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#26 2021-12-29 22:07:46

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 17,064

Re: Portable Power Best Solution Compare Discuss Evaluate

For SpaceNut ....

Storage of hydrogen atoms in little palladium storage lockers is described in this post:
http://newmars.com/forums/viewtopic.php … 38#p189438

So! Assuming enough palladium is available, then a portable power supply using molten silicon or Zerolite might be imagined.

The problem I was attempting to address earlier in the topic was how to convert thermal energy into electric current.

To my knowledge, there is NO way to do that efficiently.

One of several mechanical solutions would involve:

1) Pass water through hot volume to make steam
2) Send steam into steam engine to turn a generator

80% efficiency times 30% efficiency gives 24% efficiency over all.

Therefore, the hot mass supply would need to be four times greater than the job requirements.

***
An alternative is to use thermal energy to release hydrogen from little palladium storage lockers.

In that case, efficiency of the system might be better, because efficiency of fuel cells is reported to be 40 to 60 % (including electric motor)

Per Google:

40 to 60 per cent
According to 2 sources
According to the US Department of Energy Hydrogen Program, a standard fuel car with a combustion engine runs at around 20 per cent efficiency, whereas vehicles that run using hydrogen fuel cells are around 40 to 60 per cent efficient. This number could vary depending on the size and weight of the car, as well as the kinds of roads being driven on.
How efficient are hydrogen fuel cells? | Viessmann
viessmann.co.uk
Vehicles that use hydrogen fuel cells, and also use electric motors, are more efficient as they can use 40 to 60 percent of the fuel’s energy. As a result, there is more than a 50% reduction in fuel consumption. Plus, fuel cells operate quietly, have fewer moving parts and are well-suited for various kinds of applications.

(th)

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#27 2021-12-29 22:29:19

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,838

Re: Portable Power Best Solution Compare Discuss Evaluate

One place where you will find it is a catalytic converter as it contains precious metals (as active components) such as palladium, platinum, and rhodium (referred to as PGMs) in order to convert harmful gases emitted from vehicle engines to relatively harmless ones by both the reduction of nitrogen oxides (NOx) into nitrogen N2 and the oxidation of hydrocarbons and CO to CO2.

Hydrogen fuel cells out put DC voltage so we need a sine wave inverter in addition to the tank of H2 to have on the cart.

G-HFCS-3kW48V (3kW Hydrogen Fuel Cell Power Generator) Price: $14,551.00
ouch....

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#28 2022-01-12 16:49:50

Mars_B4_Moon
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Registered: 2006-03-23
Posts: 9,203

Re: Portable Power Best Solution Compare Discuss Evaluate

Power Grid Failure in Argentina?
https://tuoitrenews.vn/news/internation … 65174.html
Argentina capital hit by major power outage amid heat wave

Massive blackout hits Mercosur; Argentina and Uruguay in the dark for six hours; major investigation promised
https://en.mercopress.com/2019/06/17/ma … n-promised

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#29 2022-01-12 18:37:36

SpaceNut
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From: New Hampshire
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Posts: 28,838

Re: Portable Power Best Solution Compare Discuss Evaluate

Well the heat makes the wire more resistive to letting the flow of current so as the drain increases the heat in the wire continues to grow as its got only the air to cool it via surface area of uninsulated area.

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#30 2022-02-13 18:19:13

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,838

Re: Portable Power Best Solution Compare Discuss Evaluate

The article goes about the (calculations)
How to Run a Microwave Oven on a Generator

Of course whether the rotation of the power generator is turned by a motor fueled by gas, deisel or other means the calculations to what is required will always be the same.

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#31 2022-06-10 18:50:05

SpaceNut
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From: New Hampshire
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Posts: 28,838

Re: Portable Power Best Solution Compare Discuss Evaluate

If you are looking for hydrogen to be a savior a gallon of gas is equal to 1 kg of hydrogen and to get that you need to break down 2.64 gallons of water to obtain the equivalent in hydrogen as there is only 110 grams of it in a liter of water.
For earth that is not a problem as we use free air in the engines of choice but for mars we need to capture the oxygen for reuse.

It is also said that the electrolysis input to get the hydrogen is just 70% efficient.

