Too many people?

[Loren Pechtel]

So yes, that is a discussion of me specifically blowing up into a mass of energy. This was expanded to suggest that my body could be used in an involuntary human bombing mission to take out Putin.

If find it despicable that people would choose to talk about the death of their debate partners like that. What ever happened to basic human decency?

This board has a well above average quantity of those in the sciences. I think you're reading an insult where only humor was intended.

 

[bilby]

Nuclear only has a big fuel problem if you don't reprocess. However, reprocessing is also the best solution to the waste problem.

"Reprocessing" is a PITA for solid fuel systems, particularly when you use only thermal neutron reactors. It works well, but it's costly.

The reason these systems predominate is that they're well suited to naval use; You can't stand well back from the power plant on a submarine or even an aircraft carrier, you have to have a large crew living very close to the reactor on a long-term basis. And the US and Soviet navies were the big drivers of twentieth century reactor design.

The problem with solid fuel is that it requires a well defined geometry (as do all nuclear reactors), and this can be disrupted by excessive heat - a "meltdown". Meltdowns aren't particularly hazardous to life or health, but they are very expensive, as they destroy a hugely valuable asset in a way that renders it extremely expensive to repair.

Liquid fuel (typically molten salt) is far superior in a number of ways, but the R&D only got as far as the R stage before the US Navy pulled the funding on the grounds that they'd already spent a lot of time, effort and money on the solid fuel pressurised water design, and the training of sailors to operate it, and didn't feel the need for a radically new system that couldn't even be effectively turned to weapons production.

Liquid fuelled fast neutron reactors are far superior for land-based power plants. The "reprocessing" required to turn spent solid fuel assemblies (from Generation I through III+ reactors) into usable fuel in a molten salt fast reactor, is to chop it into small pieces and chuck them into the molten salt reactor, where they will dissolve.

Liquid fuelled reactors are even more difficult to redesign for weapons grade materials production than solid fuel reactors, which is a big plus if we want to deploy them worldwide as power plants, but was considered a drawback by the Pentagon in the 1960s.

There isn't a "waste problem", and as such, there's no "best solution" to it; However the use of partially used fuel is an excellent efficiency, albeit a fairly unimportant one (fuel costs are a minuscule fraction of the cost of running a nuclear power plant).

Liquid fuel makes fuel replacement easier, it does nothing relevant to the reprocessing operations. Enough neutron poisons accumulate, you need to remove them or your reactor doesn't work.

Yeah, but with a liquid fuel you can do that in-line while the reactor is operating.

A big fraction of the poison is Xenon, which readily dissociates from the fuel if it's able to convect (which obviously solids can't).

But you can extract pretty much anything, simply by drawing off a fraction of the fuel and purifying it as a continuous process. You can even combine that process with online refuelling.

And chemical processing can render a large fraction of the "waste" into useful materials for medical and industrial applications. The long and medium half-life stuff is all valuable to some degree, once it's purified. The short lived stuff is irrelevant, stick it in a cask for a few half-lives, and then just landfill it. There's very little of it and it's not very hazardous once it's had time to decay.

The big hassle with solid fuel reprocessing (apart from having to shut down the reactor to remove the old fuel) is the liquefaction of the material that is a first stage in chemical separation. Typically this is done by converting the U and Pu oxides into soluble salts, for aqueous processing. That's not necessary if the U and Pu (and maybe Th) are already in the form of chloride or fluoride. And if you have a molten salt fast reactor, you can literally just chop up spent solid fuel, and dissolve it in your molten salt substrate, which can then be fed to your reactor without any further processing.

Also, poisons are less of a concern in fast spectrum reactors than in thermal spectrum designs, and if you're using spent fuel from older reactors as a feedstock, fast spectrum reactors are the best option for a lot of reasons.

There are two "reprocessing" issues - what to do with existing partially spent solid fuel assemblies; And what to do to remove fission products from the molten fuel salt in your new reactors.

Both are made FAR easier by the availability of fast spectrum molten salt reactors.

