| Can we build an efficient hybrid solar-natural gas engine that emits no CO2?19-12-2014 01:29 | |
| Chondrally☆☆☆☆☆ (2) |
The politicians couldn't understand or respond to this even with all their advisers! In the following you can liberally substitute a conventional internal combustion engine for the turbine. The fuel efficiencies still apply, even though the energy transfer to wheels is only about 20-24%. The gas turbines would be necessary in a power plant version. Almost Perpetual motion exists in biology , its the coupled symbiotic reactions of respiration and photosynthesis where energy is supplied by the sun, also it exists with genetics and catalysts. this system of equations is NOT perpetual motion, and in fact the overall sum is endothermic, requiring energy from wind/solar or nuclear (non fossil fuel). The coupled reactions of CH4 + 2O2 --> CO2 + 2H2O (1)which is exothermic respiration combustion -74.6 + zero -->-393.5-2(285.8) =74.6-955.1=-880.5kJ/mol/K so this reaction is exothermic (gives off heat) and proceeds spontaneously. is coupled with the following reactions 4H2O --> 4H2 + 2O2 (2) by electrolysis 90-93% efficient with catalysts ( the 4H2O coming from the 2H2O in (1) and (3) respectively) 4(-285.8)--> zero + zero gives 1143.2 kJ/Mol/K/.9 = 1270.2 kJ/Mol/K is what this reaction costs and it is endothermic 4H2+CO2 -->(nickel or rubidium alumina catalyst)--> CH4+ 2H2O =-74 kcal *4.184kJ/mol/K/kcal=- 309.6kJ/mol/K (3) 74kcal =309.6kJ/mol/K is the experimental amount of energy that this reaction produces exothermically Carbon Dioxide Methanation on a Ruthenium (or Nickel) catalyst. http://pubs.acs.org/doi/abs/10.1021/i260049a005 http://www.sciencedirect.com/science/article/pii/002195178090456X as it gives off heat (but the reacting gases need to preheated to 300K or thereabouts). So the three reactions require a total of 1270-309.6-880.5+(heat to warm gases to 300K) kJ/mol/K to be supplied by wind/solar or nuclear for these three reactions to proceed. We need also to separate water from two of the reactions requiring cooling to 90 degrees Celcius at least and then heating of the gases to 300 degrees Celcius prior to catalytic reaction. All of this requires more energy still. . It wouldn't be possible at all without the catalyst being able to make the C and O2 while still bonded to some degree quantum mechanically accessible from the CO2 to the 4H2 chemically for such a low energy of activation cost. Together these coupled reactions can cycle endlessly if their rates of reaction can be controlled to allow them to react in a commensurate time frame. Parallelization of reactors helps in the second case to achieve the overall rate equivalency in terms of mols per unit time processed because the reaction (3) has a much slower time constant than the combustion reaction (1). This is NOT perpetual motion just like respiration and photosynthesis are not perpetual motion.You can argue that the catalyst provides energy bonds that hold the CO2 bonds temporarily in place while the H2 reacts with the molecule quantum mechanically and that the O2 at the beginning of the combustion reaction is added to the whole system from the environment, producing energy in combustion. There are waste products in the combustion, CO,NOx etc... in trace amounts and their is a need to top up the combustion process with natural gas. The reactions require energy to proceed like from wind /solar/nuclear. So it is not very practical except as a source of methane for the plastics industry. This process recombines CO2 back into methane which is a well documented Methanation process. Also Amine distillation towers can separate the CO2 from the other exhaust gases and deliver it to equation (3) in a quite pure form to be combined with the 4H2 from the electrolysis. Energy for amine CO2 separation must be provided from the total energy of the system, which i believe might be possible from wind/solar/nuclear. But it the methanation reaction that requires energy and the electrolysis which is endothermic, it requires energy in order to proceed. Also Electrolysis of water alone requires more energy than is provided by the combustion of methane. So the overall net energy balance is one requiring outside energy. For plastics production, providing the power for electrolysis and methanation is worth it in the end, but not as cheap as a ready supply of methane from coal supplied by microbes, or natural gas from gas wells. The Natural Gas/Methane Engine is a thermodynamic possibility only with added energy from solar. The hurdle is really the electrolysis. the