CEB Infrastructure

In order to build with the Compressed Earth Block press, and in order to produce these machines at Factor e, we need a certain level of infrastructure. Here is what we are doing:

Say you want to fabricate CEB presses. Start with a facility: CEB walls and living roof, where 1000 square feet may do for 1-machine per day production with 4 people. Give the facility some juice: 2 kW peak solar cells from Ersol will do to get you entirely off-grid. If you are off-grid, add a GNB 20 kWhr forklift battery pack for storage – it lasts one full day at average wasteful American household usage. Put in a large, 10 kW inverter if you want to run heavy duty electric equipment. Drop in a 3 kW Lister engine generator for backup, if the sun does not shine for long periods. You can run a good welder, like the Millermatic 200 MIG welder, with the inverter – but only from the beefy battery storage which can run up to 2 of these welders at one time. If you want to pop out one CEB per day, you might want to add in a CNC acetylene torch table to slice up your working metal like butter, at the tap of a button from your desktop computer and open source LinuxCNC software. A LifeTrac open source tractor will help you power the PTO generator if you need 20 kW more industrial power. It will also do the soil preparation: soil digging with the loader, and mixing with a rototiller. The latter will be open source production as well. LifeTrac is designed to run 6 Liberator 1 CEB machines at a time. We will have two Liberators by the time we start building here.

How robust is the technology package above? Let’s go through an analysis of expected maintenance costs. First, the building will be made of CEBs. We built the PTO generator, so it is essentially good for life. The Lister, off-shelf, is supposed to last 100 years. The batteries are heavy duty forklift flooded lead acid, 25 year lifetime. The welder was chosen as a proven, long-lasting one – Sweiger Shop told me that the Millermatic 200s just keep running without problems for many years – they use 8 of them – while the newer Millermatics are already having problems. The CNC torch table is designed to last, and we decided to build the open source, articulated tractor because we want reliability and we are tired of $2k/year maintenance costs on the other tractors. That in itself makes a good story – and I’ll blog about this more later.

Essentially, the package is sound from maintenance cost perspectives of low overhead – perhaps $500/year costs for the entire facility! That includes utilities and all equipment. This is prime neosubsistence in action. To me, it is absolutely exciting – this is the only off-grid industrial facility that I know of that is being built on this planet. Please let me know if you know of others.

The solar cells and inverter are the weak links. If they break, we just end up replacing them. We won’t touch OS solar cell production yet – that will be forthcoming in about 1-2 years. I will, however, touch on OS inverters. That’s something we can do now, as we had 2 of them break already. If anyone in the audience can help or provide leads on designing a scalable, stackable power inverter – scalable in, say, 1 kW units – let us know. Is this by any chance where field-programmable gate arrays are capable of providing the circuit logic? The high-power inverter is a good candidate for open-sourcing, as the commercial 10kW equivalent is about US$10k, and we should be able to reduce the cost by Factor 10.

Got to go. I’m going to build me a tractor frame today.

Yes, really. The frame is xyz-bolt together construction (one of the icons in the Open Source Technology Pattern Language) – truly the modular and lifetime Design for Disassembly (DfD). We are using sizeable 4x4x1/4 inch square steel tube and 3/4″ bolts. Easy to build, easy to take apart. This type of design, of course, is something you will never learn about in college. They say it’s too pedestrian. I call it Design for Freedom (DfF) – and douse myself with sweet thoughts of a liberated world beyond scarcity. It’s one piece of the puzzle, but surely a great leap towards the Global Village Construction Set.

Did you ever wonder what would happen if things lasted a lifetime? Mix this question with the concept that your cost of living is the cost of the technology that you use: houses, cars, etc.

Things don’t last a lifetime, and they are lasting shorter and shorter with planned obsolescence: read this article about open source as a cure for this ill. Our digital camera just broke, so we have to shell out more hard-earned nuggets to get a new one. Please let us know – of recommendations for a good, low-cost brand; if you know of any open source digital camera projects, or if you have a camera for sale. I won’t be taking any pictures today.


  1. Josef Davies-Coates

    Fantastic post!

    I’m not very practical (yet!) but I’m going to do my best to copy you on some land in Spain 🙂

  2. Marcin

    Once we have the infrastructure for teaching, we’ll be able to teach all of the above basics, plus much more exotic basics, in a 2 year deep immersion program. Permaculture and background technical literacy included.

  3. […] In about a month, we’ll be starting to build – now with reliable equipment. We’re still aiming for production of CEB presses in October, after getting up the computer controlled torch cutting table for rapid fabrication in our off-grid facility. […]

  4. Mike Petrachenko

    Inspiring site! I’m working on becoming an accountant, because that’ll get respectability, and respectability equals more financing opportunities for cool projects like yours (that’s the plan, anyway…).

    But I’ve also wondered about inverters – and I just wanted to give you a heads-up – I googled “power inverter design” and the very first page result looks like it has some basic schematics linked to it – I think power inverter design may be already a decent way down the open-source road.

    Best of luck!

