Levulinic acid is a biomass-derived compound that can be obtained inexpensively in high yields from waste cellulose-containing materials. It has been identified as a top biomass-derived chemical due to its ease of production for both five and six carbon sugars and its useful functional groups a ketone and a carboxylic acid. Levulinic acid can be used to form other more valuable chemicals including gamma-valerolactone (GVL). GVL is valuable as a renewable platform molecule with potential in developing both renewable energy and chemicals. GVL retains high energy content and performs comparably to ethanol as a fuel blending agent. However characteristics such as high water solubility blending limits for use in conventional combustion engines and lower energy density compared to petroleum-derived fuels have limited the use of GVL in the transportation sector. Therefore a method is needed to convert lactones such as GVL into liquid alkenes or alkanes with molecular weights targeted for direct use in transportation. UW-Madison researchers have developed a method and apparatus for producing olefins (unsaturated hydrocarbons) in the C8 to C16 range from GVL. The method involves two tubular flow reactors and an inter-stage separator in a single catalytic system. The chemical transformation proceeds via conversion of GVL to an n-butene which is then introduced into a second reactor where the butene is converted via acid catalyzed oligomerization to higher molecular weight olefins (C8 and longer). High pressure CO2 is an additional by-product of the reaction. In addition to GVL lactones hydroxyl-carboxylic acids alkene-carboxylic acids alcohols or a mixture thereof can be reacted using this method to produce longer-chain olefins. The olefins produced with this method are of carbon chain-length and molecular weight suited for use in gasoline jet and diesel fuels. Applications: 1) Olefins in suitable molecular weight range can be used in transportation fuels. 2) High pressure CO2 stream can be sequestered or used in further processing.