 

[Merle]

Merle keeps asking what can be done about overpopulation.

I do? I thought I was quite clear that my emphasis here was discussing whether we have a problem, and to what extant. Read the opening post and my repeated comments throughout this thread. I have been dragged into discussing the solution, only because people here have demanded it.

 

[Merle]

Energy density is everything - that's why wind and solar power are inevitably shit.

What kills wind and solar is their intermittent nature. Make a great battery and they become quite viable.

Screw it. Run both at full capacity and run overflow routing into a system of "sinks".

Assume I have 1000 hydroponics units and 5000 hydrocarbon units on the grid.

I can make a schedule schema so that when wind increases, it throws on inactive systems that have been off for a while, and shuts off ones for which it is "close enough" to the off cycle any more anyway, and have a SMALL battery for dealing with over/under margins, and buffering against instability.

As long as I have enough systems distributed across the overage.

By simply placing enough systems in the network, it fairly well guarantees enough secondary load to soak the output from all the sources without controlling source output.

Ideally, we would develop grid solutions which allow uncontrolled variable output and finely controlled variable secondary load, rather than treating demand as the uncontrolled variable.

Do the math on how big your battery would need to be. See https://dothemath.ucsd.edu/2011/08/nation-sized-battery/ .

A problem with wind and solar is that you can't always turn them on when you need power.

A problem with nuclear is that you can't quickly turn them off when you have excess power.

So alternative energy makes it hard to control the supply and demand on the grid. Most grids rely on natural gas and hydroelectric plants as swing units, which can easily be throttled to allow the total supply to meet the current total demand. If we went 100% alternative, this is a problem.

One solution that is used some places is to use any excess electricity to pump water up to a reservoir. Then, when you need more energy, you feed some of that water down through a turbine to boost the grid supply. It sounds inefficient, but it has been used and works. Heck, if you have nuclear plants producing a lot of excess cheap energy, you could run them all night pumping water up to the reservoir, and then reverse that process during the day when industry comes up to full speed.

Controlling the demand is also a possible solution, but it is very hard for an industry to agree that they will be open for business only on minutes that there is excess energy on the grid. What do the employees do when the plant loses power?

 

[Merle]

So yes, that is a discussion of me specifically blowing up into a mass of energy. This was expanded to suggest that my body could be used in an involuntary human bombing mission to take out Putin.

If find it despicable that people would choose to talk about the death of their debate partners like that. What ever happened to basic human decency?

This board has a well above average quantity of those in the sciences. I think you're reading an insult where only humor was intended.

Yes, of course, it was an attempt at humor. My point was not that the person was serious about using my body as a living bomb. He meant it as a joke.

My point is that the posts in question were designed to deliberately discuss my body being used as a living bomb, as opposed to generic comments about the amount of energy Einstein's equation shows is in 60 kg of mass. Yes, people have tried to rewrite history, and say those people were talking about any body. Go back and read what was written. They were specifically talking about my body, not any body.

 

[bilby]

A problem with nuclear is that you can't quickly turn them off when you have excess power.

That was a problem with your grandad's nuclear.

The French have been load following with nuclear plants for several decades now; The problems of the 1950s and '60s weren't permanent problems.

You might as well say that the problem with motor cars is that you need a driver who's strong enough to crank the starting handle. If you have such a dated understanding of the problems of a technology, it's not surprising that your opinions of it are rather foolish.

 

[Merle]

A problem with nuclear is that you can't quickly turn them off when you have excess power.

That was a problem with your grandad's nuclear.

The French have been load following with nuclear plants for several decades now; The problems of the 1950s and '60s weren't permanent problems.

You might as well say that the problem with motor cars is that you need a driver who's strong enough to crank the starting handle. If you have such a dated understanding of the problems of a technology, it's not surprising that your opinions of it are rather foolish.

