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This topic is inspired by recent discussions on electric vehicle technologies. Back in 2014, Peugeot produced a prototype petrol-compressed air hybrid, that was demonstrated to achieve an incredible 141mpg.
https://www.torquenews.com/1080/peugeot … k-air-cars
The manufacturing of these vehicles would have been substantially cheaper than petrol-electric hybrids, because the drive train required minimal changes. Peugeot produced the prototype and were looking for commercial partners, but astonishingly, none could be found. The petrol-air hybrid would appear to be a colossal missed opportunity.
This brings us to the topic of Mars rovers. The low temperatures prevalent on Mars, mean that very little compression work is required to compress CO2 into a dense liquid. Diesel engine exhaust gases have temperature of 500-600°C. This raises the potential to use waste heat from the diesel engine to boil and superheat liquid CO2. Because the CO2 begins as liquid, with density comparable to water, extremely high pressure and expansion ratio can be achieved, allowing liquid CO2 to efficiently convert waste heat into mechanical power in a turbine with very high power density and low weight.
The idea would be to distribute simple and lightweight solar powered compression stations across the Martian surface. Rather than attempt to synthesise methane oxygen, these would fill a tank with compressed CO2 liquid. The rover would fill a tank with liquid CO2 at these compression stations. By using waste heat to raise mechanical power in a lightweight expander, the fuel economy of the rovers' methane-oxygen engine would almost double, in effect doubling its potential range or halving the required volume of methane-oxygen.
A similar means of increasing yield could be accomplished for other power generation. For digging equipment, liquid CO2 could reduce the methane-Oxygen consumption. It could also be used to boost the electric power yield from a Kilopower unit, given that compression of the CO2 would require less energy than it would release when expanding hot.
Last edited by Calliban (2021-11-17 22:37:39)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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Calliban,
I was beginning to wonder if we'd ever get around to discussing potential solutions with at least a chance of actually working as envisioned.
Thanks for the link. That's a very interesting little development.
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The Peugeot appears to be closer to what was called a hydraulic hybrid in the US. This captures braking energy in a hydraulic cylinder for launch assist. This allows use of a small 1.2 litre engine without sacrificing acceleration. At least part of the fuel efficiency savings occur due to reduced weight. The car was an attempt to push fuel consumption as low as possible whilst retaining the comfort and characteristics of a normal car. It appears to have failed because it was not considered radical and exciting enough.
The experimental vehicle effectively proves that it is possible to build a 100+ mpg car without sacrifice of performance. The significance here is that with fuel economy in this range, there is far less urgency from problems relating to fossil fuel depletion and peak oil. At 120mpg, the price of fuel could double and still be affordable.
At these price ranges, oils resource base is substantially larger. And synthetic fuels, created from biomass and tar sands through flash pyrolysis and upgrading using heat and hydrogen; are more affordable. Another century of ICE transport is within reach if we can use simple hybrid systems and vehicle weight reduction, to achieve vehicles that get 100mpg. People are getting poorer for reasons already discussed. They need vehicles that are affordable to them with lower disposable income than might have been achievable in the past. And my guess would be that they would be prepared to compromise on expensive but unnecessary add ons if it meant that the end result was something that they could afford to buy and run. A small and lightweight hybrid like this is exactly what is needed in a world of higher resource costs, not idealistic all-electric solutions that cost more and deliver less.
Last edited by Calliban (2021-11-17 23:19:55)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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Calliban,
Seemingly mundane yet very practical technology is frequently ignored in favor of futuristic gadgetry that never quite works as well as envisioned. I could get behind something like this, or an air powered vehicle, because it doesn't require expansion of the existing electric grid to a bare minimum of a two orders of magnitude multiple of the current grid capacity. People who think they can demand 100X more power without also supplying 100X more power, are not dealing with reality.
