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#101 2023-04-04 03:12:41

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 3,542

Re: Why the Green Energy Transition Won’t Happen

This explains why steel tends not to be used for AC power transmission, even though it is cheap.
https://en.m.wikipedia.org/wiki/Skin_effect

Skin effect results in disproportionate current density in outer skin of a conductor.  This results in resistivity having an outsized effect on the overall resistance, even if a thicker conductor is used.  Conductivity scales with surface area rather than cross-section area.  Skin effect becomes more problematic as frequency increases and is not applicable at all to direct current transmission.  This is why DC is prefered in rail electrification, especially for ground level power supplies like third rail networks.  In this situation, a thick steel rail is able to carry thousands of amps at voltages of 500-1500v.

Kris DeDecker makes a case for a return to local DC power networks.
https://www.resilience.org/stories/2016 … -dc-power/

This is problematic if power must be transported long distances because DC cannot use transformers to change voltage and using DC at high voltage is dangerous.  It would work for distributed generation, like home solar, where transmission distances are a few tens of feet.

In other articles, DeDecker makes a strong case for avoiding energy storage and adjusting working patterns to make use of renewable energy when and where it is available and curtailing use when it is not.  Traditionally, this is how wind and solar based systems have worked.  Energy storage was not possible.  Even today, storage is not a practical strategy for dealing with anything more than short term fluctuations.  Instead, the strategy is to rely upon the grid, with fossil fuel powerplants supplying power when wind and solar cannot.  But this means paying for two power stations, in addition to batteries needed to provide time for running up gas turbines.  If we could adjust our energy use so that we use renewable energy only when it is available, we solve a lot of problems.  We can use energy generated on site, without transmission costs or storage costs.  It is also easier to harness mechanical power directly, rather than converting it into electricity.  But living in this way is clearly very challenging.  It would require planning tasks around the weather and working long hours when energy is abundant and fewer hours when it is not.  It would be tough to do.  But if we are forced to rely upon renewable energy for our future energy needs, this appears to be the only strategy that works.  Buildings weeks worth of energy storage does not apoear to be a viable option.

Last edited by Calliban (2023-04-04 03:30:16)


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#102 2023-04-04 07:43:18

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,542

Re: Why the Green Energy Transition Won’t Happen

Interesting podcast by Peter Zeihan.
https://m.youtube.com/watch?v=vSKywoGh7Hw

A large part of the world is facing deindustrialisation over the next few decades.  Only a handful of nations will remain 'developed'.  What this means for the majority of the world's population is nothing short of horrific.  If industrial agriculture goes away, what happens to the billions that depend upon it?


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#103 2023-04-04 08:35:33

Terraformer
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From: Ceres
Registered: 2007-08-27
Posts: 3,827
Website

Re: Why the Green Energy Transition Won’t Happen

Depends on how it goes away. Organic has a 50% productivity penalty, but corn and potatoes are four times productive as wheat on a calories per hectare basis, and the organic penalty similar across the board (potatoes have the same yield halving as wheat). Think I posted the link to the study somewhere. So there's room to change our diets around.

For a country like Britain, with productive pasture, shifting from meat to dairy would significantly boost the calories available. That means goats and sheep of course, cattle aren't raised on much of the land for a reason. We could also switch to rabbits from beef for meat, for a 50-100% gain in feed conversion ratio...


Use what is abundant and build to last

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#104 2023-04-04 09:52:49

Terraformer
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From: Ceres
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Re: Why the Green Energy Transition Won’t Happen


Use what is abundant and build to last

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#105 2023-04-04 18:11:33

kbd512
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Posts: 7,564

Re: Why the Green Energy Transition Won’t Happen

Has anyone ever tried to enclose a circular / center-pivot field with a railroad track?

I'm wondering if a robot attached to a center-pivot system using rail-based enclosure could till / plow / seed / irrigate / spray / harvest, supported on both ends of the field by the rail (a monorail), moving around in a circle to tend to the crop below it.  Mini attachments would connect to the center-pivot arm for power, seed, sprays / insecticides, water, and then the crop would be transported back to the edge of the field using the same system.  The center of the field could contain a single wind turbine to supply electrical power.

I don't think this would work everywhere, probably not on hillsides, but maybe it can reduce the movement and energy required over flat ground, since the machine is semi-fixed (only rotates) about a central point, and a gantry system moves the farming tools to the correct spot over the ground while the machine rotates.  More importantly, the grain harvest doesn't require a combine-harvester, a grain truck, and a semi-truck.  The grain gets dumped directly into an awaiting semi-truck, for transport to a nearby processing plant or storage silo.

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#106 2023-04-04 18:56:09

tahanson43206
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Registered: 2018-04-27
Posts: 17,907

Re: Why the Green Energy Transition Won’t Happen

Picking up on an idea of kbd512:

Hello again!
Hello! How may I assist you today?

