TodayApril 17, 2022

Gas-to-Liquids (GTL)

Gas-to-liquids (GTL)

GTL is on the rise. Ethanol, fuel made from corn or sugar, is already used in many countries and is making headway in the United States. It has been blended into gasoline in the Midwest, corn states, for many years, but when MTBE became outlawed because of its toxicity and oil hit $60 a barrel it became a household word. Ethanol has petroleum properties that can be blended with gasoline, not with diesel.

I understand this process. I understand taking non-fossil fuel items and, through chemistry, making a fuel that energizes our vehicles for transportation. What I don’t understand is Gas-to-Liquids (GTL).

What is Gas To Liquids?

Don’t we already use gas in our cars? Why do we need some other liquid made from gas in our cars? Where do these gases come from? What are the benefits?

It turns out that GTL means natural gas, as in vapor gas. According to Dave Foster, Professor, University of Wisconsin, Engine Research Center, “decomposed under the earth is a whole range of compounds. Above the oil, under pressure, is natural gas, known mainly as methane (CH4) or ethane (C2H6). If you find oil, you find gas. Companies used to flare it, burn it off because it was too expensive to capture. There are natural gas reservoirs that have pockets of just gas in them.

Natural gas is highly mobile, even some of the oldest oil wells will still have natural gas in them. There are fissures in the ground that trap that natural gas and as the oil is pumped out the gases are released.” Europeans already use the word petrol, not gasoline, so they don’t have the problem understanding Gas to Liquids means gas to petroleum.

Sometimes you hear GTL referred to as Synfuel or FT-diesel.

The process used to turn gas to liquid stems from a process called Fischer-Tropsch that synthesizes a gas vapor to form a diesel fuel, hence the term synthetic fuel, or Synfuel. FT-diesel stems from the use of the Fischer-Tropsch (FT) process. Natural gas is a vapor and very explosive and it is very expensive to transport. It is more profitable to separate the oil and gas vapors at the point of extraction and process the gas to liquid near the field it was extracted from. In Malaysia, and other places, there are large pockets of natural methane or ethane sitting underneath the earth, in remote areas, waiting to be extracted and turned into synfuel.

Shell has created a process for synthesis, known as “Shell Middle Distillates Synthesis” (SMDS). This process is used to make high-quality ecologically acceptable diesel fuel, or GTL, Synfuel. The process reforms natural gas into synthetic gas (syngas) with a 2:1 hydrogen: carbon monoxide ratio. The temperature at which the syngas is cooked determines whether it is a light or heavy syncrude. Coal-to-liquid (CTL) is another hydrocarbon that is turned to fuel, but it comes from coal. Because it uses the same synthesis process the properties are the same as GTL in the end (a diesel) it too is referred to as Synfuel or CTL.

Audi R10 TDI with GTL
Audi R10 TDI with GTL

One scenario put forth by the World Energy Congress is that by the year 2020 approximately 30 percent of vehicles will run on a Synfuel. He also thinks that by the year 2020 10 percent of vehicles will be diesel hybrids, 15 percent will be gasoline hybrids, 35 percent will be gasoline (with ethanol) internal combustion engines and 5 percent will be fuel cells.

Jack Jacometti, Shell’s Vice President of gas-to-liquids (GTL) stated in a telephone interview that, “GTL is already a viable option. Biomass-to-liquid could be a viable option at around $80 per barrel.”

Bio-diesel is already popular in Europe, and Volkswagen is working with Archer Daniels Midland to introduce Soya Methyl Ester (SME), or soybean oil. RME or rapeseed methyl ester is the technical name for biodiesel made from rapeseed, or canola, oil, which is used in Europe. Through the process of transesterification, the large, branched triacylglycerol molecules of the oil feedstock are altered to become smaller, unbranched methyl ester molecules, which are comparable in size to the components of classic diesel fuel.

In March of ’05, Volkswagen announced that five percent of SME was acceptable in their cars. SME and RME offer enhanced lubricity and cetane, plus similar horsepower and torque when compared to petroleum diesel. Because plant-based feedstock crops absorb CO2 as they grow, the lifecycle of biodiesel fuel can be up to 85% CO2 neutral. SME contains oxygen that reduces particulate matters in the emissions when blended with conventional diesel, but it has to be in concentrations of 10-20 percent.

