Let's dialogue about efficiency. In engineering parlance that's the Greek letter Nu and most times the similar looking eta, is often used as the standard symbol that represents the calculation of efficiency which is just the ratio of energy out divided by the energy you put in... eta is something suspiciously absent in almost every alternative energy propaganda blurb that you have probably been exposed to. You have probably never heard of energy conversion efficiency.
Efficiency has been the engineering justification to pick a certain blend of fuel, a compression ratio in an automobile engine or which jet engine has the best turbine/compressor section and wins the total life cycle cost debate and gets selected for the next re-power or new jet airplane. Nu/eta is king, but you've never heard of it. Why is that?
If indeed eta is new to you... well let me introduce you! Every energy conversion has a conversion efficiency. Burning coal or natural gas to turn water into steam and then blow that steam across a turbine blade which then creates electricity by turning a generator encounters an energy loss at each intermediate step, filling your cars fuel tank with gasoline and then burning that fuel in a piston engine has a different set of losses, everything has a conversion loss of a fuels chemical energy owing to our methods of converting these fuels into mechanical work.
For jets and power plants turbine engine efficiency... 20 to 40%
Hmmm, so if we have a turbine jet engine making power or flying around it's like 30% efficient? Which means that 70% of the energy pumped out of the ground, refined and sent to the airport ends up being waste heat blown out the back of the turbine? Yep, a very inefficient use of fuel. Lots of thrust - can make planes fly, but really burns a lot of fuel (energy) inefficiently. Energy density allows us to fly. In fact before we figured out how to combust the large amount of energy heavier than air flight was assumed to be impossible.
Tell me more, what about cars and those bad 'ole piston engines...
Blah blah blah 40 to maybe 45% efficient, so half of the btus (energy) in each tank are blown out the tailpipe or simply radiated as waste heat from surfaces along the way? Yep, but actually MORE efficient than turbines. If it were the other way around you would see turbine engines in cars and mopeds!
Say it ain't so! What about solar panels? 30% on a great day, partly cloudy much less. Coupled with life expectancy at that performance of 15-ish years in reality. Panels don't grow on trees either. There is an energy dense mining and manufacturing energy load on the front end with almost no recycling back end owing to the plasma coatings and other metallurgical chemistries needed to increase solar panel efficiency. So it costs more to reclaim an aged very inefficient solar panel than to mine stuff for a new one in the first place - so they end up in landfills. A one way path to the landfill.
So wait a sec... oil out of the ground gives us fuel that has an energy to weigh ratio that allows planes to fly and your car to go 350 miles at a go? What about those EVs, don't they meet or exceed those nasty pollution belching gas/diesel monstrosities? Depends on where the nasty belching takes place. Take note batteries are not energy they are a very energy hungry temporary energy repository. Charged batteries are akin to a filled gas tank. But not exactly, extreme heat or cold drastically reduces their capacity, but that's another story for another day.
This is at least a two-parter. First off, replacing a gas or diesel fuel tank that (when full) weighs a couple hundred pounds with a battery pack (that when charged or dead) gives you a sort of equivalent storage of energy (not so good at minus 30F) that weighs 5 to 7 times more and is bolted to the vulnerable bottom of your entire car. You then have to carry that weight around, accelerate and brake with all that extra weight too. Enough heavier so as to wear out your tires, brake pads and rotors in half the time of an ICE vehicle. Tires don't grow in gardens either, doubling your consumption of all of these components drive a waste stream of a lot of energy and resources, but we won't chase that one in this post. Just know it's there and it's big. It takes a lot of electricity to make tires, rotors and brake pads.
