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New Life-Cycle Analysis Concludes Neither GTL or CTL a “Reasonable Path” for Energy Security With Reduced GHG Emissions

High- and low-GHG emissions scenario for FT fuels. Click to enlarge.

A new life-cycle study by researchers at Carnegie Mellon University (CMU) concludes that the use of either coal- (CTL) or natural gas-based (GTL) Fischer-Tropsch (FT) liquids will likely lead to significant increases in greenhouse gas (GHG) emissions compared to petroleum-based fuels. In a best-case scenario, coal- or natural gas-based FT liquids have emissions only comparable to petroleum-based fuels.

In addition, the economic picture for either FT fuel is uncertain. There is a narrow range of petroleum and natural gas prices at which GTL fuels would be competitive with petroleum-based fuels, according to the study. Although CTL fuels are generally cheaper than petroleum-based fuels, recent reports cited by the study suggest there is uncertainty about the availability of economically viable coal resources in the United States. The CMU study was published 19 September in the online edition of the journal Environmental Science & Technology.

The study considered five pathways for FT liquid production and supply: two coal-to-liquid (CTL) pathways and three gas-to-liquid (GTL) pathways. The base CTL case was a plant that produced 53% diesel, 44% gasoline, and 3% propane. The second CTL plant design maximized gasoline production, with the product mix changed to 20% diesel, 73% gasoline, and 7% propylene and propane.

On the GTL side, the study considered a conventional GTL plant producing 62% diesel, 35% gasoline, and 3% propane, fueled by domestic natural gas or with imported LNG. In the third GTL pathway considered, the conventional GTL plant was built in Qatar or Malaysia, with the US importing the refined fuels.

The study considered GHG emissions from the production, processing, and transport of the feedstock fuels, including the refining of the synthetic crude produced in the FT reactor into liquid fuels, the life-cycle emissions from the electricity used in the plant, emissions from transporting the refined products, and the liquid fuel combustion emissions. It did not include emissions from the construction of any infrastructure.

The study considered two scenarios for the five FT pathways. The high-emissions scenario used the current US fuel mix for electricity generation (50% coal, 20% natural gas, and 30% low-carbon sources and did not consider carbon capture and storage (CCS) for the FT plants. The low-emissions scenario used carbon capture and storage in all plants, and a low-carbon source of electricity.

In the high-emissions scenario, gasoline and diesel produced from coal could emit about double the GHG emissions of petroleum-based gasoline and diesel. Using domestic natural gas to produce gasoline, or using natural gas-derived gasoline imported from Qatar or Malaysia would result in an increase in emissions of 20-25%. Using LNG would result in an increase of around 50% for both gasoline and diesel.

In the low-emissions scenario, all cases, except when LNG is used as a feedstock, show slight reductions (less than 4%) in emissions to the life-cycle of petroleum gasoline. In the case of diesel, the use of coal or domestic natural gas could result in a slight increase of less than 5% in GHG emissions compared to petroleum-based diesel.

The FT technology is constantly evolving and it could be expected to attain greater conversion efficiencies with time, particularly for coal, which is less developed. Thus, the efficiency required for CTL and GTL fuels to achieve the same lifecycle GHG emissions as petroleum-based fuels (breakeven) was calculated...This calculation shows that if a CTL plant (without CCS and powered with current electricity) converts 100% of the energy in the coal into liquid fuels, the life-cycle GHG emissions of these fuels would still be higher than the life-cycle GHG emissions of petroleum-based fuels. With CCS removing 90% of the process-generated CO2 and low carbon sources providing the plant’s electricity, in a CTL the breakeven conversion efficiency is 90%. GTL plants (without CCS and powered with current electricity) that use domestic resources and have a conversion efficiency of 70% would achieve breakeven. With CCS and low-carbon sources of electricity, the efficiency for breakeven drops to 55%.

—Jaramillo et al. (2008)

On the cost side, the study concluded that, based on March 2008 energy prices, producing CTL and GTL liquids would be cheaper than petroleum-based fuels. The economic advantage of GTL fuels becomes significant if inexpensive natural gas is available.

