# Thought experiement low tech heat generator **URL:** \ **Category:** In My Humble Opinion\ **Created:** [February 7, 2018, 2:41pm UTC](https://boards.straightdope.com/t/thought-experiement-low-tech-heat-generator/808361 "2018-02-07T14:41:22Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![HoneyBadgerDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/honeybadgerdc/32/1033_2.png) [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)\ **Post date:** [February 7, 2018, 2:41pm UTC](https://boards.straightdope.com/t/thought-experiement-low-tech-heat-generator/808361/1 "2018-02-07T14:41:22Z")
Suppose you wanted to create a low tech heat generator using rising solar heated air. You decided to cover a 4 acre plot of desert land with some kind of plastic or glass that you determined would best trap heat. The cover was sloped upwards channeling all the rising air through a turbine of some kind. What kind of controls would you need to maximize efficiency? Variable inlet holes for fresh air? Would something like this be comparable to modern solar panels in efficiency even if not as compact or practical? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [February 7, 2018, 2:50pm UTC](https://boards.straightdope.com/t/thought-experiement-low-tech-heat-generator/808361/2 "2018-02-07T14:50:14Z")
Such devices have been proposed (and even constructed) in the past. > **[Solar updraft tower](https://en.wikipedia.org/wiki/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 tower by the chimney effect. This airflow drives wind turbines, placed in the chimney updraft or around the chimney base, to produce electricity. > As of m... ---
**Author:** ![HoneyBadgerDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/honeybadgerdc/32/1033_2.png) [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)\ **Post date:** [February 7, 2018, 3:44pm UTC](https://boards.straightdope.com/t/thought-experiement-low-tech-heat-generator/808361/3 "2018-02-07T15:44:57Z")
> [@beowulff](#): > > Such devices have been proposed (and even constructed) in the past. > [Solar updraft tower - Wikipedia](https://en.wikipedia.org/wiki/Solar_updraft_tower) That was a good article, it seems like the perfect type of project for a few mechanically inclined types to set up on a small scale and then start refining for better efficiency and outputs. The height of those chimneys kind of blew me away. That alone would make it not feasible for the DYI types. ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [February 7, 2018, 5:57pm UTC](https://boards.straightdope.com/t/thought-experiement-low-tech-heat-generator/808361/4 "2018-02-07T17:57:48Z")
There is a more basic device simply for ventilation/passive cooling, called a solar chimney. It doesn’t generate electricity, but it moves air without electricity. A simple solar chimney just uses solar heating to move the air. This can be combined with use of Bernoulli effect to take advantage of breezes. It can be combined with geothermal cooling as well. > **[Solar chimney](https://en.wikipedia.org/wiki/Solar_chimney)** > > A solar chimney – often referred to as a thermal chimney – is a way of improving the natural ventilation of buildings by using convection of air heated by passive solar energy. A simple description of a solar chimney is that of a vertical shaft utilizing solar energy to enhance the natural stack ventilation through a building. > The solar chimney has been in use for centuries, particularly in the Middle East and Near East by the Persians, as well as in Europe by the Romans. > In its simplest form... [https://sustainabilityworkshop.autodesk.com/buildings/stack-ventilation-and-bernoullis-principle](https://sustainabilityworkshop.autodesk.com/buildings/stack-ventilation-and-bernoullis-principle)