Secondly, that 85 kW battery pack needs electrons from somewhere to get charged. Otherwise it is just a heavy box full of lithium, cobalt, copper wires, computer control boards and cooling circuits. That ev fueling process looks like this:
So let's start with a feedstock of something other than that bad old gasoline or diesel. Coal or natural gas power plants ultimately use fuel to boil water that then turns a turbine that spins a big generator and it's all at your nearby power plant. If you use the local utility, this is how you might go. Those electrons get sent out as power on a vey inefficient transmission line with more losses including transformer inefficiencies and phase relationships called a power factor - but lets leave that be. Let's just look at one EV. Almost 500,000 lbs of lithium got dug up by diesel powered mining equipment to make one 85 kW battery pack because the ore concentration is that low. Then an electric powered rock crusher consuming many kWs of power is used to make big rocks into little rocks and little rocks into a sort of sand that is required for separation of unwanted stuff (95% or the rock) and eventual concentration. Then enter the sulfuric acid and hydrochloric acids along with copious amounts of water manufactured, pumped and mixed via more electrons that come from somewhere (- it isn't magical, coal or natural gas turned more turbines and made more power) that extra stuff not wanted then drain eventually into a gigantic settling pond as electrically energized magnetic separators skim off the stuff for the now concentrated ore used to make batteries for your new ride. How's your green going, feeling it yet? Then we ship the ore by a train guzzling more diesel fuel to a factory that uses more electrons to convert and package that ore into its final chemistry and stuff it into those nice round, wired and packaged batteries that make up those battery packs. Let's be careful not to short out the pack or have any fires nearby - uffta not good on so many levels.
Realize what just happened. The diesel powered mining equipment consumed energy and was 45% efficient, the power needed/consumed through a common power plant came from a turbine turning a generator which kept that mine humming - maybe 35% efficient and the power transmission loss to the mine along those power lines was meh, 6%... and all of the subprocesses needed to manufacture the storage device consumed. more energy with efficiency losses. How many steps did you count? So instead of a direct fossil fuel conversion from gasoline, if we adopt the electric pathway of an ev getting charged from an alternate source like a coal fired plant (could be a natural gas plant - take your pick efficiency is the same) encounters: 13,000 BTU/lb of coal X 0.3 turbine efficiency X 0.94 transmission line efficiency X eta for many more conversion steps, which results in 3670 of those 13,000 btus actually getting into your green powered ev. And for each 85kW battery pack you see on the highway - think 500,000 lb of rock that left a big hole and a giant settling pond of toxic waste somewhere. But thankfully - not in your back yard. Don't worry about all the contaminated water because none of that acidic sludgy icky water is in your neighborhood well - lucky green virtue signaling you. Oh by the way, if you and your neighbors all recharge tonight it is just like each one of you is running a welding shop for hours and hours at night. Can your East Coast or West Coast power grid handle that extra load without brown outs? What about your new weld shop looking utility bill? Does this even make sense to you? I mean in stead of just conservation of the originating feedstock of energy replacing it with a process that consumes a huge amount of energy at a cumulative efficiency far worse than single conversion just to say it's environmentally green... Mental gymnastics and marketing Edward Bernays would blush over.
So the take away here... no free rides my friends. Energy is easy as a low density commodity, it becomes very finite when we demand the high energy density fuels that we have become dependent on to support the economics of growth in the modern world. The problem is that the high density stuff is finite and there is no easy or equivalent substitution. Sorry, that's the deal. Low density energy like the stuff to make an EV golf cart go all day - that's do-able with a small wind charger and simple battery / inverter set up. Aha, so there is a way. Much lower vehicle weight, shorter ranges and small domestic alternative power solutions could make a profound difference on the mobility life extension of our energy bounty. But realize the profound implications this has.
Converting from one energy source to another still depletes a finite energy and materials resource base. If our economic and geopolitical systems intent is to keep to an economic growth doctrine, I see a fantastic collision just ahead. This is a finite world, and the biggest lesson we as a civilization have failed to learn again and again is how to live in a sustainable way amidst finite resources. Batteries to support that vision simply store electrons that have to come from somewhere. No free lunches. Economics has to change to recognize energy as the ultimate limit to growth and so does our behavior of energy consumption. Wars and conquests to acquire someone else's resources merely deplete those resources and do not solve the ultimate problem. Living within our geophysical means.
Can we evolve?
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