Quote from: Jim on 03/31/2013 05:31 pmQuote from: Ludus on 03/31/2013 05:22 pmI'd think Spacex and a lot if other players including DOD would be interested in this if the costs long term were not much greater than conventional sources.Not really. The amount they use is insignificant and would not support the expense of building a dedicated plant.And why is Spacex singled out?For what it's worth, I've heard SpaceX is the largest consumer of RP-1. As far as whether Fischer-Tropsch fuel can be used to replace RP-1, the RP-1 spec (and even more so the RP-2 spec, which is a tighter spec that sits inside the RP-1 spec) is designed to optimize energy density, boiling point curves, and amounts of certain chemical components (such as sulfur, aromatics, and olefins) which have significant effects on combustion characteristics. Both were designed around fuels made from particular feedstocks primarily derived from refined petroleum. In order to be a drop in replacement for RP-1, the new fuel would not only need to meet the spec, but in practice closely match the typical RP-1 composition to match RP-1 performance for use on engines qualified for RP-1. In rocket engines, replicating the exact fuel performance is a much bigger deal than other applications of non-fossil-fuels, such as biodiesel and FT fuel used in cars. Rocket engines are typically operated in a regime where significant changes in heat production rate, evaporation rate, density, surface tension, viscosity, hydrogen content, or constituent fractions affect mixing and combustion in injectors. Similarly, significant changes in heat capacity, density, coking rate, and boiling point curves can effect heat rejection into regenerative cooling circuits. Energy density also affects the performance of a rocket as a whole as a change in the density would cause the vehicle to store more or less total energy. Matching all these characteristics would be relatively difficult to do with synthetic fuels and would require extensive processing of the fuels. This makes it unlikely that a drop in replacement for existing fuels is feasible. This is not to say that a good rocket fuel cannot be made by Fischer-Tropsch, bio-derived, or other alternative processes. And in fact there are several efforts underway to do this. See for instance this article which describes some testing that has been done as well as some of the challenges I alluded to above.http://www.flightglobal.com/news/articles/biodiesel-powers-atlas-rocket-engine-321321/However, at that point you would be better off developing a new specification, and any program that wanted to use the new fuel would qualify their vehicles specifically to operate on it (possibly alongside RP-1).
Quote from: Ludus on 03/31/2013 05:22 pmI'd think Spacex and a lot if other players including DOD would be interested in this if the costs long term were not much greater than conventional sources.Not really. The amount they use is insignificant and would not support the expense of building a dedicated plant.And why is Spacex singled out?
I'd think Spacex and a lot if other players including DOD would be interested in this if the costs long term were not much greater than conventional sources.
Quote from: Ludus on 03/31/2013 05:22 pmhttp://bravenewclimate.com/2013/01/16/zero-emission-synfuel-from-seawater/#more-6020I'm curious how practical it would be for Canaveral or other major space launch sites to produce rocket propellant on site in a zero net carbon method.I think spaceports should launch rockets.Fuel production should be left for petrochemical industry.
http://bravenewclimate.com/2013/01/16/zero-emission-synfuel-from-seawater/#more-6020I'm curious how practical it would be for Canaveral or other major space launch sites to produce rocket propellant on site in a zero net carbon method.
However, at that point you would be better off developing a new specification, and any program that wanted to use the new fuel would qualify their vehicles specifically to operate on it (possibly alongside RP-1).
SpaceX is mentioned specifically because given the association through Musk with Tesla and Solar City, this sort of benefit may appeal to them more.