following might spur innovation: Hydrogen Evolving Solar Cells. http://www.tandfonline.com/doi/abs/10.1080/01614948408064730#.U1tSactOXyc If this could be done by concentrating light, or better yet by concentrating heat from combustion, upgrading the quality of the light to achieve the 1.4 eV needed with tandem cells or single cells, that might do the trick. A regular internal combustion engine at 24% efficiency uses about 7 Litres of C8H18 (octane) per 100 km, or C8H18 + 12.5 O2 --> 8 CO2 + 9 H2O -250.1 + 0 --> 8*(-393.51)+9*(-241.826) gives 5074.414 kJ/mol/K released thermodynamically by 1 mol of octane where 1 mol of C8H18 = 12*8+18=96 + 18=114 g/mol gives 1/114 mol/g*.6986 g/ml*7000ml = 42.89 mols of octane per 100 km. gives 42.89 mols*5074.414 kJ/mol/K *.24 =52234 kJ/K or 52.234 MJ/K are required by the engine at 24% efficiency Methane produces CH4 + 2 O2 ---> CO2 + 2 H2O -156.3 + 0 ---> -393.51+2(-241.826) yields -720.862 kJ/Mol/K for 1 mol of methane So at 60% efficiency in a gas turbine we need 52.234/.6=87057 kJ/mol/K produced by natural gas or methane combustion in a 60 % efficient turbine this gives 120.8 mols of methane required or at 120 psi this is 362 Litres of methane required Chapter 3 of Astrophysics in a Nutshell by Dan Maoz, equation 3.6 The sun delivers 1400 Watts/(square metre) at the top of the atmosphere and about 1000 W/m^2 at the earth's surface on bright sunny days, and if heat can be upgraded by nanotechnology to electricity as Ted Sargent had originally promised, then maybe it will be possible after all. Thermocouples are a valid way of converting a temperature gradient into electricity but are not very efficient yet. More research is needed with nanotechnology. Today is a low light day=5000 lux (4 pm on Friday,April 26/2014 - a darkish overcast day in Halton , Ontario), at room temp (25 degrees Celcius) we need about 362 litres of methane per 100 km through the turbine per hour or N=120.8 mols/hour=.03356 Mol/sec we need about 24.2 Watts/K to run enough electrolysis and methanation for .03356 mol of gas/sec, or at 10000 lux = 100 Watts / m^2 yields 80.67 Watts/ Square Metre at 30% efficiency yields about 1 metre^2 is what we need in a solar panel on a low light day to generate 81 Watts=Joules/second of electricity. So between about 1 m^2 should do it. Its in the right ball park. There were moments of the day , a little brighter , that measured 17000 lux. On bright days at noon it is 100,000 lux. If we used a battery, we could store this electricity and average out the requirement and get by with only 1 m^2 for all circumstances...!!! http://www.amazon.com/Astrophysics-Nutshell-In-Princeton/dp/0691125848 Solar nanotechnology report on Ted Sargents Colloid Quantum Dot technology http://soscip.org/impact-report/energy.html http://en.wikipedia.org/wiki/Thermocouple ______________________________________________________________________________ ______ The combustion generates 880.5 kJ/mol/K and the methanation takes 360 kJ/mol/K. So if electrolysis can be achieved for next to nothing with solar energy input. We have a viable Natural Gas/Methane Engine, which would be non-polluting of CO2, only trace NOx,CO, and it would be extremely fuel efficient, perhaps achieving 3000 to 5000 km per fillup. And it could provide heat either for nanotech solar cells or just to heat the passengers in winter. Likewise the combustion turbine generator could provide electricity to power the electrics of the vehicle. 29 January 2014 - 1:49am The methane engine is a dream to aspire to: Reality sets in: Natural gas is the most likely source of methane commercially at the present time. it contains varying amounts of methane, propane and butane, as well as sulphur compounds to give it that noticeable odour so that it is detectable if it leaks. Natural gas can be used directly in this engine, The CO2 can be captured with amine techniques and probably not with zeolite techniques, as zeolite performs well in the lab, but in a real world engine it clogs pretty quickly, and there is no easy way to unclog it without some breakthrough or new material. Similarly for the zeolite that supposedly would separate the CO2 from the other exhaust gases. Natural gas varies in its concentrations of methane, propane and butane from week to week and source to source. A real world system would have to be able to handle this variation. Any carbon combustion process, even in turbines, produces soot and nitrous oxides and other carbon compounds. This would have to be filtered from the exhaust gases on a regular basis, so an air filter to trap the soot is