I went to check it out and came across this really cool website that tells you what is going on in the French power grid, almost in real time:

French National Grid status

www.gridwatch.templar.co.uk

Here is what the power grid looked like for the last 24 hours in France.
View attachment 43269

The demand (gray line) fluctuated during the day, but the nuclear power (green line) was almost steady all day.

That site says France sold power to Germany and Belgium overnight. So it looks like they keep the nukes running at a steady pace, and sell off the excess. That works when your neighbors don't have much nuclear, but doesn't work if we go 100% nuclear.

So, it might be easier to throttle nuclear up and down compared to what it used to be, but if you looked at what the power grid did in France last night, it doesn't appear to be that significant.

But, like I said, if there is plenty of cheap nuclear power, there are always solutions like using the excess power to pump water up to a reservoir. But unfortunately, that requires plenty of excess cheap nuclear power, something that may well be limited, as I discussed.

 

[Jarhyn]

A problem with nuclear is that you can't quickly turn them off when you have excess power.

That was a problem with your grandad's nuclear.

The French have been load following with nuclear plants for several decades now; The problems of the 1950s and '60s weren't permanent problems.

You might as well say that the problem with motor cars is that you need a driver who's strong enough to crank the starting handle. If you have such a dated understanding of the problems of a technology, it's not surprising that your opinions of it are rather foolish.

I went to check it out and came across this really cool website that tells you what is going on in the French power grid, almost in real time:

French National Grid status

www.gridwatch.templar.co.uk

Here is what the power grid looked like for the last 24 hours in France.
View attachment 43269

The demand (gray line) fluctuated during the day, but the nuclear power (green line) was almost steady all day.

That site says France sold power to Germany and Belgium overnight. So it looks like they keep the nukes running at a steady pace, and sell off the excess. That works when your neighbors don't have much nuclear, but doesn't work if we go 100% nuclear.

So, it might be easier to throttle nuclear up and down compared to what it used to be, but if you looked at what the power grid did in France last night, it doesn't appear to be that significant.

But, like I said, if there is plenty of cheap nuclear power, there are always solutions like using the excess power to pump water up to a reservoir. But unfortunately, that requires plenty of excess cheap nuclear power, something that may well be limited, as I discussed.

It works when you go 100% nuclear with load absorbers.

The idea is, you scatter a bunch of systems across the grid. Each of these systems, scattered across the grid, does some kind of task for which the solution is energy + time. It can be anything from converting electricity to light, to running custom manufacturing.

It can be literally any task which you can do pretty much anywhere and which only requires electricity and simple feedstock.

I have some mad pipe dreams that we could do it with connex trailers filled with hardware top to bottom, and just stashed in places across the grid.

Let's say I have a variance across a grid of three levels, high and low and base.

Let''s say that I have two facilities, and each facility can be run 3.5 times a day, assuming full capacity, and each facility consumes enough power to change grid usage from "low" to "high", or from "base" to "low".

Let's say I produce enough power at full capacity to produce a HIGH amount of power. Let's then assume that the population, normally at "base" power, occasionally consumes up to "low" power, compared to max output.

The idea is, you look at the power grid consumption and look at when peak is, and how much of the day it consumes. Let's say it consumes 1/2 of the day.

I'm going to use a 14 hour day because the math works easier
12345678901234123456789012341...
11110002222033330000044440005...
00001111222200003333444455550...
pppppppbbbbbbbpppppppbbbbbbbp...

Assuming a small battery even a capacitor on the system... or simply a more granular load absorber... and you just run at max capacity all the time and USE as much as possible on whatever people want to use it for, within reason.

There are endless things we can dump excess electricity towards, including fixing parts of the climate, recycling, and carbon capture processes.

We just need to start doing that to fill out the demand for the day.

 

[Loren Pechtel]

Liquid fuel makes fuel replacement easier, it does nothing relevant to the reprocessing operations. Enough neutron poisons accumulate, you need to remove them or your reactor doesn't work.

Yeah, but with a liquid fuel you can do that in-line while the reactor is operating.

That's basically what I said, easier fuel replacement.