...increased use of these fuels would likely increase life-cycle GHG emissions associated with the consumption of transportation fuels. If a life-cycle carbon tax is established, the economic advantage of these CTL fuels over petroleum-derived fuels may be reduced. In addition, any effort to increase production with CTL fuels implies a significant increase in coal consumption. Finally, significant increases in demand for coal would likely raise prices, especially if there is a decrease in supply of easily recoverable coal. These factors add to the uncertainty as to the economic advantages of CTL fuels.

GTL fuels from domestic natural gas could, in the most optimistic scenario, produce a slight reduction in GHG emissions, but it is unlikely that these natural gas-derived fuels would contribute to our energy security. Supply of North American natural gas is limited, so increased supply would have to come from foreign sources, which would maintain our dependence of foreign sources of fuels (and increase emissions). Additionally, it is not clear that these fuels would help maintain lower liquid fuel prices. If the US has a goal of increasing its energy security, and at the same time significantly reducing its GHG emissions, neither CTL nor GTL consumption seem a reasonable path to follow.

—Jaramillo et al. (2008)

(A hat-tip to Costa!)



Rafael Seidl

GTL and CTL have always been about energy security. If you want FT with low carbon footprint, you need to use either waste or biomass as a feedstock. Both significantly increase product cost, though.

The bottom line is that reducing annual mileage is still the single most effective way to address both energy security and GHG emissions. The problem is that such reductions are hard to achieve, especially in the short term. Even where high-quality public transportation is available, car owners tend to eschew it, citing travel times and convenience. Another factor is that cars are expensive and depreciate with calendar days even if they are not driven much.

Mandating that 5-10% of our transportation fuel comes from various alternatives has many benefits to the US economy. First is lowers the risk of black mail from OPEC. When we demonstrate competing technology, that creates US jobs our economy will have a lower trade deficit.

Second, as we get more experience doing something; we get more efficient thus reducing ghg emissions. Corn ethanol is one great example especially if advancement lead to commercialization of cellulose ethanol. Nuclear power is another example. The largest US reductions in ghg are a result of improvements in the nuclear fuel cycle and operations of the plants.

Third, when energy is more expensive but comes from domestic sources it creates more tax revenue even as consumers use less reducing ghg.

When alternatives and domestic oil production are high enough, emergency measures such as rationing could result in not needing OPEC.


@Rafael - welcome back!

a question - which is better - convert cars to run on CNG or convert the gas to gasoline and use that?


"Even where high-quality public transportation is available, car owners tend to eschew it."

Well, Raffie-baby, yes, when they can afford to ignore it.


It is becoming more and more evident that implementation of a wider energy mix would benefit USA but cannot be left entirely to the market and/or free enterprise to do it.

A closer look at what is happening to the financial businesses confirms the above. Enron was another example. There are many others.

Energy (from all sources) being an extremely important development and economic tool cannot be left in the hands of speculators looking for quick profits regardless of the national interests. USA cannot continue to import 15 million/barrel of oil + NG + Electricity + Ethanol etc every day.

Why not create a small national Energy Board (EB) to develop and implement a national energy plan to solve the oncoming energy crisis. Many knowledgeable Americans would offer their contribution to ensure that the EB decisions are in the best interests of the nation.

Waiting will lead to another crisis similar to the current banking crisis.

How many other major crisis can USA tolerate in support of free for all enterprises, lobbies, politicians and speculators.


"A new life-cycle study by researchers at Carnegie Mellon University (CMU) concludes that the use of either coal- (CTL) or natural gas-based (GTL) Fischer-Tropsch (FT) liquids will likely lead to significant increases in greenhouse gas (GHG) emissions compared to petroleum-based fuels."

Well duh!

We NEED a guy like you running the country.


Its never as simple as this. First off there is a point where too little fuel results in war.. alot of war and thus a very big mess. Also the tech of ctl and gtl is changing as they research better ways and cheaper ways to do it.. thus changing the point at wich ctl and gtl might actauly be less damaging to the world then say ultra deep oil extraction or heavy or super heavy oil refining.

I suspect the most likely outcome is one hell of a war and one hell of a co2 spike from burning cities and use of realy dirty fuels.



