retired engineer, former sailor, off grid, gamer, in Puerto Rico. Moderating a little bit.

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  • 18 Comments
Joined 1 year ago
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Cake day: June 10th, 2023

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  • not Chinese, but I cook a lot with a wok. I also have a single induction cooktop and surprisingly, the wok has enough iron to work with it while some old cheap conventional cookware did not. However, wok cooking needs to be hot all over the wok and not just in that little point where the wok is close enough to the induction coil.

    I have a conventional propane stove which I need to keep, because here in Puerto Rico the power system is quite unreliable (especially during a bad hurricane year). But the conventional stove burners are not really hot enough. With a 1/16 - inch drill bit I could increase one of the burners capacity substantially. I painted the stove knob red so people have some warning when they light that burner! It burns more gas, but wok cooking is really fast, so in the long run it is probably more efficient than lots of other cooking approaches.

    I would definitely consider a wok-shaped induction heater. Induction heating is quite remarkable.


  • Have you tried your hand at biochar? I know composting the chips for mulch is high value in a farm operation, but a few tons of biochar can work like a permanent upgrade - improving the soil permanently with one addition - though ongoing permaculture operation continues. I am about to make a biochar cooker out of two steel barrels - inner fuel chamber and outer draft shell. It would probably be more effective with wood scraps than chips though - some air passages through the fuel.

    To test it out for myself, I made a miniature version documented at https://github.com/jcadej/TLUD-biochar-reactor (uses a gallon paint can for the fuel chamber. You could test it small and see how it does with wood chips. When I make my bigger version, I will add it to the github project. My rough idea is to cut one barrel down the side and squeeze it smaller and bolt it so it fits inside the other.



  • Swimming pools are normally constructed empty. They were withstanding surrounding soil before they were filled, and concrete strength increases with age (for about 90 days, typically). On the other hand, a sunken structure like a pool that is roofed over, becomes a “confined space”. Unlike a typical structure, heavier-than-air gases cannot escape from the pool. Such gases could originate from the drain system or flow from leakage outside the pool area. For examples, leaking propane or various gases from sewer lines in the vicinity. A sunken greenhouse would almost certainly be a building code violation for that reason. If you build it, ventilate it by means both active and passive and do not enter if you can’t verify that ventilation is working.




  • Declining birth rate is not a problem that requires fixing, it is a mercifully wise collective decision by intelligent creatures who’ve become educated and aware enough of their place in the biosphere to recognize the destructive effects of their own overpopulation. The idea that declining birth rate is decidedly NOT economic - lower birth rate does not arise among the poor and uneducated in the world.

    There is no problem in today’s world that would be mitigated by increasing birth rate. I live in a region where there is a burgeoning elderly population and sometimes people say - we need more young people in this economy! But that does not mean that having more babies here is any help: by the time they are adults, the wave of excess elderly people will be gone. Economic crises are far more immediate than generational solutions - if a region lacks workers, economic forces are more effective to relocate workers than biologically growing new ones. Of course, governments often fail to anticipate needs and adjust migration policies in a timely way, or housing policies, or other such issues that create barriers contrary to the economic forces.










  • Engineers describe heat transfer with a “heat transfer coefficient”, and the rate of heat transfer is this coefficient multiplied by the temperature difference. So you can calculate what the heat transfer coefficient must be by measuring room air temperature initially, water temperature initially, and then running your system for a little while and measuring the room temperature again. The smaller room area you can cool the more accurate this will be. You will need to look up heat capacity and density of air (easy to find), and the temperature change of the air with the volume of the room and the temperature change will together give you an amount of heat you removed from the air to the water. Simple!