This is such a novel question that came up in discussion, I thought you might be able to find a match... the question is about farming, and specifically about a circular field. We know there are circular watering systems for farms in regions with limited water. This is something beyond that ... the idea appears to be to mount all farm tools on a girder that rotates about a central pivot, with railroad tracks supporting the far end. Has anyone ever tried to enclose a circular / center-pivot field with a railroad track for farming?

To my knowledge, I'm not aware of any instance where a circular/center-pivot field has been enclosed with a railroad track for farming. However, it is worth noting that center-pivot irrigation systems are commonly used in agriculture to water crops in a circular pattern. These systems are usually supported by wheels or skids and move in a circular pattern around a pivot point to irrigate crops evenly.

As for mounting all farm tools on a girder that rotates around a central pivot, this could be possible, but it would likely require a significant investment in research and development to create a system that is efficient and cost-effective. It is worth noting that some farms already use autonomous tractors and other advanced machinery that can be programmed to move in precise patterns and perform specific tasks.

Overall, while the idea of enclosing a circular/center-pivot field with a railroad track for farming is intriguing, I am not aware of any existing examples of such a system in practice. However, with advancements in technology and innovation in the agricultural industry, it is possible that we may see such systems developed in the future.

If you were asked to design such a system, how would you proceed? You noted in your reply above that there are automated tractors, harvesters, planters, cultivation machines and probably others, but these all operate on wheels or tracks, and they press down on the soil. An overhead girder would keep machinery above plants, so the maximum possible soil would be available for crops.

Designing a farming system that utilizes an overhead girder to keep machinery above the plants in a circular/center-pivot field would be a complex and challenging task. However, if I were to proceed with designing such a system, here are a few steps I might take:

    1. Define the goals: First, it would be important to define the specific goals of the system, such as maximizing crop yield, minimizing soil compaction, reducing labor costs, or improving sustainability. This would help to guide the design and ensure that the system is tailored to the specific needs of the farm.

    2. Conduct research: Next, I would conduct research to identify existing technologies and techniques that could be adapted for this system. This might involve looking at similar systems used in other industries or fields, as well as exploring new technologies such as drones or robotic systems.

    3. Develop a prototype: Once I had a better understanding of the requirements and available technologies, I would begin developing a prototype of the system. This might involve building a small-scale model of the girder and machinery, testing different materials and designs, and iterating on the design until it met the desired specifications.

    4. Test and refine: With a working prototype, I would then test the system in a real-world farming environment. This would involve monitoring crop growth, soil quality, and other metrics to evaluate the effectiveness of the system. Based on these results, I would refine the design as necessary to optimize its performance.

    5. Scale up: Finally, if the system proved to be effective, I would work on scaling up the design for use in larger farming operations. This would likely involve collaborating with other experts in agriculture, engineering, and logistics to ensure that the system could be manufactured and deployed at scale.

Overall, designing a system like this would be a complex and challenging task, but with the right resources and expertise, it could potentially offer significant benefits in terms of crop yield, sustainability, and labor efficiency.

Thank you for another interesting exchange! Catch you next time.

You're welcome! It was my pleasure to assist you. Feel free to reach out if you have any other questions in the future. Have a great day!

(th)

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#107 2023-04-05 03:28:02

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,542

Re: Why the Green Energy Transition Won’t Happen

TH, it is a novel idea.  You wouldn't neccesarily need a circumferencial rail track, just a swing arm in the centre of the field that the robot could run along and draw power from.  It would mean using relatively small, circular fields.  But it would allow the mechanical power required for farming to be direct-electric.  Farm equipment could be powered from the grid or using a wind turbine or solar array on the farm.  It would use the energy directly as it is generated, without requirement for storage.  This would represent a huge improvement in efficiency.


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#108 2023-04-05 06:16:54

tahanson43206
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Registered: 2018-04-27
Posts: 17,907

Re: Why the Green Energy Transition Won’t Happen

For Calliban re #107

Thank you for adding details to kbd512's idea ... The rail at the outer perimeter would allow the girder to be longer than otherwise would be the case, and the all important stability of the framework for the robot workers would be ensured.  There are already robot devices to attend to the needs of individual plants. I'm ** pretty sure** we have something posted about them in the forum archive, and they are worth adding if someone can find references.  A good place to put them is in one of the robot topics, such as robots+useful by Louis.

I like kbd512's idea for several reasons ... water delivery is already a proven technology for circular farming, but (as I understand) kbd512's vision would go much further.  Fertilizer can be delivered with precision, and individual plants can be attended with a database of all the plants in the circular area.

Your concept of renewable power for the plot is a good use for the land between plots.

If water can be piped underground to each site, from a distant water source, then the entire enterprise can be established in a desert region.

