# Tag Info

### Why don't hydroelectric plants use cascades of turbines instead of single turbines?

The exhaust gasses are compressible fluids, whereas liquid water is not. Here's an animation of how a gas turbine works: https://www.youtube.com/watch?v=gqNtoy2x5bU At the combustion stage, the gas ...
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### Why is hydro-electric power still scarce in some places?

Because most of the water is at the lowest point is can be, the ocean. Second issue is that you need quite a bit of vertical drop for water power to be a viable power source. There are DIY hydro ...
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### Why don't we just build a giant wind turbine?

Not everything scales linearly. In particular, the cross-sectional area of supports required scales faster than height of a structure, all else held constant. This explains why ants have tiny thin ...
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### What are the disadvantages of concentrated solar thermal power?

There are no silver bullets when it comes to decarbonising the grid. That's good news: it means you can stop looking for one, and accept that every form of generation has its pros and cons. ...
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### Why is hydro-electric power still scarce in some places?

There are two issues, harnessing and market. You need both to be viable. A market, makes most of the 70% of the land mass covered by water unusable, because even if you could harness the power, it ...
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### What are the disadvantages of concentrated solar thermal power?

Everything we do as humans has consequences of some sort. Although not a huge downside (in my opinion), critics have often cited the plant's supposed adverse effects on wildlife: Wikipedia Article: ...
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### What are the disadvantages of concentrated solar thermal power?

In the UK, the sun does not shine every day. We also need the most power in winter when the sun shines the least. Therefore every solar power station must be backed up by anther power station that ...
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### Relationship between wind velocity, turbine rotor diameter, and power output

It's not a simple relationship. First let's deal with the kinetic energy of the wind passing through the rotor. The mass of air passing through it in one second, $m$, is equal to the the density of ...
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### How to correctly size the blades for a small educational wind turbine?

As it happens, I just recently went through that calculation myself for a different site. Given the following facts from a quick web search, it isn't difficult to work out the numbers. The maximum ...
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### Why is hydro-electric power still scarce in some places?

Rivers in a flat landscape are often unsuitable because you need a height difference to make the turbine work. Let's say a 1 meter height difference is required. There are many areas where the river's ...
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### Are abandoned nuclear smoke stacks strong enough to be filled with water (for pumped storage)?

Those aren't "smoke" stacks but cooling towers designed to let hot air rise and expand optimally. These things are typically 200 m high. Static pressure of 200 m of water is pretty high. They were ...
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### Why don't hydroelectric plants use cascades of turbines instead of single turbines?

What's missing so far is an explanation why you can't expand from high pressure to atmospheric in a single stage gas turbine. There are two types of gas turbines - impulse and reaction turbines. Both ...
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### What are the disadvantages of concentrated solar thermal power?

Concentrated solar power plants are best located in isolated areas that receive a lot of sunshine all year round, which basically means arid or semi-arid regions. Most of these regions don't have ...
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### What is the exact definition of renewable energy

overview: Renewable energy is one for which the input energy is renewed on human timescales. Remember, energy is always conserved. It doesn't come from nowhere. Pretty much all the energy we use on ...
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