Time to go all electric?

SlamDunk

This from today's NYT re: solar panels on crop fields. They even branded the idea: "agrivoltaics".

https://www.nytimes.com/2022/06/28/business/dual-use-solar-panels-agrivoltaics-blue-wave-power.html

hot_rod

I remember articles about systems in Germany with elevated modules, crops below. It was in Sun, Wind Energy magazine back in 2008 or 09.

Same concept with wind turbines, where they farm right up to the towers.

Jamie Hall

For some types of crops and some types of farming, I would completely agree that solar panels can be combined with agriculture. I would never argue otherwise. Examples of completely compatibble uses are truck gardening (which may be very large scale) (the two examples posted so far) and animal (and chicken) free range pasturage.

Some types of farming are NOT compatible, however. Examples would be commercial hay production, wheat, feed corn, soybeans, and the like. The problem in these cases is the equipment used: it is simply too big (I might add a slightly snarky remark -- folks who have never encountered the equipment, which is about 95% of the population tend to be rather taken aback on their first encounter. Even my hay wagons -- a very small operation! -- are 14 feet tall. The balers are 12 feet wide, and an entire baling train will be around 50 feet long. In the midwest wheat and corn production, the machines are a good deal bigger).

Wind turbines are another matter. It is quite true one can farm right up to them, and folks do. The objections there revolve around aesthetics (you can see them for miles, literally, and they are noisy) and wildlife (forget birds if you have them around). For obvious reasons, the people they provide power for want them out of sight in the boodocks somewhere.

SlamDunk

I have doubts that wind turbines kill a lot of birds. I believe more birds are killed by cats, cars, jet engines and clean windows. I came upon a wind turbine farm in Holland. There must have been thirty of them in a synchronized spin. It was beautiful, mesmerizing. I was a quarter mile away (maybe more-they are huge)and I heard nothing from the turbines-but I'll bet people near the turbines heard noise from the highway I pulled over on. Beauty is subjective. I'd have one in my backyard.

SlamDunk

Some airliners have a RAT (Ram air turbine) that drops out the belly of an aircraft if it lost both engine and all electric hydraulic pumps. The turbine produces hydraulic power in an emergency. I wonder if a couple wind turbines mounted to an EV would be able to recharge it's battery while driving.

JakeCK

SlamDunk said:

Some airliners have a RAT (Ram air turbine) that drops out the belly of an aircraft if it lost both engine and all electric hydraulic pumps. The turbine produces hydraulic power in an emergency. I wonder if a couple wind turbines mounted to an EV would be able to recharge it's battery while driving.

That would be a violation of the laws of conservation. I think the phrase "there is no free lunch" is very applicable here. On the jet it sounds like they are just trying to provide emergency power to critical controls after a lose of engine power, and are sacrificing some airspeed to get it. With a vehicle the only time it would work is during braking. Also there is a bit of a difference between the velocities of an airliner doing 500mph at 30k ft vs a car doing 65 on an offramp.

And any kind of turbine that can recover a non trivial amount of energy from a car is basically going to stop it in it's tracks. The drivers head is likely to smack the steering wheel. Some years back I remember reading about some exotic sports cars that used air brakes. Essentially air flaps that came up to assist in braking. Most drivers would report that they could be far too aggressive.

JakeCK

Jamie Hall said:

The problem in these cases is the equipment used: it is simply too big (I might add a slightly snarky remark -- folks who have never encountered the equipment, which is about 95% of the population tend to be rather taken aback on their first encounter. Even my hay wagons -- a very small operation! -- are 14 feet tall. The balers are 12 feet wide, and an entire baling train will be around 50 feet long. In the midwest wheat and corn production, the machines are a good deal bigger). 

I grew up out in the sticks. Every fall when the combines were out it was a nightmare trying to drive. They're slow and take up the whole road. :P And the farmer that would work the fields behind my home would actually park the equipment right at the edge of our lot right behind one of our out buildings. They would be visible from my bedroom window. It was a sight to look out the window and see that.

https://youtu.be/ePjFAZKWKVo

fentonc

It is actually possible to generate wind power on a moving vehicle without violating conservation of energy, just not if the only air movement is derived from the relative movement of the car. Imagine a 100MPH wind moving in the direction of a car moving 60 MPH for instance. You just need careful cooperation from the wind

fentonc

An example of a wind powered car moving faster than the wind: https://phys.org/news/2010-06-wind-powered-car-faster.html

Jamie Hall

Anyone who has sailed a sail boat knows -- or should know -- that on any point of sailing other than straight down wind it is common for the boat to move faster than the wind.

