CO2 Conversion System Converts Greenhouse Gases

by Byron R. Núñez

Sustainable Innovations, Inc. (SI) was awarded a contract from the United States Department of Energy to continue working on its electrochemical process that converts greenhouse gases into usable byproduct. The rising levels of greenhouse gases has increased a demand for new energy solutions that address geopolitical concerns as well as economic ones. Stakeholders, for example, are actively searching for economically viable pathways that can reduce carbon dioxide emissions while developing means to produce fuels that decrease global reliance on oil. This includes, but is not limited to, searching for more efficient ways to utilize traditional fuels such as coal, as well as to capture and recycle the national production of greenhouse gases. Continue reading

Optimizing Tidal Energy Converters

by Cassandra Burgess

In order to make tidal energy converters economic enough to compete in the energy market, it is essential to build them as efficiently as possible, but also important to design them to avoid environmental impacts on the habitats in which they are installed. These impacts can be more difficult to predict when planning an array of tidal energy converters than a single turbine. Roberts, Nelson, Jones, and James worked to solve these two problems by creating a modeling framework that optimizes the placement of tidal energy converters in Cobscook Bay, Maine. The model uses restrictions on water height and velocity based on the region so it can be applied to other regional sites as well. It also allows researchers to input environmental restrictions on the decrease in velocity due to the turbines, and on changes in the bed shear stress at the site. These constraints represent points at which the turbines might change fish behavior by causing fish to congregate in the turbine wakes, and at which erosion of the ocean floor becomes serious. Using these restraints the researchers found that the non-environmentally constrained system had an output 19% higher than the originally planned placement, and the environmentally constrained system had an output of 16% higher.

For the purposes of this modeling process the environmental constraints were set arbitrarily. In future models, research would be necessary prior to the planning of the tidal energy converters to determine what levels of change the ecosystems could reasonably withstand. Once this is determined, the model can optimize the placement of tidal energy converters while minimizing the environmental impact. This model differs from previous models because it is on a much finer scale. While previous models have been able to accurately predict the impacts of tidal energy converters on a broad scale, this model looks at the fluid dynamics near the turbines themselves. This improvement allows for analysis of the environmental impacts near the turbines, as well as for better information on the turbulence and velocity changes created, both of which affect the power output of nearby turbines. Because this model was able to optimize both energy output and environmental impact, two areas most concerning when constructing a tidal energy array, the researchers recommend that it be used in the planning for future array sites.


Roberts, Jesse, Nelson, Kurt, Jones, Craig, James, Scott, 2014. A Framework for Optimizing the Placement of Current Energy Converters. 2nd Marine Energy Technology Symposium, April 15-18, 2014. [GSSS: Optimization Tidal Roberts]


Biomass to Butanol via Engineered Yeast

by Emil Morhardt

Butanol is a four-carbon alcohol, next in size after 1-C methanol (wood alcohol), 2-C ethanol (drinking alcohol), and 3-C propanol (rubbing alcohol), so it shouldn’t come as any surprise that yeast ought to be able to synthesize it out of sugar. And it burns like the other alcohols mentioned, so it is potentially a usable liquid fuel that could be mixed with gasoline (like ethanol, to increase it’s non-fossil-fuel content), processed into other types of fuel, or used as commercial feedstock to make bio-based commercial plastics such as the PET (polyethylene terephthalate) used to make beverage bottles. Gevo, Inc., a company based in Englewood, Colorado but with it’s only [troubled] production facility in Luverne, Minnesota, seems to be gradually overcoming myriad difficulties in commercializing biomass-based isobutanol, and is beginning to license its proprietary genetically-modified yeast, which produce more isobutanol than conventional ethanol-producing commercial varieties. Gevo hopes that these yeast will feel right at home in existing ethanol-production facilities (such as the Luverne plant, where they didn’t do so well initially), and that all Gevo will have to do to get isobutanol out is to bolt on a module that separates the isobutanol from the water in which the yeast are living. Continue reading