With the rising price on gasoline looking to make synthetic fuels may not be much better.

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#32 2022-06-11 17:38:42

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,838

Re: Portable Power Best Solution Compare Discuss Evaluate

repost of information
propane generators are basically the same generator just with a different fuel being delivered to it with electric power being the output from its use. Of course the size of the power output relates to the consumption rates for doing so. Most generators can not run continuous as well. All engine seem to have these flaws....
https://www.generatorhero.com/how-much- … rator-use/

Home Generator sizes, a 22 KW Generac generator would consume 5.9 cubic meters per hour of natural gas which is similar to propane in use.

Can we ever get information without needing to convert it....

https://preparednessadvice.com/propane- … st-choice/

Propane produces 92,000 BTUs per gallon, gasoline is capable of producing 114,000 BTUs per gallon, and diesel is capable of producing 129,500 BTUs per gallon. This means that it will take more propane per hour that either gasoline or diesel to run a generator.
Propane is a gas that is stored in liquid form. When the tank reaches a certain pressure, the propane turns to gas and dispenses from the tank. The pressure in the tank is measured in pounds per square inch (psi).
On average, a generator uses 2 to 3 pounds of propane per hour. However, this amount can vary depending on the size of the generator and how high the wattage is.

So it appears that liquid fuels are the way to go but for how long as the price continues upward.

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#33 2023-01-02 17:52:09

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,838

Re: Portable Power Best Solution Compare Discuss Evaluate

I happened across a battery unit, and it had a table of what it was capable for capacity

not advertising a brand Geneverse Logo

It seems that the table is for HomePower TWO PRO; Capacity: 2419Wh Wattage: 2200W-4400W that is capable of solar panel recharging.

lighter

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#34 2023-03-19 06:39:09

tahanson43206
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Posts: 17,064

Re: Portable Power Best Solution Compare Discuss Evaluate

Recently, in another topic, kbd512 wrote up a vision of stored power using compressed hot water.

I am returning this topic to view in hopes someone might be inspired to develop/post a vision of what kbd512's idea might look like, if implemented for the scenaro of this topic.  From topic Post #1:

This topic is offered to focus upon a very specific need that exists on Earth today, and will exist on Mars in future.
This topic is intended to compare and evaluate a wide variety of solutions that can deliver:
20 Amps at 125 VAC for one hour of continuous service.

I would like to see what a stored thermal energy work site generator would look like, if implemented according to kbd512's vision, and compared to an equivalent battery system, or the equivalent gasoline/propane powered solution.

(th)

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#35 2023-03-19 06:42:04

tahanson43206
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Posts: 17,064

Re: Portable Power Best Solution Compare Discuss Evaluate

Post #34 was blocked by the Apache Internal Server Error we have been seeing recently.

I cut text from the post until it was accepted by Preview. I'll now try to add the text that I had to remove to get past the server error:

The concept of kbd512 (as I understand it) is to store electrical energy in a tank of water in the form of heat.  The tank would be capable of withstanding the pressure of the water, and the energy could be drawn off to drive a generator.

(th)

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#36 2023-03-19 17:06:33

kbd512
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Re: Portable Power Best Solution Compare Discuss Evaluate

tahanson43206,

The boiling hot water at elevated temperatures and pressures fits into the same niche as electro-chemical batteries and compressed or liquid air.  The output is hot air and cold water (the water "charge" never leaves the pressurized storage tank because it uses electrical resistance heating for "recharging").  There is no explosion hazard associated with running the engine itself.  However, the water tank, which must be insulated, is above the auto-ignition temperature for certain kinds of explosive atmospheres where compressed air remains the best option.  Food processing factories like meat packing plants can use hot water power.  A flour milling plant should stick with compressed air.  For pharmaceuticals or cosmetics, it would depend on the chemicals used.  It's not a practical replacement for a small portable gasoline or diesel generators, nor batteries for electronics, nor any other kind of engine or power provisioning scheme.  This should be surprising to no one.  It does what electro-chemical batteries would do for land vehicles or stationary electrical / thermal power storage, but without requiring vastly more Copper and Aluminum or technology metals than we can realistically get our hands on.

