$7 per gallon before a hybrid is worth it

[DarrinS]

2011 Chevy tahoe hybrid - 332 HP, 367 lb-ft. torque
2011 Chevy tahoe - 320 HP, 335 lb-ft. torque

DOH!

The HIGHLY efficient 2011 Tahoe Hybrid gets 20 mpg city and 23 mpg hwy, while the regular 2011 Tahoe gets 15 city/21 hwy.

Not the "greenest" hybrid and hardly worth the extra $13K.


doh!

[MannyIsGod]

You move goalposts faster than a group of drunken fratboys after a huge college football upset.

No one is saying that Tahoe is worth the money TODAY. This has been explained to you several times in this thread but you're too god damn stubborn or stupid to realize it. However, there will be a time in the very short future where because of lowered technology costs and higher gas costs that it will be a smart purchase. Furthermore, you ed about power and that hybrid shows you that your ing is nothing more than bull (shocking - I know). No one said it was the greenest hybrid, but you're a ing fool if you don't recognize that a 33% increase in city MPG is incredibly significant.

If you want to burn barrels of oil in your backyard then go ahead but don't be surprised when most people think you're an absolute fool. Oh, and make sure the amount of oil doesn't exceed the capacity of the superdome.

[coyotes_geek]

The HIGHLY efficient 2011 Tahoe Hybrid gets 20 mpg city and 23 mpg hwy, while the regular 2011 Tahoe gets 15 city/21 hwy.

Not the "greenest" hybrid and hardly worth the extra $13K.


doh!

A 33% improvement in city mileage without having to sacrifice power sounds pretty good to me. Any idea how that 33% stacks up against other hybrid/non-hybrid vehicle comparisons?

[Drachen]

The HIGHLY efficient 2011 Tahoe Hybrid gets 20 mpg city and 23 mpg hwy, while the regular 2011 Tahoe gets 15 city/21 hwy.

Not the "greenest" hybrid and hardly worth the extra $13K.


doh!

I wasn't talking to you... I was talking to the guy upstream who admitted that more power was his main concern and that if he had to pay more for it then cest la vie.

I do think that he posted under your screen name though, so I would check the password on your account.

[Drachen]

A 33% improvement in city mileage without having to sacrifice power sounds pretty good to me. Any idea how that 33% stacks up against other hybrid/non-hybrid vehicle comparisons?

33% increase in MPG AND more power with a 27% increase in cost.

[Cry Havoc]

33% increase in MPG AND more power with a 27% increase in cost.

Do you get tax breaks with that hybrid?

[Drachen]

No, it is expired.

[Wild Cobra]

PV efficency is increasing at an exponential rate. I confess I know jack about batteries but PV panels are getting smaller and producing more energy.

If in theory, you could reach an efficiency can reach 100%, you still only have so much energy from the sun over a given surface area.

[Wild Cobra]

That's not really what I said though. I was talking about using photovoltaic paint as an additional way to gather energy for the car, not a primary one.

Let's say you had a paint that did that and collected 0.5% of the solar energy as electricity. Parked in an unobstructed area, with a noon summertime sun the profile of the car might be what, 5 sq meters? Solar energy hitting the surface at 90 degrees is in the neighborhood of 950 watts/sq meter. This is under a 24 watt-hr charge, and that is peak. Over the course of the 24 hr cycle, and reducing profile and angle, you you be lucky to average 30% as around 35% is average for a profile that doesn't change. In the end, you get about a 172 watt-hours of energy over 24 hours. Raise this paint to a 25% efficiency, and you get about 8.6 kWh of energy. Is such a cost worth it for 86 cents worth of power? It only saves $314 annually under optimum conditions. The cost for the paint and power connections would be how much?

Someone check my math please. Did it on the fly. It would probably be a little higher anyway with a 3D profile. I did it the same way as a flat target on the ground. Probably double those power figures.

[Wild Cobra]

Bottom line is 1 square foot in full sunlight at the equator receives about 100 watts of total energy from sunlight in 12 hours. Thats with 100% recovery. It is what it is.

