Compressed Air in 2100 -- Low Tech Podcast, No. 79

Do you ever feel the pressure? I often do. Often life gets busy and we feel the pressure to do 100 things at once. And unfortunately, a podcast falls by the wayside sometimes and we lapse into hiatus. But then all of a sudden, we show up in your podcast feed again. But today, we're not talking about mental [music] pressure. Uh we're talking uh we're going to go back to the future and see why compressed air has made a resurgence. This is the Lowtech podcast. Hello and welcome back. I'm Scott Johnson from the Low Technology Institute. I'm your host for podcast number 79 on January 16th, 2016. Coming to you out of the Low Tech Institutees [music] recording room in Cooksville, Wisconsin. Thanks for joining us. And today we're going to jump back forward, if that works, uh to the year 2100 and look at how uh compressed air has become an important way to store kinetic [music] energy. We'll also have institute updates. And of course, don't forget to follow us on social media. We're most active on Instagram and YouTube. Well, YouTube eventually under the handle at low techinstitute, all one word. You can also find us on Facebook and check out our website, [music] which is of course lowinstitute.org. There you can find both of our podcasts as well as information about joining and supporting the research uh going on here at the institute. Also, you might notice some podcast distributors and YouTube put ads on podcasts and unless you hear me doing the ad, someone else is making money on that advertising. Um, and while all of our podcasts, videos, and other information are given freely, they do take resources to make. Again, if you're in a position to help um support our work and become part of this community, please consider becoming a monthly supporter for as little as $3 a month through our Patreon page, and that's uh found at patreon.com/lotchinstitute. I hope you're sensing a theme. If you'd like to sponsor an episode directly, please get in touch with us uh through email. Uh you can get me. I'm scottinstitute.org. Have you ever been really excited for a TV show to come back after it's been off for a couple years and you watch the first episode of the new season and you realize I can't remember the most important plot points and the cliffhers from last season because that was 2 years ago. That's kind of where this podcast is. So, let me catch you up to why I am talking about the year 2100. Starting uh in episode 71, we began looking at what our little village of Cooksville could be like in the year 2100 if we decide to get all of our primary resources from our local environment. We're calling this localism. We started with an introduction to what history could look like in the year 2100, specifically the loss of fossil fuels, the rise of electrifying everything, and the collapse of over electrification. Then we went on to discuss how we now use a variety of energy sources in a distributed web or network. And first we talked about electricity in episode 73 before moving on to hydrogen in episode 75 and bio gas in episode 76. You should be able to find all of these in our podcast archive if they're not showing up directly in your podcast feed right now. I'm currently working to make sure all of our feeds are working properly. So please bear with us. Let me know if you can't find us somewhere. So now we're back and we're going to jump into our faithful time machine. our Delorean and move forward in time to the year 2100. And we're going to talk about another major form of power used today and namely that is compressed air. Now, we can think of energy systems on a spectrum or a couple of spectrums. We have high-tech or low tech. We can talk about quality versus quantity. We can also talk about safe versus dangerous. Things like hydrogen and electricity tend to be high-tech, highquality, but potentially dangerous because they involve chemical reactions and high level engineering and equipment and compressing lots of energy into small spaces. They're also powerful and compact, but they're potentially dangerous. So, on the other hand, bio gas is potentially dangerous because it's flammable, but otherwise, it requires pretty low technological input. If you go back to last episode on this topic, you'll see it's fairly easy to make bio gas. But now we come to compressed air which is both low tech, highquality and relatively safe. The basic material is free and abundant. Compressed air depends on simple machines and tanks. It stores large amounts of energy safely and can operate many mechanical systems efficiently. Compressed air has come to be the mainstay for small factories and shops across much of the world and has replaced many electric power tools and machines. We don't have to just go to the future to see compressed air and its uses. Compressed air has been around for millennia. If you consider bellows on a forge, a type of compressed air, anytime you've seen a blacksmith working, you've seen compressed air as bellows or fans or other mechanisms have blown air into coals to make them hot enough to work metal. Copper and iron were smelted with bellows since at least 4,000 B.CE. At 6,000 years ago, Assyrian carvings from 800 B.CE show what appear to be warriors swimming underwater with breathing bladders. Early um scuba gear, right? Compressed air did not become a major source of energy though until the industrial age. And this is when engineers decided that large-scale compressors and machines to have compressed air could be really useful. Paris even had a municipal system that serviced residential, commercial, and industrial u for over a century alongside gas, electric, and other