required, perhaps an electrostatic air filter. The residual soot will clog the zeolite filter. Zeolite only works in labs, not for any real length of time in a real world industrial chemical process except in rare special cases where multi millions of dollars have been spent to crack a single chemical problem. I'd love to know how CO2 is sequestered from coal plants and methane power plants, time to google search!!! ;-) http://irgc.org/wp-content/uploads/2012/04/power_plant_co2_capture_CN_23... amine techniques are now most favoured for CO2 capture.... as of 2009 (some in use since the 1930s). http://sequestration.mit.edu/tools/projects/index_capture.html http://www.iea.org/publications/freepublications/publication/costperf_cc... http://shadow.eas.gatech.edu/~kcobb/energy/Readings/rochelle2009.pdf http://pubs.acs.org/doi/abs/10.1021/ie801002m?prevSearch=amine%2Bcapture... http://pubs.acs.org/doi/abs/10.1021/ie801002m http://www.southalabama.edu/chemistry/davis/reprint6.pdf This last paper appears to indicate that an amine related compound could do the trick instead of zeolite for capturing the CO2 then releasing it elsewhere. These problems cannot be solved without chemistry knowledge or education. Tom Cruise isn't going to solve them and neither is John Travolta or Kate Blanchet or Leonardo Dicaprio. The solution probably will come from a multi-billion dollar multi-national corporation that will charge through the nose for it. Their competition is fierce, and a lot is at stake. Often they have an interest in preserving the status quo, because thats their only cash cow at the moment. Relax and enjoy life a bit. Its too short anyway, and we need to have healthy food, R&R, and decent exercise as well as productive work to keep us busy with a purpose. New methane engine that recycles and emits no CO2, and is very very fuel efficient with turbines, drastically reduce emissions 20 January 2014 - 5:41am The gas turbine in the engine plan is 60% efficient and can be improved to 90% efficiency with a dual system involving a steam turbine to take advantage of all the heat produced in the gas turbine. A separate steam turbine at 90% efficiency can be run from the reactors that convert 4H2 + CO2 -> CH4 + 2H2O(steam), the steam can drive this turbine separately from the other two. this 2H2O can be combined with the 2H2O output as a result of the methane combustion in the gas turbine, CH4 + 2O2 ->CO2 + 2H2O. So 4H2O can be conversted by electrolysis at 90% efficiency with potassium electrolyte (or better) to achieve 4H2O -> 4H2+2O2, the oxygen can be recycled to be the input to the gas turbine or can be exhausted to the environment, as air can be input to the gas turbine from the atmosphere, as we need the nitrogen gas and argon to moderate the rate of the combustion process. The nitrous oxides and argon and excess methane are exhausted to the environment after CO2 and H2O are separated from the exhaust stream, and heat is recaptured with a heat pump , moving the heat to the water/steam cycle generated by the catalytic reactors that convert CO2 back to CH4. two or three zeolite sieves out of phase with each other in parallel can separate CO2 from the exhaust gases of the gas turbine and with very high purity, pass the CO2 for mixing with 4H2 in a heated manifold that expands the gases in volume, while reducing pressure and flow rate to prevent explosion at the critical compression ratio of H2 and heat that would happen in constricted volume under heating and mixing as the temperature and pressure increase beyond acceptable limits. A careful design methodology needs to be applied in Comsol Multiphysics to design the efficient turbines on a small scale and model the reactors and duty cycles with a Matlab control system to generate electricity from each turbine for an even more efficient conversion of chemical reactions energy to electrical energy which could be used to power a home or power an electric motor, the heat can be vented in summer, the electricity can run air conditioners in summer; the heat can be used directly to heat the home in winter, spring and fall. Quinone batteries can be used to store energy to power the home continuously during off duty sections of the cycle to control temperatures and power output (see previous post). greenparty.ca/blog/169 for more information..... So this seems very favourable for achieving very efficient energy conversion and with little fuel consumption per cycle, with few emissions to the environment, only trace gases. This could revolutionize the energy situation and solve peak oil/methane, and render