[Varen]

this will be a spot where i'll drop bits of design work and ideas! ill update it periodically as need be

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this will be a spot where i'll drop bits of design work and ideas! ill update it periodically as need be

alright, for my current noodling ive been trying to think of ways to make a solar updraft tower ( https://en.wikipedia.org/wiki/Solar_updraft_tower ) more useful by reducing/removing the exterior collector envelope

the big barrier to these things is that they cost a ton of money to setup initially due to the land space demands and collector engineering. once theyre setup though, theyre extremely low maintenance and pretty reliable in respect to energy generation during the day (they dont work without sunlight)

there have been others who have explored options, and one of them that i do have is a solar pond approach, however im going to demo out how a geo updraft tower could work instead by just coping out my notes here so you can seem my process:
Solar updraft tower
The solar updraft tower (SUT) is a design concept for a renewable-energy power plant for generating electricity from low-temperature solar heat. Sunshine heats the air beneath a very wide greenhouse-like roofed collector structure surrounding the central base of a very tall chimney tower. The resulting convection causes a hot air updraft in the ...
Solar updraft tower
solar thermal stores hot water as added heat source in insulated tanks/thermal reservoirs during the day (can also integrate solar ponds)

heat transfer to the air via heat exchanges and piping systems - minimum air temp difference (delta T ΔT) and velocity (~3m/s) needed to sustain airflow and turbine operation in tower

assuming stable geothermal temps of ~25 C and solar thermal ranges of 50-90C depending on radiance:
pass air through heat exchanger and piping system where it absorbs heat from the hot water and the geothermal heat of the earth

efficiency depends on surface area of heat exchangers and pipes. air velocity and flow rate also impact this - too fast reduces transfer, too slow reduces airflow. thermal conductivity of all materials must be considered

you can get 24/7 operations depending on thermal storage. can reach ~10 m/s

core assumptions:

ambient temperature T ambient = 15C = 288K T ambient = 15C = 288K
heated air temperature T heated =40C =313K T heated = 40C = 313K
temperature difference ΔT =25K ΔT = 25K (achievable with geothermal + solar thermal heating)

so the calculation is 100 square root of 2 x 9.81 x 100 x 25/288 = square root of velocity (m/s)
the above would equal 170.8 or ~13 m/s at 100 meters tall


even with a 100 m tower, the theoretical air velocity can reach ~13 m/s, well above the minimum practical velocity (~3 m/s) needed for turbine operation
increasing tower height to 150 m or 200 m further boosts velocity to 16 m/s and 18.5 m/s, respectively, which can improve power output and efficiency
these velocities are theoretical maxima, ignoring friction and turbulence losses, which in practice will reduce velocity by roughly 20–40%, depending on tower design and air path
taller towers (150–200 m) increase velocity and power potential but raise structural and material costs

theoretical maximum | 60-80% theoretical
100: 13.07 (8-10)
150: 16.00 (10-13) [seems ideal mix]
200: 18.48 (11-15)

diameter is 40 | 50 | 60
so:
pie x 20^2 = 1256
pie x 25^2 = 1963
pie x 30^2 = 2827

P air=21×1.2×A×v3=0.6×A×v3
0.6×1256×9.153=0.6×1256×766=577,000 W

aka P air=0.6×A×v3 (W)
P electric=n×P air=0.4×P air

so:
height | inflow | output | total power
100 577,000 230,800 231 kW

Tower Height (m)Estimated Electrical Power Output (kW)
100 = ~230 kW
150 = ~660 kW
200 = ~1,470 kW

rough estimates, so they arent perfect. seems the 150 meter tower is the ideal middle ground at over 500 kw. the conclusion is geothermal + solar thermal heating approach aiming for a 25C temperature difference can support these power levels. that makes the core structure viable i think

we'd need to figure out the lowest possible energy draws in the actual physical structure though

wind turbines at the small scale achieve this all on their own. so i guess the question is how to integrate these things in a useful way..
im pulling from both these concepts while tweaking things
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[color=oklab(0.298112 0.00109589 -0.00903481)][url=https://cdn.discordapp.com/attachments/1459315387140407368/1461049630807818484/Screenshot_2026-01-09_at_16-42-21_Hybrid_solar_chimneys_A_comprehensive_review_-_ScienceDirect.png?ex=69765300&is=69750180&hm=27eec5107d3f8e47a7f021b41409fff4d66aec3f48bfc80258f6afaf9c00b5ca&][/url][/color]

and this was proof of concept done by others that shows how you can integrate it with geothermal power stations

however, for my purposes, im using 50-100 meter deep holes in the earth drilled in sufficient areas (like you would for a geothermal home heating system) to get the thermal heat from the earth mixed with the hot water from the solar thermal system

all in all, the notion seems to theoretically work on paper, but whether that means anything is up in the air. cant exactly go drilling holes in the ground

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this will be a spot where i'll drop bits of design work and ideas! ill update it periodically as need be

another thing ive been dabbling with is trying to find ways to solve the energy storage problem. theres a lot of the obvious takes - sand, salt, etc. i wanted something a bit less complex and more efficient in terms of space, so i thought "why not put the water tank inside the home?" im in favor of basically getting rid of SFH in favor of comfortable, well designed complexes. in that sense, the center of the complex becomes hakka-like, where its more of a community space. 

anyways, specifically i was thinking that if you used a 10 meter tall tank and then a thermosiphon, you could then couple it with solar thermal heating to warm the water at the top of the tank and cycle the water through a contained system. water comes out the hot end and is used for district heating etc and to spin vortex turbines to reclaim the power at night. during the day, excess solar heat helps move the water back up the tank. 

water is an exceptionally good way to store power like this, and merely moving it up and down an elevation produces enormous amounts of power. this systems a bit simpler and doesnt try to scale to something like a hydro dam. instead, it tries to use each individual building to essentially create a dams worth of water across a village/city/whatever. if each building houses a sufficiently sized tank, then in effect, the entire city becomes the gravity battery.

like everything i design, this is based on organic processes - think of it like being the blood pumping through the body. in this case, the water cycle is the literal energy stream powering the city and all the things within it. this directly ties people to it, creating a symbiotic relationship, which i hope will psychologically result in a fostering of more engagement->empathy->collective concern.

this isnt just fantasy either (even though i prefer a certain aesthetic~), its real: https://www.reddit.com/r/solarpunk/comme...?context=1

and it works! by utilizing closed energy systems as much as possible, you can transform not just how a city functions but how *people* relate within a complex meta-system.