Actually, it's about 100 watts when the solar cells are perpendicular to the sun. Six hours before or after, the angle is insignificant and the energy almost zero, without solar cells that track the sun.

approximate:

6 AM 0% (6 PM)
8 AM 50% (4 PM)
10 AM 87% (2 PM)
noon 100%

You end up getting about 35% of the max rated energy over 24 hrs. A 100 watt max solar cell design would yield about about 840 watt-hours of power per sq. ft. Not 1200 watt-hours per sq. ft.

[Wild Cobra]

2011 Chevy tahoe hybrid - 332 HP, 367 lb-ft. torque
2011 Chevy tahoe - 320 HP, 335 lb-ft. torque

DOH!

What do the power curves look like? That makes a big difference. Torque needs to be in the right place.

[RandomGuy]

Bottom line is 1 square foot in full sunlight at the equator receives about 100 watts of total energy from sunlight in 12 hours. Thats with 100% recovery. It is what it is.

100 watts/hour average not per day.

Off by a factor of twelve. An order of magnitude plus a bit.

It is though, an important point. There is a theoretical maximum and that is easy to see.

What that single factoid misses, is context, like cost per unit of energy, and cost per square area.

If a square foot were to cost $0.0001, then the costs of PV power would crush any competing form of energy at anything approaching current production efficiency, let alone experimental efficiency.

Context:
You get a lot of energy loss converting electricity into chemical energy in a battery.
You get a lot of energy loss burning gasoline.

The best way to really compare is to start doing some conversion.

First, let’s get some common units. A joule is the best way to go.
http://www.phy.syr.edu/courses/modul...CY/tables.html

Gallon of gasoline: 130,000,000 joules
Kwh: 3,610,000

Of course, out of any gallon of gas, only about 20% of any given gallon is actually converted into work, i.e. moving the car.
http://en.wikipedia.org/wiki/Engine_efficiency

I get that most common electric motors can convert electricity to work at about 90% efficiency.
http://www.best-solar-energy.com/ren...lectric-motor/

So let’s dial back both joules to better reflect the percentage of both available to actually do work.

130000000*0.2= 26,000,000 joules
3610000*.9= 3,249,000 joules

Getting energy into/out of a battery is about 75%-80% efficient:
http://www.enviroharvest.ca/pv_efficiency.htm

3,249,000 *.75 = 2,436,750

So a gallon of gasoline, will get you roughly 10.66 times the amount of work that a kilowatt hour would.
26,000,000/2,436,750= 10.66

With 1200 watts being our theoretical maximum at the equator for a square foot in a day, but that converted at 50% to electricity, you get 600 watts. One watt = One joule.

Factor in storage losses, and that drops to 600*.75= 450

26,000,000/450= 57,777 square feet of PV at the equator. 240 feet by 240 feet, a pretty large area. Northward la udes easily would require more.

This is the ultimate crux of the “density” argument that Darrin makes, albeit awkwardly.

It would be quite impossible to fully replace gasoline with PV, and keep our driving habits in terms of both distance of commute, and size of vehicle the same.

[LnGrrrR]

Let's say you had a paint that did that and collected 0.5% of the solar energy as electricity. Parked in an unobstructed area, with a noon summertime sun the profile of the car might be what, 5 sq meters? Solar energy hitting the surface at 90 degrees is in the neighborhood of 950 watts/sq meter. This is under a 24 watt-hr charge, and that is peak. Over the course of the 24 hr cycle, and reducing profile and angle, you you be lucky to average 30% as around 35% is average for a profile that doesn't change. In the end, you get about a 172 watt-hours of energy over 24 hours. Raise this paint to a 25% efficiency, and you get about 8.6 kWh of energy. Is such a cost worth it for 86 cents worth of power? It only saves $314 annually under optimum conditions. The cost for the paint and power connections would be how much?

Someone check my math please. Did it on the fly. It would probably be a little higher anyway with a 3D profile. I did it the same way as a flat target on the ground. Probably double those power figures.

You might be right WC, I don't know the physics. Perhaps it would be more useful to save the PV paint for large buildings. *shrug*

[RandomGuy]

The obvious implication is that, as gasoline gets less and less efficient to produce (the rough proxy of a cost of a gallon of oil is a good measure), something will have to change.