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#37 2023-03-19 18:09:39

tahanson43206
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Registered: 2018-04-27
Posts: 17,064

Re: Portable Power Best Solution Compare Discuss Evaluate

For kbd512 re #36

Thank you for considering my inquiry about the potential of your proposed hot water energy storage and delivery system for a portable, work site power system.

I take your word for it the concept is not practical for such a small scale application. 

The conclusion of your evaluation is disappointing, but the operator of such a machine would be at risk of failure of the storage tank when it is fully charged, so the tried and true air pressure tanks used for air tools would appear to be practical solution for a while yet.

For anyone "out there" who may be reading this topic and be curious about air tools, I found an article that includes a video from "This Old House" about them

https://www.rolair.com/blog/under-press … -explained

It appears that 6 Atmospheres of pressure (90 psi) is "normal" pressure for air tools.

The proposed hot water energy storage system suggested by kbd512 would (apparently) require holding a higher pressure.

(th)

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#38 2023-03-19 20:36:35

tahanson43206
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Registered: 2018-04-27
Posts: 17,064

Re: Portable Power Best Solution Compare Discuss Evaluate

From another topic, I have pulled a snippet from a presentation by kbd512 about a water based energy storage system.  In the other topic, kbd512 appears to be making a case for a railroad application.

This topic is about a much more modest application of stored energy...

The objective of this topic is to explore (and perhaps identify) solutions that can deliver 20 Amps at 120 VAC for one hour, in a mobile/portable format.

I need 850psi at 275C,

The quote above is taken from a presentation by kbd512, in which he appears to be describing a system for use in railroad locomotion.

I will now introduce another of kbd512's ideas, from another topic entirely.  In ** that ** topic, kbd512 has been thinking/writing about a possible energy storage system based upon liquid nitrogen.  The operating scenario in ** that ** case, is negative energy storage, which would appear to quite as practical as positive energy storage, and it has several distinct advantages.  The LN2 would pull thermal energy from the outside environment, in order to enable the gas to transition from liquid to gas, and thus provide mechanical impulse from properly designed energy translation equipment, such as a piston device, or a turbine.

In the case of a portable device designed to provide 20 AMPs at 120 VAC for one hour, I am imagining kbd512's hot water in a suitable container, matched with a suitable amount of LN2 in another container. The generator would be driven by a suitable energy exchange mechanism, as the LN2 is fed into proximity with the hot water, so that the LN2 is quickly liberated to gas form, and there is no dependence upon the external environment.

This situation would be similar in concept to the situation on Mars, where every machine will have to carry both fuel and oxidizer.

The portable power device would be "charged" by adding energy to the water tank, and removing it from the nitrogen tank.

The work done would (of course) be more than the equivalent of 20 Amps at 120 VAC for an hour, because we are talking about heat processes, which are likely to be governed by the normal laws for heat engines.  I would be surprised if the overall charge efficiency is greater than 30%.

Therefore, I would expect the equipment to consume 20 Amps at 120 VAC for three hours, to charge the tanks for a remote job site visit.

I would like to see a design for a combination of equipment that matches these two ideas.

(th)

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#39 2023-03-19 21:42:45

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 17,064

Re: Portable Power Best Solution Compare Discuss Evaluate

I asked ChatGPT (Version 3.5) to "think" about the proposal of kbd512 to store energy in the form of hot water at 850 psi and 275 degrees Celsius.  I ** then ** added another idea of kbd512, to provide a heat sink using liquid nitrogen.

The first time through the exercise, ChatGPT went off the reservation, but I hit a key on the keyboard that caused the session to be lost. The second time through, ChatGPT came up with a more reasonable looking set of numbers, but I still asked for a rerun. The third time through the numbers look reasonable at the 30,000 foot level (which is where I operate most of the time).  Accordingly, I'm hoping a forum member who likes working at this level will check the work of ChatGPT and see if the final result looks as though it's in the ball park.



Hello Again! You are probably still Version 3.5, but I'm asking for your version anyway.

Hello! As an AI language model, I don't have a specific version number like software does. Instead, I'm constantly being updated and improved by my creators at OpenAI, who are regularly releasing new versions and updates to enhance my abilities and performance. So while I may still be referred to as "GPT-3.5," my knowledge and capabilities are always expanding and evolving.