utilities. You could just plug into it. And compressed air is one of the safest or really the safest of all of our energy sources I've talked about. The material is naturally occurring, abundant, and non-toxic. And if you think about it, for every electric, hydrogen, and natural gas generator, storage device, and appliance, we have to build so-called fail safes. This means that if something breaks, it shuts down in a safe manner. This creates minor inefficiencies in every system. Compressed air systems though need little in the way of extra this extra step uh for a fail safe. Things are basically safe if you don't blow air into your skin or debris into your eyes. Um, as long as the machines and storage tanks are in good working order, there's really very little risk of rupture. Not to mention the low environmental impact of compressed air systems. The only effects come from the creation and disposal of the equipment. Air is already everywhere around us causing very little problem. I actually enjoy having the air around me. Uh so let's talk now about how we generate compressed air. And then we're going to go take a tour around our village and see some of the systems we have in place and meet the people that use them on a daily basis. So um as with all of our energy today, we have local generators to make any scale of need. Since air compression is such a simple technology, the variety of compressors is large and many people have homemade systems. And the great thing about a DIY system is that if you can build it, you can fix it. And really, this is one of the safest systems to be experimenting with because if it doesn't work, we don't have flammable hydrogen or methane leaking all over the place. We've all we've also maintained many so-called legacy generators which use electricity or other means to run a compressor or absorb excess electricity produced in other systems u to store that power as compressed air instead of storing it as electrons in a battery or hydrogen in a tank. All compressors though operate using the same physics and are subject to identical challenges. The underlying principle is simple. Atmospheric air which is made up mostly of nitrogen coming in at about 78% and oxygen 21% is put under pressure by mechanical means. It's stored in a tank and then the kinetic energy is released back when it's expanded uh to standard atmospheric pressure and that expanding energy is used to run machines. It's completely kinetic. There's no loss of energy for phase change or chemical reactions. It does create two challenges though. The first is moisture. Let's dive in. Uh I think it's clearer with a concrete example. A 10gon air tank holds about 1.3 cubic feet of air. That's about 40 L holding 0.04 uh cubic meters. And when that air is held at one atmosphere, that is standard atmospheric pressure that you're breathing right now if you're at sea level. Um it's about 14.7 PSI. Uh but now if we pressurize that tank and bring it up to 120 PSI, it's holding uh or 8.2 2 atmospheres. It's now holding 2.3 cubic feet of air or about a third of a cubic meter. The the problem of moisture comes in because at standard atmospheric pressure, if you have 50% relative humidity and 68° F or 20°C, that 12.3 cubic feet of air holds about a tenth of an ounce of water. Not much, uh, just a few grams really. But when that air is compressed down to less than a ninth of its typical volume and that 10-gon tank u in that 10-gon tank the water content represents more than six times more than 100% relative humidity. And what do we all learn in elementary school? When the humidity is over 100% we get things like clouds and precipitation. This means that the water vapor becomes liquid and condenses on the inside of the tank. We have a tiny little rainforest inside of a metal tank. Not very useful. Without dealing with this problem, the tank would slowly fill with incompressible water, number one, and the unusable volume would decrease. Also, this would create rust because of the high oxygen content of our atmosphere. So, to solve this problem, most small systems have drains where you can bleed off the condensation, while larger ones have dryers that pull moisture out of the air before it's pushed into the storage tank. But moisture is just one of the problems. The other is heat. There is a phenomenon known as the uh adibiotic process and I had to look it up. It's spelled adi b io t i c. Um it's just Greek and it means heat retaining. Uh in short when gases are compressed they give off heat and when they are decompressed they are endothermic which means they are cooling. This is how your refrigerator works. A compressor pushes low pressure refrigerant through a condenser to give off heat as it expands and then they go through an expansion valve to reduce the pressure and temperature to chill the fridge. The gases are then cycled back to the compressor to start the cycle all over again. The larger or uh the larger a compressor is, the faster it works, the more heat it produces. So on large compressed air systems like in some factories they use this extra excess heat and cooling to help regulate the temperature of the factory depending on the season. Other large systems use water to cool the compressor and then use the hot water for other purposes. So this helps reduce the heat of the compressor and dries the air going into the system even more. And even small compressors have heat absorbing systems to catch otherwise unused heat. Even if it's just a few thermouples placed strategically to draw off a little bit of power for free light or monitoring. Um, our air compressors are as diverse as our electrical generators. Small or large, they all try and convert kinetic