Could Diesel Fuel Made from US Natural Gas Compete with CNG and LNG?

The announcement last month of a $21 billion project to capitalize on abundant, low-cost US natural gas should have caught the attention of everyone interested in this resource. As reported in the New York Times, Sasol, a South African energy company, intends to build a 96,000 barrel-per-day gas-to-liquids (GTL) plant in southwestern Louisiana, in conjunction with a new gas processing plant and ethylene cracker. The synthetic diesel fuel produced by this facility would provide a different pathway for shale gas to displace imported crude oil in the US transportation sector, in competition with compressed or liquefied natural gas (CNG or LNG.)

GTL involves a two-step conversion of the methane that makes up the bulk of natural gas into synthesis gas and hydrogen, which are recombined into liquid hydrocarbons by means of the decades-old Fischer-Tropsch (FT) process. GTL is also energy-intensive, with an overall efficiency around 60%. South African companies have vast experience with such synthetic fuels. Sasol are partners in the Oryx GTL plant in Qatar, and their coal-to-liquids plants in South Africa utilize a similar syngas step and the same FT process as GTL.

With the US suddenly perceived to be sitting atop a century's worth of natural gas, mainly in the form of unconventional gas from shale, tight gas formations and coal-bed methane, T. Boone Pickens isn't the only one to see an opportunity to displace imported oil with gas. Yet as attractive as that sounds for reasons of energy security and trade, it isn't obvious whether the public or even fleet operators are willing to switch on a larger scale to a lower-density gaseous fuel requiring both new distribution networks and new or modified powertrains. Only 0.1% of the natural gas consumed in the US now finds its way into vehicles, equivalent to less than 0.1% of US oil demand. Under the circumstances, it would be surprising if someone weren't looking seriously at GTL, one of the few practical ways to circumvent the mechanical and logistical barriers that have impeded the fueling of more US cars and trucks with natural gas.

When I read about Sasol's proposed project, I immediately thought of another, less well-known South African synfuels facility. Since 1992 the Mossel Bay GTL plant has been turning natural gas into gasoline, diesel and other fuels, drawing first on the Mossel Bay gas field and then on newer fields as the original one depleted. Although owned by another firm, the ongoing struggles to keep the "Mossgas" plant supplied are well-known in South African energy circles. I can't imagine Sasol embarking on a project like the one in Louisiana if they had any doubt about their ability to keep it supplied for decades.

Of course volume and price are two very different aspects of supply. A decade ago, conventional wisdom held that GTL required a gas cost of around $1 per million BTUs to be viable. Even with the shale bonanza today's US natural gas price is well above that level. What now makes it possible to conceive of GTL in the US is that the price of the crude oil used to make diesel and other fuels has risen so much higher than that of natural gas. That comparison is more obvious when one converts natural gas prices into their energy equivalent in crude oil. Today's US natural gas price is below the $23 per equivalent barrel that it was in 2001. Meanwhile crude oil has increased from about $26 to $95 per barrel. The drastically improved attraction of GTL becomes even clearer when comparing ten years of wholesale US Gulf Coast diesel prices to natural gas prices using the approximate GTL conversion rate of 10 million BTUs of gas per barrel of liquid product.

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As the chart above reveals, this theoretical GTL margin has exploded since 2009. Yet it also shows that if gas prices returned to the levels we experienced just a few years earlier, the proposed project would encounter significant risks. Perhaps that helps explain Sasol's concept of a larger integrated gas complex with multiple sources of margin, capitalizing on the waste heat from the GTL process and the lighter hydrocarbons it yields as byproducts.

It remains to be seen whether GTL will prove an attractive means of leveraging the US shale gas revolution to back out imported oil. However, if Sasol and others proceed with US GTL projects, anyone eyeing our gas surplus for other purposes, whether in manufacturing, fertilizer production or power generation, would face serious competition linked to the global oil market. That includes potential LNG exporters, who passed an important hurdle with the publication of a favorable analysis by the Department of Energy.