We will simply have to use less energy on transportation. Smaller cars, shorter commutes, or simply other forms that use less energy per person, think bicyles or mopeds.

One might also start considering mass transit.

(edit)

Although, there is some data that suggests mass transit like trains isn't the answer either.

Telecommuting anyone?

[DarrinS]

26,000,000/450= 57,777 square feet of PV at the equator. 240 feet by 240 feet, a pretty large area. Northward la udes easily would require more.

This is the ultimate crux of the “density” argument that Darrin makes, albeit awkwardly.

It would be quite impossible to fully replace gasoline with PV, and keep our driving habits in terms of both distance of commute, and size of vehicle the same.

We just need to increase the size of driving lanes.

[RandomGuy]

We just need to increase the size of driving lanes.

You joke, but one of the most obvious implications is that long-term spending on new highway projects is probably a waste of money.

Shorter commutes means a LOT less traffic.

[lazerelmo]

http://www.washingtontimes.com/blog/...-capitol-hill/

$7,500 tax break to become $7,500 rebate at the dealership.

[Drachen]

This is interesting

About the size of a playing card, the solar cell - which uses inexpensive and widely available materials like silicon - is able to split water into its two components, hydrogen and oxygen. Placed in a gallon of water in bright sunlight, the device could produce enough electricity to supply a house in a developing country with electricity for a day.

I have read other better articles on this the last few days, but it is interesting considering the conversation that we are having. I would like to see some more data regarding its power output as well as how it works.

But one has to wonder, if one can power a home in the developing world off of only one of these, you have to imagine that 4 of these could power a car of ours.

[RandomGuy]

This is interesting



I have read other better articles on this the last few days, but it is interesting considering the conversation that we are having. I would like to see some more data regarding its power output as well as how it works.

But one has to wonder, if one can power a home in the developing world off of only one of these, you have to imagine that 4 of these could power a car of ours.

Still ultimately limited by physics, as was noted earlier. You can ONLY capture 100% of the energy from the sun, as an upper boundary.

You have to remember that moving a 1,500- 2,000 pound object involves a lot of physical work, in the physics sense of the word.

Going back to the earlier figures, if you completely discount losses from storage and friction, and assume 100% capture, at the equator:

26,000,000 joules = 1 gallon of gasoline available work energy

One square foot can capture at this theoretical maximum per day: 1200 watts or 1200 joules

26,000,000/1,200 = 21666 square feet of capture in one day, the equivalent of ONE gallon of gasoline or an array of 148 feet on each end.

A good-sized home floor plan is about 2500 square feet, so that gets you a rough picture of what it takes to replace a gallon of gas on a daily basis.

It is worth noting though, that PV cells last a good 30+ years, with some drop off. We honestly don't know how long the lifespans are, because the first production PV cells are still producing power some 50 years later.

That means if you installed enough PV cells to replace a gallon of gasoline per day, they would replace just shy of 11,000 gallons of gasoline over 30 years, and keep on cranking. Things that don't have moving parts tend to last a loooong time.

If you figure the average commute consumes two gallons or more of gasoline (a guess on my part), you can start to see the difficulties involved in running vehicles using the sun only. Make the car smaller, and the distance shorter, and it becomes much more feasible.

Scale it down to an electric scooter, when even larger gas powered ones get close to 75 miles per gallon, and using PV to power transportation needs gets more feasible, but not by much.

We are simply going to have to live a LOT closer to where we work in 50 years.

[boutons_deux]

http://www.dailyfinance.com/story/ga...pump/19895547/

[Drachen]

Still ultimately limited by physics, as was noted earlier. You can ONLY capture 100% of the energy from the sun, as an upper boundary.

You have to remember that moving a 1,500- 2,000 pound object involves a lot of physical work, in the physics sense of the word.

Going back to the earlier figures, if you completely discount losses from storage and friction, and assume 100% capture, at the equator:

26,000,000 joules = 1 gallon of gasoline available work energy

One square foot can capture at this theoretical maximum per day: 1200 watts or 1200 joules

26,000,000/1,200 = 21666 square feet of capture in one day, the equivalent of ONE gallon of gasoline or an array of 148 feet on each end.