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It astounds and depresses me that people are actually trying to stop development of the Combo oil field. As any decent economist will know, the fastest way to sink an economy is to cut off its supply of energy. That is what cost the Germans both world wars. In both cases they had better technology. But without resources technology has no meaning. A tank without fuel is a monument. A soldier without oil powered supply lines will lack food and ammunition and will rapidly be overrun. An economy with less energy will produce less and people will be poorer. I have never understood why people have trouble understanding that. And the fuels that run almost 100% of goods transportation are diesel and kerosene, two middle distillates of oil that don't come from anywhere else. Presumably, we are concerned about global warming because of the impact it may have on human health and prosperity. Want to know how to destroy human health and prosperity straight away? Shut down the supply lines that keep them warm, fed and clothed. Those supply lines run on diesel power and nothing else.
https://www.zerohedge.com/energy/800-mi … on-trouble
UK oil product consumption is about 1.5m barrels per day. Production is less than half that. An additional producing 800m barrel oil field could cover a year of UK consumption. Too many people in the UK are entirely disconnected from reality. I once watched a UK based environmental group board an oil rig to protest against oil production in the name of climate change. They got within a few hundred yards of the rig in a diesel powered fishing boat. They then donned lifejackets and warm clothing made from polymers, before boarding dinghies made from polymers and started the petrol engines that took them up to the rig. They then proceeded to climb up the rig, using polymer ropes, before unfurling a giant sign made from polymers, carrying a message written in polymer based ink. One of them got stuck and had to be rescued by helicopter that burned aviation kerosene. At no point do these people appreciate the irony of what they are doing.
Greta Thunberg is the archetypal champaign socialist. A young woman who wouldn't be alive without fossil fuelled agriculture and is clueless about just how much fossil fuel goes into maintaining her cosseted lifestyle. How easy it is for her to stand behind a microphone and shout "How dare you!" at the people whose job it is to keep her safe and well fed. How dare she! How dare this uneducated teenager, with living standards beyond the dreams of her own ancestors, lecture the world about problems she doesn't understand? What a brat! For her to complain about global warming is the moral equivalent of a wealthy Roman complaining about the health hazards of slave shit. If this woman wants to help, she should go to university and get an engineering degree. As things stand, I am clueless as to why anyone listens to this stupid and naive teenager.
It will be extremely difficult and expensive to maintain first world lifestyles without the consumption of fossil fuels, especially oil. There just aren't that many options for replacing it that don't suffer from either poor energy density and range, high embodied energy, cumbersome infrastructure (I.e rail) or energy sources that people object to (fission). And most people don't appreciate just how much additional infrastructure would be needed to replace transportation and heating with renewable electricity. The systems would be country sized and the embodied resources would exceed those invested in the entirety of human infrastructure that has been built to date. Trying to do this using an energy base that is shrinking makes it all but impossible to achieve the energy transition without large declines in living standards and human wellbeing. Of course, that is the side of this problem that no one wants to talk about and most of the green lobby appear to be barely aware of.
The declining EROI of oil, coal and gas production receives virtually no recognition in official or environmental circles. Yet its effects have been dragging on the living standards of OECD countries for longer than I have been alive (I am 42). This problem severely constrains the solution set for eliminating fossil fuels, because a shrinking energy base makes it impossible to build new infrastructure without simultaneously reducing disposable consumption (I.e living standards). Living standards are already sliding for most people in the west. Wealth inequalities are rising. Government tax receipts cannot cover budgets anywhere now and spending levels are sustainable if interest rates remain low. Under these circumstances, we need to look for easy wins in reducing dependence on fossil fuels. Nuclear power, expanded on a scale that can exploit scale economies in supply lines, is one way of reducing fossil fuels needed in the electricity system. Renewable energy may have niche applications, but its high infrastructure embodied energy and need for backup, make it a poor way of reducing FF dependence. Hybrid vehicles and smaller more efficient cars are a relatively easy win. Biomass fuelled ships. More walkable towns and cities and cycling for short range trips. Extension of rail infrastructure for freight. Hydraulic hybrid trucks. Passive solar and ground source heat pump based heating. Combined heat and power and home thermal energy storage with electricity storage. None of these things are exciting to idealistic people. They are about reducing rather than eliminating FF dependence and doing so in ways that avoid increasing energy expenditure and infrastructure costs that no one can really afford. The transition to a non- fossil economy will take at least another century. It will be incremental, rather than revolutionary. A lot of people don't want to hear that. Idealists are fond of revolutionary solutions. Those are the solutions that tend to leave people hungry or dead.
Last edited by Calliban (2021-11-18 05:42:26)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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So a mars deseil engine would require it to be able to carry the co2 compressor which is either heat driven or mechanical to save that as a liquid in a tank. The fuel for the desiel must also carry the oxidizer and fuel for the engine to run. I would hope that the exhaust would be added to the intake of atmospheric co2 to increase the volume stored. That makes this a mass equation for the vehicle carrying it as well as for doing the work it needs to do. A bull dozer would be ok but a light transport would be at a disadvantage.
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