Quote from: QuantumG on 04/01/2013 03:52 amQuote from: Ludus on 04/01/2013 01:21 amNobody concerned with CO2 and climate change would question that.Yes they would.You're making a logical argument for something you already said was irrational.Any human activity that increases CO2 levels in the atmosphere is suspect to some people. Messing with the oceans just gives them bonus points.Not quite sure what you mean. This does not increase CO2 levels in the atmosphere. I don't think it's irrational, just that the main reason it might be interesting is not it's direct impact (since space launches are a tiny fraction of fossil hydrocarbon use) but it's impact on public image and it's utility as a pilot project for broader uses of the same technology. I think this approach in general has huge promise and it's use for rocket propellant might be an interesting choice for some of the same reasons that Tesla is better off competing with the BMW 7 series than making econoboxes. Rocket fuel is the upscale high image end of the fuel biz. To me people who criticize Tesla for not making cars for the masses don't get the point.
Quote from: Ludus on 04/01/2013 01:21 amNobody concerned with CO2 and climate change would question that.Yes they would.You're making a logical argument for something you already said was irrational.Any human activity that increases CO2 levels in the atmosphere is suspect to some people. Messing with the oceans just gives them bonus points.
Nobody concerned with CO2 and climate change would question that.
Quote from: Ludus on 03/31/2013 05:22 pmCanaveral is sunny, on the sea and has a lot of open space for safety and security that might be used for pv arrays.No, not really. It is a wildlife refuge which is not compatible with array farms.
Canaveral is sunny, on the sea and has a lot of open space for safety and security that might be used for pv arrays.
Would building a "dual fuel" rocket engine be economically and technically feasible?
Do alternative fuels affect aircraft performance? Effects can be positive or negative. For example, lower density fuels can improve fuel burn but adversely affect payload range. The current fuel alternatives can absorb more heat than existing fuels an important factor for newer aircraft with more electronic equipment. CAAFI is exploring all performance impacts.
How would they extract the CO2 from ?1 ) the air
How would they extract the CO2 from ?2 ) sea water
...The SpaceX BFR\BFS system requires this system to synthesize Methane on Mars and in the last IAU speech Elon mentioned the potential to make BFR sustainable by this path....An example system might be an offshore wind farm built in cooperation with a Power company where the grid takes power when it needs it but off peak excess goes to a power to gas plant.LOX production from entirely zero carbon power sources like wind maybe affordable at current cost levels and would be a big step in itself. https://en.m.wikipedia.org/wiki/Power_to_gas
Quote from: Ludus on 10/03/2017 04:58 pm...The SpaceX BFR\BFS system requires this system to synthesize Methane on Mars and in the last IAU speech Elon mentioned the potential to make BFR sustainable by this path....An example system might be an offshore wind farm built in cooperation with a Power company where the grid takes power when it needs it but off peak excess goes to a power to gas plant.LOX production from entirely zero carbon power sources like wind maybe affordable at current cost levels and would be a big step in itself. https://en.m.wikipedia.org/wiki/Power_to_gasCape canaveral is downstream from Orlando, Disney world and a bunch of cattle farms. Modern cities and cows generate sewage. You can inject small amounts of a steam/oxygen mix into a large vat of sewage/sludge and thermophilic anoxic bacteria will produce methane. If you run out of sewage (unlikely) you could add yard waste and other agricultural waste. This requires trivial amounts of energy which could be generated with some of the methane produced. The high temperature generated will kill everything except the thermophilic bacteria which makes it sterile with respect to pathogens. Florida has issues with water pollution. http://www.cnn.com/2016/07/01/us/florida-algae-pollution/index.html Would be best to concentrate the sewage, generate methane, and avoid the algae bloom. But if you wanted to you could collect algae (or duckweed) from open waters and then feed them to the bacteria for methanogenesis. Tourists, turtles and porpoises do not like sludge on Florida beaches. Building bioreactors and associated piping costs infrastructure. There is no need to drain energy from other areas. If the carbon and hydrogen in our rocket fuel are coming from bodies of water it is best to get it before it dilutes the ocean. Pipping ocean water inland and then adding energy to process it would be very wasteful.
Quote from: Jim on 03/31/2013 05:31 pmAnd why is Spacex singled out?He's just following the general rule of NSF, which basically is that the longer a conversation goes on at this site, the chance of Spacex appearing in that conversation approaches 100%.
And why is Spacex singled out?