Physics of Sustainable Energy: Using Energy Efficiently and Producing It Renewably - AIP Conference proceedings

Do you like talking about energy? Cars? Alternative and renewable energy? Need more info? This looks like a good place to start. This is the presentations from the AIP-APS-AAPT forum on Energy stuff.

Physics of Sustainable Energy Presentations (both pdf and powerpoint)

I looked through some of these and there are some interesting graphs I might come back to in the near future. You might want to bookmark this page or something.

Tags: energy

Starting Assumptions (estimations)
How many drive-throughs are there in the U.S.A.? When I think of drive-throughs, I think of McDonalds. Wikipedia says there are 31,000 restaurants world wide. I am going to say there are around 20,000 in the U.S. that have drive-throughs. So then, how many total drive-throughs? In my town, there are two McDonalds and probably 8 other major drive-throughs (Wendy’s, Burger King, Taco Bell etc....). This will give an extremely rough estimate of 100,000 drive-throughs in the U.S. (drive-through fast food).

There are also other kinds of drive-throughs. Drive-through banks, starbucks, pharmacy, liquor (yes, they exist). All of these will have different times, so I will first just deal with the fast food drive-throughs.

How many cars go through the drive-through a day and how long do they idle? I am going to estimate that the average over 8 hours a day is 2 cars in the drive-through line with an average wait time of 2 minutes. Yes, at lunch time there is a longer line, but sometimes there is no line. This is my estimation and I am sticking to it.

Calculating the hours of idle time
From this, I can calculate the average idle time. If there are 100,000 drive-throughs and for 8 hours there are two cars idling (I guess the wait time does not matter), that would be 1,600,000 idle-hours per day (100,000 x 8 hours x 2 cars). How much fuel does this use? Anecdotal claims from the internets say that cars use around 0.3 gallons per hour idling (I would have guessed higher than this). For this calculation, I will use 0.25 gallons of gas per hour idling. So, the total fuel per day wasted in drive-through (just restaurants) would be: 400,000 gallons.

Comparing to the U.S. oil used per day
Now to compare this to the 20 million barrels of oil used per day. 1 barrel of oil produces about 20 gallons of gasoline. So 400,000 gallons of gas saved would be 20,000 barrels of oil saved. This is just 0.1% of the oil used per day. Not nearly as much as the claimed 3% savings from tire pressure (although that is for people that don’t already have properly inflated tires). Also, that 3% is for individual savings, not for the whole nation.

Slow Down
I still think the best way to save oil is to drive slower.

Either way, the real issue is (as stated in the time article) how much would we get from off shore drilling? How much can we save by changing stuff.

Tags: energy

Can you believe it? Have you seen this video?


Are you thinking what I am thinking? WOW. How could these people not follow my rules for cool internet video. Once again, here they are:

1. Keep the camera stationary. This way I don’t have to keep moving the origin in the movie.
2. Don’t Zoom. Same reason, this video followed that rule.
3. Include a clear and obvious calibration object. A meter stick would work, or even a Kobe Bryant (I can look up his height). Maybe it could be a Ford F-150 that has a known length. Something!
4. Include the mass and height of all people involved.
5. Use high quality video.
6. Don’t talk about fight club - oh wait, wrong list.

Despite failure to follow all these rules, I have managed to analyze this video. Really when I saw it, I said “wow” - was that real? It looked real, but who would get shot up that high? (it is on break.com, so fake is a possibility).
Read More...

Tags: kinematics, video, energy

I have tried to talk about energy and perpetual motion machines before (and how they can’t work). Surprisingly, people keep coming up with ideas about energy creation that just shouldn’t work.

http://www.lhup.edu/~dsimanek/museum/physgal.htm

This site is very comprehensive in covering the different ways people make mistakes about perpetual motion machines. Great examples also.

Tags: energy

So, here is a video (from break.com - so you know it is likely fake).

Extreme Catapulting - Watch more free videos
If for some reason, you can not view this video, here is the plot.
1) Guy wears parachute and brings a portable thing like a see-saw.
2) Guy approaches large crane dropping a large mass repeatedly (I assume to flatten a dirt road)
3) Guy sneaks up an puts the see-saw under the area that the mass drops on and then stands on the other end of the see-saw.
4) Mass drops, guy shoots up and parachutes down. Read More...

Tags: forces, video, fake, energy

I have been thinking about gasoline (I can’t help it). In an effort to show my students different energy sources, I realized the power of gasoline. There is a reason we have an oil-based energy system, its cheap (still cheap comparitively) and it has lots of energy. Yes, we need to move past oil that is clear. Yes, fossil fuels lead to pollution and green house gases. But still, it is important to realize why we are here.
Read More...

Tags: gas, energy

So how much would be enough to be useful? I am going to ballpark 500 Watts (although certainly less could also be useful). What kind of flow rate would one need to get this? I will assume some type of stream where someone could produce a 1-meter vertical drop.


How much energy would you get from moving a mass of water m down 1 meter? The change in gravitational energy of a mass of water would be:

Suppose I want 500 Watts, that would be 500 Joules/sec. Suppose also I have 1 kg “pieces” of water. Each piece would give 9.8 Joules (at best). So how many of these pieces of this water would I need each second? I would need 500/9.8 = 51 pieces per second. This would give a flow rate of:

Of course this assumes 100% conversion from gravitational energy to electric energy. Clearly that is not going to happen. If I assume a 50% efficiency, then I would need a flow rate twice that - 102 kg/sec.

