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‘Solar’ jet fuel made out of air

• dia80 13y ago
  Articles claims 20k litres per day from 1km sq. solar farm maybe possible in the future. At current (retail) prices that's about 10,000GBP per day or 3.5M GBP per year. Doesn't sound like a lot to run a 1km sq. facility...
  • notahacker 13y ago
    Ironically, the areas with an abundance of sun and low-value undeveloped land near major aviation hubs tend to be in petro-states...
    • NegativeK 13y ago
      Sounds like a match made in heaven.
• Tloewald 13y ago
  $18.25/year/square meter at $2.50 per liter of kerosene. The US currently generates 0.6kg/year/square meter of cereal -- and that's on fertile (irrigated...) land. So, assuming that most of the plant is low maintenance and not too expensive to manufacture it's not that bad. Certainly I don't think that turning corn into fuel is anywhere near as efficient.
  • masklinn 13y ago
    Where do you get the $2.5 figure? According to http://www.transtats.bts.gov/fuel.asp http://www.transtats.bts.gov/fuel.asp, in 2013 the average was $3/gal of kerosene, or 0.8$/liter.
    • Tloewald 13y ago
      I got the figure from Amazon (having guess $4/gallon initially) but am happy to stand corrected. Even so, far more efficient than corn -> ethanol.
• z3phyr 13y ago
  This is one of the concepts I actually thought about, when I was in middle school. Really excited about it again :) One thing I want to ask right now, Will the ratio between the input carbon consumption and the carbon emission + residue remain the same in such a process?
  • eloff 13y ago
    How could it not? It's not a nuclear process so carbon in must equal carbon out. All carbon is sourced from the atmosphere and returns to the same. There may be different ratios of carbon compounds though, e.g. less co2 out than in and more other types of carbon compounds out.
    • z3phyr 13y ago
      It is highly likely that CO will be a possible residue. Could it be considered a lot more harmful in a different way?
      • dredmorbius 13y ago
        In unconfined spaces, CO tends to dissipate. It's fairly reactive (binding with O2 to form CO2) and will be pretty short-lived. Not something to worry about. https://en.wikipedia.org/wiki/Carbon_monoxide https://en.wikipedia.org/wiki/Carbon_monoxide
• dkokelley 13y ago
  For comparison, global jet fuel consumption for major airlines in 2013 was over 60 billion liters. (http://www.transtats.bts.gov/fuel.asp http://www.transtats.bts.gov/fuel.asp) My envelope calculations show that we would need 8,334 km^2 (roughly 3% of Nevada) of plant space at 20k liters/day to roughly cover global jet fuel consumption. (I welcome sanity checks on this math.) That's actually an encouraging and apparently achievable number.
  • yxhuvud 13y ago
    I wonder what the energy consumption would be though.
    • dkokelley 13y ago
      How do you mean?
      • rozap 13y ago
        I think he means that a lot of experimental energy sources require more energy than they produce, so it's a net loss.
        • bdamm 13y ago
          This problem is worth dedicating a few nuke plants to the problem, if in fact all you need is 1500 or 2200 deg C. Especially in Nevada, which has plenty of radioactive surface already.
        • dkokelley 13y ago
          Isn't the point that this process can be completed with the components in the air and the energy from the sun? At ~15% efficiency we're losing 85% of the potential energy from the sun, although we were previously capturing 0% of it. It should take an insignificant amount of input energy to begin the process, and then be a net energy positive for us.
          • 13y ago
• phorese 13y ago
  Anyone know what the "purge gas" is in the O2 half cycle?
• jbert 13y ago
  This is the 2nd part of the "we need lots of clean/carbon free energy" - a way of storing and transporting it. Chemical fuels have a great energy density. Problem is, they dump carbon into the air when you burn them (and also basic pollutants). So we just need: 1) fusion or similar "lots of 'free' energy" 2) a process like this to soak up that energy + CO2 + H2O and emit nice energy dense hydrocarbons 3) decent catalytic convertor/filter tech (we're pretty good on this at the moment when we want to spend the money?) then we've got a long-term energy future.
