YOU!: Fix the US Energy Crisis

mheslep

A mass transit follow up. Energy efficiency of mass transit is not impressive. Cars are more efficient than buses, commuter rail is a little better than cars.

DoE Transportation Energy Data Book
Chapter 2, Energy
http://cta.ornl.gov/data/tedb27/Edition27_Chapter02.pdf
Table 2.12, pg 2-14

Energy used (BTUs) per passenger per mile
Cars: 3512
Personal Trucks: 3944
Buses: 4235 (20% worse than cars, buses are the most inefficient of all DoE listed means of commuter transportation)
Rail, commuter: 2996 (15% better than cars)

Issues of congestion, pollution, and growth planning are another matter.

Sam Lee

From a pure science perspective, a bus is more efficient than a car.
A bus carrying a full load of 40 passengers will use less energy than 10 cars, each car carrying a full load of 4 passengers, when they travel the same distances.

And 4 people in a car will be more efficient than 4 cars with only one driver each, when they travel the same distances.

mheslep

Perhaps, but that doesn't have much to do with a practical assessment of efficiency. Some significant percentage of busses are always driving around with few people on board besides the driver (or no one to/from the bus barn), and they are making many, many more energy burning stops and starts than the four passenger car making the same commute. So given a bus that is already funded and going to be driving around empty or full, it is perhaps justifiable for one to use the bus vs your car, but not to support increasing the number of them on the road, strictly from an energy usage perspective. Congestion, mobility for those w/ out other means, etc are another story.

Sam Lee

That is precisely the point. Start using public transport instead of driving whenever feasible. That will save lots of oil and reduce carbon emissions.

mheslep

No the point is blanket statements like this are not possible. Just saying go go public transport leads to more buses which will not save lots of oil and reduce carbon emissions. You'll do more for the energy cause in your (average) car rather than buying another bus. You can say take the train whenever feasible, just barely.

Constructe

Are you including all our exported energy dependence like the fact that we consume so much overseas that we are responsible for like 50% of China's energy useage and pollution? If not, our energy solution will go something like this. A declining population caused by weater related disasters and pollution even if we cut carbon emmisions in the US to 0. Lower consumption due to increasingly scarce goods and the fact that our money is being owned by everyone overseas (all we have is debt). So in the end, conservation or not, we will not be able to afford too much power besides hydroelectric. We basically burn about everything we can get in our country or countries we invade (Canada has lots of wood). Sounds silly grim but I bet your children's kids won't think that when they have kids. They will probably ask, "Why didn't you do something about it back when you could of?"

Af course we could build tons of nuclear power plants willy nilly and set up mass transit all over and encourage people to live close together. That will help alot whit the gas problem. And we won't need air conditioning except on the top of the rocky mountains and in Alaska anymore. That will save loads of electricity if you don't mind no air conditioning. Now onto brighter topics... lol.

Alfi

wow.
nice post.
That took time, effort and thought.

thank you




if I may ask.
1) Do you think one presidential candidate or the other is better at understanding what you posted?
2) same question about the running mate for each.

Ivan Seeking

Carnot efficiency.

wildman

Here is an interesting proposal from the CEO of the Bonneville Power Administration a few years ago:

He proposed building additional power houses on the large dams in the Pacific Northwest to capture the lost energy from the spring runoff (which is a huge amount of water). This power would be then converted into hydrogen which can be shipped to Texas in gas pipelines. Once in Texas, the hydrogen would be piped into the salt domes where natural gas has already been extracted. This hydrogen would then be pumped out when needed. I can't find the link but I recall that he said that all the oil used by cars in the US could be replaced with this hydrogen.

wildman

Here's the link:

http://www.bluefish.org/todrivea.htm

And keep in mind that the article was written by Jack Robertson the deputy CEO of Bonneville Power. This isn't some dreaming hippie freak.

mheslep

Former. He's long retired.

Robertson does not mention pipelines, nor is it possible to ship H2 around in existing CNG pipelines. Making H2, burning H2 in an ICE - these are not the main problems. Moving H2 around and storing it in today's vehicles are; at the moment nobody has a workable solution.

Ivan Seeking

Huh? The biggest problem is the source of energy - that hydrogen is an energy carrier and not a source. Hydrogen is already in use worldwide.
http://www.fuelcells.org/info/charts...ngstations.pdf

Also, afaik, no one intends to run the hydrogen market like the petro market [pipelines and ships]. There is no reason for it. Part of the advantage of an H2 economy is that energy can be decentralized. It may be that the only real hydrogen pipelines will be carrying water.

mheslep

A handful of state sponsored H2 stations worldwide does not make them common. There are close to 200,000 gas/diesel station in the US. Note that it takes 15-20 tankers of 3k-5k PSI H2 tankers to deliver the energy of one gasoline tanker truck.

Decentralized helps, still have to get heavy grid multi MW connections or local power generation, and so far nobody has sufficient on vehicle H2 storage (DoE target vehicle range 300miles - nobody is close yet). Anyway Wildman's posted piece from Robertson was about centralized hydro power.

Ivan Seeking

I didn't say H2 is common. I said it is already being used. There are certainly issues, but you made it sound like the over 15 pages of stations listed couldn't exist.

I would debate this point if only because in the end, the practical production of H2 might be done by means other than electric. For example, one facility intends to use solar flux to crack methane, leaving nothing but pure Hyrdrogen and pure carbon-black. But I saw that there has allegedly been a big breakthrough at MIT? I saw that but didn't have time to read it.

https://www.llnl.gov/str/June07/Aceves.html

mheslep

Sorry, I didn't intend that.

Yes Nocera's efficient electrolysis. Thats a big deal. With that coming down the pike, and setting storage aside for the moment, for fun I posted up somewhere the numbers to do an onsite solar fueling station. I came up with only ~3-5 acres out behind the station.

EDIT: Yes here's the solar powered fuel station musing.
http://www.physicsforums.com/showpos...2&postcount=14

Yes liquid H2. The cryo process eats up ~30% of every unit of energy in the H2. IMO, it is compressed H2 at 10K PSI (carbon fiber tanks $$$) and the tanks are still 3-4x the volume of existing gasoline tanks, or some kind of chemical hydride storage, or nothing. Levin et al and their ultralight 'Hypercars' make a plausible case for compressed H2, they get ~300mi, but one has to completely redesign the car and thus the auto industry - no more steel, all carbon fiber, etc.

Some wild speculation now: I wonder if it makes sense at all to use local solar/grid electric/whatever to make methane and not H2? That is, use the Sabatier process or some such - H2 from electrolysis and pull CO2 from the atmosphere. That is still carbon neutral, the storage / transportation of methane is a not a problem, 8 million CNG vehicles on the road already (just not in the US )

russ_watters

I'd say you guys are talking past each other. mheslp is simply saying that it isn't viable, while Ivan is saying it is being done. But the fact that it is being done doesn't have anything to do with whether it is viable or not. What makes it not viable is that it can't provide anywhere near the same performance (specifically, range) in a car as gasoline. That's a storage problem. And he's right: "there is no workable solution" to the storage problem.

Moreover, energy production is a practical problem, while the storage issue is a technical problem. Practical problems are known to be solvable - we can just build more power plants. Technical problems are not necessarily solvable, but even if they are eventually, there is no answer right now.

mheslep

Yep, what RussW said.