energy into compressed air. Early on we had many systems that used solar or wind power uh to run compressors electronically. Um, but this had extra links in the chain meaning converting kinetic energy into electrical energy back into kinetic energy. These have been phased out. Today's compressors are slow but reliable. Most households use air in some way. Our neighbors, for example, the Curries, just installed a new small wind turbine uh compressor. This is a simple unit. It's got 4ft rotors. That's about 1.25 m. And they turn at about a half a horsepower to compress air. The compressor is a piston-driven oilless compressor that uses that has very little maintenance need and produces cleaner air. Um, it'll be a little less efficient than other types of compressors. Um, but the wind turbine parts are interchangeable with our electric wind turbines. By which I mean the rotors and the housing, the pole and all the other things that are they're standardized, so they're really easy to fix and the parts are abundant. Um, a hose connects the compressor to a simple 60-gallon tank through a small dryer, and this removes excess moisture. And in the years before they installed it though, they would just pop over with one of their portable tanks to the workshop to fill up a few um a few uh pressure tanks when they needed it. But now with this new slow but steady rotary compressor on their property, most of their basic compressed air needs are met. And we'll talk about how he uses that later. But uh we should now pop over to the workshop. And the workshop uses a mediumcale air system for most of its tools. One of the benefits of compressed air is that it travels well over long distances. The Badfish Creek runs on the north side of the village. And in the 1800s, it was used to turn a water wheel for a flower mill. And further down the creek, uh, there was a sawmill. But today, we have a dedicated bypass turbine similar to a 15 kowatt, uh, one that we have upstream that drops off a portion of the flow and drives an air compressor. So, um, this air compressor, uh, running on on the on the water, uh, links to a dryer and a buried pipe which leads to the tanks by the shop. The compressor is a 20 horsepower oil lubricated screw compressor with a large capacity and the water flow is pretty constant and fills their tank for each workday with room to spare. They usually give away their excess air to neighbors actually um because really it's free once it's up and running, right? One of the most spectacular um large scale compressors I've ever seen was in Duth, Minnesota near Lester Falls. Uh, a trumpete compressor uh uses falling water to compress large volumes of air. So, imagine this. Imagine a bathtub with a straight drain pipe on the second floor. And when the plug is pulled, the water falls down the pipe creating pressure. But if a few holes are drilled at the top of the pipe below the tub, air gets sucked into the falling water. And at the bottom of the pipe is a box, a sealed box. And when that water collects it, the compressed air separates out to the top of the enclosure and that can be drawn off and the water flows out of this type of compressor. This has been used for centuries and a big one was built in Duth. It diverts a small portion of the water going over the falls uh through a trumpet compressor and a compressor system. It provides huge amounts of compressed air for the municipal um air system there, but it requires water to drop a pretty significant amount of distance, which is why they're not available everywhere. So, we've seen a few ways that we generate compressed air, but now we're going to turn to how we store it. Just like people have been using compressed air for millennia, we've also been refining our storage systems. Uh, even in 1495, Leonard Da Vinci was playing with ideas for storing compressed air. Over time, however, pretty much all the systems use some sort of tank. And because almost all of our compressed air systems are stationary, it really simplifies our storage needs, unlike hydrogen, um, bio gas that we sometimes use mobile. Uh this also means we can use uh we can use the problems of heat, cold, moisture as benefits with interconnected systems to avoid moisture buildup and increase the longevity of our tanks. Almost all the tanks have some sort of air dryer in the front end. It's easier to replace a dryer than a storage tank. Uh the steel walls will eventually fail if enough water vapor is allowed to condense inside. Most of the dryers used today um are lined with a membrane uh and with a filter and a cartridge that gets replaced periodically. But the filter is just a bundle of hydrophilic tubes that absorb water vapor as it passes through. Uh a small amount of dry air from the downstream side of the dryer is vented back to draw off the accumulated water. So it's a little inefficient, but it's worth it in the long run. Just imagine a filter uh that uses a few PSI to rid the compressed air of water before it gets into the tank. The simplest compressed air storage tanks are simp are just steel pressure vessels. Although a spherical vessel would be stronger than any other shape, they're hard to produce and tend to roll around on the floor of the shop. So, it's not really useful. Most air receiver tanks, which we just call art or arts, um are capsule-shaped. If you think about it, if you cut a sphere in half, pull it apart, and put uh the round hemispheres on the ends of a cylinder, you have a capsule, which has lots of round sides and can hold the pressure well. All of them have built-in pressure relief valves to keep contents under uh rated working pressure so they don't over pressure and explode. Our