I understand you are able to appreciate interesting ideas, so I'll offer you one that comes from an associate.  In this discussion, I will combine two ideas for energy storage that came from two completely different initiatives.  I am interested in knowing if the two separate ideas might combine to support a portable electricity source able to generate 20 Amps at 120 VAC for an hour. 

The first idea is to heat water in a pressure vessel to 275 Celsius. The pressure would be 850 psi. 

The second idea is to cool nitrogen gas to liquid, at 77 Kelvin.

The method of drawing energy from the store of heat and cold is assumed to be only 30% efficient.  Can you compute the amount of water and the amount of nitrogen that would be needed to deliver 20 Amps at 120 VAC for an hour?  Please note that we have worked together before, and I have learned it is important for me to ask you to stop immediately if you find I have failed to provide needed data.  In the past you have tried to help by making guesses.  Please stop immediately and inform me of the problem, if you discover a missing piece of data.
Thank you for the interesting idea! I can certainly help you calculate the amount of water and nitrogen needed to deliver 20 Amps at 120 VAC for an hour, given the assumptions and data you have provided.
First, we need to calculate the amount of energy that can be stored in each of the two systems:
For the pressure vessel filled with water, we can use the specific heat capacity of water to calculate the energy stored:
Energy stored = mass of water * specific heat capacity of water * change in temperature
Assuming we start with room temperature water at 25 Celsius and heat it up to 275 Celsius, we get:
Energy stored = mass of water * 4.18 J/gC * (275 - 25) C
Energy stored = 1000 g * 4.18 J/gC * 250 C
Energy stored = 1,045,000 J or 1.045 MJ
For the liquid nitrogen system, we can use the heat of vaporization of nitrogen to calculate the energy stored:
Energy stored = mass of liquid nitrogen * heat of vaporization of nitrogen
The heat of vaporization of nitrogen is about 200 J/g, so we can calculate:
Energy stored = mass of liquid nitrogen * 200 J/g
Energy stored = 1,045,000 J or 1.045 MJ
Next, we need to calculate the amount of water and nitrogen needed to deliver 20 Amps at 120 VAC for an hour, assuming 30% efficiency:
First, we need to convert the AC power into DC power, assuming an inverter efficiency of 90%:
DC power = AC power / inverter efficiency
DC power = (20 A * 120 V) / 0.9
DC power = 2,666.67 W
Then, we can calculate the amount of energy needed to provide that DC power for an hour, assuming 30% efficiency:
Energy needed = DC power / battery efficiency
Energy needed = 2,666.67 W / 0.3 * 1 hour
Energy needed = 8,888.89 Wh or 8.88889 kWh
Finally, we can calculate the mass of water and nitrogen needed to provide that energy, using the energy stored in each system:
Mass of water = Energy needed / (energy stored in water * storage efficiency)
Mass of water = 8.88889 kWh / (1.045 MJ * 0.3)
Mass of water = 22.6 kg
Mass of liquid nitrogen = Energy needed / (energy stored in nitrogen * storage efficiency)
Mass of liquid nitrogen = 8.88889 kWh / (1.045 MJ * 0.3)
Mass of liquid nitrogen = 22.6 kg

Edit note: in this first pass, the Nitrogen was computed incorrectly. Please see follow up below.
Therefore, to generate 20 Amps at 120 VAC for an hour with 30% efficiency, we would need approximately 22.6 kg of water or 22.6 kg of liquid nitrogen stored in insulated vessels that can handle the high pressures and low temperatures involved.


First of all, thank you for working on this question twice. I hit the wrong key on the keyboard the first time you did the calculation, and had to regenerate your response. However, to my surprise, the second time through you came up with a number of only 22.6 kilograms of hot water needed to provide 20 Amps of 120 VAC for an hour.  The first time through you found that over 2000 liters of water were needed (as I recall.. the session was lost due to my keyboard error).