(th)

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#109 2023-04-05 11:53:18

kbd512
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Re: Why the Green Energy Transition Won’t Happen

I don't see how this is going to work very well without using some form of stored energy.  In farming, when you do something is not optional past a certain point.  Delays either reduce crop yield or ruin an entire crop.  This is from personal experience growing corn and vegetables in Nebraska.  If you harvest too late, then you may not get anything.  I suppose you can harvest frozen corn if it's going to be stored as ears of frozen corn, but if you intended to, store it as grain in a silo or grind it up to make corn meal or use it in other products, then you're going to harvest the corn before it freezes.  There's a window of about 2 to 3 weeks to do this.  Whether or not intermittent energy is available for use is irrelevant to when you need to harvest the corn.  That's why the farmers have tractors that run on diesel fuel.

If all of the farming tractors in America start their engines at the same time (and there are around 4.2 million tractors), with an average engine power of 200hp, in order to plow a field or harvest from it, and a very healthy percentage of them will due to seasonality, that's 626GW of combined engine output.  Let's say my proposal reduces that to 1/4 of what it previously was 156.5GW is the output of 157 GW-class nuclear reactors.  If it's more than that, say 50% of the energy consumed by diesel powered tractors and trucks, then we're talking about 1/4 of the entire generating capacity of the US.  That brings us right back to why we use so much diesel fuel.  Generating that output level using any existing generating systems that don't also burn fuel to produce electricity, would be exceptionally difficult to do.

Anyway, the most common size of center-pivot system covers 1/4 mile diameter circle, or about 125 acres or land.  These systems require somewhere between 25hp and 125hp of power to run.  It depends upon the water pressure required.  In addition to that, we must add pumping power to supply fresh water, perhaps from an ocean.  The 125hp would be entirely sufficient to run the kinds of attached tools I wish to run.  Heck, 25hp is probably sufficient.

Overhead shot of center-pivot irrigation systems installed in Kansas:
Crops_Kansas_AST_20010624.jpg

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#110 2023-04-05 13:11:46

kbd512
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Registered: 2015-01-02
Posts: 7,564

Re: Why the Green Energy Transition Won’t Happen

Is it obvious yet from the horsepower required to run a large-ish center-pivot irrigation system that all we're doing is eliminating additional fuel consumption associated with more machines / more manufacturing of farming machines / more complexity?

We're reducing consumption through simplification.  If we start going the other way and demanding more complexity, then we're going to start consuming more energy in the form of various fuels required to create a bunch of new stuff.

There are 894 million acres / 1,396,875mi^2 of farmland in the US.  We might be able to use this all-in-one center-pivot farming system for half of that acreage.  At best, we could reduce fuel consumption by a quarter or so, which is still very significant.  I don't think you can do center-pivot for a lot of the farmland in California or Florida, for example.  Orchards don't lend themselves to this kind of farming, only grains, beans, and vegetables.  It won't work for rice, either, obviously.

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#111 2023-04-05 13:30:50

tahanson43206
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Registered: 2018-04-27
Posts: 17,907

Re: Why the Green Energy Transition Won’t Happen

For kbd512 re #110

As often happens in this forum what is obvious to you is not obvious to everyone.

Please develop your vision of a circular mounted crop tending system to rice, if such a concept makes sense.

Perhaps you were thinking that rice likes to grow in a ** really ** wet environment, so you wouldn't need to water the plants?

But rice could grow in the desert if there were enough fresh water (not that the idea makes a lot of sense)

Thirsty Crops
WWF-UK
http://assets.wwf.org.uk › downloads › thirstycr...
PDF
It takes 3,000 – 5,000 litres of water to produce 1 kg of rice. Asian rice growers use. 13 percent of global pesticides. The urban population has grown from. 43 ...
20 pages

However, if an area has plenty of rain, then your rotating girder could support tools that do whatever needs to be done to keep rice happy.

(th)

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#112 2023-04-05 14:48:29

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 17,907

Re: Why the Green Energy Transition Won’t Happen

As a follow up, here is a set of snippets about robots for rice growing ...

About 17,000,000 results (0.43 seconds)
Swiss company ECO Process & Solutions developed the Moondino rice paddy robot. The robot is able to autonomously perform weeding and padding operations. The latest version is ready for production and will be officially launched in 2021. The robot will be commercially available in 2022.Dec 28, 2020

Moondino rice paddy robot for autonomous weeding

Future Farming
https://www.futurefarming.com › tech-in-focus › moond...
About featured snippets

3:34
The Future of Rice Farming in Japan Is a Robotic Duck
Interesting Engineering · 日産自動車株式会社
Jun 24, 2019

0:36
Moondino rice paddy robot
YouTube · Future Farming
Dec 28, 2020

1:52
Rice Planting Robot Awarded "The Robot Award 2008" Grand ...
YouTube · ikinamo
Dec 28, 2008

3:56
Aigamo Robot - "Duck Robot" keeps weeds out of rice paddies
YouTube · Espacio Robot
Jul 2, 2019

Rice-Planting Robot | Science and Technology | Trends in ...

