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Massive Solar Updraft Towers Planned For Arizona
MikeChino writes "Australia-based EnviroMission Ltd recently announced plans to build two solar updraft towers that span hundreds of acres in La Paz County, Arizona. Solar updraft technology sounds promising enough: generate hot air with a giant greenhouse, channel the air into a chimney-like device, and let the warm wind turn a wind turbine to produce energy. The scale of the devices would be staggering — each plant would consist of a 2,400 foot chimney over a greenhouse measuring four square miles. The Southern California Public Power Authority has approved EnviroMission as a provider, although there’s still plenty of work to be done before the $750 million, 200 megawatt project can begin."
This DOES (essentially) reduce thermal energy in the atmosphere.
:)
Typically, the solar energy just heats up the ground, and also bounces around in the atmosphere and heats it up. This thing works by trapping the energy in a small area (greenhouse) and then using some of that heat to generate electricity. By the time the air is pumped out into the open atmosphere, it has less heat energy than if the thing wasn't there to begin with.
This really boils down to being just like a photovoltaic panel. Rather than the Sun wasting its energy heating up the atmosphere, we use the energy to make electricity... which we then waste by turning electricity back into heat which heats up the atmosphere.
-Bill
Back in the 70s there was a proposal to build a very tall cylinder (1 mile or so), inject water mist at the top, and let the resulting downdraft drive a turbine a ground level. Interesting idea, fairly well developed and into the engineering stage. Of course, nobody funded actually building one. The engineer who designed it couldn't overcome the skeptics, and nobody thought it would be competitive with cheap natural gas/oil-fired generators.....
What precisely do you think they're trying to do? Where do you think this thermal difference comes from exactly? Every single process that generates usable electrical power generates thermal energy. Simple thermodynamics dictates that a process must be less than 100% efficient and must create more disorder than order. So instead of converting coal and air into CO2, electrical power and heat; we're converting solar thermal energy into electrical power and waste heat. The thermal energy is already there and is going to waste otherwise.
Sigs are too short to say anything truly profound so read the above post instead.
It doesn't generate a shitload of radioactive waste, perhaps?
Most of the nuclear waste in the US is recyclable. The amount of waste produced for a given amount of power is small compared to coal, pil and other fossil fuels. Thorium reactors produce even less waste than Uranium/Plutonium reactors do and is more common as well. There is also the problem of low carnot efficiency of solar updraft towers relative to other solar thermal designs because of the relatively small thermal gradient. The larger the thermal gradient, the higher the efficiency.
Sigs are too short to say anything truly profound so read the above post instead.
Many, if not most wastewater (sewage) treatment plants in the US produce a net energy surplus, which is then returned to the grid.
You vastly underestimate them. In addition to their US and Australian projects they are also not building one in Namibia .
The Namibian project is more ambitious as it will be used also to grow food in the hot and windy conditions under their greenhouse.
Impractical. Lightning is dramatic(in large part because it wastes most of its energy in hard-to-collect light and sound); but doesn't actually contain that much energy, compared to the needs of even a modestly sized city.
The combination of "hardly enough energy to bother with, once you've averaged it out over the year" and "peak energy high and fast enough to blow a hole through anything not specifically engineered to take it" just isn't very exciting...
A giant greenhouse, designed to heat massive ammounts of air, and dump it into the cold upper atmosphere... So we have given up and are going to proactively warm the earth's atmosphere directly now?
Dumping hot air into the upper atmosphere cools the Earth. As air is circulated higher up it more readily radiates energy out into space, bypassing some fraction of the greenhouse gases of the atmosphere.
True confidence comes not from realising you are as good as your peers, but that your peers are as bad as you are.