homes immune from the vicissitudes of the grid, thus providing security to homes in power outages and snow and ice and thunder storms which will become more numerous as climate change progresses. This engine could allow geo-engineering on its own. It does not reverse the process, and we still need to work on that, but it does effectively halt the progress of it. Solar research and solar power promise much, but its really also the Peaceful Thorium Nuclear that needs to be pursued: Generally speaking i am against nuclear power (political , military or energy), but i fail to see a way to supply enough non fossil fuel energy without it and let the climate recuperate. I would say it would be too late for the ocean based on my pH calculations within the 8 year deadline. But if enough nuclear thorium gets achieved in the next 20 years and nanotechnology delivers on electrolysis from heat or light, the ocean may yet recover in time. We should not give up hope on this front. Natures recuperative powers are considerable. Life has a strong will to live, and the living ocean wants to live. Lets hope we all make good choices. As Al Gore's book said 'It's our choice'. He also has his new book out 'The Future'. Without resonance techniques like those employed in music, there is no free lunch. And those are faddy and don't last indefinately but keep having to be changed like with any ear worm. There must be something wrong with using 1 m^2 solar to do electrolysis on a regular basis, within an engine cycle, otherwise people would already be doing it like crazy, the hydrogen and oxygen released alone are sufficient fuel but they can't be stored. They'd have to be utilized as a fuel at the point of generation (or a little distance away in a cylinder). The oxygen can be stored but there is no really acceptable way to store hydrogen gas as of yet except temporarily in stainless steel. Also it is too unstable and too dangerous to store as it leaks almost always and many many people have been hurt working with hydrogen gas, when it has exploded unexpectedly. Noone who knows chemistry really trusts it as a fuel. It causes embrittlement of metals that it passes by and thus corrosion on a very real basis. So i don't trust any engine that makes use of hydrogen gas. Fuel cells are too limiting , because they rely on platinum and rare earth metals and they are too expensive and there just aren't enough of them to go around on a mass production basis. That was the flaw in the Ballard fuel cell approach and market model. We can turn CO2 into limestone by injecting it as a liquid carbonic acid into basalt rock. Perhaps thats what we should do with all the CO2. But that requires calcium carbonate, and that, though in abundance, is limited as a sink in and of itself. Only thorium nuclear makes sense. As much as i hate to admit it. The US Department of Energy is working on thorium nuclear after the work of Eugene Wigner and Enrico Fermi who built the first sustainable fission reactor for thorium in the 1950s and 1960s; the Chinese and the people of India are all working on thorium nuclear reactors (witness Baba reactors). SNC Lavalin in Canada, that took over from AECL (Atomic Energy of Canada Ltd), is working with both the Chinese and the people of India. They really give us no choice. If we accept we have a choice... to choose to be a forest manager for instance or a forest ranger, then all we really need are fertile soil, fresh water and fresh air. Perhaps, like Schauberger, thats what we should choose. |
| 20-12-2014 20:41 | |
| orogenicman★☆☆☆☆ (57) |
It is customary, and also required by the user rules, to attribute to the author items that you have copied and pasted into the forum. It would also be a lot easier for all involved if you would, instead of posting the entire citation, to post a brief summary followed by a link to the article. Just sayin |
| 29-01-2015 13:54 | |
| greyviper☆☆☆☆☆ (44) |
The thread starter's post is quite a bummer. I mean he could have broken it by components and made it simpler. He does, have nice idea. It only needs to be harnessed well. |
| 05-10-2017 04:36 | |
| ChristianC123☆☆☆☆☆ (6) |
All new technologies need to be tried to find their strengths and weaknesses. Until one uses a new full-scale system, one doesn't dig out the engineering problems. CO2 emissions are dropped by more than 90% for each unit of electrical power, and we are learning how to make systems better.It would be interesting to compute how much CO2 is reduced by the "speckled" use of gas Regards, Christian |
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