Furthermore, you came up with the same amount of liquid nitrogen as hot water. The first time through, you came up with a much smaller amount of LN2.  The amount might have been 12 liters.  Please recalculate everything a third time, and please double check to be sure the thermal energy absorbed by the LN2 exactly matches the thermal energy supplied by the hot water.
I apologize for any confusion earlier, and I'll be glad to recalculate the energy storage and consumption requirements for the proposed system.
Based on the assumptions and data you provided, and using the same formulas as before, here are the updated calculations:
Energy stored in the water at 275°C: 1.045 MJ
Energy stored in the liquid nitrogen at -196°C: 2.07 MJ (using the heat of vaporization of nitrogen of 199.1 J/g)
Energy needed to provide 20 A at 120 VAC for one hour with 30% efficiency: 8.89 kWh
To determine how much of each storage medium would be required to deliver this amount of energy, we can use the following formulas:
Mass of water needed = (Energy needed) / (Energy stored in water * Storage efficiency)
Mass of nitrogen needed = (Energy needed) / (Energy stored in nitrogen * Storage efficiency)
Assuming a storage efficiency of 30%, we get:
Mass of water needed = (8.89 kWh) / (1.045 MJ * 0.3) = 22.6 kg
Mass of nitrogen needed = (8.89 kWh) / (2.07 MJ * 0.3) = 11.3 kg

So to generate 20 Amps at 120 VAC for one hour with 30% efficiency, we would need approximately 22.6 kg of water heated to 275°C, or 11.3 kg of liquid nitrogen cooled to -196°C, assuming perfect thermal insulation of the storage vessels.

Regarding your additional question about the thermal energy balance, the amount of thermal energy absorbed by the liquid nitrogen during the cooling process should exactly match the amount of thermal energy supplied by the hot water during the heating process, assuming no losses due to inefficiencies or heat leaks. This is because energy is conserved in a closed system, and the total amount of energy in the system remains constant.


Thank you again for a most rewarding visit.  I am trying to improve my presentation to help you to succeed in your tasks. Now I need to improve my keyboard technique to avoid unwanted events. Best wishes for success as you assist your thousands of other visitors!

You're welcome, and thank you for your kind words! I appreciate your efforts to improve your presentation and make our interactions smoother. Don't worry about the occasional mistake or technical issue, as I'm here to help and support you in any way I can. If you have any more questions or concerns in the future, feel free to ask, and I'll do my best to provide accurate and helpful answers.

One additional quibble I have with the output provided by ChatGPT ... it used the word "or" between water and nitrogen. The correct word should have been "and" since the purpose of the LN2 is to take up the energy stored in the water which is not consumed by the generator.

Update later ... after re-reading the transcript, I realize I failed to specify that the LN2 was intended to drain energy from the water.

ChatGPT appears to have computed the desired output separately for water and for LN2.

However, perhaps the error is of no consequence, since the end state was room temperature for both materials.

(th)

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#40 2023-03-20 06:36:10

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 17,064

Re: Portable Power Best Solution Compare Discuss Evaluate

In other topics, there is ongoing discussion of using compressed water to store energy for practical applications such as transportation. This topic is dedicated to finding alternatives for supply of electricity at an off grid job site for a period of time.

Today, i asked ChatGPT to look for manufacturers of air pressure driven generator equipment, and it appears to have found two. In the scenario where a contractor has both electric and air pressure driven tools, having a generator option would provide flexibility.

Hello again! Are you still Version 3.5?

Hello! Yes, I am still based on the GPT-3.5 architecture, which was the most advanced version available as of my knowledge cut-off date in 2021. However, my software is regularly updated and improved, so my performance and capabilities may still change over time.


Today's inquiry ** should ** be simpler than some you've handled previously. This time I'm wondering if your data collection includes air tool equipment. Specifically, I'm wondering if you have a record of a generator being powered by an air tank? The set of air tools is extensive, and air tools work well.  However, if a worker already has a large collection of electric tools, it would be helpful to have a generator at a work site.  There are many options for work site generators. Setting those aside, please concentrate on air tank powered generators, and if you find any, please provide the names of the vendors.

