Transport is by far the most difficult application to squeeze LENR into but it is the only credible new energy source that has a shot at getting there. Domestic and industrial applications usually have the benefit of a grid to smooth out consumption, no significant space or weight restrictions and in the case of domestic relatively low electric/heat requirements, which makes it ideally suited for CHP generators.
By contrast transport is constrained in many of these dimensions.
The below table should give an overview of the constraints each segment faces, in order of likely adoption:
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Marine
Adoption there will be easy: lots of space, a history of using novel power in the military (nuclear subs/warships/aircraft carriers), very high utilization rates will mean that this segment will convert as soon as practicable. If civilian applications are considering nuclear reactors then LENR will be a no-brainer.
Cars
Any future vision of automobiles will have to include robocars - if you look at the rapid pace of development and the constantly falling costs of technology the odds of this coming through in the next two decades are very high in my mind. Other people have done a lot of detailed analysis on this so I won’t go into detail here. Nicolas Chauvin of lenr-cars has interesting ideas but misses this aspect entirely in his vision.
The reason this is relevant here is because robocars will change car usage greatly: more driving will be done as everyone is a passenger and can just sit back and relax/sleep. Add in zero fuel cost and demand will rise even more. Distances travelled will also go up as many trips will be overnight: at 80mph/130km/h average speed an 8 hour overnight trip creates a radius of 640miles/1040km.
To outline power requirements for LENR in cars it’s helpful to do some simple maths: taking the Tesla S as a normally sized saloon car the 85kWh model at 55mph/90km/h has a range of 265 miles/426km. This gives us a consumption per of 200Wh/km. This speed is usually the most efficient point for a car, consumption rises after this point. As energy consumption rises with the square of speed let’s assume that at 80mph/130km/h we get 400Wh/km. Designing for unlimited range at that speed would therefore require 400Wh/km while covering 130km in that hour, 0.4kWh/km*130km/h=52kW.
Going with existing technology only this 65 kW turbine fits this power envelope. Its electrical efficiency is 29% and I think that with 1000C from a Hot Cat we could get similar numbers. The required thermal energy therefore is 224kW. If the latest COP figures of 12 are true the required drive power would be 19kW, leaving 46kW for driving, almost matching the requirements above.
The thermal requirement divides into 16 14kW hot cats. The total weight of such a package would be 130kg for the generator+16*4kg for the hot cats or 200kg, in line with normal engines. Space is also not an issue and could fit a normal engine bay.
However there are challenges:
• Heat rejection: in an ICE a lot of the heat rejection is done via the exhaust, so there will be an engineering challenge of removing 159kW of heat. Better turbines at up to 50% efficiency (JTEC, SCO2) could reduce this challenge.
• Battery requirement: Ecat drive vs. SSM however probably won’t be an issue given the number of units in the car, which would ensure that most of the time a majority of them are in ssm. A battery would still smooth out dips but for this purpose does not need to be very big. However, startup time is a major issue. If startup time is measured in hours the battery would have to be very large and this would not be economical. The only way to deal with it would be to keep it running 24/7, not an option if parked in a garage and also noisy.
• Running costs: given the number of hot cats the marginal cost for the recharges isn’t negligible anymore; however given the likely hours of use this may never be required. Mass production should make these very cheap as well over time.
• All-weather / shaking robustness: nobody knows yet how these modules would behave under extreme external temperatures and how the shaking from the bumps in the road will affect performance.
Fuel taxes that help finance road building and maintenance would need to be replaced by tolls as part of this transition. With advancing technologies and robocars this would be very easy and accurate to collect, with differential pricing to spread usage. The entire field, not just highways could then be handed to private companies. Given the natural monopoly operators would enjoy governments should still regulate the sector to ensure safety and set pricing caps but largely step back from providing this kind of infrastructure.
A lot of the points made on Brad’s site about robocars talks about not owning vehicles and having the right sized vehicle for the right job in the name of efficiency and lower emissions – I think that with near-zero marginal cost a lot of these arguments go away. Outside city centers people like to know that they have a car exclusively available to them at all times and that it can take them to pretty much wherever they want within a large radius without any further bookings. That freedom is psychologically important and will continue to drive car ownership.
In a slightly more distant future with robocar roads only and more advanced software and even better LENR “engines” cars could speed up all the way to 150mph/250km/h, if safety at these speeds is comprehensively established. If trains can do this on purpose built tracks why shouldn’t ultra-safe cars either…
Demand for short haul air travel is likely to reduce considerably – travelers pressed for time would still pay a premium to get there fast but driving will become more and more viable as the all-in time balance constantly shifts in favor of driving.
Trucks/trains
A lot of points about cars will apply to trucks and trains as well. Adoption should happen faster though as due to high utilization rates the economic rationale is much bigger. An interesting technological demo here is Wrightspeed’s drop-in hybrid part for trucks.
Aviation
Given the catastrophic consequences of technological failure it will be a long time before aviation will be using LENR for propulsion though electrical systems could see this sooner. Unmanned and military planes however have less strict safety requirements and could be the pioneers in this area. In the meantime synfuels could bridge the gap and make this mode of transport zero emission as well.
Space
Personally not that interested, Earth should be our priority!
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Originally Posted by ajb