    – Mike

  5. Marcin


    We are looking for a schematic of an inverter, scalable in units of 1 kW. We want to be able to build 1 kW or 10 kW inverters. If you have any insight on this – or friends that do – let us know. Right now we’re dependent on either throwaway or very expensive inverters. We want to build a 10 kW inverter to power welders. We have the battery bank to support that. Off-the-shelf, it is $10k for 10 kW inverters.

  6. […] you observe our digital fabrication program for CEB machine production a few posts ago – you’ll see that the solar cells are its central power source. This is 100% off-grid […]

  7. […] CEB fabrication facility will be built after completing LifeTrac, which powers the CEB machine and prepares the […]

  8. Rasmus

    You should test how well the CEB press works for other purposes as well. Think biomass bricks ! Rather than wormcompost all biomass waste, it could be turned into bricks, dried and used for heating and electricity (wood gasifier).

  9. […] design-for-disassembly articulating multipurpose tractor/loader. It is the key to powering the CEB Press, permacultural operations, as well as: well-drilling, sawmilling, powering the Multimachine, power […]

  10. […] that entire package a reality – a community-supported manufacturing (CSM) operation, utilizing open source digital fabrication in the process. We are talking about an economically significant […]

  11. […] We are on our way to neocommercialization of the CEB press, starting with the building of a flexible, digital fabrication facility. This building addition is planned to feature CEB walls, a living roof, solar design, CEB masonry […]

  12. […] discussed the computer-controlled torch table in a prior post about our digital fabrication facility for producing The Liberator – the open source, high performance CEB press. After almost one year of […]

  13. Open Source Torch Table | Open Source Ecology

    […] The design has come a long way since our initial work from 2008 and redesign of 2009. The open source torch table has now reached the technical design stage, according to our open source product development method. The project is part of our flexible fabrication workshop infrastructure, which we discussed initially in an earlier post. […]

  14. mimarob

    Thoughts on inverters.

    I think most inverters use some MOS transistors. These things are made with ridilously high amperages and small power losses at reasonable prices these days.

    The most power loss comes when you switch the transistors on or off.

    A simple square wave inverter is usually cheaper. I think because you only need to switch on and off 2×50 (2×60 in US) times per second. So you can get by on smaller transistors and less cooling.

    A sine wave needs to be “chopped” or PWM:ed to look like a sine wave so it needs more on-and-off per second to approximate a sine wave.

    An arduino or similar would probably handle the controller circuit in a versatile way (why not make one for both Europe an US for a change :-).

    Good news might be that only sensitive low power units, computers, tv’s etc. need sine wave.

    Another thing that brings the price up, I think, is the transformer. You need to go up in voltage, generally because these things are designed to run on 24 or 12V car-systems.

    Maybe the batteries could be connected in series to form the correct voltage 12×20=240v (12×10=120V for US)?

    This would of course mean you have letal volatages on both sides of the inverter!!!

    For sinewave you need slightly more since the peek voltage of the grid is larger than the effective voltage

    This might be cheaper since you don’t need upwards conversion. Also you get to work with 10-20 times less the current, giving you cheaper transistors. (It is much easier to make a transistor withstand high voltage than high current)

    For the welding, I just found there are tons of suicidal people out there using the car battery directly as a welder, it also happened with me once, it made my wrench into a permanent 1/2″ *grin*

    In the long run, that might be a way to go, make the welder without the transformer? Don’t really know a lot about welders only that they use a transformer to produce high currents. We already got that in the batteries!

    Here it might be best to connect batteries in parallel, thus gaining huge amperages. But since they are often unevenly charged, I’d suggest a big diode on each cell and perhaps individual current limiters. Individual current limiters could also be used to regulate the current to the weld.

  15. Jack Driscoll

    Hi, I did some preliminary research into modular inverter designs and found some pretty informative documents. Texas A&M has a document describing a modular 10kW inverter designed for running off 48V provided by a fuel cell, complete with schematics and lots of EE details available . The providing an overview of a design they evaluated for a modular inverter for PV.

  16. Marcin

    Jack, this is exciting. The paper you linked to indicates $500 cost for a commercially-produced, 10 kW inverter. The paper provides good insight on the power electronics of such a system – including the component choice that allows for controlling costs.

    What indication of scalability/stackability did you find in the paper?

  17. […] Our infrastructure for flexible fabrication along the lines of the Open Source Fab Lab, RepLab, is evolving nicely. We reported recently on Prototype I the heavy duty, open source, drill press, and here we are reporting on Prototype I deployment of our 150 ton hole puncher. Both of these are critical to fabrication ergonomics optimization for resilient communities in general, and, in particular – for Factor e Farm’s present fabrication of The Liberator open source CEB press and the LifeTrac open source tractor. For comparison, see earlier notes about our off-grid flex fab facility in a blog post from 2 years ago. […]

  18. seema

    In the long run, that might be a way to go, make the welder without the transformer? Don’t really know a lot about welders only that they use a transformer to produce high currents. We already got that in the batteries!

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