A slightly different version of this posting was previously published on the website of Pacific Energy Development Corporation

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Pickens Plan, the Sequel

How can you not love T. Boone Pickens? Here's someone who made his fortune in oil, and now he's advising us to switch major parts of the US economy to wind and natural gas. And unlike some of the other concepts for taking a big bite out of our oil consumption, his current idea actually stands a chance of making a significant difference on a timescale of years, rather than decades. At the same time, however, Mr. Pickens has sometimes been a tad bit less than accurate with the numbers he uses to make his points. Remember those ads about the $700 billion per year we were sending overseas to buy oil? Even at its absolute peak in July 2008, reality was more like $500 billion, and the total for 2008 ended up around $385 billion, based on net imports and the average refiner acquisition cost for the year. That's hardly peanuts, but it's roughly half his cited figure. So let's take a look at the key numbers behind his proposal to convert long-distance trucking to natural gas. It's a great idea, though not quite as much of an economic slam-dunk as it might seem when he describes it.

I just finished reading the interview with Mr. Pickens in The American Spectator, published yesterday. The big shift in the Pickens Plan since the first time I examined it in detail is that he has switched his emphasis from using wind to free up natural gas to replace gasoline in cars, to using the abundant natural gas from our enormous shale gas reserves, which are already transforming the US gas and power markets, to replace diesel fuel in big-rig trucks. He is also in the process of lining up the legislative support to nudge this along much faster than market forces alone would. But does it make as much sense as he suggests when he talks about using $4.50 worth of natural gas to replace 7 gallons of diesel fuel at $3 per gallon?

Strictly in energy terms, that 7 gallons might even be a bit low. A million BTUs of gas (roughly 1,000 cubic feet or one MCF) would deliver as much energy to a truck as 7.8 gallons of diesel. And fundamentally, he's right that the recent price relationship between natural gas and crude oil makes gas a tremendous bargain, BTU for BTU. However, the prices he mentions in the Spectator interview constitute an apples vs. oranges comparison from both sides. Even if natural gas remained at a steady $4.50/MCF at the wellhead for the next 20 years, which seems unlikely despite the bounties of shale, that's not what you'd pay at the natural gas pump.

Start with the fact that it costs something to transport gas from the wellhead, wherever that might be, to market. Based on current pricing relationships, if gas starts out at $4.50, then by the time it's sold to a commercial account, which is probably how filling stations would be classified, it could cost as much as $9. And someone has to invest in the equipment to compress it to 3,000 or 3,600 psi and pump it into an 18-wheeler's tanks. Even with tax credits to help, a station owner will need to make a return on that investment, and some profit, too. Add another buck an MCF to cover that, and we're up to $10/MCF, which equates to $1.28/gal. of diesel. For a reality check on this, I took a look at cngprices.com, which shows the locations and pricing for stations selling compressed natural gas (CNG) for vehicles around the country, expressed in dollars per gasoline-equivalent-gallon (GGE). Prices range from roughly $1.25 to around $2, with a few outliers over $3. Since a GGE contains about 10% less energy than a gallon of diesel, you'd have to bump these prices up by about 10% to get the equivalent for a fair comparison.

Under $2 is still pretty cheap, but you shouldn't compare that to the $2.90/gal average retail price of diesel this week. The latter includes federal excise tax of $0.244/gal. and state excise and sales taxes that range from $0.08-0.49/gal. and average $0.281/gal. As best I can tell, CNG is taxed at the federal gasoline rate of $0.183/gal., while states seem to tax it to a much lesser extent than gasoline and diesel, as for example the $0.085/gal rate in Utah, compared to their state fuels tax of $0.245/gal. However, this is only viable as long as demand for CNG is tiny, relative to other fuels. If Mr. Pickens succeeds in displacing large quantities of diesel with CNG, then it will either need to carry a similar tax burden, or the lost revenues must be collected in some other fashion. If you strip out the taxes to get to an apples-to-apples price to compare diesel to CNG, it works out to around $2.50, give or take a dime or two, depending on location. So while CNG is still clearly cheaper than diesel, it's rarely $1/gal. cheaper on a truly comparable basis. This, together with conversion costs as high as the $65,000 per truck that Mr. Pickens cited, might explain why market forces alone haven't led to a rapid switch to CNG-fueled transport.

