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If this concept catches on it could suck back all the NG earmarked for LNG export since current vehicle fuels have a higher equivalent thermal price, even allowing for taxes. A bonus of this system is that even if there are few CNG filling stations to begin with you can get by on petrol until that happens. Suppose you run out of CNG while driving through the back woods you can always get home on a small amount of petrol, even if you have to phone for help. No range anxiety with 800 km nor worries about draining the battery with AC or heating. To free up NG supplies for quite a few years I suggest not burning it in power stations but using nukes for that task. The higher petrol-equivalent price for NG should make gas too expensive for power stations. In Australia we're talking about $45 per GJ or mmbtu versus around $10 to go into Japan export LNG. Power stations don't want to pay more than $5 so CNG cars will outbid them.
Another issue to consider is the sunk cost in methane based infrastructure when fossil gas is gone or prohibitive. By fossil gas I mean natgas, shale gas and coal seam gas. My guess is that despite the hype over fracking that fossil gas will be very expensive world wide, perhaps as soon as 2030. The end of gas scenario kills a lot of essential activities such as convective heating for thermal comfort and process heat, chemical input for Haber Bosch fertilisers that feed the world, fuel for peak power and backup for intermittent wind and solar. If the gas grid is abandoned it is a huge write off. We will still need hydrocarbons for most long haul transport. I also suggest that by year 2030 we are so freaked out by climate that we cannot use coal for these purposes. Synthetic methane will store better than hydrogen and can fuel engines (albeit inefficient) that can be repaired by backyard mechanics unlike fuel cells. These kinds of issues need to be factored into the case for synthetic methane.
This shows the versatility of methane as it can be blended from natural gas, scrubbed biogas and synthetic sources. Unlike gas-to-liquids via Fischer Tropsch most of the starting thermal energy is retained. So far there doesn't seem to be a fugitive emissions problem as we see with fracked gas; think kitchen taps catching on fire in farms near shale gas drilling. In this case the methane could leak from the methanation plant or the garage pumps. If e-gas becomes popular for vehicles the CO2 source may not keep up. More and more original natgas will be used for vehicles. I wonder if this will drive up the price of grid gas. A fourfold increase will be too steep for home use, factories, power stations and so on.
You suspect those who prefer the gas-electricty-BEV route over gas-NGV are well to do and live in inner city suburbs. What about semitrailers, builders with pickups, farmers, long distance commuters and those who can only afford cheap cars? One way to reduce the risk of methane leakage would be to give priority to transport not power generation. Generate more baseload electricity with nukes not combined cycle gas plants. Save NG for NGVs. If some methane escape is inevitable don't burn more gas but burn the same amount of gas in different ways.
The reason the schemes fail is because the referee is about as tough as those employed in TV wrestling. Too many illegal moves are allowed such as free permits or exaggerated offsets. The customers are out there waiting to buy low carbon/sulphur/nitrogen products and whoever can meet that demand wins. In the case of say coal fired power stations we never seem to hear of authorities shutting them down for exceeding their CO2 permits. We all know governments are soft. They need to get tougher.
Some googling suggests that the well-to-wheels efficiency of internal combustion engines will always be under 20% compared to 40% or so for BEVs powered by electricity from the same fossil fuel. Therefore I was wrong upthread saying they could be comparable. A simple fix for that could be to double the number of vehicle occupants. The point being that we're going to have to change from happy motoring to less happy motoring. We'll have to put up with more cost, fewer trips, less range, slower filling or recharge times, slower speeds, higher occupancy rules or some combination of these restrictions.
EP with CCGT-->BEV I think you have to multiply two efficiencies. If that is 60% X 60% that works out at 36% combined from the starting thermal energy of the NG. My guess is that NGVs with piston engines, gear boxes and tail shafts can still get 36% of the combustion power to the wheels. As a bonus you get to drive hundreds of kilometres without needing to 'recharge'.
I agree with what Henrik says that converting to room temperature liquid fuel is wasteful. I believe GTL has only about 55% of the thermal energy of the gas feedstock that went into each litre. I also believe that despite the efficiency of electric drive trains it is slightly less efficient overall to use the gas fired electricity->BEV route than using NGVs directly. You also have the range advantage of hundreds of kilometres on a 'fill up'. The answer to the space taken up by pressure cylinders is for the standard car design to become a mini-van rather than a saloon. We could free up a lot of gas by not burning so much in power stations which is the job for nukes. In any case the price of NG might rise too high for industrial users like power stations. The great thing about getting a petrol-CNG car is that even if there aren't many filling stations now they can build up over time as the petrol price escalates.
