Where do we waste energy most at?

[magnemoe]

17 hours ago, wumpus said:

Car energy "waste" is pretty complicated.  Basically, it takes about 30hp to maintain a fairly aerodynamic car at highway speeds (double or triple that for light trucks).  Also note that most cars do more poorly driving around city streets accelerating and decelerating, so obviously that is typically done in an inefficient way.

If you are driving something like a prius that has a ~60hp (gas) engine, your engine will be relatively efficient producing 30hp.  For everyone else, producing 30hp isn't something they are all that good at.  Oddly enough, larger engines are (technically) more efficient at producing power, the problem is that they tend to produce power efficiently at 100hp or more (which is great if you are going 100mph+, otherwise it will simply accelerate you until you are going 100mph+).  A graph of Brake-specific-horsepower is shown below.  The red part is the area where the engine is most efficient, and the dots indicate random samples of the car's driving.  From poor memory, I think the car was an early saturn, which had around ~120hp.  Expect modern engines to have islands twice as high as seen in the graph (but the dots only slightly higher, although modern cars are *much* heavier than plastic saturns).

My understanding of fossil fuel plants (at least the more recently built ones) is that they are pretty close to Carnot efficiency (meaning that there is *no* *way* to increase efficiency beyond that while burning the fuel).  This means they should be about as good as possible for turning motors in machinery, but that you should avoid using them for direct heating (heat pump efficiency depends largely on the heat source they are pumping).

Modern car engines are pretty economical over an wider performance span, with an primary focus on the 30 hp efficiency. back then we used carburettors this was true, but not much for modern engines. you don't care much about efficiency at kickdown as you rarely use it, here its about peak performance, but you want good performance from idle up to heavy standard load.  And yes an hybrid will win well here on performance. 

Heat based power plants is close to their theoretical performance, main issue is waste heat, perfect is to use it industrial as use is stable and controlled, second best is heating. 

[wumpus]

4 hours ago, magnemoe said:

Modern car engines are pretty economical over an wider performance span, with an primary focus on the 30 hp efficiency. back then we used carburettors this was true, but not much for modern engines. you don't care much about efficiency at kickdown as you rarely use it, here its about peak performance, but you want good performance from idle up to heavy standard load.  And yes an hybrid will win well here on performance. 

I'm pretty sure the car in question had fuel injection.  Probably OBD-II (if not, certainly OBD-I) compliant.  It might significantly more efficient over carburetors, but they don't really appear to have much chance at getting better.  One of the big problems is that most of the few remaining ways to increase efficiency do so at the expense of emissions.  Running a bit lean will increase power for the same amount of gas, but also create a bunch of nitrogen-oxygen compounds.  Honda used to sell cars that would do this (with three different catalysts to break things down), but I'm not sure if that is even possible with current (US) standards.

My understanding is that the current thought is to use much smaller engines (like most hybrids) to move the "sweet spot" down to where the car is typically used, then allow the turbocharger to produce (with horrible efficiency) more power when [rarely] needed.  This works fine as long as you drive like the official standards (or more efficiently), but lead footed drivers whine all over the internet.  It also isn't quite as effective as a hybrid, but is typically much cheaper to build (I'm still wondering why Toyota hasn't made a Lexis that marries a prius engine with a more powerful (not quite Tesla, but you get the idea) electric engine).

[Nuke]

the most inefficient thing humans do? id have to say war. the amount of energy that is wasted in order to keep others from doing same is likely astronomical. america spends most of its money on this than anything else. the armies them selves push their soldirers hard enough to need an above average caloric intake. then the machines of war eat through fuel and munitions like crazy. weaponry is also heavy and with how globalized we are that is a lot of weaponry, vehicles, equipment, personnel and ammunition to move about the globe. fighter planes, warships, and tanks burn tons of fuel. then when we have a massive war like ww1 and ww2, whole cities are ruined and out goes all the energy that went into building them. how much energy did we waste building the cores for nuclear weapons, material we could have put to better use for civil purposes.

of course war pushes technological advancements. it sure makes good subjects for movies and games. and it does keep the human population in check. its in our blood and a core aspect of human nature.

