Final Report: Technology for Enhanced Biodiesel Economics

EPA Contract Number: EPD08061
Title: Technology for Enhanced Biodiesel Economics
Investigators: Kittrell, J. R.
Small Business: KSE Inc.
EPA Contact: Manager, SBIR Program
Phase: II
Project Period: May 1, 2008 through April 30, 2010
Project Amount: $225,000
RFA: Small Business Innovation Research (SBIR) - Phase II (2008) Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Agriculture and Rural Community Improvement


Because of the relatively high cost of biomass feedstocks compared to fossil fuels, biomass conversion processes must be highly efficient to provide a near-term contribution to the U.S. energy balance. Biodiesel is recognized as an important potential fuel, which is obtained by relatively simple esterification of fats or seed oils (soybean, rapeseed, etc.). In the manufacture of biodiesel, the production of each gallon of biodiesel produces about 1 pound of byproduct glycerol. If biodiesel is produced to meet only 3% of the U.S. diesel fuel demand, more than 1.8 billion pounds of glycerol will be coproduced. For comparison, the current annual worldwide demand for glycerol is only 0.5 billion pounds. Not only will biodiesel economics be depressed by the substantial surplus production of glycerol, but also the physical disposition of byproduct glycerol becomes a challenge.

One of the few realistic markets that can absorb glycerol production at nearly any manufacturing location is the propane market, which represents about 75 billion annual pounds in the United States alone. It is readily able to absorb an additional several million pounds of propane from glycerol. Furthermore, propane is one of the most valuable energy products, with historical prices greater than natural gas, kerosene, or No. 2 heating oil.

To fully exploit the potential of biodiesel, an effective glycerol upgrading technology is needed, which is the subject of the current research program. The Phase II technology can utilize the excess glycerol, is not limited by market capacity, and can be distributed in plant sizes feasible to be located near each biodiesel plant.

The overall goal of this SBIR Phase II project was to complete the research and development of an innovative process technology to enhance the economics of biodiesel production, through upgrading the byproduct glycerol to a propane fuel, which (a) is widely used today, (b) has an existing distribution system, (c) can accommodate the large volumes of byproduct glycerol, and (d) has attractive economics to support the biodiesel production. Ideally, the upgrading technology would not require extensive supporting services, such as a hydrogen plant.

Summary/Accomplishments (Outputs/Outcomes):

The Phase II program entailed the development of new catalyst compositions for the glycerol conversion reactions, laboratory studies demonstrating the performance of the technology, including catalyst activity and selectivity, prototype and scale up studies, and the design and economic evaluation for a propane manufacturing plant based on the conversion of glycerol from raw biodiesel byproduct. New catalysts, process operating conditions, and plant configurations were established as part of the Phase II program. No feed to the plant other than glycerol is required. Part of the reactor feed glycerol is converted to hydrogen, which then is used to convert the rest of the glycerol to propane. The plant is inexpensive, simple, safe, and operates at moderate conditions. Propane can be produced from the plant, and distributed in locations throughout the United States, where biodiesel plants are built. When propane is sold at local prices, the manufacturing cost for producing propane will pay out the plant investment in less than 1 year.

Raw biodiesel byproduct glycerol may contain from 35% to 75% glycerol, with the remainder consisting of fatty acids, unreacted triglycerides, and residual salts from the biodiesel production chemistry. Recovery of glycerol from raw biodiesel byproduct was successfully demonstrated as part of the Phase II program. Phase II catalysts were shown to be capable of converting glycerol recovered from raw biodiesel byproduct with activity and selectivity similar to that obtained using USP grade high purity glycerol.

Annual U.S. domestic biodiesel production reached 700 million gallons during the 2007/ 2008 time period. The resulting production of biodiesel and crude glycerol byproduct during the 2007/2008 time period resulted in the collapse of the crude glycerol market. Inability to upgrade the crude byproduct to refined glycerol left traditional glycerol markets unable to absorb even a portion of the volume. Alternative end uses or conversion technologies remain insufficient to absorb the rate of byproduct production. Industry experience during this time period confirmed both the growth projections for the biodiesel industry, and the need for a novel technology to upgrade the byproduct glycerol to a useful product, such as propane fuel.

To accomplish this Phase II goal, the Phase II research program consisted of four scientific and engineering tasks.

Task 1 was designed to develop and study the properties of the various catalyst compositions that will be tested in the program. The output from Task 1 provided a better understanding of the effects of compositional variables of the catalyst preparations, as well as the production of a large number of catalysts to be evaluated in the program. From Task 1, optimized glycerol conversion catalysts were identified. The final production prototypes of the catalysts were produced in Task 1. These prototypes successfully provided physical characteristics compatible with the reactor vessel chosen.

Task 2 was designed to provide reactive testing of the catalysts prepared in Task 1 under realistic conditions simulating commercial conversion of glycerol to propane. The effects of raw glycerol impurities were assessed, and the preferred type of reactor was determined. The tests assessed the activity, stability, and selectivity of each catalyst prepared under Task 1. In addition, selected catalysts were subjected to kinetic studies designed to provide insight into limiting mechanistic steps and the role of catalyst preparation variables in relieving these limitations. The kinetic studies also provided the basis for large-scale process design.

In Task 3, the best catalysts were used in prototype and advanced system design studies. These Task 3 studies confirmed the activity and selectivity of the catalysts in large-scale catalyst preparations. It enabled the catalyst to be operated for sufficient time period to demonstrate that catalyst deactivation is not be a deterrent to the commercial success of the system. Similarly, detailed product analyses were performed on the system to verify that no reaction selectivity issues remain unresolved at the conclusion of the Phase II program. Catalyst performance was demonstrated with a process feedstock based on glycerol recovered from raw biodiesel byproduct. Finally, engineering design studies were performed to implement and demonstrate the utility of advanced design techniques to reduce capital and operating costs.

Task 4 provided design and cost analyses for full-scale applications of the technology, drawing upon the results of Tasks 1, 2, and 3. Competitive comparisons were performed for the Phase II technology. These comparisons identified the features, advantages, and benefits of the Phase II technology in the commercial marketplace.


The Phase II program developed and demonstrated a new technology for economically producing propane in high yields from glycerol. The program developed novel catalysts for the balanced reforming and hydrogenation, defined process operating conditions, and operated a prototype unit. Projected economics are highly attractive. The process is inexpensive, simple, safe, and operates at moderate conditions. Propane can be produced from the plant, and distributed in locations throughout the United States where biodiesel plants are built.

The application of the technology will significantly improve the economics of biodiesel production, and provide an economic disposition for the major quantities of byproduct glycerol, thereby facilitating the rapid introduction of low-cost biodiesel manufacturing operations.

Supplemental Keywords:

Sustainable Industry/Business, Scientific Discipline, RFA, Technology for Sustainable Environment, Sustainable Environment, Environmental Engineering, Economics, propane fuel, biodiesel fuel, propylene glycol, alternative energy source, environmental chemistry, alternative fuel, biofuel, glycerol byproduct, catalyst, activity, selectivity, propane, RFA, Scientific Discipline, Sustainable Industry/Business, Sustainable Environment, Economics, Technology for Sustainable Environment, Environmental Engineering, glycerol, environmental chemistry, alternative fuel, biodiesel fuel, propane fuel, alternative energy source

SBIR Phase I:

Technology for Enhanced Biodiesel Economics  | Final Report