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|User Info||When All You Have Is A Hammer (Oil -- Again); entered at 2011-11-20 04:59:38|
First a quick quibble with the details of one of the statements in the original post: "A side benefit of this path (LFTRs + coal -> synfuel + electricity) is that we reduce the CO2 output into the atmosphere by the amount of the formerly-burned imported oil." If you are burning as much synfuel using your energy dense (but still derived from fossil source (in this case coal)), the amount of CO2 emissions due to replacing imported oil burning will be roughly the same.|
The problem as I mentioned in an earlier thread is that the energy density is only an advantage if one has to carry the fuel in the vehicle as well as all of the mechanisms to turn that into a propulsive force for the vehicle and its payload. That is not required at all. Consider for a moment the electric bike (http://www.electric-bikes.com/). There are many studies that indicate average city traveling speeds are in the 12-18mph range (based on end to end trip times and distances). Most mass transit systems have overall trip speeds slower than a human powered bike. If you like, use the get direction facility of Google maps to look up your common trips. You can see the distances and times for driving, and in most cases biking and mass transit. Now as for the electric bikes, most use electric motors consuming 400-1000W (or about .6 to 1.4 hp). These can achieve top speeds above the average noted above, with ranges of as much as 30 to 40 miles on a charge. An urban road system with overpasses at major intersections sufficient to carry the weight of such vehicles would produce end to end trip times no worse than today's system based on 2000 to 6000 # personal vehicles.
Note that the power requirements and range can be greatly increased using recumbent layout and a reasonable fairing. For example: http://www.wired.com/culture/lifestyle/n.... has a human powered bike achieving 80mph, although sustained rates by trained athletes are more in the 30-40 mph rate. Note that such humans can only maintain 150-200 W outputs for any reasonably sustained period. But if the 400W electric motor were to replace the human such enhancements would double the efficiency, while substantially increasing the peak speed, of the electric bikes noted in the previous paragraph.
There are still issues with cargo and emergency vehicles and the way they would interact with such light-weight personal vehicles. But those are easily solvable. Note that this is even more deployment ready technology than the LFTR option and the power here is stored in the low density batteries that as Karl notes do not have the energy density required if one desires to push around 2000 - 6000 pounds to move on average much less than 300 pounds of humans.
Further note that a system based on such light-weight vehicles would also greatly reduce all other energy requirements not just those of the energy to directly power the vehicle during movement. At https://docs.google.com/spreadsheet/ccc?key=0AiH-Amyx50i4dFpTVm9hbTgwTWxwUnFkX0RaemU3Wnc&hl=en_US#gid=1 I have posted to Google docs a spreadsheet obtained in Excel from the Natural Resources Canada web site. See the AllSector2 tab. This lists total use in the transportation sector of ~30% of total Canadian energy consumption. But the actual number directly related to our transportation system is closer to 50% of the total. For example, according to other studies the energy needed to construct our vehicles (produce the steel, assemble, ...) is between 10 and 15% of the total energy consumed as fuel during use. This is buried in the mining, iron and steel and other manufacturing categories (which total 17.9%). So add another 5% for that. Much of the petroleum refining category (3.7%) goes to fuel production. More than half of the mining category (of 8.5%) goes to the tar sands and other crude generation. Significant parts of the commercial and institutional are directly related to our current car culture (e.g. car dealers, gas stations, admin services related to roads, licences, etc.). There is also a substantial amount related to road construction and maintenance which is buried in the other numbers. Net is if we could cut these numbers to 10% of today, which is possible using existing technology, we would have a system with comparable trip time performance and much better safety, other pollution reduction (e.g. even Karl's synfuel option would produce emissions which would generate smog and related health issues).
As an aside this same spreadsheet also reveals where we can reduce our requirements for energy for most other sectors. For example, light pipes / skylights for commercial/institutional lighting. Such things are starting to be deployed. Another point in which I disagree with Karl is his often made assertion that each unit of GDP has a unit of energy consumption required. The implication is that this is relatively constant. But to me he under-emphasizes the point that it is not money that is important, but what one can buy with the money. In fact, a careful analysis of this sheet reveals many opportunities for having "the same or even more of the ultimate demand (e.g. food, shelter, speed and safety of travel)" with far less consumption of energy.
Finally, what we should be going to for moving people and goods around a city would be a PRT with the following characteristics:
- truely personal
- off-grade (as with a subway or elevated train do not compete with other traffic such as pedestrians or cyclists). This should also eliminate most ROW needs.
- suspended (fail safe design for cornering and dealing with weather)
- external power storage
- extremely light weight vehicles (low energy consumption during use and for production)
- low land use requirements
- end to end trips with no stopping
- ground level, low cost, stations/stops
Shweeb (http://www.shweeb.co.nz/Shweeb/what-is-t.... demonstrates most of these principals in an operational system. In an earlier post when I brought this up someone asked about specific studies related to PRT. I did not respond because most are case studies of PRT designs that violate 1 or more of the above principals (e.g. Morgantown is not personal and like the one at Heathrow is not suspended). Further, Shweeb has satisfied the Google 10^100 reviewers to obtain money from them. Most people when I show them the Shweeb video concentrate on the human powered aspect, but just assume that the same drive were replaced with one of the 500W electric motors from the electric bikes noted above.
It is relatively easy to estimate the cost of a Shweeb type guideway including stations/stops. I came up with something substantially less than $1M/km. In consulting with the Shweeb people they indicate that is the ballpark they have determined too.
The only two things the existing Shweeb does not demonstrate that would be required for a real urban deployment are:
- a high speed switching system. A true network will need this and it should operate at speed. The Shweeb people appear to be assuming 15mph cruising speeds (which would still be competitive with the car in most urban settings as no stops are required), but one should be able to do much better. The Mister PRT design from Poland (http://www.mist-er.com/home-page.html?se.... specifies a patented switch that should work for substantially higher speeds in a suspended structure.
- the complexity and cost of station/stop structures. Again the Mister page describes a detailed solution in this area. Some PRT designs illustrate stations that operate at the level of the track. These have numerous issues, including substantial expense. As Mister notes it is far better to bring the vehicles down to street level for loading and unloading. There are lots of demonstrations of such systems at amusement parks all over the world, and these are typically using vehicles far heavier than what would exist in a proper PRT.