You made a point, this country has proven unable to anticipate problems even when they are looming (like the collapse of the banking system that we are seeing right now). This country only accpeted to change after disaster happened never before, so you have to wait that a few more hurricane devastate Huston or Miami, that the healtcare system collapse, that the oil price shoot up to the sky and automaker and airline are bankrupt to decide to take action. That how US is and in a more general manner that the nature of humans, why should you change a bit of your confort as long as you are confortable. When the disconfort come to the point that the population are so angry and frustrated just organise a war (for what ever good or bad reason) to divert the population from their frustration and focus the collective concisousness on some futile but bloody purpose. Let's invade Venezuela, after all this country is a threat for US security with its crazy leader fostering a return of communism in latin america. There is 300 billions barrel of heaavy oil in the orenoque if not more


Unfortunately, public transport does not compete with automobiles on raw cost (parking not included.) A $4 gallon of gas gets a 10mp/day commuter around three commute days. That same commute by bus (in 80% NA cities) averages $4/day. That does not include cost of inconvenience, time, access, etc. to public transit. Making public transit ALOT cheaper is imperative to its growth.

While pilot tests of free public transit have their own set of problems (e.g. requiring greater security) it is a proposal in need of consideration.

John Baldwin

Transport via CNG in diesel-CNG dual fuel will give around 25% lower emissions than transport on GTL.


More seriously,

Welcomeback Rafael, everybody missed you here

this an interesting study indeed, but the result is hardly surprising just a confirmation that what a simple rule of thumb was telling us, without care CTL will double the CO2 emission per mile, unless vehicle like Aptera or Chevy Volts are used. So CTL should only be developped if average CAFE standard is at least doubled so 50 MPG. CCS would pobably make CTL uneconomical and make the energy efficiency even worse, better grow Algea with the CO2 then use the Algae as fertiliser to store the Carbon. The study points out that it is unclear if coal reserve in US are that big to sustain a massive CTL development, clearly a massive development of CTL will send the pice of COAL to the roof. If you look at the number the quantity of coal extracted in US keeps going up but the energy content extracted every year has already peaked a few years ago because of the decreasing quality of coal we extract these days. The reserve of coal in US are vastly overestimated if you consider traditionnal extraction technology. They are probably bigger if you consider in-situ combustion.

Anyway very scenario based on fossil energy is just a transitionary scenario. CTL in my view should be used with extreme moderation to reduce our exposure to oil but better invest in PHEV, EV, biofuel, Alternatve vehicle, electric public transportation, geothermal, wind, solar, nuclear than this durty CTL.

Fat Knowledge

Does anyone know if there is a free link to the report available? $25 seems a bit steep to read it.


"public transport does not compete with automobiles on raw cost"
That's right it doesn't, but only if "commute by bus" is the public transit in question. Up until the 1930s every city in N. America worthy of the title had a streetcar system to move people, buses were an idea sold to cities to destroy public transit. Read-
LRT[if done smart] is far more cost effective than the car and has additional advantages like increasing tax revenue through Transit-Oriented Development. We KNOW this to be true because city after city that has tried it has seen it happen.

Of course LRT isn't the last word in public transit[in fact it's one of the first]. PRT is an idea that looks very good (on paper) and only needs one city with courage to try it.


The XTLs also consume a lot of water. More and more CNG looks like the way to go. A 50kg fibreglass tank with 200km range is still better (and perhaps safer) than a 100kg battery pack with 50km range, or whatever the true numbers are. NG is freeing up with new drilling methods as is coal seam methane. When that runs out there is syngas though I'm not sure how the CO2 and net energy works out. Hydrocarbons both liquid and gas are so far in front for energy density it is hard to see them being replaced.

Henry Gibson

The answer is quite simple, and the researchers have not the intellectual honesty to present it. Generate all electricity with nuclear and use the coal to make FT fuels. In addition, use plug-in-hybrid cars that also use nuclear electricity for some of their travel.

There is no scientific fact presentation that concerns green house gas emissions that is complete without the presentation of the fact that the adoption of nuclear reactors to replace even the most efficient of fuel powered electrical generation is the cheapest way to reduce CO2 emissions whilst maintaining current levels of energy consumption.