A big fraction of the poison is Xenon, which readily dissociates from the fuel if it's able to convect (which obviously solids can't).

Only a minor benefit, Xe-135 has a half life of 9.2 hours. You would avoid getting your reactor into a xenon hole (the start of the Chernobyl disaster) but you don't reprocess to remove Xe-135.

But you can extract pretty much anything, simply by drawing off a fraction of the fuel and purifying it as a continuous process. You can even combine that process with online refuelling.

Agreed. Continuous refueling is certainly the easiest fuel replacement.

And chemical processing can render a large fraction of the "waste" into useful materials for medical and industrial applications. The long and medium half-life stuff is all valuable to some degree, once it's purified. The short lived stuff is irrelevant, stick it in a cask for a few half-lives, and then just landfill it. There's very little of it and it's not very hazardous once it's had time to decay.

Fully agree. Most of it is useful.

 

[Loren Pechtel]

It works when you go 100% nuclear with load absorbers.

The idea is, you scatter a bunch of systems across the grid. Each of these systems, scattered across the grid, does some kind of task for which the solution is energy + time. It can be anything from converting electricity to light, to running custom manufacturing.

It can be literally any task which you can do pretty much anywhere and which only requires electricity and simple feedstock.

Disagree on converting electricity to light. Nobody sets out to make light--you make light to light something up. Thus it's not remotely useful as a load absorber. Custom manufacturing also isn't a good case--you need people, you probably need expensive machinery.

Good load absorbers are cheap, energy intensive systems--stuff where it's quite reasonable for some of it to spend most all it's time idle. That's why I proposed cracking water as a major load absorber--it's a very simple system, you capture the outputs and so long as you have enough storage (just big tanks) you can use it at a demand-driven rate. The hydrogen will be useful as a feedstock for other chemical processes, some of the oxygen can be sent to the medical market etc, I suspect most of it gets dumped.

 

[Merle]

Several people have asked me what I am suggesting we do. I did not come here prepared to talk about that. However, I have been asked that many times, so I will address that in more detail now.

First, let me clarify the problem: I believe we are in ecological overshoot. According to the Global Footprint Network, it would take 1.7 Earths to sustainable hold our population at current levels of impact. I think we would do well to cut our impact in half. That would be a huge goal. A more modest, perhaps attainable, goal would be to aim for a 10% reduction in our impact in the next 30 years.

The impact on the planet is popularly given by the formula, I=PAT, where I is the impact on our planet, P is the population, A is the average level of affluence, and T is a factor based on the technology used. T represents the level of impact per unit of affluence. That gives us three levers that affect our impact on the planet.

The most obvious place to begin is with technology. Let's just live smarter, and make less detrimental impact on the planet. I am all for that. But how has that been working out so far? Clearly, our efforts to solve climate change, ocean acidification, ozone depletion, nitrogen and phosphorus pollution of rivers, freshwater depletion, loss of natural land, loss of biodiversity, atmospheric aerosols, chemical pollution, and depletion of fossil fuels has not gone well. We are losing these battles. So realistically, I don't see technology reducing our impact per unit of affluence any lower than 80% of the current level.

Don't get me wrong. I love technology. I have dedicated my entire career as an engineer, working to use technology to improve people's lives. I am for technology. But we need to be honest about the limits to what it can do. I do not see that we can simply engineer our way out of this problem.

The next lever is affluence. Think about that one. There is no way we are moving that lever down. Poor countries rightfully want to increase their affluence. And rich countries don't want to go backwards. So if poor countries increase in affluence, and rich countries stay the same, this does nothing to reduce the factor A in our equation. I think we need to assume people will want A to be at least 125% of today's value 30 from now. If A is 125% and T is 80% of today's values, those factors cancel out. We have gotten nowhere.

That brings us to the factor P. That is a tough factor to discuss. I love people. I want there to be billions more people on this planet. But if Earth is like a lifeboat with limited capacity, then there are only so many more that we can invite on.