neighbors, the Curries, have a 60-gallon tank or ART filled by the remote compressor. And it's built exactly like this. Um the ART at the Cooksville workshop is typical of more midscale systems. It has a 1000gallon capsule tank, which is about um 13 uh 3,800 L. It has a working pressure of about 250 PSI. That's 17.2 bar. A century ago, these tanks would have been used to hold liquid propane. You've probably seen them if you used to drive around rural areas, these propane tanks. This tank holds just under 2400 cubic feet of air or about 68 cubic meters. And thus, this runs their pneumatic nailers, drills, and other tools for the entire workday while the constant flow of water at the creek recharges the tank constantly. Larger factories need much more compressed air, and they store it in a variety of ways. Of course, some larger manufacturers simply use a series of large arts plumbed together to provide as much storage as they need. Really, large compressed air systems are underground. They can use caverns, abandoned mines, and other wells to store air, but these are rare and idiosyncratic kind of custom systems. It's also worth noting that the larger the storage, the more sophisticated the drier intake and distribution system tends to be. We also have a few mobile applications which I'll mention in here, but they require compressed air, but these cases the usually this we just use the standard hydrogen tanks which we talked about a few episodes ago. These can hold compressed air to 5,000 and 10,000 psi which is about 350 or 700 bar respectively. The standard 5 and 50 gallon tanks can hold either 227 or 500 454 cubic feet of air. So quite a lot of air in a small space. These tanks are polymerlined and therefore more forgiving of internal moisture, but these are used only for specialized uses and they're pretty rare actually. And we'll talk about how we use them uh in a bit. So, but now that we've looked into storage, let's see how we use these compressed air systems in the year 2100. We can really divide our use into mechanical or what we call pneumatic uses and specialty uses. Most workshops and factories now use compressed air where we previously used electric machines or motors. From rotary tools such as drills, saws, grinders, and wrenches to linearly activated cutters and pliers, hammers, nailers, staplers, handheld pneumonic tools are incredibly common. Factories have larger machines which can push, bend, stretch, and perform really any action that was previously done with electric motors. our neighbors who recently installed the windmill compressor um that we were just talking about the curries. They um is a avid beekeeper and woodworking enthusiast and he uses his small nail gun, saw, drill and other pneumatic tools to keep his hives and other woodworking projects in order as well as doing repairs and other projects for other villagers. The small factory in Cooksville also deals in wood products and drives most of their machines with compressed air. um their shop has a pressure line running around the perimeter of the shop. So each workstation um has its own hookup that provides constant pressure throughout the day. Another use of um pneumatic power is specialized transportation and powering of tools uh in unusual environments. Even though hydrogen creates only water vapor when it's burned or converted into electricity, nobody wants to be down in a mine with a tank of compressed hydrogen. The compressed air continues to power tools and machines below ground or underwater. Many other specialized systems use compressed air. Um dentistry, unsurprising, diving, uh industrial work that requires breathable air. Legacy compressed air systems are still around. Some food and industrial um material processes require compressed air um as ingredients and artists and manufacturers use air to blow paint or other atomized chemical coatings. So there's lots of specialized uses. um injection molding of metal or glass or bio the bioplastics that we make now we'll talk about in another time. Um it's still used in sand blasting and refrigeration. In these cases oil is often used in compressors um and extra filters are used to provide cleaner air for human consumption and finicky industrial tolerances. But by far the most common non- mechanical use is stacking heating and cooling on an existing compressor system. We already talked about this a little bit, but whatever compressed air uh whenever air is compressed, it gives off heat generated by the adibiotic phenomenon. Small, slow compressors such as our neighbors wind turbine create such minimal heat that collecting it just isn't worth it. Our mid-size compressors though use thermouples to capture heat and put it to use running electrical and monitoring systems. The largest systems and factories can be used for space or water heating even. Conversely, the release of compressed air absorbs heat from the surroundings and can be used to harness har uh can be harnessed on the medium scale to run refrigerators. Larger systems can even provide more systematic cooling for hot factories. Alternatively, if the temperature swing is not needed for another purpose, a heat exchanger can even uh help even out the high and low temperatures of compression expansion, making the system more efficient. Compressed air is the last major power source that we use today. Of course, a number of niche power sources and other systems are out there, but in most households and communities, you will see electricity, hydrogen, bio gas, and compressed air as the major energy sources. As we visit other sectors of our economy, we will see other types of fuel that are used like wood for heating in some cases in the winter, but