Edited March 12, 2016 by Nuke

[Vim Razz]

On 3/10/2016 at 8:39 AM, NuclearNut said:

The only issue with CHP is the air pollution it produces assuming you utilize fossil fuels.

Not so much.  Modern boilers run pretty cleanly.  And it's actually easier to burn petro-chemicals cleanly than biomass fuels, for example, because they have simpler and more consistent chemistry.  In either case, there's more pollution involved in the extraction/collection, processing, and transport of materials than final combustion.  Transport energy is inherently inefficient because it needs to be portable, and efficient combustion hardware is too heavy to move around like that.

The biggest challenge in CHP development is finding enough reliable customers for the heat within an economically viable range of the plant -- customers that are going to be around and pay the bills every month for the ~10 years it takes to pay off the cost of the plant and distribution system.

 

6 hours ago, Nuke said:

the most inefficient thing humans do? id have to say war.

This one gets my vote.

 

Edited March 12, 2016 by Vim Razz

[Waxing_Kibbous]

Christmas lights.

[fredinno]

20 hours ago, Waxing_Kibbous said:

Christmas lights.

Only occurs for a month every year.

[Nuke]

12 hours ago, fredinno said:

Only occurs for a month every year.

its up to 3 months now. xmas is gaining at a rate of 2 days every year. in needs to be stopped.

[YNM]

On 3/12/2016 at 7:14 PM, Nuke said:

the most inefficient thing humans do? id have to say war. the amount of energy that is wasted in order to keep others from doing same is likely astronomical. america spends most of its money on this than anything else. the armies them selves push their soldirers hard enough to need an above average caloric intake. then the machines of war eat through fuel and munitions like crazy. weaponry is also heavy and with how globalized we are that is a lot of weaponry, vehicles, equipment, personnel and ammunition to move about the globe. fighter planes, warships, and tanks burn tons of fuel. then when we have a massive war like ww1 and ww2, whole cities are ruined and out goes all the energy that went into building them. how much energy did we waste building the cores for nuclear weapons, material we could have put to better use for civil purposes.

of course war pushes technological advancements. it sure makes good subjects for movies and games. and it does keep the human population in check. its in our blood and a core aspect of human nature.

Because... guess humans put their own on top of everything. Individuals, not groups.

But then, in a war the most inefficient thing are anything that results in collateral damage. So... massive guns ? WMDs ?

Edited March 14, 2016 by YNM

[peadar1987]

2 hours ago, Nuke said:

its up to 3 months now. xmas is gaining at a rate of 2 days every year. in needs to be stopped.

How do I sign up for this "war on Christmas" I keep hearing about?

[micr0wave]

Beside the mentioned war, the greed for money is a huge part of wasting energy in absurd ways (in some way war also falls a bit into this category).

e.g. shrimp fishers from north sea unload their catch, the shrimps get transported to marocco, peeled there, and transported back. Just one really tiny example of how energy is wasted in a somewhat stupid way.

Probably there were already aliens visiting us, seeing examples like the one above, and left quickly to avoid contact with those daft lifeforms on that blue planet

.

[fredinno]

3 hours ago, peadar1987 said:

How do I sign up for this "war on Christmas" I keep hearing about?

The Grinch's lair.

[wumpus]

On 3/12/2016 at 9:18 PM, Waxing_Kibbous said:

Christmas lights.

Compared to gas stations (yes, originally gas stations, but I think other retail places have taken the idea an run with it), shopping centers, industrial parks (especially heavy) that need to light up huge amounts of area to near daylight you won't notice it.  Even on Christmas Eve.

Also note that Christmas lights should already be LED (red and green LEDs have been around long before anyone thought of CFD light bulbs).  It will take many more people with insane Christmas decorations (powered by LEDs) to make a dent in electric use.  The power used above is typically mercury lamps, and unlikely to switch to LED anytime soon (and already uses much power).

Um, considering this is a space forum, do we have any astronomy buffs here?  Just how much extra light pollution do you get during Christmas season?