Catalysts are the key for using biomass as fuel - Part II

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Catalysts are the key for using biomass as fuel - Part II

January 07, 2013 - 01:31
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BRUSSELS, Jan. 7, 2013 (RISI) -The elusive goal of a refinery with biomass as a feedstock has moved a step closer to reality, thanks to technology developed by the Gas Technology Institute (GTI) of Des Plaines, IL,and Houston-based Catalytic Research Institute (CRI).Read Part I here.

Demaline says there are various things to look at when considering a feedstock. Elemental analysis provides a hydrogen to carbon atomic ratio which correlates with both the liquid fuel yield and liquid fuel quality; a higher ratio predicts better yields and fuel properties. For example, the H/C ratio for wood is 1.4, equal to or lower than other feedstocks studied such as micro algae (1.7), macro algae (1.6), lemna (1.5), corn stover (1.5) and bagasse (1.4)

With wood as the feedstock, yield of the liquid hydrocarbon is 28 wt% using the current generation of catalysts. With each new generation, yield is expected to increase. Also, the boiling point curve can be moved, which allows one to shift the ratio of the product one produces, e.g, more gasoline or more diesel.

Demaline explains that a refinery takes crude oil and separates it by boiling point, a process known as distillation or fractionation. Successively heavier products are collected by boiling at higher temperatures, the liquids are then produced by condensing the vapors it to get the various products. The boiling points increase as one goes from gasoline to jet fuel and then finally diesel .

Catalysts are the key to translating distillation and fractionation into a biorefinery, Demaline states. The pilot plant at GTI is now running a third generation catalyst while work on the fourth generation is underway at the Bangalore laboratory. Demaline says one benefit of the fourth generation catalyst will be to increase the diesel yield and cetane. Cetane is to diesel what octane is to gasoline; the more cetane, the higher the performance.

Diesel engines are currently more popular than gasoline everywhere outside of the US. Demaline points out that increasingly stringent regulations expected from the US government concerning greenhouse gas (GHG) emissions, could push US auto manufacturers to increase mileage per gallon, through all means that they may have at their disposal, with a key one being diesel engines in passenger automobiles, which is already becoming more popular in North America.

"We hope to get to a point where someone comes up with a feedstock and says they want to produce only diesel so then we would develop a catalyst system to do just that," Demaline adds. "We have standard catalysts which are versatile for multiple feeds and then we have custom catalysts designed for specific types of feedstock and products desired."

The GTI pilot plant achieved a continuous feed rate of 50 kg/day in September 2011

Pilot results encouraging

Work started in a laboratory-scale unit at GTI. All the products emerged together and were then distilled and used for a feedstock qualification.

In September 2011, an automated 50-kg feed/day continuous pilot plant output was achieved at GTI.

The pilot plant is being used to confirm earlier yield estimates at smaller scale and confirm catalyst life. Thus far, Demaline says that all concerned are very pleased with the pilot plant's performance, which has been in continuous operation since
March 2012.

The pilot plant also allows CRI to produce fuels in sufficient quantity to start fuel qualification. The US Environmental Protection Agency has to look at the product as it relates to various standards, such as ASTM as well as the European equivalents. The toughest specification is for jet fuel. Demaline says the process can take three to six months.

What will all this cost? In the US, the National Renewable Energy Laboratory (NREL) is involved with estimating process economics from a broad spectrum of biomass processes under similar economic conditions. NREL examined a 2,000-ton/day design of wood (received at 50% moisture dried in situ to 10%). The plant design takes the hot flue gases from the HMU to dry the incoming biomass, which frees all the heat generated by the process to go back to, for example, the paper machine.

Using a "greenfield" site, total installed equipment (TIC) cost was estimated at the time of the study to be US$112 million of which the HMU is the most expensive single piece at approximately 45% of the total.

Total capital investment (TCI) was estimated to be $232.8 million. In 2012 dollars, minimum sales price to provide overall IRR of 10% on top of 60% financed at 8% was calculated to be $1.76/gal with wood at $71.97 per dry ton. Feedstock accounted for 55% of the operating cost.

To achieve a 10% IRR on a $232.8-million investment, Demaline says the study suggested a company would need a selling price of $1.76/gal. If the unit was integrated with a refinery and did not need to purchase the HMU, using refinery hydrogen instead, a selling price of $1.49/gal would be needed to achieve 10% IRR.

He says that a pulp and paper company might be positioned to spend less than the full $232.8 million, and might be able to reduce costs to as low as $112 million. Demaline adds that these numbers have no subsidies attached, but some are available in the current market . He also points out that the reformulated blendstock for oxygenate blending (RBOB), i.e., gasoline, has been running about $3/gal in recent months.

Look to Europe

Demaline says a pulp and paper producer would under the current business model buy a license from CRI for the technology (based on annual design production) and a fee for the engineering design. That firm could own and operate the plant or perhaps enter into a joint venture with another pulp and paper producer or even a refinery. CRI started talking with pulp and paper producers about 24 months ago .

Actually, the first interest in joint ventures came from some refineries. "They don't know how to source, handle or treat the biomass, but they can do the rest, which a pulp and paper producer can't," Demaline explains. But, to be cost effective, the biomass should be available within a 75- to 100-mile radius.

One excellent model, Demaline says, could be a site where a mill has shut one or two large paper machines. This would mean that the wood supply is available. Another model might involve a company that may want to reconfigure a mill site that has been mothballed. "We would not go to a world-scale mill and ask to co-locate unless the owner knew the feedstock was available. We will always defer to the biomass owner because they know what's available."

Scales up to 2,000 dry tons feed/day are possible as single trains. For wood, a company must look for sources greater than 500 tons per day to be economic, the larger the better. "When we talk with a producer, we ask what they can sustainably provide as a feedstock," Demaline says. "We've been told from 500 to 1,500 tons/day on a co-location basis, i.e., a brownfield site." The 2,000-ton/day model cited previously refers to a greenfield site.

Demaline believes the first commercial scale plant fed by wood might be built outside of North America. "It will take the one at commercial scale and then you'll see many. The first will be in a mature market with good access to feedstock."

In summary, Demaline says it is important to remember that the IH2technology provides more than high quality transportation fuel range renewable hydrocarbons, but also renewable CO2, high-pressure steam/power, char ( which can be combusted to recover more energy), and water that can be sent back to the HMU. The process produces little waste and all of the hydrogen needed in the process can be self-generated from the incoming biomass.

Demaline says other benefits that distinguish IH2from other biorefinery processes include: feedstock flexibility; attractive economics (low capex and operating expenses); both stages are exothermic; it integrates existing technology; fungible high-purity hydrocarbon products made that replace the "whole barrel", i.e. the products are not specific to one fuel.

In the near future, CRI is expecting completion of a contracts for front end engineering and design for a 5-ton/day demonstration plant. And, work is about to start on the design for commercial-scale plants of 500 and 1,000 tons/day. A commercial-scale reactor would be about 65 ft high and 9 ft in diameter. The numbers should be in by 1Q 2013 and Demaline hopes basic engineering on the first site would begin early in 2014. The plan is for the first commercial-scale site using IH2technology to begin in early to mid 2016.