we'll see a mix of energies used to power our transportation network. We'll get to that in later episodes. We should though circle back to one of the most important changes and reiterate this of energy used in the year 2100. It isn't necessarily the specific technology or energy source. The biggest change we see is that people are using significantly yet less energy per person about a quarter and a wide diversity of energy systems. We made the mistake of becoming overly dependent on fossil fuels only to replace that with trying to electrify everything. Just like animals that depend on a single source of food become in danger of going hungry if something happens to that one source of food. We want to be like generalists on they can simply switch from one source of food to another making their diet more resilient. Similarly, redundancy and not relying on a single source of energy has made our world more stable and robust. We don't worry about one system failing and then needing repair and our lives being greatly disrupted because we can just depend on the others to get us by in the meantime. And now let's get to a quick research uh update uh brief recap of what we've been doing around the institute and why there haven't been podcasts. I hope that we have more coming up uh soon. I'm going to make an effort uh to get uh episodes out. We're going to start talking about food in the next episode which will be really exciting. We also have a garden expo coming up in early February. I'll be talking on a variety of topics. Uh if you're in the Madison area um check out our website um for more details about that. Um and I'll put the uh lectures uh and seminars that I give. I'll probably put those out on the podcast as well. Um but yeah, uh we have been or we I have been uh building a code compliant small house. Not a tiny house. Uh it's 725 ft. Um, but it's built of local materials. I uh cut the trees uh out of my neighbor's wood lot. I got the stones uh for the foundation from my other neighbor's um field stone pile. Um it's up and now I'm installing the electrical system. And so I've just been every spare minute I have has been working on this project. I'm basically building a house uh by myself. Um, not not to me not to say that I haven't had uh help from um friends and others. Um, but the majority of the the day-to-day labor um has been coming from me, which has kept me out of the podcast uh booth and out of the uh away from writing uh which I really enjoy doing. Um, but I do appreciate those of you who have written in and said, "Hey, you doing okay? Everything uh good? Haven't heard from you guys in a while." So, I do appreciate those uh emails and uh and contacts uh through social media and stuff like that. So, thanks for that. Um, I really do hope to have more podcasts out more regularly. Um, so, uh, where are we going next? Uh, this summer we should have some classes. We're going to have a prairie, uh, prairie seed collection in the fall, but in addition to that, we're going to have a class on, uh, starting and, uh, creating your own prairie. Uh, so keep an eye out for that. That's going to be a joint uh workshop that we have uh with a couple other local organizations here in Cooksville. The his Cooksville Historic Trust uh being one of them. And uh yeah, so we do have some more classes probably this summer related to the build. We're going to be doing a light straw clay. Light straw clay is uh basically compressed straw that is uh rammed into forms in the wall cavities to replace or instead of uh that pink bat insulation that you've sometimes seen in construction. So, we're going to have a weekend build where we're going to need uh people to come out and uh in addition to learning from one of the people who is a founder of this technology uh who happens to live in Madison is going to lead that. Um we'll need help uh just bodies to pack the walls of the of the build. Uh then uh we are going to have classes on uh plastering um and all kinds of other building related things. Uh, and hopefully by the end of the year, we'll be moving back to our regular programming, uh, with all kinds of fun classes not related to building. Uh, although building's great, uh, it'd be great to have a better to have a variety of classes coming out. So, please stay tuned for all that. Um, I'll do more updates uh, next episode. So, do stay tuned. I'm really excited to [music] start diving into the food uh, in the future of cook. Well, that's it for this week. The Low Tech podcast is put out by the Low Technology Institute. [music] The show is hosted and produced by me, Scott Johnson. This episode was recorded in the Low Technology Institute recording room. Um, you can [music] subscribe to our podcast on iTunes, Spotify, Google Play, YouTube, and elsewhere. We hope you enjoy this free podcast. If you'd like to join the community and help support the work we do, please consider going to patreon.com/lotchinstitute [music] and signing up. Thank you to our forester and land steward level members Tony Neil and the [music] Hambuses for their support. The Low Technology Institute is a 501c3 research organization supported by members grants and [music] underwriting. You can find more information about the low technology institute membership and underwriting at low techchinstitute.org. Find us on social media or reach me directly. I'm Scottinstitute.org. Our music intro music was bouncing off the album uh Powerpop by Helisna. That song is released in the public domain and this podcast is under the creative common attribution and share a like license, meaning you're free to use and share [music] it as long as you give us credit. All right, thanks so much. Take care.