Web Japan
https://web-japan.org › trends › science › sci051014
Oct 14, 2005 — The robot can plant at a speed of 1,000 square meters every 20 minutes without having to reload seedlings. ... For many people working in ...

People also ask
Can rice farming be automated?
What is the green weeding robot Japan?
How do you make a rice field?
How robots are used in agriculture?

(th)

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#113 2023-04-05 18:54:04

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 17,907

Re: Why the Green Energy Transition Won’t Happen

Following up ...

tahanson43206 wrote:

For Calliban re #96

Thank you for the link to this report!

I've scanned it enough to realize this is a document worth careful study.

It contains historical data that I had not seen before, such as the US Army supply of 10 MW from a ship in the Panama Canal Zone while onshore facilities were being renovated/improved.

(th)

I scanned through the paper just now ... it is most definitely worth a slow read.

Thanks again for finding and posting the link!

Nice illustrations of Off Shore operations of various kinds ...

(th)

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#114 2023-04-06 01:17:21

kbd512
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Registered: 2015-01-02
Posts: 7,564

Re: Why the Green Energy Transition Won’t Happen

tahanson43206,

This entire thread is about attempting to replace a very dense form of energy consumed at a global scale, via comparatively low technology and effort, with a variety of far less dense forms of energy at a much greater scale.  Lower energy density implies you'll be using a lot more of something to provide the same amount of energy.  That greatly restricts which proposed technical solutions are workable.

If we were talking about building bridges, shouldn't we ask how long the bridge has to be and what load it has to carry?

These are some of the most fundamental questions that require answers before you can even think about replacing what we presently use.  I'm a little disappointed that more people haven't asked such questions, especially the hordes of scientists and engineers claiming to have solutions to problems they've clearly given so little thought to.  This is why we messed with photovoltaics and batteries for the past 50 years while failing to produce anything that's remotely scalable to the degree required to actually replace hydrocarbon fuels.

If replacement of hydrocarbon fuels is the end goal, then the machines to do that have to be very simple so they last long enough to offset their much greater aggregate cost (embodied energy cost, not fiat currency).  You also have to consume less energy than we presently do by choosing significantly more efficient ways to use whatever energy we have to work with.

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#115 2023-04-10 14:15:31

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,542

Re: Why the Green Energy Transition Won’t Happen

In 2016, energy use in the US agricultural sector was 1,872 trillion Btu, of which 44% was diesel.  That is about 2 trillion MJ of diesel, or a continuous power consumption of 62.5GW.
https://www.ers.usda.gov/data-products/ … rtId=87964

That works out to 70W/acre of diesel power, or 150W/acre total power.  If we assume that all diesel is used to raise mechanical power and diesel engines are 40% efficient, then time average mechanical power is 28W/acre.  But of course farming does not use energy at a steady rate all of the time.

The world's largest wind turbine is 280m tall and produces 15MW at full capacity.
https://electrek.co/2023/04/03/worlds-m … -vestas-2/

Assuming a 33% capacity factor, the turbine will produce an average of 5MW.  Assuming 20% transmission and motor losses, that is sufficient mechanical power for 140,000 acres.  A smaller 1MW turbine would be sufficient for 9,500 acres.  But this assumes we can use direct electricity to raise requisite mechanical power and we can work around intermittency.  A mixture of wind and solar thermal power would deliver a more reliable, but still variable power supply.

A while back, Terraformer introduced an alternative to nitrate fertilisers that could be produced on a farm using electric power.  This was aqueous nitric acid, which would be sprayed onto fields as liquid.  Maybe this could function as a swing load, with nitrate solution produced at times when power is in excess.  From the exert below, some 13% of agricultural energy use is natural gas, much of it used to produce nitrate fertilisers.  On farm nitric acid could replace this.

From the link:

'In 2016, the agricultural sector consumed 1,872 trillion Btu of energy, accounting for about 1.9 percent of total U.S. primary energy consumption. Farms consume energy in many forms, mainly diesel (44 percent of direct energy consumption), electricity (24 percent), natural gas (13 percent), gasoline (11 percent), and liquefied petroleum gas (7 percent). Diesel and, to a lesser extent, gasoline are used to power farm machinery. Electricity is used mainly for irrigation, cooling, and lighting.  Natural gas and LP gas are used in heating and grain drying. Large amounts of natural gas are required in the manufacturing of fertilizer and pesticide, so these amounts are categorized as indirect energy consumption on farms. Overall, about three-fifths of energy in 2016 used in the agricultural sector was consumed directly on-farm, while two-fifths were consumed indirectly in the form of fertilizer and pesticides.'