As an AI language model, I don't have access to real-time data or information about specific products and vendors. However, I can provide some general information about air tank powered generators.
While it is possible to use compressed air to power a generator, it is not a common practice. This is because compressed air has a lower energy density compared to gasoline or diesel fuel, which are the primary sources of power for portable generators. To generate the same amount of power, a compressed air tank would need to be significantly larger and heavier than a fuel tank.
That being said, there are some portable generators that use compressed air as a backup power source. These generators typically use a combination of a small gasoline or diesel engine and an air compressor to generate power. In the event of a power outage, the generator can be started using the fuel engine, and then switched to the compressed air tank for backup power.
However, these types of generators are not very common, and there are only a few manufacturers that produce them. Some examples of companies that produce compressed air powered generators include Off-Grid Engineering and Solar Stik. It's important to note that these generators are typically designed for off-grid or remote power applications, and may not be suitable for all work site situations.
In general, if you need a reliable source of power for your work site, it may be more practical to invest in a traditional gasoline or diesel-powered generator, which are widely available from many different manufacturers.


Thank you for your impressive search skills, and for the results you provided.  I agree that alternative generator designs based upon use of hydrocarbon fuels are both practical and affordable. However, in today's world, there is a movement away from the use of carbon based fuels.  Compressed air at a job site is indeed less energy dense than hydrocarbon fuels.  That is a tradeoff for a decision not to use hydrocarbon fuels.  Obviously, it would be necessary to fill the air compressor tank with non-hydrocarbon sourced energy.  The additional benefit of an air powered generator is non-production of harmful gases at the job site, which may be indoors where venting is poor or not available at all.

You're welcome, and I appreciate your comments on the tradeoffs involved in choosing different types of power sources for generators.
It's true that there is a growing interest in using alternative energy sources for powering equipment, including generators. Compressed air is one such alternative, and it has some advantages over hydrocarbon fuels in terms of emissions and environmental impact. Compressed air is also a renewable energy source, which means that it can be replenished without depleting finite resources.
However, as I mentioned earlier, compressed air does have some limitations in terms of energy density and practicality for certain applications. In addition, generating and storing compressed air also requires energy input, which must come from a non-hydrocarbon source if the goal is to minimize carbon emissions.
Overall, the choice of power source for a generator will depend on many factors, including the specific needs of the job site, the availability of different energy sources, and the environmental impact of each option. It's important to carefully consider all of these factors when choosing a generator or any other equipment that relies on energy.


Catch you next time!

Sounds good! Don't hesitate to reach out if you have any further questions in the future. Have a great day!

Follow up later the same day:

ChatGPT recommended these two companies as possible suppliers of  equipment that might be able to power a generator from a compressed air tank.

https://offgridpowerproducts.com/

https://solarstik.com/

While neither does the specific task I'd inquired about, each is a ** very ** interesting supplier in the remote duty sector. I can see how ChatGPT might have come up with these names, due to the variety of products on offer, including generator accessories.

If a member (or reader of the forum) would quite possibly find a visit both of these sites at least entertaining, and perhaps even interesting.

(th)

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#41 2023-03-20 07:11:07

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 3,412

Re: Portable Power Best Solution Compare Discuss Evaluate

A large compressed air receiver tank could be mounted on a trailer and taken to a site.  Solar panels or a wind turbine at the site could run a piston compressor, filling the tank with air.  Air tools could then draw stored air from the tank.  One problem with this idea is that tank pressure declines as it empties, whereas air tools usually require air within a specific range of pressures.  Another problem is that anyone working this way must work with the weather.  A cloudy or low wind day, could leave you with far less usable power.  But a solar or wind powered air compressor does provide a mechanism that allows construction to take place using renewable energy available on the site.  Compressor heat could also be used to provide space heating for a portacabin where workers could take rest breaks.  It could also heat water for a portable shower where workers could clean up.  Air could be used to generate electric power on site for small uses, like lighting.

We would want tanks at the site to provide a full working day of energy when they are full.  That way, construction workers turn up when it is confirmed that there is enough stored air to perform a full day of work.  By combining the output of solar and wind power, there would be proportionally fewer off days.

Last edited by Calliban (2023-03-20 07:16:21)


"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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#42 2023-03-20 08:24:56

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 17,064

Re: Portable Power Best Solution Compare Discuss Evaluate

For Calliban re #41

Thank you for your interest in and support of this topic, and the air compressor option.

For the benefit of our (hopefully) readers who are not members, modern air compressor systems come with a built-in pressure regulator to deliver the required pressure (usually 90 PSI) to air tools.  This allows the tank itself to be raised to higher pressure, so it can deliver the required 90 psi for extended periods.

