Tuesday, March 20, 2012

Unlimited Supplies of Renewable Jet Fuel On the Way

The global shale oil & gas bonanza has pushed back "peak oil" and the need for large scale biofuels production. But the technology which will allow large scale future production of renewable fuels, chemicals, polymers, and other materials, is pushing ahead anyway, financed by governments and a few venture capitalists.

There is no practical limit to the amount of biomass that the Earth's bio-system can produce, other than limits to sunlight and atmospheric CO2. The planet can produce massive amounts of biomass on marginal soils, on saline soils, in deserts, and on oceans, without the need to displace food production from prime cropland.

Scientists are developing better ways of converting non-food biomass to valuable chemicals and fuels, which will increasingly reduce demand for petroleum feedstocks in those areas, as processes become more economical, and economies of scale begin to kick in when needed. Here is one approach being promoted by the US Navy:
Cobalt converts non-food feedstock such as woody biomass into renewable butanol for both chemicals and fuels, including jet fuel. The combined science team from Cobalt and the NAWCWD focused on scaling and optimizing the dehydration chemistry for the conversion of bio n-butanol to 1-butene, followed by oligomerization of the bio-butene into jet fuel, based on the process developed at NAWCWD in China Lake, CA. (Earlier post.)

Alcohol to Jet
Alcohol is attractive as a feedstock for the production of renewable jet fuel partly because all the steps required are currently in use at commercial scale in the petrochemical industry.

The ATJ process broadly consists of four main steps: dehydration of the alcohol; oligomerization; distillation; and hydrogenation. Key to the cost-effectiveness of ATJ is reducing the production cost of the alcohol, as well as of the ATJ process itself.
Just as there are many types of crude oil that can be refined to produce petroleum jet fuel, and just as there are many types of feedstocks that can be used in Fischer-Tropsch and natural oil hydrogenation processes to produce renewable jet, so are there different alcohols produced by a variety of pathways and feedstocks that can be converted into renewable jet.

ATJ is one of the alternative jet fuel pathways being supported by the Federal Aviation Administration, and ASTM has formed an ATJ task force.

Once the team completed its initial research, the search for a large-scale processing partner began, which resulted in the awarding of the contract to Albemarle. NAWCWD said that Albemarle was the only contractor that had the expertise, materials and facilities necessary to provide this large scale synthesis in the amount of time required. Specific production activities covered under the contract include:

Dehydration. Utilizing the reactor rig constructed in an prior stage of work, selective dehydration of bio-butanol to 1-butene shall be conducted utilizing a supplied catalyst operating at a temperature of approximately 380 °C. This step will occur in the High Pressure Laboratory (HPL) section of the Process Development Center (PDC) and will be performed over a duration of 1 week.

Butene Drying. The butene will be dried over molecular sieves, in a small packed bed set up. This shall be done in the HPL section of the PDC immediately following completion of the previous dehydration step and shall be performed over a duration of 1 week.

Oligomerization. Using a Ziegler-Natta type catalyst system that will be supplied by NAWCWD and activated at the PDC, for the oligomerization of 1-butene to the ethyl branched higher olefins. This step shall be conducted in the South Lab section of the PDC in a 30-gallon reactor system and will be performed over a duration of 1 week.

Stripping / Olefin Mixture Recovery. The dimer product 2-ethyl-1 hexene will be stripped out of the olefin mixture. This shall be done in a 30 gallon reactor system and shall be performed over a duration of 1 week.

Dimer Oligomerization. The recovered C8 liquor shall be treated with Dow Amberlyst-15 catalyst (protonated form, dry). This step shall occur in the High Pressure Laboratory (HPL) section of the PDC and will be performed over a duration of week.

Hydrogenation. The olefin mixture shall be hydrogenated to yield paraffins. A Raney Nickel catalyst system will be used. This step shall occur in the SPU-North section of the PDC in a 50-gallon glass lined steel reactor system and shall be performed over a duration of 1 week.

Distillation. The paraffins shall be vacuumed and distilled to remove C28 and C32 paraffins to obtain jet fuel that meets the standard navy specifications. This step shall occur in the kilo lab section of the PDC using a small wiped film evaporator distillation system and shall be performed over a duration of 1 week. _GCC
Interestingly, some butanol producers are getting closer to competitive production, compared to butanol from petroleum. The cost of industrial butanol is similar to the retail cost of gasoline, although butanol has lower energy density than gasoline. Expect the price of renewable butanol to continue to drop, as costs of biomass production become somewhat more de-linked from the cost of oil in the future.

Biomass is produced in dispersed form, with relatively low energy density compared to oil or coal. The energy density of biomass is particularly low in comparison to nuclear energy. But biomass has the advantage of convertibility to a wide range of valuable chemicals, polymers, and fuels -- and biomass can be grown virtually anywhere on the planet. This is in contrast to hydrocarbon resources which cannot be found virtually anywhere, but must be shipped to more remote locations.

It is crucial that this type of technology continue to be developed, as a type of backstop alternative fuel, should geo-political conditions drive the costs of oil into a dangerous economic zone.

We will never see the type of peak oil that the acolytes of doom imagine. Political peak oil is an altogether different can of worms.

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