Fermentative Production of Ethanol Using Pinus patula as Raw Material: Economic and Energy Assessment

The production of cellulosic ethanol has been gaining attention in the industry sector because of the high availability of lignocellulosic biomass from agricultural and forestry activities. Pinus patula is one of the most typical softwood species in Colombia. The aim of this work is to evaluate the production of ethanol using Pinus patula as raw material using dilute acid pretreatment and enzymatic hydrolysis to produce sugars able to be used as substrate for the strain Saccharomyces cerevisiae. Three fermentation configurations were selected to evaluate the performance of the microorganism: configurations 1 and 2 used glucose in a percentage of 80%w/v and 70%w/v, respectively, as substrate to establish the adaptation requirements of the microorganism. The configuration 3 considered the use of concentrated P. patula hydrolysate. An experimental yield of 0.364 +/- 0.009 g ethanol/g sugar (73% of the theoretical) was obtained. Additionally, the economic and energetic comparison between the biochemical (ethanol production through fermentation) and thermochemical (synthesis gas through gasification) pathways to produce bioenergy was performed through simulation approaches. As main results, a higher ethanol production cost (1.53 USD/L) was obtained in comparison to the market price (0.77 USD/L) and a low energy efficiency (20%). Different alternatives such as waste integration and energy incentives must be considered in order to produce ethanol in a feasible way.