Every organism that lives or ever lived, ingested naturally radio-active potassium its entire life. There will never be any live creature that is not exposed to the natural radio-activity internal and external to the body. In short, there will never be any nuclear Jungfraus. Humans and other live organsisms survive well at several times the natural radiation that they now get on the average. Soil radio-activity was much higher two thousand million years ago. Rare individuals meet their demise from this natural exposure, but far more do so with man or nature caused exposure to organisms.

Life cannot be made free of risk. All risks must be statistically and economically balanced. Most people do not know that the three remaining reactors at Chernobyl were kept in operation for many years. It would be statistically far more conducive to continued existence to live in the abandoned town near that reactor than in any part of Zimbabwe or Haiti.

At the present high prices of uranium that are twenty times what they were ten years ago, it is now economical to extract the remaining uranium from used fuel rods to be used again. Many used fuel rods contain more U235 fuel than natural uranium does. Each pound of plutonium extracted from used fuel rods eliminates the need to mine 200 pounds of natural uranium. There are known and tested methods to get nearly 300 times more energy out of a pound of uranium or thorium which is three times more abundant.

There are also large stockpiles of uranium with about half the U235 that is in natural uranium. The current high prices and the now more efficient methods of extracting U235 make these stockpiles very valuable.

Used fuel rods are not all waste. They are at least 96% reusable. At the low efficiency of 20 percent, the actual products of fission per kilowatt-hour weigh about 0.001 grams. Every person in the US has an average consumption of 20 KWH a day. The use of nuclear electricity over a hundred years would produce 166 grams which is less than the weight of 34 nickels of fission products per person. It is less than the weight of a cup of water.

If all 300,000,000 people in the US got their electricity from nuclear power plants, less than 3000 pounds of fission products would be produced every day. At this rate, the estimated surplus weapons uranium thought to exist in Russia, 600 tons, would power the entire US for one to two years. Since less than 20 percent of US electricity comes from nuclear. The Russian uranium could fuel all US reactors for five to ten years without any new uranium being mined. Three thousand pounds of fission products could fit into a two drawer file cabinet.

Fission products are a one to one match with the amount of U235 fissioned except that in some reactors, plutonium produced internally from U238 can almost double the efficiency. At $0.01 per kilowatt hour, the plutonium in spent fuel rods could be converted to at least $10,000 a pound and nearly double with the mentioned additional plutonium prodution during the reactions. Surplus weapons plutonium is worth double this in energy.

The estimated 20 tons of surplus plutonium could supply all of the US electricity for less than a month. At only 20 percent this is about five months. One of the reactors near Phoenix can and would take twenty years to burn it if mixed with used fuel that had only the fission products removed.

A CANDU reactor could be started with 100 tons of thorium combined with 2 tons of surplus weapons plutonium or uranium. Less than a two tons of thorium could be added each year and the fission products extracted on site. No new plutonium or uranium would have to be added ever.

France is now producing nearly 80 percent of its electricity with nuclear reactors. Writers in the US falsely state that no new reactors have been built since about 1980. Some US reactors were finished after 1980 and many reactors were ordered and built outside of the US.

France is now in the position that, even with sales into the neighboring countries, it has excess nuclear power at times. Power can be sent from France all the way to Norway and Sweden. Holland is getting a lot of power from Norway over the new undersea cable. Some German coal fired power plants could be shut down and all the excess power sold into to Germany if there were adequate transmission lines. But it would be economical to electrolyse water to get hydrogen with any electrical capacity not being used. The CO2 from wine fermentation can be fed with hydrogen to organisms to make ethanol. Just over the border, the Germans on the Rhine could make Eau des Wasserstoffs from their CO2. Just adding hydrogen to some fermentations might reduce or eliminate the CO2.

It can be assumed, that with all expenses paid or amortised, that nuclear electricity costs $0.05 for a kilowatt hour. The efficiency of water electrolysis can always be made higher than %50. A gallon of gasoline has less than 36 kilowatt hours of combustion energy in it, so the amount of expensive electrolysis hydrogen that equals the combustion energy content of a gallon of gasoline would cost 2*36*5 = $3.60. An electric car can go 360 miles on this electricity. A car with an engine can go a maximum of 50 miles on this hydrogen, but it still might be less expensive than gasoline. Excess electricity from any kind of power plant can be bought regularly for less than $0.02 a KWH.

