Gevo Supplied Isobutanol-Gasoline Blend Runs Well in Small Engines

ENGLEWOOD, CO--October 28, 2911: In side by side performance, durability and emissions testing of small engines, gasoline blended with isobutanol performed better than blends using ethanol. Gevo, Inc. , a renewable chemicals and advanced biofuels company, provided the isobutanol to the Outdoor Power Equipment Institute (OPEI) and Briggs & Stratton (B&S), who tested both fuel blends in B&S small engines. The results demonstrated that unlike ethanol, blends incorporating isobutanol do not cause any irregular or unstable engine or performance issues. The outcome suggests that isobutanol blends at 12.5% could ease the pressure on moving to higher ethanol blends to meet biofuel mandates with no impact on small engines. Isobutanol is a drop-in fuel that requires no flex fuel engines, special blender pumps or pipelines.

“In the economic interest of our members and the safety interest of consumers, we need to be open to a biofuel that can perform reliably in the millions of products on the market -- lawnmowers, chainsaws, motorcycles, snowmobiles, ATVs and UTVs, boats and older cars.”

"Briggs & Stratton is encouraged by the results of the isobutanol testing on our engines," said Todd Teske, Chairman, President & CEO of Briggs & Stratton Corporation. "We are very interested in alternative fuels that do not cause damage to the substantial number of engines in use today while lessening the country's dependency on foreign oil."

"The OPEI test results provide further evidence that isobutanol is a superior gasoline blend stock for engines of all kinds," said Patrick Gruber, Ph.D., CEO of Gevo. "In addition to the issue of engine compatibility, our technology addresses other limitations of ethanol -- infrastructure compatibility, evaporative emissions and the blend wall -- to the benefits of all consumers. Isobutanol eliminates barriers across the fuels value chain and provides a very significant opportunity for growth in biofuel use for small engines and for automobiles."

"These results show us that isobutanol could be a biofuel alternative that can be introduced into the existing supply chain without the potential for disruption and harm to our outdoor power equipment engines," said Kris Kiser, President and CEO of OPEI. "In the economic interest of our members and the safety interest of consumers, we need to be open to a biofuel that can perform reliably in the millions of products on the market -- lawnmowers, chainsaws, motorcycles, snowmobiles, ATVs and UTVs, boats and older cars."

Kris Kiser announced the results today at the industry's largest trade show, GIE + EXPO. After testing three different B&S engine models on isobutanol, the following test results were reported:

• No engine or performance issues were found while running on an Isobutanol blend.
• Horsepower and torque levels remained the same while running on Isobutanol.
• Equivalent or better performance than E10 at temperatures ranging from 40°F to 120°F.
• No significant change in emissions (HC+NOx) levels.
• Isobutanol does not absorb water like ethanol. This will lead to fewer problems in the seasonal use conditions and long storage periods that are common with small engine applications.

About Gevo

Gevo is converting existing ethanol plants into biorefineries to make renewable building block products for the chemical and fuel industries. The Company plans to convert renewable raw materials into isobutanol and renewable hydrocarbons that can be directly integrated on a "drop in" basis into existing chemical and fuel products to deliver environmental and economic benefits. Gevo is committed to a sustainable biobased economy that meets society's needs for plentiful food and clean air and water.