With gas-to-liquid you're throwing perhaps 45% of the chemical energy you begin with. This is because the Fischer Tropsch process needs partial combustion to generate the required heat and pressure. Today we see the typical car as a sleek sedan but that could change to a van or boxfish shape. That way you can store both gas cylinders and luggage. If that seems like a step backwards remember we had supersonic airliners once but liquid fuel prices forced us back to reality.
I agree that CNG bifuel cars are the way to go. If you run out of CNG on a back road presumably you can get a few litres of liquid petrol or diesel to get home. The Opel Zafira van appears to have this capability. CNG pumps can be installed in service stations gradually over time. If CNG takes off as a vehicle fuel that may create a price shock for industrial users of gas such as combined cycle power stations. In Australia diesel is priced at about $40 per gigajoule of energy where a GJ and mmbtu are about the same amount. When CNG becomes mainstream the price rise may be too much for piped gas users. Suppose for example power station NG went from $4 to $10. I think new generation capacity should be nuclear not gas to free up supply.
The Opel Zafira CNG seems to be dual fuel using turbocharging. I like the idea that when you run out of fuel on a back country lane you can siphon or buy a small amount of liquid fuel to get to the next service station. Drivers of pure NGVs and EVs can expect to get towed at least once.
I think it should be bifuel so it can run on both CNG and petrol. That way the number of filling stations can build up gradually. It will also enable a fill up in small towns that may not have CNG for years. Henrik suggests the range is up around 400km. Maybe not with 4 occupants, luggage, a/c and hill climbing. The Bollore Bluecar EV has 250 km range but is effectively a 2 seater I gather. Regardless of current fuel prices I think we will still have NG 20 years from now but I wouldn't bet on affordable petrol. With a bifuel option this should appeal to many.
What they don't mention is that Arckaringa Basin adjoins the large Olympic Dam uranium deposit. It would be crazy if they mined oil shale while Australia maintains its antinuclear policy. Some uranium may have washed out of the granite basement rocks into the shale. See
The stumbling blocks appear to be the cost of hydrogen from water and getting pure enough CO2, just 0.04% of air. The cheapest 'meth' type fuel is currently the methane in natural gas. Perhaps we shouldn't be burning so much in power stations but saving it for these other applications. We never seem to get cost estimates for these meth fuels. For example the Audi e-gas system or how much DME costs per litre.
A couple of other factors need to be considered 1) range between 'fill ups' 2) future gas supplies. If a full CNG tank can get you 300 km that beats any reasonably priced EV. Ideally vehicles should be dual fuel so if there are no CNG pumps you can get by on diesel or petrol, which itself could be a form of GTL. Methane can come from NG, biogas and synthetic like the Audi e-gas approach. When NG runs out or gets expensive bio and syngas can replace them in the same pipes and compressors. Make it smell bad so as to minimise leaks.
This sounds similar to the Audi e-gas system though they don't nominate a source of concentrated CO2. The 70% recovery of electrical input sounds impressive. If reversible fuel cells could make syngas at 70% efficiency, store it simply then turn it back to electricity perhaps the round trip efficiency could be over 40%. A hydrogen based system (Stuart Island) was 7% efficient if I recall. Unlike heavy and perishable chemical batteries this could store energy for megawatt level generation later on. What we need to know is the EROEI and the price per litre equivalent of the synfuels.
'Waterworld' comes true. Hate to be cynical but I think the idea of a floating process plant was to avoid the drama of piping to a land base; google James Price Point. 200 km is a a lot shorter than the 1200 km undersea gas pipe from Norway to the UK. The West Australian govt has a policy that 15% of gas must be reserved for domestic consumption. It seems wasteful to liquefy the gas, ship it to nearby iron ore mines then regasify it. My guess is that nearly all the gas will go to Asia, the WA govt will get some royalties and Shell stockholders will get the biggest benefits. It is not clear if gas burned to drive the equipment will be liable for Australia's 2012 carbon tax.
