Generating electricity -- 2?

Question

If heat is a product of running a car engine, could we use that same heat to power a small generator, thus producing voltage? Other than charging batteries, not really sure if it could be useful, unless you could somehow download power into your house when you arive home.

Answer 1

You could probably power a small turbine and if your engine is not already turbocharged you could use this extra turbine to charge your battery and power the lights etc - thus saving on alternator V-belt drive loads

Save fuel a bit - that's all.

Just needs some calculations to see if the turbine is strong enough to substitute the alternator

Answer 2

See its is not that much easier to convert heat energy to electrical energy. My question is how will you give heat as an input to the generator? If so, you will not be using a generator in your working model. You can use a thermal device which coverts heat to electricity. Refer Books for your hardware design.

Answer 3

yes and no, theoretically you could build a boiler system which would turn a turbine which would produce electricity, however there are trade offs. The biggest thing would be storing the extra electricity for use, then there is the added weight to the car which will cause it to use more fuel in order to produce the electricity, so there is a cost-benefit trade off, but otherwise it could be done.

Answer 4

In theory, yes.  Have to build a working model to find out, though.

Answer 5

Well... Thermocouples convert heat directly into electricity, but they aren't nearly efficient enough to use all of the heat coming from the engine. Power plants actually use water, which turns into steam as it cools the plant, which turns turbines, hooked up to generators, making more electricity... Once again, in theory, it's an excellent idea. Engines need to be cooled, and we generally pump liquid through them to achieve this. However, for maximum efficiency, we're going to just submerge the engine in water.

Back to the calculations. Building from your first generating electricity post, 80 percent of the energy in an engine is wasted. While we can assume that most of this is heat energy, we also need to consider the energy wasted in the sound of the engine, along with the heat wasted out the exhaust, and any vibrations of the engine, random internal friction, etc. So, we'll say 60 percent of the energy used is pure heat. That's 18,600,000 calories. Remember, one calorie is the heat required to heat 1 mL of water one degree Celsius. Assuming the water is pumped from the ground for this engine, it will be at around 12 degrees Celsius. How many liters of water can be converted into steam?  18,600,000/(88*1000) = about 200, after factoring in the extra 11.3 liters as wasted energy. How much steam (volume)? There are 18 mL of water in one mole, so 200,000/18, times 22.414 for the expansion of one mole of a liquid to one mole of a gas, which is about 249,000 liters of steam. I'm not sure of the precise calculations involving pressures, once you start working with them, the necessary temperature of the water changes. I do know, however, that steam turbines are about 60 percent efficient.

Since we know one gallon of gas can ideally produce $120 worth of energy at 8 cents per kilowatt, 60 percent of that, for the heat generated, times 60 percent of that sum, for the turbine efficiency, equals a total of 36 percent- $43.20, on just the heat itself! Of course, after you take into account the necessary pumps to induce water flow, and the extra energy required to pressurize the steam beyond one atmosphere (you'll want to go to around 10 atmospheres, or roughly 140 PSI), which divides the total output by ten, meaning about four dollars, taking into consideration even more energy loss. So... All this work to make a net profit of nine dollars per gallon of fuel burned, mechanical and heat energy combined? If you're burning six gallons of gas per hour, as my original calculations showed, that's $54 an hour. That's a bit more money than I make, I know that for sure! This might not be a bad project for an entrepreneur with the time, money, and tools needed to invest in. Good idea, Michael C! Who would have thought one could do something like this?!?

**EDIT: After finishing this, i realized you actually wanted to USE the car at the same time... oops! Oh well, that's what U-Haul trailers are for...! This idea does produce an overwhelming amount of power... an average home uses around 10-15 kilowatts per hour (with typical appliances turned on), and this system generates 112. It could easily power 8-10 homes, even being as inefficient as it is. Once again, I hope this helped! It's a relatively unrefined idea, so feel free to buff out the scratches!

~Sean