Nuclear power appears to be a powerful way to make steam that spins a turbine. Same with geothermal, wind, & hydro. Maybe not solar? Isn’t energy lost in the multiple energy conversions (heat, water state, kinetic)? Is it theoretically possible to have a power source that more directly moves electrons through a circuit? If solar is the only one that can, it’s limited in efficiency and where it can be used. What about power generation undersea or on Ganymede or something?
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Electricity is generated by the movement of electrons through a circuit. You seem to understand that part. That motion of electrons can be cause by several different methods. Solar uses photons of light to push electrons across a semiconductor and generate a voltage. Fuel cells use hydrogen and a catalytic material to strip an electron off and generate a voltage. Spinning rotors use mechanical motion to cause changing magnetic fields to generate voltage. Thermocouples use heat differentials across different materials to generate voltage.
Thing is, all of these methods include losses. Transferring one type of energy to another always will. It just so happens that spinning rotors have some of the best efficiencies, so they’re used most often.
We have the two types of energy potential and kinetic. Potential is to storage as kinetic is to work. All energy is in one of these forms. Now in simple answer yes we can make power without steam turning a turbine. Look at the ICB (internal combustion engine) powering your car! It uses controlled explosions, not steam, to spin something.
But when it boils down you are right most of our electricity is the result of some convoluted turbine rotation. You are also right that there is plenty of inefficiency in these systems. [The average coal-fired power plant in the United States operates near 33% efficiency.](https://en.m.wikipedia.org/wiki/Fossil_fuel_power_station) I’m no expert but feel free to ask any follow ups.
Firstly, Hydro Nuclear Geothermal and Wind energy are not comparable. Same with Solar. Each option has a pro and con varying from expense of building plant, availability of usable land, cost of maintenance, and environmental impact.
Nuclear is the most efficient way of producing power by large. Others don’t even compare.
For energy production, technically energy has to be sourced from somewhere. Heat from sun, or earth core. Wind cycle driven by solar energy, earth’s gravity. These are usually sustainable forms. Nuclear power is arguably limited and only issue with it is waste disposal.
Only one way one form of energy is converted is using the Electro magnetic waves/radiation exciting electrons and hence transfer of energy. The Solar panel is direct excitation, and other forms employ the Dynamo.
There really isn’t another option known yet to excite the electrons in a solar panel or the Dynamo. Or even options other than exciting an electron.
Turbines are used in the Brayton cycle. Which is by far the most practical heat engine cycle at power plant scales. There are other types of heat engines. Small backup generators (small is relative they are bigger than most cars) use reciprocating diesel engines. There are more exotic engine types like the Sterling and Ericsson engines that are used in very niche use cases. Then there are things like radioisotope thermoelectric generators which use the Seebeck effect of heating dissimilar materials together. You can also get really exotic with things like magneto hydrodynamic generators. Those are just experiments as far as I know though.
You have more effects like Solar, but they are usually less efficient than spinning turbines. For example the Piezoelectric effect turns physical tension directly to electric voltage. Or the Peltier effekt turns heat to electricity. Oh and you can do it chemically in batteries and fuel cells, but then you need a constant supply of your chemicals from somewhere. Oh and nuclear batteries (RTG radioisotope thermoelectric generator) also have no moving parts.
These all work by using some outside force to kick an electron over a barrier and force it to take the long way back through your circuit
One big advantage of spinning turbines is that they can smooth out changes in energy flux before it reaches the grid. They also have limited ability to continue generating power if the reactor has to be shut down quickly (RIP Valery Legasov). They’re also just incredibly efficient in general, so conversion losses aren’t that big a deal.
In large scale steam turbines are a great way to convert thermal energy into electric power. In smaller scales we also use reciprocating engines (diesel/gas generators) even in not so small scales (think boats and trains). There is also solar power as you mentioned. As someone else mentioned there is also the use of thermocouples in RTGs and other low power high reliability generators. There are also turbines that use other gases instead of steam (CO2, Nitrogen, ammonia, etc) and then the regular gas turbines (like helicopter engines) that use air and burn fuel as a heat source. There is a lot of variety out there but very large scale it almost always turns out to be a steam turbine.
The shortest answer is that we have spent a LOT more time working with steam than anything else
We started with steam power engines a long time ago (1700s is when it really took off) and over time we got really, REALLY ridiculously good at making steam spin turbines at both small and large scale.
Then when electricity comes around we learned that AC current can very easily be generated from any constant motion, just get a magnet and a conductor and boom, you have current. So we could take a century of progress with steam engines and advance these concepts to make things like the hoover dam. A happy coincidence.
There are other methods being developed but they are still less efficient, for a variety of reasons. For example Solar Power has a maximum theoretical efficiency near %70 for realistic use cases but the best we have developed so far is around %45 efficiency while industrial power generation from steam turbines is between %65-%90
For power generation outside of earth where weight/ease of maintenance/reliability matters, then if solar works (Mars is about as far from the sun where it works well) then that’s the solution. Further away then an RTG (radioisotope thermal generator) then is usually the choice. Heat is generated by radioactive decay (not like a nuclear fusion reactor) and the heat transformed to electricity by using thermocouples. If you don’t need power for a long time (space shuttle, Apollo missions) then you can use a fuel cell where you combine oxygen and hydrogen to make electricity and pure water. They also are relatively low maintenance and very reliable (when your fuel tanks aren’t exploding that is). If you need A LOT of power then there is research on using a small fission nuclear plant and in that case generally a closed cycle using CO2 or some other easy to handle gas is used. Look up supercritical CO2 cycles. The gas is cooled (like the water condensers in a steam plant), compressed (like in a regular airplane turbine), heated waste heat from the turbines exit used to further heat it (for efficiency to recover heat and reduce the amount of cooling needed), heated even more using the nuclear plant heat, then it is expanded through a turbine to make electric power and drive the compressor, finally the hot CO2 goes through the heat exchanger to heat up the gas coming out of the compressor and cool down some, then it goes to the cooler I mentioned at the beginning and the whole cycle starts again. It could be done with water like on earth but the maintenance and weight doesn’t make up for the gain in efficiency.
Steam turbines are the most common heat engine and we have lots of experience with them so have got the efficiency about as high as it will go. There are alternatives though that could be more efficient, supercritical co2 turbines could be significantly more efficient than steam (supposedly 50% more). There are test plants being built at the moment.
Certain types of fusion power could allow us to use a direct conversion method getting electricity directly from a charged particles kinetic energy at a higher efficiency than any heat engine. This would probably be in tandem with a heat engine though.
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