Here's an alternative calculation for synthetic methane that doesn't seem so bad. CH4 consists of carbon atomic weight 12 and four hydrogens each of weight 1. Suppose you could get the waste organic CO2 for nearly free but the hydrogen cost $2 a kg. Then 16 kg (12 + 4) of CH4 would only cost $8 or so. A kg of methane has about the heating value of about 1.1 litres of diesel. Thus we get 16 kgs or 17.6 litres of diesel equivalent for not much more than $8. That's 45c per litre equivalent. In Australia recent diesel prices have been around $1.50 a litre. Even if the production costs are way higher it seems like a worthwhile avenue to pursue, particularly getting hydrogen costs down and not using fossil carbon.
This is more proof that the energy return from liquid fuels is declining fast. GTL made in Malaysia 'throws away' about 40% of the possible energy of the gas so I guess Qatar is similar. Wouldn't it be simpler if we just converted to NGVs? I think we'll always need liquid fuels for aviation, PHEV range extenders and gas/liquid bi-fuel vehicles. However the percentage of liquids per distance travelled must decline as they get more expensive. Think of the alternative uses for the gas wasted in making GTL just so we can drive SUVs and fly to places we could take the train instead.
Toggle Commented Mar 24, 2011 on First gas flows to Pearl GTL at Green Car Congress
Bi-fuel has a couple of advantages in that the number of NG filling stations can grow as the market expands. When an EV runs out of battery 'juice' it will have to be towed but a small canister of liquid (petrol, diesel, E85 whatever) will get the bi-fuel vehicle home. I wonder if other automakers like Ford who are wary of EVs will take this path. It's hard to see a PHEV having a liquids tank, a traction battery and a gas cylinder. A bi-fuel hybrid would be bulky and expensive.
It would be interesting to know the EROEI or the percentage of energy in the finished fuels as opposed to the feedstock. The next question is whether that would easily cover the harvesting, drying and milling of the biomass. We currently assume we can get biomass from sawmills and crop processors but that won't last when petroleum is gone. I suspect the reforming process to get the internal hydrogen saps a lot of energy from potential output of liquid fuels.
I think there are some other objectives researchers should aim for 1) not using coal as a carbon source or alternatively capturing 90% of the CO2. Make bio carbon which is already 'in the loop' the preferred source. 2) not using air as an oxidant. The problems with NOx and low calorific value stem from too much nitrogen. Maybe chemical or electrolytic oxygen will solve that. 3) meeting a price point, say $2 per litre of liquid or $8 per US gallon.
How much do the microturbines actually cost? A diesel engine is said to cost $35 per kw so a 100 kw/132 hp engine costs $3500. Next question how does the all up weight of a CNG turbine range extended EV compare to a straight diesel? That is including the weight of the fuel tanks, engines and traction batteries for either system.
If the feedstock was all biomass then CCS shouldn't be necessary since the carbon was already in the biosphere and would be mostly recycled. The addition of coal sounds like a greenwash maybe to confuse the carbon tax people. Note that coal is plant material that accumulated over millions of years and biomass is realtime. Therefore coal has to be cheaper until it runs out. It would be good if FT could be done small scale to use local crop wastes and heat or electricity used nearby. Therefore the next step seems to be either 1) get CCS to work with large scale coal + biomass 2) get small scale FT to work with biomass alone.
I agree; the methane economy has some huge advantages. True it's a GHG but then again it's wafting up our noses from our guts. Nat gas is 80+% CH4 and it can be blended with fermentation biomethane and bio-syngas. When NG is pricey because we've burned too much in power stations the gas grid will still have a use as a vehicle fuelling network. I see from the Robert Rapier article in The Oil Drum that GTL has less than half the EROEI of natgas. We're throwing 50% of the energy away just for the convenience of liquid form. Compression of methane into 200 bar cylinders (c.f. scuba tanks) is relatively safe and uses less than 5% of the contained energy. Piston engine cars may need to be van shaped to fit a large cylinder and the engines may need souping up to get petrol style performance. Provided guvmints don't slap huge fuel taxes on CNG then NGVs should compete with PHEVs. The sticker price of the vehicles should be lower since they won't need lithium batteries. Of course when NG is used up sooner than we think bio-syngas could also run combined cycle generators that cut in when wind and solar fade out. This line of research should be encouraged and also the use of nuclear or renewable hydrogen as an input.