  • Dn_Ab 13y ago
    Chemical fuels have a great energy density. Problem is, they dump carbon into the air when you burn them (and also basic pollutants) Exactly! > So we just need: 1) fusion or similar "lots of 'free' energy" Utilizing geo, hydro and solar (carpeting them in inhospitable areas) and fission is enough. Fission is particularly effective, the energy yield per kg of fuel for fusion is only 4x that of fission. Between less wasteful alternate reactor designs and extracting fuel from the ocean, if we start figuring things out now, things will be fine. > 2) a process like this to soak up that energy + CO2 + H2O and emit nice energy dense hydrocarbons This is well studied by the US Navy and others. It's especially cost effective when drawn from the ocean. Wikiterms: 'sabatier reaction', 'power to gas', 'carbon neutral fuel'. > then we've got a long-term energy future. We're still going to have to act quickly, before the energy (and resources) required to initiate this industry is more than could be had with the then current reserves. A true debt. Thus squandering the selfless sacrifice made by dinosaurs many kilomillennia ago in order that we at least could bootstrap a space faring civilization.
    • XorNot 13y ago
      It's a hilariously under-appreciated fact that the US military is on track to be one of the biggest investors in green power and fuels, as both are major logistics hassles and strategic concerns for it. The USAF would love to not have to worry about the long-term availability of fuel oil, and just depend on a desert array of concentrators somewhere in the US.
• ndonnellan 13y ago
  Now we just need to figure out how to keep a quartz window from shattering after cycling from ambient to 1500C ...every time a cloud passes.
  • durkie 13y ago
    why? it seems like it'd be one of the best materials out there - it has a super low coefficient of thermal expansion, especially in comparison to many other materials.
    • ndonnellan 13y ago
      Oh it absolutely is, but if the chamber is under pressure (which they don't mention, but probably affects yield), there still will be a lot of stress. Syngas solar receivers are one of the unicorns of the solar industry.
      • durkie 13y ago
        interesting -- i wonder if they could have a 2 lens system where your overall system would look like: sun / outer lens / pressurized gas / quartz lens from diagram / reactor you could adjust the pressurized gas chamber pressure to match that of the reactor so that you're subjecting the quartz lens to a net zero bending moment/tension. ideally you could then make the outer lens out of something tougher than quartz and it wouldn't need as much high temperature strength since it's farther away from the reactor.
• danielweber 13y ago
  I post about LANL's "Green Freedom" every once in a (long) while, so I really enjoy more articles about manufacturing liquid fuels from atmospheric CO2. One issue I've found is that it can be expensive to concentrate CO2 from the air to feed into this process. For the first version, I would recommend putting it on the smokestack of a coal or natural gas plant, which is putting out majority-CO2. It's not getting us carbon neutral fuel, but it gets us double-use out of each CO2 molecule, and it makes the first version much easier to build.
• oDot 13y ago
  Where will the water come from?
• jboggan 13y ago
  Sweet. Venus has a very dense CO2 atmosphere with negligible amounts of oxygen and about twice the insolation of Earth. Let's set up some high altitude blimps above the cloud layers as floating solar syngas factories. I'm a little busy right now but in 10 years when Musk has the launch vehicles figured out I think we should do it. Edit: I didn't type it because I thought it was obvious, but this would be producing fuel for rockets and other vehicles operating in exploration, not for bringing back to Earth to put in your car.
  • bhousel 13y ago
    It's not too early to patent the process..
  • nostromo 13y ago
    I wouldn't look to Musk to create cheap and environmentally friendly hydrocarbon fuels. ;) At least not until every house already has an outlet for their Tesla.