Dave Carpentier

SlamDunk said:

I was a quarter mile away (maybe more-they are huge)and I heard nothing from the turbines-but I'll bet people near the turbines heard noise from the highway I pulled over on.

We drove right up to one at a somewhat remote wind farm, stood under it etc. The design is for 2.3Mw each (43 of them), but I dunno how the wind speed that day compared to design/max output. We had to stop talking to hear the blades go by above us. The blade circle is 300ft, so I wouldnt stand under them in a stiff wind without a bit of fear lol.

jumper

Jamie Hall said:

Anyone who has sailed a sail boat knows -- or should know -- that on any point of sailing other than straight down wind it is common for the boat to move faster than the wind.

ice boats go so fast that people hurt themselves

KC_Jones

jumper said:

Jamie Hall said:

Anyone who has sailed a sail boat knows -- or should know -- that on any point of sailing other than straight down wind it is common for the boat to move faster than the wind.

ice boats go so fast that people hurt themselves

Whatever happened to @icesailor ?

Jamie Hall

Haven't seen him for years. I miss him.

ratio

KC_Jones said:

Whatever happened to @icesailor ?

He rage-quit over some forum issues he couldn't get resolved.

ChrisJ

ratio said:

Whatever happened to @icesailor ?

He rage-quit over some forum issues he couldn't get resolved.

Where's @Fred

MaxMercy

SlamDunk said:

I wonder if a couple wind turbines mounted to an EV would be able to recharge it's battery while driving.

You can't believe how many times I've been asked why EVs don't have on board alternators to keep the batteries topped off like regular cars do.

My answer is that alternators consume more energy than they produce. In some folks, the light goes off. In others, they argue with me.

Jamie Hall

It's that nasty Second Law of Thermodynamics... get you every time, @SlamDunk

JakeCK

Was going over my utility bills and looked at the past year usage. You can easily see the yty reductions from the work on the house. I have an old excel spreadsheet that has all of the gas and electric bills going back to when I bought the house. I need to find the time to enter all of the past few years into it and really see the difference.

I would really like to eliminate the gas bill entirely. $39 for 2 ccf of gas.

SlamDunk

Jamie Hall said:

It's that nasty Second Law of Thermodynamics... get you every time, @SlamDunk

Yeah, but noone would drive their car without an alternator, right? You will always have relative wind when you drive, what if it also got you another thirty to sixty minutes on a long trip? There are electrostatic wind generators, with no moving parts, that could be aesthetically and aerodynamically installed somewher on an EV.

The laws of Gravity didn't stop the Wright Brothers, @Jamie Hall 😄

ratio

Jamie Hall

Joking. I hope. But it's still sorry, nope. It takes a certain amount of energy to move a car X miles. If you add a turbine driving an alternator, that turbine will take additional energy to drive the alternator. Some, but not all of it, will go into the battery. But in the meantime you have taken more out of the battery than the turbine and alternator can put in, to keep the car moving with the added drag of the alternator.

Same principle with regenerative braking -- yes you can store energy in the battery going down hill, but it is less energy than it took to get to the top of the hill in the first place.

And to generalize -- it is thermodynamically impossible to get more work out of a closed system than you put energy in in the first place. That is the exact statement of the Second Law.

JakeCK

Just want to add to @Jamie Hall comment that regenerative braking is an awesome perk of ev's. Yes you get back less then you spent initially but it would have been wasted energy anyways stopping with conventional brakes. Which by their very nature use friction to turn the movement of the vehicle into heat.

ChrisJ

JakeCK said:

Just want to add to @Jamie Hall comment that regenerative braking is an awesome perk of ev's. Yes you get back less then you spent initially but it would have been wasted energy anyways stopping with conventional brakes. Which by their very nature use friction to turn the movement of the vehicle into heat.

Ever since I realized brakes are just a dummy load ive actually been getting better life out of them.  For example I traded my last car in with 145k and it had all original brakes.

Jamie Hall

I had a 2004 Honda Civic Hybrid and I did almost as well with it -- and it was an early implementation. Regen braking is really wonderful.

JakeCK

I made it to about 60k. But my truck is a bit heavier than a car and it tows occasionally.