Let me be clear. I am in no sense advocating suicide or genocide. Human life is a marvel. We should not be snuffing it out. That must be off the table.

Neither am I advocating forced birth control. I see no way we could do that in a way that is fair and effective. And we must confine our efforts to things that are fair and effective. First do no harm. Forced birth control is out.

Which brings us to voluntary birth control. We can make abortions and contraceptives readily available. We can empower women and encourage them to choose ways of finding fulfillment other than by giving birth. We can further study our ecological footprint, and educate people on the dangers it poses.

How much would we need to reduce the birthrate to reduce our impact 10% in 30 years? There is this little thing called population momentum that gets in our way. Since population has been growing rapidly, the younger generations are larger than the oldest generation alive today. And so, even if we were to reduce the birthrate, it takes a long time for nature to bring the population down to the desired level. If we really wanted to reduce our impact on this planet by 10% in 30 years, and we find that this realistically requires a 10% decrease in population (which we will do by voluntarily limiting birthrates) then we need to reduce the rate of births by 50%.

Who would this affect? Some people might argue that countries with higher birthrates should do more. Others might argue that richer countries, which often already have low birthrates, should do more, since their children have a greater impact on the environment. I am not here to decide that. All I am saying is that we, as humans, should work together to persuade people to have fewer children in a way that is fair to all.

I think 50% fewer childbirths per year is a good goal for now. Not only would that reduce our impact 30 years from now, but it would eventually stabilize population at 4.8 billion people about 75 years from now. I think that is a good thing. For by then we will have burned through most of our inheritance of fossil fuels, and possibly most of our accessible concentrated uranium. That will make it harder to maintain the Green Revolution, and might well limit population to the 2 billion people we had before the Green Revolution started. But that is 75 years down the road. I don't expect to be alive then. (If I am, I will be 141!) Future generations will need to deal with that problem. They should be trusted to make that decision.

If the current trend continues, with 1 billion people added to the planet every 12 years, there would be 16 billion people on this planet with no appreciable fossil fuels available 80 years from now. If we followed the trajectory mentioned above, there would be 4.8 billion, which would be much more manageable. We need to at least give our descendants a chance.

The plan I suggested above may fall far short of what is needed. If we are indeed at 175% of the current Earth capacity, a 10% reduction in our impact on the planet within 30 years might be too little too late. Perhaps we should do even more. How?

We might not be doing all that needs to be done, but if we got behind a plan such as the one above, at least we would know that we did what we could. We saw what was coming to our near descendants, and did something about it. At least we tried. That is better than doing nothing.

So, for what it is worth, that is my recommendation. Others will differ, probably somewhat strongly. That's fine. Respectful debate of the ideas discussed here is certainly welcome.

 

[Jarhyn]

It works when you go 100% nuclear with load absorbers.

The idea is, you scatter a bunch of systems across the grid. Each of these systems, scattered across the grid, does some kind of task for which the solution is energy + time. It can be anything from converting electricity to light, to running custom manufacturing.

It can be literally any task which you can do pretty much anywhere and which only requires electricity and simple feedstock.

Disagree on converting electricity to light. Nobody sets out to make light--you make light to light something up. Thus it's not remotely useful as a load absorber. Custom manufacturing also isn't a good case--you need people, you probably need expensive machinery.

Good load absorbers are cheap, energy intensive systems--stuff where it's quite reasonable for some of it to spend most all it's time idle. That's why I proposed cracking water as a major load absorber--it's a very simple system, you capture the outputs and so long as you have enough storage (just big tanks) you can use it at a demand-driven rate. The hydrogen will be useful as a feedstock for other chemical processes, some of the oxygen can be sent to the medical market etc, I suspect most of it gets dumped.

The light being discussed here would be "grow lamps" for hydroponics.

I suppose that's "lighting some stuff up" but not quite what I was talking about.

 

[bigfield]

If the current trend continues, with 1 billion people added to the planet every 12 years, there would be 16 billion people on this planet

Maybe I just missed it, but where did you provide the evidence for this population trend?