    • jboggan 13y ago
      I hope Musk would have better business sense than lifting hydrocarbons from Venus back to Earth in order to burn them in cars! This would be for fueling transport and exploration of the solar system, it's always cheaper to make it there than bring it with you.
    • trhway 13y ago
      i think efficient fuel cells converting "cheap and environmentally friendly hydrocarbon fuels" straight into electricity would definitely be of interest to Musk - replace the 500Kg battery with 200Kg of the cell and the fuel and double the range of the Tesla. Of course there is also batteries (metal-air) with 10x capacity vs. current lithium-ion - in couple years they may make even the above mentioned fuel cell improvements obsolete.
    • mikeash 13y ago
      I don't see why not. He builds electric cars, yes, but he also builds rockets. Falcon 9 burns kerosene with liquid oxygen and burns about 30,000 gallons for a launch.
• tim333 13y ago
  Hope it works. Another interesting approach is Algenol's using algae to make ethanol - they've been saying it will be up an running any moment for a while now but you never know (https://en.wikipedia.org/wiki/Algenol https://en.wikipedia.org/wiki/Algenol)
• sespindola 13y ago
  some physicists at Sandia labs have been working on a similar technology: the counter rotating ring receiver reactor recuperator, or CR5[1]. Though it seems to be a long way from reaching the necessary efficiency for it to be comercially viable. It was festured in Daniel Suarez's Freedom, as the main fuel generator for a native self-sustaining community. [1] https://share.sandia.gov/news/resources/releases/2007/sunshine.html https://share.sandia.gov/news/resources/releases/2007/sunshi...
• zackmorris 13y ago
  Converting sunlight to heat is trivial, at 1368 watts per square meter. The problem has always been energy storage. A single acre is 4047 square meters, or 5.54 MW (7429 hp). As a rule of thumb, I generally divide the area by 3 because collectors are usually arranged in troughs, slightly spaced for low sun angles. Still, thinking in terms of 1 MW of heat per acre, or 2000 hp, puts things in perspective. Dams and power plants are usually in the GW range, so it would take 33x33 acres to capture 1 GW of heat. Since an acre is about 209 feet on a side, that's between 1 and 2 square miles. At the quoted 1.73% efficiency, we'd have to multiply by the inverse, 58, to convert from heat to fuel. So we're talking 50-100 square miles to create the output of a GW power plant for say 8 hours of daylight. Figure a 200 square mile plant to withdraw 1 GW worth of fuel continuously. However, we get down to the 20-40 square mile range if they can get the efficiency to 10%. Of course this all ignores the combustion efficiency which is probably only about 25% so we have to multiply by a factor of 4 again. Probably a more practical way to store energy, and in my mind the most likely way to power vehicles, is compressed air at 300-700 atmospheres, which is within the same order of magnitude energy/mass density as batteries, depending on the storage tank: https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density A solar plant can be built on top of an empty natural gas well and store energy in compressed air underground. Another possibility is compressed air in large bags at the bottom of the ocean, that would displace less water than a dam since the height difference can be several thousand feet (pumping water uphill is not very effective due to the elevation required). We’ll also never have enough batteries or supercapacitors to store that much energy. I wish I had money to invest in fiberglass or carbon fiber wrapped storage tanks and micro turbines/pistons that convert the energy in compressed air to rotational energy. I think we’ll be using them instead of something more exotic like magnetic bearing flywheels, and future electric cars will have a small natural gas/hydrogen turbine that tops off an air tank that will take the car 10 or 20 miles without having to tap into batteries. Also, refilling air tanks at a fueling station can happen almost instantly, at least as fast as filling up with gasoline. Still, I think making hydrocarbons is an exciting development for distributed generation, where people are only making a few liters of fuel a day from water basically. I imagine that it might be more efficient to make propane also, and this is a little off topic but propane engines are much easier to build/more efficient because they don’t have carburetors or fuel injection. I’m honestly surprised the world went with gasoline and diesel, although it was probably for safety reasons.
