Just scale up a spring-powered toy car

Range scales as the zeroth power of size, i.e., doesn’t change. Insects that specialize in jumping, and people that so specialize, show the same phenomenon, because both have the same limitations on energy stored in fast-acting muscle: both fleas and basketball players can, by jumping straight up, raise their centres of mass about one metre.

Interestingly, they do this with muscle that is only a small fraction of their total mass, but a coiled spring, which is 100 percent strained metal, can’t jump any higher. You can probably easily confirm this if you have a retractable ball-point pen: they usually contain a small spring.

keep an alternator of some sort going to keep the batteries charged

And presumably the batteries feed an electric drive motor. These intermediary stages consume energy. If a directly spring-driven Prius would go 25 metres, one with the electric stuff between the springs and the wheels would go 15 to 20 metres.

(How fire can be domesticated)

There are several more like that. Nuclear is not even required. All of these recycling technologies; boron, aluminium, carbon work on a time independent basis. They can use solar and wind power when its available and pause the factory when these power sources are unavailable.

(Could the reprocessing plant be built within a space sufficient to later add the GenIV plant — which would basically mean building the reprocessing plants next to the older coal power plants, I guess? — well, they’d need the railroad connections for that.)

http://www.gnep.gov/pdfs/Goff_Electrochemicalposting.pdf

Electrochemical Processing of Spent Nuclear Fuel
Dr. Michael Goff, Idaho National Laboratory
Nuclear Regulatory Commission Seminar
Rockville, MD March 25, 2008

____excerpt_____

Electrochemical Processing
Until 1994, focus was on demonstration of closed fuel cycle
with a fast reactor.
– Recycle of fast reactor fuel
– Limited work on production of fast reactor feed material from LWRs
In 1994, activities were redirected to treatment for disposal.
– Engineering-scale experience was gained with spent fuel.

With the formation of the Advanced Fuel Cycle Initiative (AFCI) in 2002 and the Global Nuclear Energy Partnership (GNEP) in 2006, recycle focus was renewed and stressed.
_________________

Is this astonishingly high?

Is there any oxygen concentrator now available that produces … oxygen … pure enough for a boron engine to run on?

Yes, see the paper‘s “Oxygen denier readiness” section.

Also note that if fuel cells were long established as cars’ main fuel energy converters at mid-30s gross efficiency — has any vehicle fuel cell done better? — and heat engines were the putatively keen putatively new thing, their fans could point to their conceptual efficiency. Automotive heat engines operate between the temperature of a fuel-air flame, mid-2000s K, and that of a heat exchanger suitable for lightweight dumping of kilowatts, maybe 320 K, so the cars being driven off lots today are conceptually getting heat-to-work efficiency percentages high in the 80s.

Is there any oxygen concentrator now available that produces pure oxygen? Or pure enough for a boron engine to run on?

The medical references I find comparing concentrators to oxygen tanks comment that the oxygen level the patient is breathing is lower when supplementing from the concentrator than from the tank. But I didn’t find numbers.

I found mention of aircraft devices that can produce pure oxygen, e.g.

US Patent 5,071,453, 1991 – freepatentsonline.com
… oxygen output … in either, dilution mode (less than 100
percent concentrator output) or the 100 percent mode (pure oxygen)

Compared to those of liquid hydrocarbon-burning cars, zero-local-emission cars’ stores of propulsion energy have been significantly less convenient to replenish and much smaller. The bargain they have offered early adopters has not been cachet for a price, but cachet for two prices: pay more and tolerate more inconvenience. Early adopters of tame combustion cars would also have to pay more, but convenience would become one of two benefits rather than one of two costs…

… one such potential convenience … is the option of buying the car and its whole lifetime supply of about 10 m^3 of fuel at the same time. Neither geometry nor prudence would forbid storing the fuel in one’s 200 m^3 basement apartment, and refuelling at home.

Last July 22 I noted at http://www.oxlifeinc.com/freedom5.php a claim that the oxygen denier advertised there would give 300 litres per hour of3 purified oxygen while consuming 0.25 kW. That’s 0.40 kilograms per hour if the temperature is 20°C and the pressure is 1 atm. Weight of the unit, approximately 14.5 kg.

How much power can a boron-oxygen heat engine, with a typical 30-percent heat engine efficiency, make using 0.40 kg/h of oxygen? 1.85 kW. 1.6 kW would be net. A car with 200 kg of the units — 14 of them — would net 22 kW, 30 hp, with which to cruise all day.

Or anyway, that is how it was six months ago. Medical technology developers have been driving rapid reduction in these things’ size and power consumption. Blees performs an invaluable service by writing enthusiastically, but he tends to take American national laboratory authorities too seriously. They’re likely enough to explain to you at length that an oxygen-concentrating boron motor must put at least a third of its output back into oxygen concentration, interrupting themselves only to take a hit of medical oxygen from a device that, as above said, would take less than 14 percent.

Still, without ORNL, the world might never have had that visualization of the word “BORON” swooping spectrally into a gas tank. At http://www.eagle.ca/~gcowan/BonCu2.jpg you can see some actual boron.