I've looked at the House bill containing the natural gas vehicle tax credits mentioned in the interview. It would cover as much as 80% of the incremental cost (over the diesel version) of a truck that can only burn CNG or LNG, up to $80,000, depending on weight. It would also extend the $0.50/GGE tax credit for CNG and LNG through 2027. These changes would drastically shorten the payout of an investment in a natural gas-powered truck, even if the per-gallon advantage of CNG appears to be somewhat less than Mr. Pickens suggests. That could move CNG into the truck-fuel market pretty quickly.

The remaining question is what the $7 billion investment Mr. Pickens wants the government to make in this proposition would buy us. He believes that converting the US heavy truck fleet to CNG would save 2.5 million bbl/day of diesel, or about two-thirds of the diesel and heating oil now sold in the US. That would have a much bigger impact on our oil imports than ethanol, although it's hardly an either/or proposition. I'm surprised that Mr. Pickens didn't go on to suggest that this benefit could be leveraged further by utilizing the resulting surplus diesel in diesel automobiles. Given their approximately 30% improvement in fuel economy vs. comparable gasoline vehicles, that could save an additional 750,000 bbl/day of gasoline, while reducing greenhouse gas emissions on those cars by about 20%. If you play all this out, then just under 5 trillion cubic feet per year of natural gas, or less than a quarter of current gas production, could save more than 3 million bbl/day of gasoline and diesel, or nearly a third of our net petroleum imports.

That sounds like a pretty good deal for $7 billion, though it could be made even better if the vehicle tax credits involved were converted into low-interest loans and loan guarantees, instead. If the main impediment to switching to gas is the up-front cost of natural gas conversions and the time involved in recouping that cost, then let's make it much easier for truckers to borrow the money for this purpose, and for banks to lend to them. Giving everyone taxpayer money to induce them to do what we want makes a lot more sense when the government has plenty of money to spend. With the US running large deficits and the private sector holding lots of cash earning next to nothing, we should use our tax dollars as efficiently as possible to achieve the same outcome. Otherwise, Mr. Pickens seems to be on to a sensible idea, and I wish him luck selling it.

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How Many Miracles?

Over the weekend I was catching up on articles, and one from Technology Review last week caught my attention. It was a brief interview with the new Secretary of Energy, Dr. Chu, covering nuclear power and fuel cells. In the back half, Secretary Chu explained why the DOE has cut funding for fuel cell R&D, suggesting that fuel cell cars were always a long shot, because they required "four miracles" to happen. Although I haven't mentioned fuel cells very frequently here in the last few years, I must say it's hard for me to consider the commercialization of something that I've already driven as requiring quite so many miracles as that. At the same time, I don't trivialize the obstacles that explain why fuel cell cars are still not available in large numbers, despite previous expectations--including my own--that they would be by now.