• Gravityloss 13y ago
  It's remarkably stupid to burn coal in a power plant and then in the neighboring lot trying to take the carbon from very diluted (less than one part per thousand) carbon dioxide in the air. If these solar plants just fed the electricity into a well built power grid, the coal plants could be turned off and a huge amount of CO2 would be left unemitted. Coal is unbeatable as a carbon storage method, and what's best, it's free as it already is in the ground, we just have to leave it there! I'm sorry to say, but most of these energy schemes just make many people who understand anything about power generation cry. It's like to an IT guy, some client suggested you ran their enterprise databases on an Arduino over Bluetooth, because they heard it's a cool new thing.
  • icegreentea 13y ago
    The point is to make more super energy dense liquid fuel for mobile applications that require that density. IE, airplanes. Thats the reason why the are seeking to make jet fuel specifically. The energy density requirements for flying makes the current headaches over EV cars look like a joke. The scientists and engineers have no illusions that this method will be used for general energy generation. This is for a niche application. And the 'sequester carbon from the air' part? All they care about is that its carbon neutral. And honestly, it's pretty smart. Pretty much a guarantee way to get defense funding all around the world.
    • Gravityloss 13y ago
      You would have a better climate impact by just creating coal replacing grid electricity with the panels, and flying the airplanes on normal kerosene.
      • dredmorbius 13y ago
        "Normal kerosene" is a nonrenewable resource which will be running out by and by. Hence the interest in synthesis.
• dredmorbius 13y ago
  The US Naval Research Laboratory's electrically-powered fuel from seawater research appears vastly more viable than this project. It's been covered previously at HN. Briefly: • It creates aviation-quality fuel (long-chain liquid hydrocarbons equivalent to kerosene or diesel fuel, longer than those in gasoline) from electricity, hydrogen electrolyzed from seawater, and CO2 present at 140x atmospheric concentrations in seawater in both dissolved (2-3%) and bound (97-98%) forms as carbonate and biocarbonate. • It utilizes two very-well established and understood principles: electrolysis and Fischer-Tropsch process fuel synthesis. • The novel aspect is also relatively conservative: extraction of CO2 at industrial levels from water via partial vacuum and pH changes induced largely via electrolysis. • Efficiency looks to be reasonable and largely governed by electrolysis at 60% in terms of net recoverable energy from H2. Even if operational efficiency is only 10% of this it's still 3.5x more efficient than the method described in the article here. • Scale of operations envisioned is significant at 100,000 gallons/day. Scaling this to national levels of present petroleum consumption strikes me as plausible, though not trivial or inexpensive. Capital costs are not incommensurate with existing and projected petroleum capex spends (trillions of dollars), and may provide greater return in terms of net energy supply. • Plant requirements are, as fuel synthesis schemes go, profoundly modest. Rather than tens or hundreds of millions of hectares envisioned for biofuel schemes (along with freshwater and ag infrastructure requirements), a volume of roughly 10m x 4.5km x 4.5 km might provide US national liquid fuel needs. At envisioned Navy deployment levels, the plant would occupy a modest industrial site or possibly a shipboard or floating platform (though not fit within existing warship envelopes while preserving combat operations capabilities). • Power requirements at 100kgal/day are ~240 MW (roughly an aircraft carrier's reactor output). At national scale, about 2 TW, or equivalent to a solar collector surface of roughly 6,700 km^2 (82 km on a side). • The process should be highly amenable to utilizing surplus generating capacity on an intermittent basis to create fuel. It could be used for both electrical generation storage or for large-scale fuel synthesis. • The technology isn't inherently large-scale. Smaller modular installations, or large centralized ones should, from an engineering perspective, be roughly equally viable, as contrasted, say, with nuclear technologies which are inherently centralized for engineering, safety, security, and operational reasons. More: http://redd.it/22k71x http://redd.it/22k71x