How are gas prices and inflation going to affect your diving?
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DogDiver
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No effect at all. Living in cave country Florida. I have over 40 cave systems within a 50 minute drive. No charter fees. Annual Ginnie pass is $400 state parks $4 per car per day. And most sites are free. 
The efficiency of a Carnot engine depends on the temperatures of the input and output "heat reservoirs." So yes, for a certain input and output temperature, the Carnot efficiency can be 40%. But that percentage is not fixed... it can be greater or lower.
The efficiency also has nothing to do with the debate here, i.e. how electricity is generated and how "green" electric cars are vs ICE cars.
I remember my engineering classes quite well. Because I've been teaching them for a couple decades.
Wind farms are really only economically viable if hundreds of turbines can be put up in the same area. And the regulations are tough. I'm sure there's a reason we see a lot of them in the desert area of So Cal, west of Arizona. Lot of flat, open land that isn't viable for housing, far from inhabited areas. Availability of wind is likely just one thing on a list of requirements to make a site viable for a wind farm.
This is not really true. All of the water departments here have issued drought restrictions. Many of my neighbors (and I) have removed our lawns. Lot of "natural" yards popping up in their place (mine is all decorative rock.) Our local water department has patrol cars that drive through a few times a week, looking for violators. Golf courses are typically irrigated with "reclaimed" water, i.e. treated wastewater.
The media will make a big show about the extreme case of a rich person using millions of gallons to water the landscape of their compound, but ordinary So Cal residents are dealing with the same drought and restrictions as everyone else in the state.
But but... not really comparable.
First, the engines used to create electricity can have much higher efficiency than a typical car engine. This is because they can operate at a much higher temperature (that Carnot thing again...) due to their design, than a typical ICE.
So if you want to compare using fossil fuels to generate electricity, which is then used to power an electric car, to fossil fuels used to power an ICE directly, you will find:
fossil fuel --> electricity can be as high as 80% (again, Carnot thing.)
electricity transporting ---> lose 20% (a rough estimate)
battery charging and discharging ---> lose 20% (again rough estimate)
so how much of the energy stored in the fossil fuel gets is output by the electric motors? 80% of 80% of 80% = approx 50%
If you put that same fossil fuel directly into an ICE... oh wait a second... you can't. Because it's not that simple. Your ICE requires either gasoline or diesel fuel, which requires processing, transportation and distribution of the original fossil fuel. Which means a rough estimate of the original energy available by the time the gasoline is put into the tank of your car might be around 80%.
And then the efficiency of your car engine? As you pointed out, it's not running on a Carnot cycle... so your car engine will be less efficient than the Carnot efficiency. But a Carnot cycle run with temperatures typical for an ICE (and yeah, I give my engineering students this exact scenario as part of their work) is around 40%. So let's assume a really efficient ICE and we'll use that 40% as an upper estimate.
Which means for the fossil fuel powered ICE, of the original energy stored in the fossil fuel, we would get...
80% of 40% = 32% of that as work output by the engine.
And there it is. Fossil fuel used to create electricity to power an EV... about 50% of the energy gets through. Powered an ICE using fossil fuel... about 32% gets through.
Oh but wait... this means EVs win this little battle (although the battle for energy used to build and assemble the vehicle is a separate, and far more contentious, issue) IF all of our electricity is produced with fossil fuels. That is, if the only energy sources we had available were fossil fuels, it would be much more efficient to use the fuel to generate electricity, transport that electricity and use it to charge batteries to run an EV, than it would be to put that fossil fuel directly into a traditional car with an ICE.
But currently in the US we only generate 60% of our electricity using fossil fuels. Which means if the electricity we use to charge the EV comes from a variety of sources that are representative of the entire production of the US, then that 50% becomes effectively much greater... far more than double the 32% from the ICE.
It's also worth noting that we hardly use any oil to generate electricity in the US (burning oil accounts for about 1% of electricity generation.) Burning coal and natural gas is much much more efficient than burning oil.
Why would a typical greenhouse have a high CO2 level? CO2 comes from either the respiration of animals (which typically do not live in greenhouses) or from burning stuff (which, hopefully, doesn't happen in greenhouses.)
Greenhouses are designed to help plants grow, but it has nothing to do with enhanced CO2 levels.
CO2 in the atmosphere causes a "greenhouse effect", but traditional greenhouses don't cause more CO2.
You also need to factor in the energy to make the batteries, which is very extreme. Then compare how much you get out. That results in a negative number, it cost more to make the batteries then what they save.
Plus your assuming getting the max 40 out of it, not going to happen.
Plus your assuming getting the max 40 out of it, not going to happen.
Absolutely... the big picture has to include the cost to build the car and the cost to operate. Electric cars cost a lot more to build, but are then cheaper to operate. Which is why most people are still driving cars with an ICE, and we slowly see EVs gaining market share. As with any advance in technology, it takes time to convert.
Not sure which "max 40" you're referring to, but if it was the 40% I assumed for the ICE... then yes, I agree with you. I said I was using that as an estimated upper limit. Which means I'm giving the ICE to much benefit. The real value of the ICE efficiency will be lower, which makes it even less competitive with the EV.
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