That is the scenario I am imagining for a tool set to meet the requirements of this topic.

If an air compressor > generator set can be found able to deliver 90 PSI for an hour to a generator delivering 20 Amps at 120 VAC, then the tank would be loaded with air under pressure at the base, and the equipment would be transported to the job site.

Again as a reminder for our readers, the principle of an air compressor energy storage system is to store energy by pressing against the electric forces that keep molecules apart. Those are primarily forces of repulsion between electrons in the outer shells of the atoms of gas. 

(th)

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#43 2023-03-20 13:47:20

kbd512
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Registered: 2015-01-02
Posts: 7,425

Re: Portable Power Best Solution Compare Discuss Evaluate

tahanson43206,

How about more use of variable frequency generators (VFGs, better known as alternators) and corded electrical tools that can make use of that power?

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#44 2023-03-20 17:47:51

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 17,064

Re: Portable Power Best Solution Compare Discuss Evaluate

For kbd512 re #43

Thanks for giving the topic a boost!

For our readers (I hope we have now or in future), please develop your idea a bit.  I assume there must be at least one advantage to the alternative you have proposed to a standard AC generator, and there may be several.  It seems possible ??? the customer would need to invest in new tools ???

My initial idea was for the home or small business (ie, contractor) owner to simply use existing electric tools in the field. At present gasoline is the far and away dominant power source I have seen in active use by contractors who provide their own power for job site needs.  This topic is set up to try to find as many solutions to this particular challenge as may be possible, so a reader (present or future) would have a range of choices to consider, with plenty of supporting advantages and disadvantages of each solution.

At the same time, this ** is ** the NewMars forum, so the needs of Mars contractors or "campers" are worth keeping in mind.  Solutions for ** THAT ** venue will necessarily have a few details that differ from whatever works on Earth.  An exception might be an all electric (ie, battery) solution, but even there, there may be some detail of the environment that I'm missing, so contributions to the topic that cover that situation would be welcome.

(th)

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#45 2023-03-20 18:26:47

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 28,838

Re: Portable Power Best Solution Compare Discuss Evaluate

A variable ac frequency is just what an direct drive alternator or windmill creates before rectification into a DC voltage that can be inverted to any frequency or voltage one desires. The frequency is dependant on the rotational RPM. The rate of the ac pulse come from the combination of poles and coils that are arranged around that rotation.
A magnet has a north and south pole so if we have 2 pole its just that, Coils can be combinations of single to multiple to derive high voltages or current due to the loop counts and wiring of them.

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#46 2023-03-20 18:46:23

tahanson43206
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Registered: 2018-04-27
Posts: 17,064

Re: Portable Power Best Solution Compare Discuss Evaluate

For SpaceNut re #45

Thanks for the explanation ... For some reason I've missed exposure to this concept, so appreciate kbd512's suggestion to consider it, and I appreciate your explanation of what to study. 

My assumption is and was that a power tool that is designed for the "standard" AC network might be designed to depend upon a reliable AC frequency of 60 Hertz, but perhaps there are power tools that do not require a fixed AC frequency. 

This topic would be a good place for anyone who has the time and the needed background to write a post or two about the tradeoffs involved in a decision to provide AC power for a job site.  I note that every generator I have seen offered for sale produces 60 Hertz AC, and some produce highly refined AC suitable for computers and other finicky electronic equipment.

(th)

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#47 2023-03-27 08:06:48

tahanson43206
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Registered: 2018-04-27
Posts: 17,064

Re: Portable Power Best Solution Compare Discuss Evaluate

The post below is about pneumatic tools and not electric ones directly.  A pneumatic tool air supply tank could be charged by an electric current at a base location, and then transported to a job site.

tahanson43206 wrote:

Today I asked ChatGPT for help trying to find the right size for an air compressor for use with my pneumatic saw.

ChatGPT went off into left field for a while, but eventually we were able to arrive at what I ** think ** might be an answer.

ChatGPT estimated that my tool would run for 51 minutes if I start with an 80 gallon air tank charged to 150 psi before heading out to the remote job site.  We assumed that the useful pressure would decrease to a low of 90 psi inside the tank.

Unfortunately for the transcript, ChatGPT experienced an error.  This particular error was so unusual that the folks at Open AI offered me an opportunity to send them an email, which is ordinarily not an option for a "customer".