Suppose all this water was coming through a pipe, how fast would it have to go? If I have a 1 inch pipe, then I would need to first look at the volume flow rate.
Assuming water with a density of 1000 kg/m³ then the flow rate would be:


How fast would the water have to flow to get this?

How long would this pipe have to be to get 0.051 m³?
Well, the cross sectional area would be:

So, if the volume = 0.051 m³ then the length would be:

If all of this moves through in a second, that would make a flow speed of 100.6 m/s or 225 mph. Seems kind of fast.

Tags: energy

Ok, I this just came up and I had to write something about it (even though I have tons of other things to do). Here is a video of a guy jumping 35 feet into a pool of water only 1 foot deep.

How does this work? Read More...

Tags: acceleration, video, gravity, energy

I see alternative ideas about powering cars on the internet all the time (as you probably do also). The latest is a car that runs off of water from Japan. My problem has always been “where does the energy come from?” If you use water as an energy source, you would have to reduce its energy somehow. Not sure how you would do that. Robert Rapier has done a little investigation and found that the car likely uses metal hydrides to release hydrogen from the water.

Read his post, it includes a good explanation.
Read More...

Tags: energy

I like to ride my bicycle. I like to ride it well. I ride it to work whenever I can. I think this is a good thing and not one bad thing about it. However, occassionaly I will have someone in a car yell at me. It usually goes something like this:

“Get of the silly road you person”

But occasionally they will say things a little more colorful. But the question remains. Should I instead ride on the sidewalk?


Read More...

Tags: rant, bike, energy, momentum

Tom, Ray, I still think you are Awesome
However, your physics seems to be incorrect.
In CarTalk episode #0821 the car talk guys take a caller with a physics question. "How does a car crashing into an immovable wall compare to a car crashing into another similar car going in the opposite direction?" This is the basic question. Tom and Ray claim that a car crashing into an immovable wall going 120 mph is equivalent to two cars going 60 mph crashing head on. Read More...

Tags: work, energy

Which wastes more fuel? (and thus produces more carbon dioxide). This is a difficult to question to answer for a variety of reasons. The main reason is that a speed change from 71 mph to 70 mph is different than a reduction from 56 to 55 mph. Read More...

Tags: energy, cars

I try to stress to people that driving faster on shorter trips doesn't really make THAT big of a difference in time. Also, you can save money by driving slower. This was essentially the idea behind my optimal commuting speed calculator. The problem is that this calculator doesn't really work if you don't get paid by the hour. I decided to make a graph anyway that shows the decrease in your efficiency (and thus increase and how much you spend on gas) at the same time showing how much time you save. That way, you can use your own weighting of the importance of time.

For this graph, I used an efficiency of 25 miles per gallon when driving 70 mph. The trip distance is 20 miles and the cost of gas is $4 per gallon.

You can see going 90 mph instead of 50 mph save you 10 minutes, but cost more than $2.50 dollars MORE than going 50 mph.

Tags: energy, cars

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Tags: energy, cars

Everyone is concerned about power and carbon dioxide, right? Well, maybe we should look at some alternative energy sources. I previously proposed using the rotation energy of the Earth, but that didn't go over too well with the internet community. How about people power?

Can people be used to produce power? Obviously. Do people produce carbon dioxide? Sure, its called breathing. Would we do better to use people? I don't know, but I will try to make some simple calculations. Read More...

Tags: energy, cars

I was recently re-watching a MythBusters episode and I found something I had wanted to explore previously (but accidentally deleted the episode). Here is a short clip from the "shooting fish in a barrel" episode:


Did you see what I found interesting? That big barrel of water left the floor from being hit by a bullet - here is a quick analysis Read More...

Tags: video, energy

I don't know why I even suggest a new energy source. Fusion power is only a few years away in the future (just like it as always been). This will replace any other sources of energy that we could come up with. But, I can't help myself, I need to share my idea and save the world. Its what I do. (call me a superhero is you want).

We can get all of our energy from the rotation of the Earth. Read More...

Tags: energy

Let me start with a story.

A guy calls me up in my office (this happens sometimes). He says he wants to know if he can run a car off of hydrogen. I tell him I imagine it is possible, but it probably wouldn't work too well. Here is his plan. He wants to have the engine run an system to break water into hydrogen and oxygen. The hydrogen will then be used back in the engine. Maybe you already see the problem with this situation, but many clearly don't see the problem. Let me draw a little diagram to help.
Read More...

Tags: energy

I think it is time for me to talk about energy. My ultimate goal is to give some insight into the many stories about perpetual motion. To do this, I will first talk about the fundamentals of energy. In part II, I will talk specifically about perpetual motion. Read More...

Tags: energy

Line Rider. Yes, its a game. Yes, I know its not real life. Nonetheless, I analyze what I see. How is the physics in line rider? Does it agree with Newtonian mechanics? What is the scale of the line rider? What other questions are there? What other questions are there? Read More...

Tags: forces, kinematics, momentum, energy