LPG is used for grain drying.  Maybe hydrogen, biogas, direct electricity or crop residues could be used for this purpose.  Vacuum drying is another possibility.  Microwaves are typically used to heat food that is being vacuum dried, because conductive heat transfer is a slow and inefficient means of keeping the food warm under vacuum conditions.
https://en.m.wikipedia.org/wiki/Vacuum_drying

If US agricultural energy consumption could be replaced with direct-use renewable electricity generated on farms, then an average power of 142GWe would be needed.  That is about 430GW of wind capacity, or 28,400 of those 15MW turbines, assuming 33% capacity factor.  More likely, a mixture of wind and solar capacity.  This all assumes that we can develop mechanisms for using the electricity directly as it is produced, without storage and by adjusting demand to match supply.  As soon as large amounts of electricity storage are needed, the metal resource requirements go to the moon.  But there are ways of building wind and solar based systems that could meet these demands sustainably if users can adapt to a variable and intermittent supply.

One way of doing this without straining the world's rare metal reserves, would be to build multiple wind turbines with stone or concrete towers, over an area of say 100km2.  We could build numerous small solar thermal plants over a comparable area.  Each wind machine and solar plant steam turbine, would drive a hydraulic pump rather than an electric generator.  Hydraulic mains would then drive a single centralised generator, with a power output of several hundred MW.  Energy storage would be provided by both hot rock energy storage built into the solar thermal plants and by a flywheel attached to the hydraulic generator.  But these would provide hours of storage, rather than days.  But that is at least sufficient time to allow processes to finish.

Last edited by Calliban (2023-04-10 15:55:39)


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#116 2023-04-10 16:19:03

kbd512
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Registered: 2015-01-02
Posts: 7,564

Re: Why the Green Energy Transition Won’t Happen

Calliban,

It would appear that trying to electrify farming could reduce fuel consumption by 2%, at most.  2% of quite a lot is definitely something, but in the grand scheme of things it makes almost no difference to total consumption.  It would be great if we could do it for reasonable cost, but that means radically different methods of farming.  We'd probably need to spend some extreme multiple of what we presently spend to enable industrial agriculture without hydrocarbon fuels.  This fact strongly suggests that we really should focus more on efforts that have outsized impacts on fuel consumption reduction.  In 2021, transportation was 67.2% and industrial applications accounted for 26.9% of petroleum fuel consumption, or 94.1% in total.  Pretty much everything else was consumed to generate electricity.  Everything else is also a minor fraction of total consumption.  That means cars, buses, and trucks need alternative energy supplies or they need to burn a lot less fuel.

We might be able to extend railways, as you suggested, or we might be able to use more cable cars in places where railroads would cost too much or create other major disruptions.  Getting rid of all the cars is not practical.  There is nothing to replace them at the present time, assuming most of the people in the country won't be unemployed.  We spent decades messing with batteries, yet there are still no batteries mass-produced at the scale required.  Some of us know why that is so, but the rest of us don't want to know why that is so.

Going right back to what I said about needing practical electric vs impractical electronic cars / trucks / trains, are we going to try to do that first, given that course of action will have the greatest impact of all?

I know my proposed solution looks very ugly.  That's because it is.  You either synthesize hydrocarbon fuels and burn a lot less in your fleet of road vehicles, or you go nuts with Big Iron vehicles powered by paraffin wax or hot water storage.  As I've said many times before, this is not about what I want, nor what I'd rather.  Practical mass-produced EVs can be had, but not with batteries.  We've been messing with batteries for long enough now.  They're not replacing anything.  I want to get straight to the point.  We need to get useful work done, rather than signal our lack of virtue to others, and then move on to solving all the other problems.

Batteries are an ugly scarcity-based solution.  My proposals are equally ugly abundance-based solutions.  If anyone here thinks something will truly replace what we presently use, despite much lower energy density, then it had better be some of the simplest and most abundant stuff we have laying around, or it won't happen.

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#117 2023-04-10 17:03:14

Mars_B4_Moon
Member
Registered: 2006-03-23
Posts: 9,772

Re: Why the Green Energy Transition Won’t Happen

Thorium’s Long-Term Potential in Nuclear Energy: New IAEA Analysis

https://www.iaea.org/newscenter/news/th … a-analysis

UK budget set to back carbon capture and nuclear power

https://www.politico.eu/article/uk-budg … remy-hunt/

Last edited by Mars_B4_Moon (2023-04-10 17:04:48)

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#118 2023-04-11 10:27:56

kbd512
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Registered: 2015-01-02
Posts: 7,564

Re: Why the Green Energy Transition Won’t Happen

Based upon what Calliban stated, 430GW of wind generating capacity is required to replace 62.5GW of diesel generation capacity, by which he means 28,400 of the new Vestas 15MW wind turbines.  Each 15MW wind turbine is the size of a small skyscraper.  It has a 240m diameter rotor diameter, 150m hub height (center of the axis of rotation of the blades), and each blade is 115.5m in length with a 5.2m diameter blade root and 5.7m max chord length.  Each blade weighs 35t.  I wouldn't be the least bit surprised if each blade was holding back a 25 G load under nominal power output, meaning each blade "weighs" 875t.  In other words, a colossal amount of force.  StratoLaunch, the largest aircraft in the world by wingspan, has a wingspan that measures 117m in length.  Max G-load for that mega-jet is 3g and MTOW is 590t, which places it in the utility category of aircraft (not acrobatic).

