from the sun.

The metric you mentioned, which uses "average", runs into the same ambiguity as the "average" distance between planets. For example, average could be interpreted as the semi-major axis of the orbit, or the time-average, or something else.

Sorry, I'm being way too pedantic about this. I was just curious about how your interpretation of the question differed from the ones described on the show. I think I get it now. Thanks!  :)

I was interpreting it as the distance between the orbits rather than between the planets. Since the planets orbit in ellipses, you take the average between the closest and the furthest distances. Basically, averaging the distance abstracts the orbits into concentric circles, and the circle which represents Venus' orbit is closer to the circle that represents Earth's orbit than that circle is to the circle that represents Mars' orbit.

Trust me, it's much simpler in my head.
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Offline The Latinist

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Re: Episode #727
« Reply #43 on: June 17, 2019, 09:27:44 PM »
At Venus’ perihelion it is closer to the aphelion of Earth than Mars is at is perihelion.  In other words, no part of Mars’ orbit is closer to any part of Earths orbit than is any part of Venus’ orbit.

Also? Venus has a virtually circular orbit, and Earth’s is only slightly elliptical. Mars is the only of the three with any significant eccentricity.
« Last Edit: June 17, 2019, 09:35:22 PM by The Latinist »
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Offline fuzzyMarmot

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Re: Episode #727
« Reply #44 on: June 18, 2019, 02:54:30 AM »
At Venus’ perihelion it is closer to the aphelion of Earth than Mars is at is perihelion.  In other words, no part of Mars’ orbit is closer to any part of Earths orbit than is any part of Venus’ orbit.

Also? Venus has a virtually circular orbit, and Earth’s is only slightly elliptical. Mars is the only of the three with any significant eccentricity.

It seems desirable to have a way of defining distance that can be applied to any two objects in a solar system, including things like long-period comets that have highly eccentric orbits. The authors of the Physics Today magazine article note that their circular, coplanar, concentric assumptions make their method not applicable to Pluto.

The question of how to define the distance between two orbits is particularly interesting when orbits are not circular. Should you define the "average" distance from a body to the sun by integrating over time, angle, or arc length? These will all give the same answer for circular orbits, but not for elliptical ones.

A rough analogy: suppose you want to measure the average altitude of a rollercoaster car. You could look at the rollercoaster track, and find the average height of the track (but should you average over horizontal distance or track length?). Or you could ride the roller coaster, and find the time-average of your altitude.

 

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