At $100 a tonne, the coal cost of hydrogen at %50 efficiency is $2.40 for gallon of gasoline equivalent. Coal at a big mine only costs about $5 per tonne to produce.

Eventually liquid fuels will be produced directly from hydrogen produced by nuclear heat and recycled CO2.

The current expense of imported oil cannot be sustained in the US. The worries about global warming are of low concern to the people of the US compared to digestion and avoiding damage from environmental forces such as lack of heat. ..HG..


Oh I think some will jump to bev/erev and fuel cells bio and cng before things go too wonky.. but I still expect things to go too wonky;/

I expect alot of countries will dissolve into civil wars as thier main fuel sources dry up or as others outbid em for the last fuel sources. I think the us will be ok with enough biofuels wind geo nuke and of course the h2 and bev/erevs that will draw from those power sources.

Mind you I also expect many americans will be driving MUCH smaller lower powered cars in 50 years. Not because they want to or are green but simply because thats all they can afford to get to work with...

As far as mass transit goes.. alot of mass transit will die in the next 50 years simply because its been a very huge lie that they were ever better then cars. Most never were they simply allowed more people per bit of land to move about. Those systems will be replaced by simpler cheaper to run cheaper to build systems like prt and automated VERY light trollies. Those systems will mostly fail simply because of the lack of money. Because here is a little secret.. while the 700 BILLION bailout will keep all bleep from breaking loose for now.. it did nothing about the titanic drop in home values and thus the immense plunge in property taxes.... wich will trigger just as much of a mess in the years to come.

Roger Pham

Welcome back, Rafael.

GTL and CTL are most valuable for future air transportation, which requires the fuel that has the highest energy density, as well as sport and luxury cars which must have high performance.

For reduced GHG emission, biowastes or algae oil can be used instead of coal or NG.

Trucks and economy cars can run more economically on methane, both NG and biomethane now, and H2 later.


"That how US is and in a more general manner that the nature of humans, why should you change a bit of your confort as long as you are confortable. (sic)

Let's not get overly caught up in the idea that any of these virtual disasters have any real meaning or import. The truth is they do not (unless you're in virtual denial.) What they do show is an apparent urge to manipulate behavior in overbearing, authoritarian ways. These are the approaches of ineffective education and planning policy. Bludgeoning a people never makes them act as you want - it temporarily suppresses behavior while growing animosity which eventually boils over into revolution, violence or both.

We have seen unfortunately over-zealous gasoline price rise solidify the "drill now" political movement. Even as the price of oil falls precipitously, the move to drastically increase domestic energy production threatens offshore waters and pristine parkland. This is a major failure of the green movement. Managing transitions on the order of energy resources will not be accomplished by impatient fanatics. It requires diplomacy, finesse, technical knowledge and original understanding of human nature.

We see few exhibiting these skills in this and other arenas hereabout. In spite of this, great progress has been made in the last six years. There is a genuine move to electrification of transport. There is significant movement toward non-fossil liquid fuels as part of electrification. There is acute awareness of global warm cause and effect and energy mitigation to blunt it. There is also a movement to rebuild the grid system in NA which will increasingly move us away from large centralized power brokers. The iron fist of big oil will not be replaced by big utilities. Global energy independence begins with domestic resources of ALL technical means - and that will greatly disturb old monopolies and entrenched power systems. This is good. People will come to fully understand the meaning of energy independence with the move away from old energy gateways. All in all - a positive outlook.

Kit P

@Fat Knowledge

I have read several CM LCA and they are worth the effort to find. CM emails me at work a link with a password for some of their research at no cost. However, I would not subscribe unless it was directly work related. Reading LCA can be rather tedious but when it comes to reducing environmental impact, the devil is in the details.



thanks for the links. Yes, the loss of old trolley lines was damaging to public transit in many cities. The old Red line in Los Angeles took people all the way to Long Beach before freeway mania prompted by auto
/oil industries. Nowadays the light rail systems do a good job in many cities but cost and convenience issues remain. Be it light rail or city bus lines - the cost to operate are a function of passenger volume. Low volume results in higher fares or higher subsidies.