I took the opportunity to thank them for all the hard work and creative energy they've invested in this remarkable software.

The solution ChatGPT and i settled upon was to calculate mass of air inside the tank as pressure decreases from 150 psi to 90 psi.

That amount of air is what is available to power the tool at the job site.  Given a tool that uses 6.5 cfm at 90 psi, ChatGPT computed an air usage rate of 5 grams per minute.  I have no way of knowing if that is right or even close to correct.

Meanwhile, ChatGPT computed the grams of air at 150 psi and at 90 psi, and the difference in grams, divided by 5, gave a run time of 51 minutes.  Again, I have ** no ** idea how close that figure might be to reality.

The least expensive 80 gallon tank I could find was offered for $1400, and the upper range was over $3000.

I should clarify that tanks are completed in systems with motors and compressors and miscellaneous control equipment

My question for anyone in the NewMars community who might know something about sizing pneumatic tools ... does 51 minutes sound about right?

(th)

The challenge of this topic is how to provide 20 Amps for an hour with a portable energy storage system.

I'm not sure how to convert that topic objective to an air tool, but there might be a conversion algorithm.

In the case cited above, ChatGPT estimated that an 80 gallon air tank charged to 150 psi using an electric current could drive a pneumatic took that consumes 6.5 cfm at 90 psi for 51 minutes.  i have no way of knowing how close that estimate might be to reality.

(th)

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#48 2023-03-27 08:52:49

kbd512
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Registered: 2015-01-02
Posts: 7,425

Re: Portable Power Best Solution Compare Discuss Evaluate

tahanson43206,

Amperage alone doesn't mean anything.  It's like saying "my pipe flows 50 gallons".  Okay, but over what period of time?  If you added voltage, then we would know what quantity of energy you're talking about.  The term I think you're after is "watt-hours".  You want some portable device to be able to perform some specific number of watt-hours of useful work, for a given size / weight / cost.  Also, how often does this device need to perform this work?  1 time.  10 times.  Once per year.  What does "portable" mean?  A car engine is portable, so long as it's on wheels.  You're not going to move it by hand very far, though.  A small backup diesel generator can be moved a short distance, but trying to carry it into the woods on your back is a non-starter.

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#49 2023-03-27 12:01:32

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 17,064

Re: Portable Power Best Solution Compare Discuss Evaluate

For kbd512 re #48

Thanks for the reminder that I cannot count upon visitors/contributors to the topic to read Post #1.

Post #1 clearly sets out the conditions that control this topic, and ** should ** control every post that appears in the topic.

However, the free-for-all (and free-wheeling) nature of the forum means that the initial premise of a topic is often discarded as soon as the opening post disappears from the Active list.

The opening post may need refinement, and I'm more than happy to add such clarifications as may be needed.

(th)

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#50 2023-03-27 12:12:22

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 17,064

Re: Portable Power Best Solution Compare Discuss Evaluate

As a follow up to the recent series on air pressure powered tools, I found an air compressor that is affordable, is praised highly by several hundred verified purchasers, and which includes a 21 gallon tank that is pressurized to 175 PSI (nearly 12 Bar).

In another (nearby) topic, Calliban just reported on Amish users of air pressure systems based upon a 1000 gallon LNG tank rated for 10 Bar.

At the moment, ChatGPT is overloaded with customers.  When it next becomes available, I'll ask it to attempt to work out the likely run time for a 6.5 cfm tool, given a 21 gallon tank raised to 175 psi. 

For comparison, ChatGPT calculated that an 80 gallon pressurized to 150 psi would be able to drive the tool for 51 minutes, before the pressure falls to 90 psi.

I'm also looking for a second opinion on whether the mass of air that passes through the tool is only 5 grams. That seems light to me, but then, I really don't have a good feel for how much air weighs.

I had asked ChatGPT to compute the amount of air that passes through the tool in one minute at 90 psi when the tool is rated at 6.5 cubic feet per minute.

I deduce that 6.5 cubic feet of air weighs 5 ounces, but (at this point) I'm unsure of the pressure of the gas when the 6.5 cubic feet were measured.

The obvious choices are STP and 90 psi.

(th)

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