@ DavidJ -

it's still a spark ignition engine, so thermodynamic efficiency will be lower than for a diesel. That's not the point, though. What matters is where you get your fuel from, at what price and how much CO2 you emit.

Europe has access to Russia's abundant natural gas resources as well as those of the North Sea, the Netherlands, Germany and Italy. A new pipeline (Nabucco) to Iraq, Iran and Qatar via Turkey is stalled only by politics. Sweden, Switzerland and Austria are ramping up production of pipeline-grade biomethane, the only cellulosic biofuel that can be produced at industrial scales today. If Europe's transportation sector shifts to gas, that leaves more oil for other countries (e.g. the US).

Wrt pricing, NG is subject to zero or low transportation taxes in Sweden, Switzerland, Germany, Austria and Italy - though how long the tax break will last varies by country. Some countries offer other incentives for NGVs as well.

The biggest remaining hurdles are the high cost of maintaining a dual-fuel system on board the vehicle and, those of compressing NG to 200+ bar. The two represent something of a chicken-and-egg conundrum that is slowing NGV fleet growth.

Metal-organic framework materials like BASF's Basostor can adsorb methane at lower pressures, which will ease the cost issues without compromising range. VW has conducted extensive field tests but it's not clear if this Passat CNG already takes advantage of the new technology.

@ Eric -

the latest tiff with Ukraine actually says more about that country than it does about Russia. Turkmenistan failed to deliver enough of the cheap gas they had promised Ukraine. Russia made up for it in volume but is insisting on the higher price it negotiated for its own gas. Frictions between the two countries will become less relevant to supply security once the new NordStream pipeline at the bottom the Baltic Sea is ready. Russia depends as much or more on revenue from gas sales to Europe than Europe does on Russian supplies.

As for Europe's indigenous reserves of fossil gas, they are indeed modest and declining. Norway is developing some new gas fields in the Barents Sea but it's very far from all markets. That's why LNG and biomethane will become increasingly important supplements to Russian gas.

No-one knows how long the Nabucco pipeline project will remain stalled for, but the analogy with the Arab-Israeli conflict doesn't strike me as appropriate. Except for the PKK, this is about money - a far more manageable issue. Much depends on how quickly Iraqi politicians can settle on a scheme for sharing oil & gas revenue between the country's various ethnic and sectarian groups. Reportedly, there are significant undeveloped gas reserves in Anbar province. The country could also collect transit fees for Qatari gas.

Iran is a separate problem, largely because the US still holds a grudge against those that dared to overthrow its puppet dictator in 1979.

We should convert the cars and trucks here in north america to run on natural gas instead of just gasoline or diesel. In canada they extract oil in the tar sands
with natural gas heating process and fresh water in a natural and beautiful land ?? This land look a desert after the process and the water and lakes are poluted
and toxic. If we bypass gasoline and diesel then the natural gas can feed the cars and trucks
directly with way lower cost.

@ JamesEE -

we're getting off on a tangent here, but consider this: perhaps Iran wouldn't have a cooky President and nuclear ambitions if the US weren't so hellbent on demonizing the mullahs. Actio = reactio. Other examples of long-held grudges: the Cuban missile crisis was in 1962 and US trade sanctions are still in place - 17 years after the fall of the Berlin wall. In Vietnam's case, normalizing relations took decades.

My point is that Europe and indirectly, the rest of the world, would benefit from access to Iranian natural gas. The goal should be to defuse tensions such that all sides can save face. The Iranian people are sovereign, it's up to them to decide if and when they've had enough of the clerics - not us.

Rafael,

If Iran held an election today the mullahs, and their kooky president, would be out of power. The Iranian people should be sovereign, but they're not.

Likewise, after the fall of Vietnam to the communists there were the aftereffects, purges in Vietnam and Cambodia. Normalization happened pretty quickly after they decided to follow China's economic policy, i.e., free markets.

Cuba? I agree. The economic embargo hasn't helped anybody. Only electoral politics in the USA can explain our bad policy there.

Rafael,
two questions:

Can you provide a link to industrial scale (bio)methane production? CNG engines on biomethane look like a silver bullet to me, since biomethane production should be carbon-neutral.

Also, more technical: since methane has much greater octane number (130?), why hasn't VW put up some more boost to raise power on CNG. Yeah, I know that most guys here will say that you don't need more power, but it can be good at least for marketing reasons (that's why SAAB is pushing their "Biopower" thing).

Thanks in advance.

@ Mirko -

sorry, last post was mine.

So far, NG engines rely on port injection of the gaseous fuel, which displaces far more fresh charge in the manifold than liquid fuel does. The result is reduced specific power because the oxygen supply is limited. NG direct injection would eliminate this problem but isn't available yet, presumably because it's much more difficult to ensure a reliable seal at the injector tip.

VW's TFSI uses a supercharger-turbo combo to boost engine torque. The geometric compression is comparatively high at 10:1 because GDI uses fuel evaporation to cool the gas in the cylinder and avoid knock. That means the engine gets decent fuel economy on both fuels.

Perhaps at some point in the future, we'll see an engine optimized for NG operation via turbocharging + high geometric compression ratio + NG direct injection, with gasoline port injection + severe ignition retardation as an emergency backup.

You can get some methane from biodigesters, but for vast quantities it is better to gasify the biomass in BTG plants.

http://www.btgworld.com/technologies/gasification.html

Perhaps because it might be news to others.