If someone suggested that we sink more steel / CFRP / GFRP than what would be required to build 28,400 StratoLaunch aircraft, most people would think you're reaching a bit.  To begin with, this would grossly exceed the air transport capacity of all the world's commercial aircraft, which stood at 25,578 in 2022 (anything from a tiny Cessna 208 turboprop air mail carrier to a Boeing 747 or Airbus A380).  For whatever reason, we're willing to consider this to replace 1.9% of the US diesel consumption.

To replace all of the US diesel consumption, 1,420,000 StratoLaunch aircraft equivalents in terms of wind turbines.  To both build and then turn over that many airframes, every 15 years, would be difficult to fathom.  On top of that, we'd need to build an even greater number of StratoLaunch aircraft equivalents to replace gasoline.  I'm having a hard time understanding how we're going to build the equivalent of 200,000 StratoLaunch aircraft per year, merely to replace what the US consumes, in terms of gasoline and diesel energy.  In fact, I think it's highly unlikely that such a thing happens, because we're talking about a production rate that's greater than America's entire WWII aircraft output in terms of total tonnage and using more energy-intensive materials, every single year, from now until the end of time or something better comes along (fusion power, hopefully).

The notion that such a thing is practical, let alone truly sustainable, seems facially absurd.  I think it's far more likely that we run short of materials or resort to burning things for badly needed energy.  We've grossly overshot our sustainable energy production capabilities.  We need much more efficient uses of materials and energy, combined with machines that last for a human lifetime, and preferably much longer than that.

All I'm saying is that we need better tech that's much less consumptive of energy-intensive materials.  I think nuclear thermal and solar thermal are the closest to fitting the description of what we need.  I'm agnostic on nuclear power.  I think it's great and works great and has the lowest materials consumption by far, therefore is the most sustainable option presently available.  I think fusion would replace both if we knew how to do it.  If we want an energy transition to actually happen, then we need to help our decision makers arrive at their "Come to Jesus" moment about what we can actually do in a practical manner.

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#119 2023-04-11 17:23:58

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,542

Re: Why the Green Energy Transition Won’t Happen

Kbd512, there is no way of making a silk purse from a sow's ear.  Harvesting a lot of energy from low power density resources implies a lot of embodied materials.  There is no way of avoiding that.

The embodied energy and materials requirements for wind and solar power are inevitably high, because their energy sources (moving air and sunlight) are diffuse.  The most optimised wind turbine provides an average of about 100W of harvested electric power for each square metre of swept area.  Solar flux depends upon where you build the plant.  A very sunny equatorial location might give you a time average solar flux of 300W/m2, with the flux reaching almost 1kW/m2 at noon, but varying sinusoidally between sunrise and sunset, followed by 12 hours of darkness.  If we couple the solar collector to a steam plant which is 33% efficient, then we get 100W/m2 of collector area.  Not disimilar to wind power in terms of power density.  But this power density is weak compared to the combustion chamber of a gas turbine, or a pulverised fuel boiler or a light water nuclear reactor.  A PWR reactor core has power density of ~80MW/m3.  That is about 250,000x greater than a solar collector built in the sunniest part of the world.

This makes most renewable energy sources bulky relative to the power they produce.  And it is an unavoidable consequence of the poor energy concentration of the resource they are exploiting.  We used the best ones first.  Hydropower was the first renewable to be exploited to generate both direct mechanical power and electricity.  Ever wondered why?  Water is 1000x denser than air.  This means that the power density of the pelton wheel turbine will be about three orders of magnitude greater than a wind turbine per unit swept area.  Sure, you need a big dam to build up enough water head to achieve that power density.  But the huge gravity dam is made of compressive concrete or rammed soil.  Energy cheap materials and the dam could easily last for a century.  Power density is king when it comes to powerplant economics.  Designing an energy system capable of sustaining high (energy intensive) living standards based upon a diffuse and intermittent renewable energy source is contradictory.  But try we must, because our political masters have ruined the prospects for anything better.

I find that the US DoE quartennary energy review, is a source that I keep returning to over and over when trying to assess the art of the possible with energy systems.  The good folks at DoE worked out the materials needed per TWh of electricity produced.  They did this by working out how much materials of different kinds were embodied in different powerplants and then dividing by the number of TWh produced by the plant overan expected lifetime.  You can find the results in Chapter 10.
https://www.energy.gov/quadrennial-tech … eview-2015

Here is a summary for wind power in tons per TWh: Aluminium: 35; Concrete = 8000; Copper = 23; Glass = 92; Iron = 120; Plastic =190; Steel = 1800.