A good-sized home floor plan is about 2500 square feet, so that gets you a rough picture of what it takes to replace a gallon of gas on a daily basis.

It is worth noting though, that PV cells last a good 30+ years, with some drop off. We honestly don't know how long the lifespans are, because the first production PV cells are still producing power some 50 years later.

That means if you installed enough PV cells to replace a gallon of gasoline per day, they would replace just shy of 11,000 gallons of gasoline over 30 years, and keep on cranking. Things that don't have moving parts tend to last a loooong time.

If you figure the average commute consumes two gallons or more of gasoline (a guess on my part), you can start to see the difficulties involved in running vehicles using the sun only. Make the car smaller, and the distance shorter, and it becomes much more feasible.

Scale it down to an electric scooter, when even larger gas powered ones get close to 75 miles per gallon, and using PV to power transportation needs gets more feasible, but not by much.

We are simply going to have to live a LOT closer to where we work in 50 years.

My understanding here may be flawed, and I am sure I will be quickly corrected if it is, but from where I sit, there is a fundamental difference between what this "solar leaf" is doing and what a PV cell is doing. The SL seems to be a chemical process that derives its energy, not only from the sun, but from a chemical reaction using a catalyst and water. The way I am reading it is that this addition of these "chemicals" allows for greater energy harvesting in a much smaller package.


Edit: otherwise, it would seem, that this wouldn't be something to write an article about, instead it would just be a small card sized PV cell capable of what any PV cell is capable of (proportional to size)

[MannyIsGod]

My understanding here may be flawed, and I am sure I will be quickly corrected if it is, but from where I sit, there is a fundamental difference between what this "solar leaf" is doing and what a PV cell is doing. The SL seems to be a chemical process that derives its energy, not only from the sun, but from a chemical reaction using a catalyst and water. The way I am reading it is that this addition of these "chemicals" allows for greater energy harvesting in a much smaller package.

The point that is being made - and it is a correct one - is that you can only ultimately harvest 100% of potential energy from any particular source. I'm not sure what the potential energy from your source is if it is also relying on stored chemical energy but energy from sunlight is not enough to power TODAY'S vehicles.

Whether or not it would be enough for vehicles in the future is debateable, IMO, due to lower weights (cars today don't weigh what they did 40 years ago, for instance), better aerodynamics, and better engines and drive train systems.

I think solar definitely has a role and I think that eventually all of our planets needs will be solved with solar energy but it may require indirect production and transmission in some manner to vehicles. Even if thats as simple as having to plug in your car at night to recharge batteries.

We'll see.

[Drachen]

The point that is being made - and it is a correct one - is that you can only ultimately harvest 100% of potential energy from any particular source. I'm not sure what the potential energy from your source is if it is also relying on stored chemical energy but energy from sunlight is not enough to power TODAY'S vehicles.

Whether or not it would be enough for vehicles in the future is debateable, IMO, due to lower weights (cars today don't weigh what they did 40 years ago, for instance), better aerodynamics, and better engines and drive train systems.

I think solar definitely has a role and I think that eventually all of our planets needs will be solved with solar energy but it may require indirect production and transmission in some manner to vehicles. Even if thats as simple as having to plug in your car at night to recharge batteries.

We'll see.

But in this process there is energy being harvested from the water, catalyst, and sun as opposed to just sun. No?

edit: something like heat energy alone can't move my truck, but heat, fuel, and oxygen can. Once again, I may be misunderstand the premise of this solar leaf, but this is the way I am reading it.

[boutons_deux]

Correct, totally different physics: photo-voltaic energy conversion vs splitting water into H and O.

The hydrogen of course is then a fuel for a fuel cell, which reverses the splitting to produce pure water. Too good to be true.

The key problem with hydrogen economy is transport of the hydrogen fuel. Requires and entirely new infrastracture, can't use oil pipes. Pure hydrogen is explosive and corrosive (highly reactive, as is distilled water).

[Wild Cobra]

The SL seems to be a chemical process that derives its energy, not only from the sun, but from a chemical reaction using a catalyst and water. The way I am reading it is that this addition of these "chemicals" allows for greater energy harvesting in a much smaller package.

So....

You need a fuel for that chemical conversion. How much is the fuel and what type of waste does it generate?