 

[Jarhyn]

If the current trend continues, with 1 billion people added to the planet every 12 years, there would be 16 billion people on this planet

Maybe I just missed it, but where did you provide the evidence for this population trend?

They didn't. Some people don't understand logistics curves. Just because a curve jumps does not mean it lacks an asymptote.

 

[Merle]

If the current trend continues, with 1 billion people added to the planet every 12 years, there would be 16 billion people on this planet

Maybe I just missed it, but where did you provide the evidence for this population trend?

See, for instance, https://en.wikipedia.org/wiki/World_population_milestones and https://ourworldindata.org/grapher/population?time=1950..latest

The rise in population since 1970 has been very close to a straight line for 50 years. We added about 83 million per year until COVID hit, when it dropped to about 67 million increase per year.

 

[Merle]

If the current trend continues, with 1 billion people added to the planet every 12 years, there would be 16 billion people on this planet

Maybe I just missed it, but where did you provide the evidence for this population trend?

A better chart might be the one at https://ourworldindata.org/grapher/population-growth-the-annual-change-of-the-population . This plots the rate of change (first derivative) of the population. Its easier to see there that the rate of change was consistently between 80 and 90 million per year until COVID hit. It is too early to tell if this represents a permanent downturn, or perhaps just the result of COVID. The rate of change is still far above zero.

 

[bilby]

So, it might be easier to throttle nuclear up and down compared to what it used to be, but if you looked at what the power grid did in France last night, it doesn't appear to be that significant.

Just because you can, that doesn't mean you will if you don't need to.

You don't have sufficient evidence to judge it's significance, so your assessment that nuclear power couldn't work if you can't sell the power to neighbours or find a storage solution is deeply flawed.

The French sell a lot of electricity to Germany, because German electricity policy is batshit crazy.

 

[Jarhyn]

So, it might be easier to throttle nuclear up and down compared to what it used to be, but if you looked at what the power grid did in France last night, it doesn't appear to be that significant.

Just because you can, that doesn't mean you will if you don't need to.

You don't have sufficient evidence to judge it's significance, so your assessment that nuclear power couldn't work if you can't sell the power to neighbours or find a storage solution is deeply flawed.

The French sell a lot of electricity to Germany, because German electricity policy is batshit crazy.

The fact is that there are already good solutions floating out there for making nuclear viable, and among the best of them are "use the excess". If you can't vary supply, soak demand.

 

[bilby]

So, it might be easier to throttle nuclear up and down compared to what it used to be, but if you looked at what the power grid did in France last night, it doesn't appear to be that significant.

Just because you can, that doesn't mean you will if you don't need to.

You don't have sufficient evidence to judge it's significance, so your assessment that nuclear power couldn't work if you can't sell the power to neighbours or find a storage solution is deeply flawed.

The French sell a lot of electricity to Germany, because German electricity policy is batshit crazy.

The fact is that there are already good solutions floating out there for making nuclear viable, and among the best of them are "use the excess". If you can't vary supply, soak demand.

You can do either.

Or both.

It's not a problem.

 

[bigfield]

If the current trend continues, with 1 billion people added to the planet every 12 years, there would be 16 billion people on this planet

Maybe I just missed it, but where did you provide the evidence for this population trend?

A better chart might be the one at https://ourworldindata.org/grapher/population-growth-the-annual-change-of-the-population . This plots the rate of change (first derivative) of the population. Its easier to see there that the rate of change was consistently between 80 and 90 million per year until COVID hit. It is too early to tell if this represents a permanent downturn, or perhaps just the result of COVID. The rate of change is still far above zero.

That doesn't support your claim, though. In fact it shows quite clearly that the UN predicts the world's population will reach a maximum of about 10.4 billion before going into decline:

Here's a summary, charting not just the growth rate but also the total population.

Future Population Growth

What can we expect for the future? What determines how large or small the world population will be?

ourworldindata.org

So why should we think that the world's population will follow the trend you suggested and grow to 16 billion?