Going back to the diesel consumption of US agriculture.  This works out to be 62.5GW-years, or 547.875TWh.  If we assume that diesel engines are 40% efficient and we can optomistically replace 1kWh of harnessed mechanical energy with 1kWh of electricity, then we need some 219TWh of electricity.  Let us multiply that by 1.2 to account for transmission losses and motor losses.  That works out at 263TWh per year.  If we were to supply all of that energy from wind power, we must use 473,000t of steel each year.  Also 74,000t of glass and epoxy for the blades.  Huge volumes of materials to be sure.  And this assumes we have reached some kind of steady state and are replacing turbines as they wear out.  That won't be true to begin with.  We would need more steel, glass, concrete, etc, per year, to build up the turbine stock.  None the less, it is worthwhile comparing the mass of required to US annual production.  I am going to focus on steel, because it has 20-30x the embodied energy of concrete on an equal mass basis, and we need about 4x as much concrete per unit wind energy as we do steel.  If we can produce enough steel, then we can probably produce enough concrete as well.  Copper and aluminium requirements can be reduced if wind turbines raise hydraulic power, which then drives a central generating station on the ground.  So, I will focus on steel.
https://en.m.wikipedia.org/wiki/Iron_an … ted_States

The US produces 29 million tonnes of pig iron and 81 million tonnes of recycled steel each year.  So 473,000 tonnes, although clearly a great amount, is only 0.43% of US production.  What about replacing all US diesel consumption with direct wind generated electric power?  In 2021, distillate fuel consumption by the U.S. transportation sector, which is essentially diesel fuel, was about 46.82 billion gallons.
https://www.eia.gov/energyexplained/die … diesel.php

That is 1,887.57TWh.  Using the same conversion ratio as we used before, that equates to 906TWh of electrical energy.  Replacing the wind turbines needed to generate this much electrical energy would require some 1.48% of annual US iron and steel production.

Of course, it would not be at all practical to replace all US diesel consumption with direct grid-electric from wind power.  It would mean having third rails or catenaries on every road and swing arms with sliding contacts above every field.  The variability of wind would also pose a major problem, even if we were able to use some energy consuming activities as controllable loads.  But the calculations above tell us that a low power density renewable could in principle drive the economy on an acceptable materials budget, if we could build systems that: (1) Consume energy as electricity drawn directly from the grid without storage; (2) We are able to adjust demand to match supply, without pouring too much energy and materials into energy storage systems.  For a farm, grid power may in fact be an offgrid system, with the turbine electricity output consumed locally.  The farm would have to adjust energy consumption to match supply.

Using solar derived chemical fuels avoids the rather extreme logistical difficulties of having to run society on intermittent, direct-electric power.  It avoids a lot of the end-use infrastructure cost that that sort of arrangement implies.  The price to pay is thermodynamic energy losses in converting electricity and thermal energy into chemical fuel and then back into mechanical work in an engine.  If you are starting with electricity, making a liquid fuel and then burning it to raise mechanical power, then realistically, only 10-30% of each kWh you begin with is converted to kinetic energy in a vehicle.  For AC electric power drawn from the grid and used to power a motor, about 80% of each kWh that is generated is converted into kinetic energy.  Compared to direct-electric, a lot more materials and energy must be invested in the energy supply and fuel synthesis plants.  But synfuels avoid the added embodied energy needed to make a direct-electric future work.  We can have a smaller grid.  We don't need catenaries over every road.  I think the future will use a combination of many different energy technologies.  But as far as an electric future goes, we have both run through enough numbers to know that battery-electric technologies will never be more than niche parts of any real energy system.  We have used electricity as a transport fuel for a long time and electricity does provide a large fraction of transportation energy in many European and Asian cities.  But with few exceptions, real systems have been direct-electric, consuming energy from the grid as it is generated, through a sliding conductive contact with an overhead cable or third rail.  This is what real life electric transport looks like.  For some reason, green tech enthusiasts think electric transport means battery powered cars.  In real life, it means trains and trams.

Last edited by Calliban (2023-04-11 17:40:12)


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#120 2023-06-07 04:05:52

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,542

Re: Why the Green Energy Transition Won’t Happen

Soeren Hansen on why the green energy transition won't work.
https://m.youtube.com/watch?v=WlKbkLCTWRY

In a nutshell: When you add up the amount of energy needed to manufacture the wind and solar harvesting machines, power transmission and storage infrastructure, the surplus energy produced is insufficient to run an industrial economy.  The overall EROI would be comparable to that of ancient Roman civilisation, where a tiny elite lived comfortable lives by yoking the forced labour of most of Europe, North Africa and the Near East.  Roman civilisation was based upon stolen surplus energy.  When energy gets expensive, life becomes cheap.

