4 ms·

I've recently become enamored with micro-hydro generation, having seen ways in which it can be totally non-destructive to local wildlife and/or fish going throu

I've recently become enamored with micro-hydro generation, having seen ways in which it can be totally non-destructive to local wildlife and/or fish going through the generator, and while I completely agree with everything you've said regarding nuclear vs micro-anything, for personal power generation on a farmstead, nuclear is pretty inaccessible. On the other hand, this guy's[1] manufactured a micro-hydro 2km drop generator capable of producing 5-12kWh per day for ~$50 in parts (turbine 3D printed). That's of course limited to drop power (meaning you have a high body of water and a low body of water and generate power, like a dam, by capturing energy from passing the falling water between them through a turbine) but for relatively level bodies of running water (read: creeks, streams, etc) a small, non-destructive weir dam can capture 100kWh per day from a single diverted turbine if conditions are good.[2] Of course, conditions aren't always, and not everywhere has access to any immediate water supply from which to generate power, but it seems to me that for those places that do, capturing their own power via micro-hydro frees up other generated power for the folks that don't -- but that might be a naive view. [1] - https://www.youtube.com/watch?v=1KyL1-0A0Gw&t=2s https://www.youtube.com/watch?v=1KyL1-0A0Gw&t=2s [2] - https://www.youtube.com/watch?v=61lZn1sUkzE&list=PLtTypVpmDd-vkT9bJQkXw4I1t0e_4jMYA https://www.youtube.com/watch?v=61lZn1sUkzE&list=PLtTypVpmDd...

steeve 7y ago
Yes, this is exactly what a dam is (pumping or releasing, or using rain). Hydo is very cool, and very green. Some things to remember, however: - need to drown whole valleys (very high impact on local wildlife) - energy density is not that good (i don't have the numbers but the volumes of water moved are huge, hence dams) - very rapid piloting and low maintenance, so nice to absorb spikes
- ch4s3 7y ago
  > Hydo is very cool, and very green. Well, maybe. I think this depends on what you mean by "green". If you mean low on CO2 emissions, then sure, but we need to consider habitat loss, methane emissions from decomposition, and the possibility of triggering earthquakes. Hydro is also quite expensive to build, and often requires seizing land through processes like Eminent Domain (in the US).
  - steeve 7y ago
    You are right, I was meaning green in the sense of gCO2eq/kWh.
- bmelton 7y ago
  Hydro may require drowning valleys, but micro-hydro with a weir utilizes existing waterways with minimal impact. As to energy density, there's no fixing that, but for most people, density is far less a concern than 'enough' -- solar isn't a viable solution for my current household because it would require clearing enough trees that it feels counterproductive. So, I can go with solar, but I couldn't be self-sustaining on solar. For most people, that's not a real concern. If you can capture enough solar power during the day to offset your energy bill to zero or near zero, that's good enough, but my concerns are a little more esoteric. That said, for either method, density hasn't really played a factor beyond local storage into battery banks - which is normal enough, but a very different concern.
- hinkley 7y ago
  I've heard it argued that depending on the kind and quantity of vegetation in the valley being flooded, the net methane release from so much rotting plant matter may upend the whole carbon balance of the project. That is not to say that all dams do this, but that consideration is necessary and may require modifying or rejecting certain proposals.
westmeal 7y ago
I've looked into this and in the states you have to go through rigorous wildlife committee approvals, indian reservation approvals (?), have surveys done, blah blah blah. In the end if you do this on your own land you still have to sell excess power back to the grid. Kind of sucks because whether you like it or not you have to work with energy companies and the government.
ferongr 7y ago
That will not produce anywhere close to the claimed power. 50-100W output is more likely, as under load the turbine would slow down reducing output voltage. Measuring no load voltage and claiming some output power based on that is bogus.

steeve 7y ago

Yes, this is exactly what a dam is (pumping or releasing, or using rain). Hydo is very cool, and very green. Some things to remember, however: - need to drown whole valleys (very high impact on local wildlife) - energy density is not that good (i don't have the numbers but the volumes of water moved are huge, hence dams) - very rapid piloting and low maintenance, so nice to absorb spikes

ch4s3 7y ago
> Hydo is very cool, and very green. Well, maybe. I think this depends on what you mean by "green". If you mean low on CO2 emissions, then sure, but we need to consider habitat loss, methane emissions from decomposition, and the possibility of triggering earthquakes. Hydro is also quite expensive to build, and often requires seizing land through processes like Eminent Domain (in the US).
- steeve 7y ago
  You are right, I was meaning green in the sense of gCO2eq/kWh.
bmelton 7y ago
Hydro may require drowning valleys, but micro-hydro with a weir utilizes existing waterways with minimal impact. As to energy density, there's no fixing that, but for most people, density is far less a concern than 'enough' -- solar isn't a viable solution for my current household because it would require clearing enough trees that it feels counterproductive. So, I can go with solar, but I couldn't be self-sustaining on solar. For most people, that's not a real concern. If you can capture enough solar power during the day to offset your energy bill to zero or near zero, that's good enough, but my concerns are a little more esoteric. That said, for either method, density hasn't really played a factor beyond local storage into battery banks - which is normal enough, but a very different concern.
hinkley 7y ago
I've heard it argued that depending on the kind and quantity of vegetation in the valley being flooded, the net methane release from so much rotting plant matter may upend the whole carbon balance of the project. That is not to say that all dams do this, but that consideration is necessary and may require modifying or rejecting certain proposals.

westmeal 7y ago

I've looked into this and in the states you have to go through rigorous wildlife committee approvals, indian reservation approvals (?), have surveys done, blah blah blah. In the end if you do this on your own land you still have to sell excess power back to the grid. Kind of sucks because whether you like it or not you have to work with energy companies and the government.

ferongr 7y ago

That will not produce anywhere close to the claimed power. 50-100W output is more likely, as under load the turbine would slow down reducing output voltage. Measuring no load voltage and claiming some output power based on that is bogus.