Fats and greases and inedible oils are opportunity feedstocks, but the US supply of fats and greases is probably on the order of less than 10 million barrels, closer to 1-2 million barrels on an annual basis. That’s a big sum. But in the context of worldwide demand it’s nowhere near what we need. When you sit down and think about how to scale, if that doesn’t scale to the full extent that we want it to, what does? So we looked at solid biomass. That’s really why we were driven to it. We recognize the need to expand the feedstock pool. There’s not a single silver bullet.

—Jim Rekoske

Green Diesel. The hydroprocessing technology used in the Green Diesel process—and also used for Green Jet—is relatively mature, Rekoske noted. UOP is moving faster commercially on the Green Diesel side, with the Diamond Green project with Darling International and Valero Energy nearly complete. (Earlier post.) That plant, in Norco, Louisiana, will have the capacity to produce more than 9,300 barrels per day of renewable diesel product.

UOP also has licensed plants in Italy and Portugal to use the EcoFining technology.

More recently, UOP signed an agreement to license technology to Emerald Biofuels LLC to produce Honeywell Green Diesel at another facility in Louisiana. (Earlier post.) Emerald is expected to use the UOP/Eni Ecofining process technology to produce 85 million gallons per year of Honeywell Green Diesel from non-edible, second-generation oils and animal fats.

Under the current set of prices and slate of feedstocks available, you can produce Green Diesel fuels from renewable fats and greases at a price competitive with petroleum diesel—provided you get feedstock at the price needed. The refining technology is probably about $4-5/barrel more expensive to make renewable diesel out of fats and greases...there’s not a lot of extra cost on the refining technology. Really the question is can the feedstocks be procured at a price competitive to petroleum oil.

Obviously, we want to make the window of circumstances as wide open as possible. We are working on the catalysts to make the process as inherently efficient as possible. On the diesel side, that’s going to be hard to do. There are two drivers to the cost of production: the feedstock cost and the yield of product. Our technology produces about 90 to 95 gallons [of renewable diesel] for every 100 gallons of raw feedstock that comes in. It’s pretty doggone efficient; it’s hard to make dramatic changes in overall efficiency of that process.

—Jim Rekoske

Another area of refining cost is the hydrogen consumption, which is required for taking the oxygen out of the natural feedstocks. Lowering hydrogen costs would thus lower production costs. However, right now in North America, Rekoske noted, it’s pretty inexpensive, since the majority of hydrogen is produced from natural gas and natural gas prices are low.

We think that [making hydrogen] is a better use of natural gas, instead of worrying about CNG and LNG vehicles. We see it as a great enabler to allow us to revitalize the chemical industry and the renewable fuel industry in the US.

—Jim Rekoske

Envergent. Envergent Technologies uses Ensyn’s Rapid Thermal Processing (RTP) to produce bio-oil from biomass. RTP rapidly heats biomass feedstocks to approximately 500 °C in the absence of oxygen using a circulating transported fluidized bed reactor system similar to the one used in the UOP Fluid Catalytic Cracking (FCC) technology. The result is a bio-oil that—depending upon the feedstock—delivers up to 8,680 Btu per pound.

Something like 85-90% of energy process is retained in the pyrolysis liquid. It’s just a way to densify and to move the biomass into a convenient format that we know how to handle in refining technology.

—Jim Rekoske

Although bio-oil (or pyrolysis oil, or pyrolysis liquid) has the potential to be co-processed with petroleum-derived feedstocks, it presents processing challenges. It is highly viscous, corrosive, and relatively unstable. It also contains significant amounts of oxygenated compounds, including acids, aldehydes, ketones, alcohols, esters, ethers, glycols, and phenols. Upgrading thus is essential for use as a transportation fuel or blendstock.

Upgrading of bio-oil produced from biomass for various applications can be accomplished by catalytic hydroprocessing. Catalytic hydroprocessing has several advantages over other processes, such as fermentation, pyrolysis, and trans-esterification...catalytic hydroprocessing is one of the most viable options for downstream upgrading of bio-oil.

...The hydroprocessing of pyrolysis bio-oils is a very important step because upgrading pyrolysis oils often leads to the formation of significant amounts of tars, chars, and coke and to irreversible catalyst deactivation due to the high oxygen content in the feed. The elimination of oxygen compounds by hydrotreating results in hydrodeoxygenation (HDO) material that is cleaner and easier to co-process with conventional petroleum-derived vacuum gas oil (VGO) in downstream processes.

—Al-Sabawi and Chen (2012)

Challenges for the upgrading of pyrolysis oil include contiguous carbon chain length in biomass, carbon efficient condensation chemistry, and ways to avoid polymerization.

In August 2011, UOP began construction in Hawaii of a demonstration unit that will convert forest residuals, algae and other cellulosic biomass into renewable drop-in transportation fuels via a rapid pyrolysis process integrated with a catalytic upgrading process. (Earlier post.)

The Integrated Biorefinery will utilize rapid thermal processing (RTP) technology to convert biomass into a pourable, liquid bio-oil which will then be upgraded to gasoline, jet and diesel fuels using catalytic hydroprocessing technology being developed by UOP.

On the pyrolysis side, we have done the work necessary at the pilot scale to optimize the process. Simultaneously, we are building the plant in Hawaii with the help of the DOE grant. We expect that demo plant fully up and working in 2013—at that point, we will be ready for commercial sale of the technology. The end product is more like a mixture of 50% gasoline, 40% distillates, 10% LPG, and potentially C₄ chemicals, things like that. It’s a really good mix and a good split of refining capacity.

We are only at the pilot scale—too early to talk about costing. We feel very confident that with biomass available at prevailing prices, we will be able to make gasoline and distillates at parity with the cost of production of gasoline and diesel at $80/barrel—cost competitive without subsidy.

This is a young field; we’ve been at this in UOP for about 6 years—that’s a very short period of time in the world of new process development, and a very short time in the world of fuels. We’re in it for the long run, we don’t expect miracles to occur. We are very happy with the progress made thus far; the combination of technology development and business development has been very encouraging for us. We’re excited to see how the industry is progressing. Yes, there are challenges, but there were challenges for last 6 years, and will be for the next 20 as well.

—Jim Rekoske

Resources

• Mustafa Al-Sabawi and Jinwen Chen (2012) Hydroprocessing of Biomass-Derived Oils and Their Blends with Petroleum Feedstocks: A Review. Energy & Fuels doi: 10.1021/ef3006405