ChrisJ

JakeCK said:

I made it to about 60k. But my truck is a bit heavier than a car and it tows occasionally.

I cheat, manual transmission.

Hot_water_fan

Hybrids make me doubt many people truly care about payback, because they have incredible economics and minor market share 

jumper

ChrisJ said:

.

I cheat, manual transmission.

Is it not easier to reline brakes than clutch?

jumper

May not be practical but a sail powered car can work. So why not a windmill powered one?

ChrisJ

jumper said:

.

I cheat, manual transmission.

Is it not easier to reline brakes than clutch?

The clutch isn't wearing any amount that matters.  In fact I'd say in my case most of the time it doesn't wear at all.

I've heard that argument so many times... And it seems to always be from people who don't really know how to drive a manual.


You don't use the clutch like a brake.

Jamie Hall

jumper said:

May not be practical but a sail powered car can work. So why not a windmill powered one?

It can. Didn't say it couldn't. It's purely a matter of relative wind and the amount of power you can derive from the windnill vs. the power you require to drive the vehicle. But... you do require a natural wind to make it work. Can't do it in still air. Unlike a sailboat, it could go directly upwind. I haven't worked it out, but I would imagine that -- like a sailboat -- it would go best on a beam reach.

Solid_Fuel_Man

I've wondered why hybrids haven't made much in the way of sales. 

It seems Tesla has pushed the hybrid idea out....

Jamie Hall

Solid_Fuel_Man said:

I've wondered why hybrids haven't made much in the way of sales. 

It seems Tesla has pushed the hybrid idea out....

Technically -- at least in the places which make the most noise -- a hybrid is not a zero emissions vehicle, and will be treated the same way (that is to say, banned) as any other fuel powered vehicle. So why bother to invest in them?

ChrisJ

Jamie Hall said:

I've wondered why hybrids haven't made much in the way of sales. 

It seems Tesla has pushed the hybrid idea out....

Technically -- at least in the places which make the most noise -- a hybrid is not a zero emissions vehicle, and will be treated the same way (that is to say, banned) as any other fuel powered vehicle. So why bother to invest in them?

Well

I haven't noticed this answered though im sure it was...

Is an EV ultimately more efficient than a typical car?  Seems like that wouldn't be very hard to make happen considering how inefficient a 150-300hp producing 20hp is.

I got 20hp from my personal usage.  I haven't checked this car but my last one averaged 15-20 hp on my commute.

You combine that with regenerative braking I've got a feeling a normal car isn't coming close especially with the way most people drive.

Hot_water_fan

Is an EV ultimately more efficient than a typical car?

Yes, it’s not particularly close 

JakeCK

Your typical EV is around 4 times more efficient then your typical ICE

Jamie Hall

JakeCK said:

Your typical EV is around 4 times more efficient then your typical ICE

From original energy source to going down the road? Um... depends on how your electricity is generated. But yes, I'd agree it is more efficient -- but how much more is quite variable. It also varies quite widely with the type of driving. In situations (we're talking pure EV here, not hybrid?) where all, or almost all, of the braking can be and is done with the regenerative brakes, the efficiency is remarkably high -- not as much as the original energy source, but still very high. On the other hand, if the nut holding the steering wheel is using the friction brakes a lot, either by preference or by habit, then it kind of takes a big hit.

In some ways it's actually easier to see the effect of the braking with a hybrid vs. the same vehicle (or nearly so) without the hybrid power train. In most hybrids, the ICE itself is strikingly efficient -- much better than ICE's even 20 years ago. Even so, the hybrid will be considerably more efficient than the straight -- if regenerative braking is used extensively. If not, it won't be much better (if even as good, due to the extra weight) as the straight ICE.

JakeCK

Of course you need to consider the, what, 60% line loses for transmission and generation at the power plant. But one could also make an argument of all of the energy wasted extracting, refining, and transporting the fuel you pump out of the tanks at the gas station too. For me it is a mute point. I just wish I could find one that doesn't cost an arm and a leg. And tbh Im really loving not having a car/truck payment again.

And I must add, I type this as I sit in my backyard In front of a propane fire pit. Probably not the greenest thing to do but I don't feel like lighting the wood fire pit at 1am. 

Dave Carpentier

Do the vehicles indicate a % of max regenerative braking ? If you had a regular commute, could you train yourself to optimize by slowing down earlier ? I assume at some point the generator is overrun and friction brakes take over, are some models/brands better than others for the capacity of regen braking ?