Dr. Chu helpfully breaks down the challenges facing fuel cells into four categories. Start with his concern about the principal source of hydrogen (H2) today, via extraction from natural gas. This route certainly undermines the "zero emissions" claim often attached to fuel cells. In practice, that means zero tailpipe emissions, but hardly zero emissions overall. Still, it's worth considering what else we could do with the natural gas in question. We could compress it and burn it in a modified internal combustion engine (ICE). T. Boone Pickens is quite fond of that idea, and it's not as foolish as some suggest, since it can displace a lot of petroleum and reduce emissions by 15-20% compared to a conventional car, on a well-to-wheels lifecycle basis. We could also use the Fischer-Tropsch process to convert natural gas to top-quality synthetic diesel at a somewhat smaller emissions savings, because the higher efficiency of a diesel engine is largely offset by the energy lost in fuel synthesis. Or we could produce H2, which as Dr. Chu notes involves throwing away about a third of the original energy in the gas by the time we've compressed the resulting H2. Yet the latter is the only one of these pathways that, despite the high energy price paid in producing H2, affords the opportunity to cut our overall lifecycle vehicle emissions in half, because producing electricity in a fuel cell is inherently so much more efficient than burning a fuel in an internal combustion engine. It's not perfect, but it's far from awful--unless you put the H2 into an ICE--and no miracles at all are required to make the H2.

Miracle number two involves H2 storage, and this looks a bit tougher. I am not keen on carrying around compressed gases at 5,000 or 10,000 psi in the same vehicle with my family, and that is no irrational fear. In my refinery days I saw examples of how much mechanical energy even 2,000 psi held, and I will never trust a Kevlar-wrapped tank enough to be fully comfortable with this option. Moreover, I don't think Dr. Chu is entirely correct that "compressed hydrogen is the best mechanism." ECD, a company that my former employer once invested in, has a technology for storing H2 via chemical absorption in metal hydrides, and you can buy canisters that use their technology today. The advantage of this system is that it doesn't involve high pressure. The disadvantage is that these hydrides are heavy, a drawback shared by the nickel-metal-hydride batteries (same basic technology) used in the Toyota Prius and other non-plug-in hybrids. None of these systems yet stores energy at the equivalent density (and thus driving range) of gasoline, but then neither do Lithium-ion batteries.

The third challenge concerns distribution, and this is a doozy. Transporting H2 in tube-trailers is fine for servicing demonstration refueling stations, but can't be scaled up to handle millions of cars. That may not be necessary, because the "reformers" that extract H2 from natural gas can be built on a scale that fits into a service station dispenser, drawing feedstock from local gas lines and delivering fuel without any need to transport it as H2, other than in the car. Installing such devices in thousands of locations would be a massive undertaking, but frankly the same can be said for the goal of installing E85 pumps at 10% of service stations, compared to about 2000 today. To me, cost-effective H2 distribution is a matter of engineering and economics, not scientific breakthroughs.

That leaves us with the one item on Dr. Chu's list that might qualify as requiring a genuine miracle: bringing the cost of a fuel cell stack down to a level comparable to an internal combustion engine, or at least to a point not so much more expensive as to render a fuel cell car inherently unaffordable. Fuel cells still cost over $1,000/kW--implying that just the fuel cell stack for a real car would cost more than an entire luxury car today. Forecasts that this would fall to anywhere near the roughly $35/kW of today's car engines remain theoretical, relying mostly on learning-curve effects analogized from other industries. Given the current state of the car industry, manufacturers will struggle enough just absorbing the initial high cost of low-volume plug-in hybrid car production, without taking on tens of thousands of dollars in losses per car for vehicles like the Honda FCX Clarity. Absent a breakthrough, an investment like that might truly require a miracle.

Whether making fuel cell cars a practical reality requires four miracles or only one, I have to agree with Dr. Chu's conclusion that their commercialization looks neither imminent nor assured. It's important to recall that hydrogen is merely another energy carrier, like electricity, rather than an energy source like petroleum or biofuels. The smart money today is on battery-electric cars, including plug-in hybrids. In order to beat them an automotive fuel cell stack must cost less than the battery pack required to give drivers the 250-300 mile range they seem to want, because in every other respect that matters a fuel cell vehicle is an electric car. However, we must keep in mind that the smart money is not always right. Cutting back federal R&D on fuel cells to a level that puts a higher priority on other options that can deliver meaningful results sooner seems prudent, as long as we don't abandon this option entirely, or cede our competitive position to others.

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