At today's typical round trip fare on municipal buses/LRTs, it is cheaper, more comfortable, far more convenient to drive a car. And PRT has huge resistance from planners and LRT proponents. I expect that auto-guidance on highways will be tried before PRT. Many of the same principles apply and most of the technology is here. If commuters were offered door to door service with auto-guided freeway segments - mini-buses would be viable long before building new PRT rail systems.


That reminds me, your earlier post comparing the cost of car and bus transit only looked at the fuel cost. Both have other costs so it is only when you look at the total that you can say for sure which is cheaper.

Take the car; Let's say the price of gas is $4, but that's only the price you[as a driver] pay at the pump. Back when gas was only $1 they did a study and found out you[as a taxpayer] was actually paying $4 extra because the oil companies get favourable treatment; lower taxes, grants etc. and you have to pay for that with higher taxes on other stuff-

You[as a property owner] are also paying for the infrastructure the car needs. Sure, you[as a driver] must sometimes pay for parking but it is you[as a property owner] that pays for the land the parking spot was built on, and the street in front of your property too. And of course cars don't just travel inside a city so you[as a taxpayer] pay for the highways (gas taxes aren't near high enough to cover those).

However even though you[as a driver] have the help of all of us[even those of us who don't drive] paying for all that you[as a car owner] still have to pay the other costs of owning a car; insurance, maintenance, etc.

One last thing; the convenience of a car is relative. Back when I went to school it was more convenient to ride transit because it gave me extra time to study or sleep during the trip. It was time far more productively spent than the commute I now do by car.

Although oil companies are earning record profits they get more in corporate wellfare each year than will be spent on the Wall Street buyout this year. That just makes me sick.

Kit P

The CM LCA is an example of we can influence public policy based on making informed decisions based on accepting the choices people make.
The reason people and own and drive cars is freedom. Your link to the ICTA junk science report reminds me why I want to avoid living in a big city where liberals think they can figure out simple life choices better than their citizens.
“The growth of low-density suburbs has increased the amount of time commuters spend traveling to and from work (see chart, page 24) and sitting in traffic.”

While there is no chart on page 24, there is a table on page 27 that indicates the increased time is less than one minute. I also learned from the table on page 20 that CO2 causes cancer.

My point is not to nit-pick but to point out that your source is not very credible.

“It was time far more productively spent than the commute I now do by car.”

So why does ai_vin not use public transportation?


Research, what research?
These students are merely expressing an opinion and reference only existing 2007 sources (mostly DoE).

This is really a tract which seeks to influence policy.
The DoE source references could easily support a different approach.
For starters, their headline is contradicted by their own admission that CTL with CCS achieves GHG emisions "about equal to today's gasoline & diesel.
They then go on to ignore CCS, even though their own head of department describes CCS as essential to achieve large reductions in CO2 emissions.

"This paper basically says under the best possible assumptions (using CCS and low carbon electricity to make the coal-based gasoline or diesel), life cycle GHGs of CTLs are about equal to today's gasoline and diesel. It's more liklely that CCS and low-carbon electricity won't used in the near term, so CTLs could close to double GHGs compared to oil."
"It was also calculated (but not graphically shown) that with CCS removing 90% of the process generated CO2, in a plant powered with low-carbon electricity, a CTL conversion efficiency of 90% would achieve the same life-cycle GHG emissions as petroleum-based
fuels (breakeven). GTL plants that use domestic resources and have a conversion efficiency of 55% would achieve breakeven."

CCS is seen as an essential part of achieving low CO2 emissions by the students' own head of department,
M. Granger Morgan, Head, Department of Engineering and Public Policy, Carnegie Mellon University:
"Everyone who has done serious quantitative analysis of how the U.S. or the EU could achieve an 80% reduction in CO2 emissions in a few decades has concluded that no single technology can reach this goal. The only way to achieve such a reduction in a timely and affordable way is with a portfolio of technologies that includes coal with carbon capture and deep geological sequestration (CCS)."


I work the graveyard shift in an area not serviced by a bus route because the city has short changed its transit system to cut costs. However that could change now that the our mayor is feeling the heat. I did take the bus to work every night during my first 10 years on the job and still use the transit system during the day for shopping and rec time on my days off.

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