According to Stuart Johnson, Volkswagen is in its initial phase of a research program with ADM to use 10-20 percent of SME in their diesel vehicles. This presents a true reduction in emissions and energy savings. Biomass-to-liquid (BTL) is a more expensive chemistry that doesn’t involve fossil fuels. Instead, cellulose (corn stalk, wood chips, etc) would be turned into a gasifier, then produced as BTL. BTL is also known as a Sunfuel. Sunfuels are up to 90% CO2 neutral and their properties are similar to GTL fuels in the end. The one difference between BTL and ethanol is that BTL has the properties of diesel petroleum whereas ethanol has the properties of gasoline. Ethanol gets 25 percent less energy per gallon than gasoline. BTL gets about the same amount of energy as diesel, 25 percent more than gasoline.

Currently, there are no BTL plants producing Sunfuel. There are three GTL facilities in operation currently: the Mossgas Plant (South Africa), the Shell Binemergining Bintulu (Malaysia), and a methanol gasoline project in New Zealand. There is only one GTL demonstration plant and that is in Bintulu, Malaysia. That plant produces 14,700 barrels per day. Sasol & Qatar Petroleum (QP) will be opening the first production-scale plant in Qatar within the month, producing 34,000 barrels per day. The world will watch the Oryx GTL plant, a joint venture between South Africa’s Sasol Oil Company and Qatar petroleum. Shell is planning a large GTL production plant, Pearl GTL, in 2010 in Qatar. Nigerian National Petroleum and Chevron are constructing a plant in Nigeria, using Sasol’s technology. Nigeria is another country rich in natural gas.

According to Shell, Shell Deutschland Oil GmbH has acquired a minority equity stake in CHOREN Industries GmbH, Freiberg/Saxony. Shell’s commitment sets the stage for the construction of the world’s first commercial facility to convert biomass into high-quality synthetic bio-fuel, already marketed by CHOREN as SunFuel. A 15,000 t/a plant is planned for the production of SunFuel. SunFuel is supported by carmakers such as Volkswagen and DaimlerChrysler because it can be used without modification in any diesel engine without compromising performance and with a substantial reduction in harmful emissions. Shell’s stake in CHOREN is still subject to approval by the German cartel authorities.

All of these fuels and new engines will have to meet Tier 2 Bin 5, a part of EPA’s new Tier 2 emissions program being phased in through 2009. Tier 2 bin 5 represents the average level of emissions performance that each auto manufacturer’s fleet will have to achieve. Bin 5 also is equivalent to the emissions level that all vehicles must achieve under the California LEV 2 standards enforced in 5 states at present. In each of those five states, diesel vehicles are not sold, in part because the diesel fuel itself is so dirty. In effect, cars to be sold in 50 states must meet at least the tier 2 bin 5 limits. The Tier 2 program works in concert with new rules for sulfur levels in gasoline and diesel fuel.

The GTL process will optimize the energy we are getting from hydrocarbons, giving us a very valuable, and cleaner, energy for motor transportation. The added benefit of being able to produce BTL, a renewable resource blended with diesel, is that it will give us 25 percent more miles per gallon, when combusted in a vehicle, than gasoline. Ethanol, a renewable that can be blended with gasoline, produces 25 percent fewer miles per gallon when combusted in a vehicle, than gasoline. Both BTL and ethanol are renewables that have their own attributes, but BTL produces 66% more miles per gallon when combusted in a vehicle, over ethanol. In either case, both BTL and ethanol is part of the solution that will get the global economy off hydrocarbons and allow us to breathe easier and cleaner.

Lou Ann Hammond

Lou Ann Hammond is the CEO of Carlist and Driving the Nation. She is the co-host of Real Wheels Washington Post carchat every Friday morning and is the Automotive, energy correspondent for The John Batchelor Show and a Contributor to Automotive Electronics magazine headquartered in Korea. Hammond is a founding member of the Women's World Car of the Year #WWCOTY, and board member of the Women in Automotive.

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