I agree with his assessment, because I have done the sums myself and reached the same conclusions.  In the North Sea bordering parts of Europe (UK, Netherlands, Denmark) the wind is relatively strong, and the nameplate EROI of wind turbines can be as high as 20, if we assume a 25 year life for the turbines.  But the only way of using that energy in a way that preserves a reasonable net energy return, would be to largely abandon the idea of energy storage and adapt to a way of life where energy demand adapts entirely to supply.  You use it when it is there and go without when it isn't there.  This would change the way we live completely.  I can think of ways in which specific processes might adapt to this.  I have no idea if it could be done at a societal level.  One thing is clear.  A technological civilisation that livesin this way would look nothing like the one we have now.

Last edited by Calliban (2023-06-07 04:09:29)


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#121 2023-06-07 19:10:12

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,215

Re: Why the Green Energy Transition Won’t Happen

For complete replacement with the ever-growing energy needs we are never going to catch up when using these and other types of alternative energy sources.

We know the take of nuclear, but will others have the same sighting of fear for fusion as well will be the question.

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#122 2023-06-08 07:35:17

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,542

Re: Why the Green Energy Transition Won’t Happen

The difference between American and European suburbs.
https://m.youtube.com/watch?v=mV6ZENGko1I

A lot of the politics this German man associates with suburbs is BS in my opinion.  But he does make the valuable point that US suburbs are rubbish places to live in a lot of ways.  You really are stranded without a car and cannot reasonably survive without one.  The German suburbs are more compact and have tram and rail links into the urban core.  Whereas restaurants, sport facilities and other establishments are spread over many miles in US cities, in Germany they are mostly within walking distance of the urban centre.  In many ways, Europeans would better endure an oil xhortage than Americans could.


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#123 2023-06-09 11:54:42

Void
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Registered: 2011-12-29
Posts: 7,308

Re: Why the Green Energy Transition Won’t Happen

I can make a bit of a counter argument, about things which are under development and advantages that in part are accidental between the two situations.

Covid 19, self-driving cars are featured.

Because of the possibility of a new respiratory pandemic, subways and other mass transit situations are not completely innocent things at all.

If we get the self-driving cars, then we don't have to own two cars in a suburb or possibly not own one at all.

I can see where a mini-bus type self-driving vehicle might serve a particular group of people.  People who have noted bad behaviors might be excluded.

And for interest different interests.  Prudish people for one, people who like whatever recent weird (to me) fad in another.  So, a way to integrate and segregate people in accordance with the content of their character to reduce social frictions.  In that manner diversity to be more tolerated.

As for disease which is contact related, hand washing, cleaning surface, and proper interaction between passengers might handle that.  Also, when the vehicle was not carrying passengers, UV light might be used to reduce contaminations.

And this would be about self driving.  I can imagine self driving could be applied to ICE vehicles as well, if they burn something like Ammonia, or Hydrogen.

More space makes it easier for people to have children, and we need some new people to replace those of us who are on the way out.  But life extension and health extension may be important as well.

A ride on a Mini-Bus might be a minor social event, as you would not be associating Nudists with Muslims for instance.  Some countries might have that problem.  That would be incompatible.

Done.

Last edited by Void (2023-06-09 12:08:28)


Done.

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#124 2023-06-09 13:06:43

Void
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Registered: 2011-12-29
Posts: 7,308

Re: Why the Green Energy Transition Won’t Happen

I occurs to me that in accordance to your recent post Calliban about Ammonia, there could be a "Right Sized" vehicle for passenger and repeating groceries deliveries by self driving vehicles.  Perhaps with a Tesla Bot passenger, to distribute goods from the vehicle to a location on private property as arranged for some security, I presume.  This would help promote more frequent bus traffic as it would not depend on passenger service as it's only purpose to pass by a location.  People would simply have to get used to a pause to drop stuff off, but that delivery service would pay in part for their passenger ride.

Calliban did this post which stimulated my post: http://newmars.com/forums/viewtopic.php … 13#p210613

Actually, while repetitive deliveries might be a big part of it I would presume special deliveries may also be includable.

So, then personal cars used much less to go get such items.  So, less energy consumed by those cars I presume.

Perhaps these smaller "Trucks/Vans" could be battery powered though.

Done

Last edited by Void (2023-06-09 13:13:05)


Done.

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#125 2023-06-22 12:59:59

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,542

Re: Why the Green Energy Transition Won’t Happen

Peak oil appears to be upon us.  Permian production represents the last big oil growth story on planet Earth.  But there isn't much tyre 1 acreage left to drill.  By next year, it will have crossed the halfway point and production will decline thereafter.
https://blog.gorozen.com/blog/hubberts- … nally-here

At least that is the opinion of resource investors Goehring and Rozencwagj, who are about as competant as it is possible to be on the subject.  Absent a new previously overlooked oil discovery capable of rivalling Saudi Arabia, we are at or very near to peak oil.

Last edited by Calliban (2023-06-22 13:03:42)


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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