Search

The past decades have seen a diversification of the sugarcane industry with the emergence of new technology to produce bioenergy from by-product and waste process streams. Given Brazil’s ambitious goal of reducing green-house gas emissions by over 40% below 2005 levels by 2030, it is of paramount importance to develop reliable decision-making systems in order to stimulate investment in these low-carbon technologies. This paper seeks to develop a more accurate optimization model to inform risk-conscious investment decisions for bioenergy generation capacity in sugarcane mills. The main objective is for the model to enable a better understanding of how Brazilian government policies, such as the electricity price in the regulated market, may impact these investments, by taking into account the uncertainty in sugar, ethanol and spot electricity markets and the interdependency between production and investment decisions in terms of saleable product mix. The proposed methodology combines portfolio optimization theory with superstructure process modeling and it relies on simple surrogates derived from a detailed sugarcane plant simulator to retain computational tractability and enable scenario analysis. The case study of an existing sugarcane plant is used to demonstrate the methodology and illustrate how the model can assist decision-makers. In all of the scenarios assessed, the model recommends investment in extra bioelectricity capacity via the anaerobic digestion of vinasse but advises against investment in second-generation ethanol production via the hydrolysis of surplus bagasse. Furthermore, the decision to upgrade the cogeneration system with a condensation turbine is highly sensitive to the electricity price practiced in the regulated market, capacity constraints on the sugar-ethanol mix, and the accepted level of risk. Another key insight drawn from the case study is that recent market conditions have favored a production focused on the sugar business, making it challenging for policy-makers to create attractive scenarios for biofuels. Long-term electricity contracting appears to be the main hedging strategy for de-risking other products and investments in the sugarcane business, provided it is priced adequately. more...

This paper describes the obtaining of fatty acids ethyl esters from Acai (Euterpe oleracea Martius), Buriti (Mauritia flexuosa) and spent coffee grounds oils using a Beauveria bassiana lipase expressed in Aspergillus nidulans, which gene was cloned in pExpyr vector. Carbon sources were tested to enhance recombinant lipase secretion. Cassava peels, corn meal, corn syrup, sorghum seed and wheat bran induced higher lipase activity. Monosaccharides, when combined to previously cited carbon sources, interfered at lipase production: fructose and glucose enhanced lipase production, especially on sorghum seed and wheat bran cultures; while xylose diminished its production. Lipase was immobilized on hydrophobic resins, and derivatives were characterized using pNPP transesterification with ethanol as co-substrate. Sepabead-C18 derivative demonstrated as better pNPP transesterification catalyzer, being 2-fold higher than butyl derivative. The Sepabead-C18 derivative was biochemically characterized using different temperatures and solvents. The transesterification of Acai, Buriti and coffee spent grounds oils were performed with cyclohexane, and the product content was quantified using gas-chromatography as 17.1%, 5.0%, and 3.4%, respectively. The results demonstrated the potential of immobilized heterologous lipases to produce ethyl ester from Brazilian natural oils and a common food waste. This work will improve the enzymatic methodologies for biodiesel industry. more...

Greenhouse gas emissions are one of the most critical worldwide concerns, and multiple efforts are being proposed to reduce these emissions. Shipping represents around 2% of global CO 2 emissions. Since ship power systems have a high dependence on fossil fuels, hybrid systems using diesel generators and batteries are becoming an interesting solution to reduce CO 2 emissions. In this article, we analyze the potential implementation of Li-ion batteries in a platform supply vessel system through simulations using HOMER software (Hybrid Optimization Model for Multiple Energy Resources). We evaluate the impact of battery characteristics such as round trip efficiency, rated power, and energy capacity. We also evaluate the potential CO 2 emissions reduction that could be achieved with two of the most common types of Li-ion batteries (lithium titanate, lithium iron phosphate). Furthermore, we consider that the Li-ion batteries are installed in a 20 ft container. Results indicate that the lithium iron phosphate battery has a better performance, even though the difference between both technologies is lower than 1% of total emissions. We also analyze the potential emissions reduction for different parts of a mission to an offshore platform for different configurations of the ship power system. The most significant potential CO 2 emissions reduction among the analyzed cases is 8.7% of the total emissions, and it is achieved by the configuration including the main and auxiliary diesel engines as well as batteries. Finally, we present managerial implications of these results for both companies operating ships and ship building companies. more...

Due to environmental effects of extensive use of energy, solar collectors are being installed on a large scale in many countries. The accurate determination of its efficiency by a test laboratory strongly affects the system performance prediction, cost-benefit valuations, technology introducing in public policies and certification programs. In this context and considering that indoor efficiency tests using solar simulators are increasingly used by test labs, this paper presents an assessment of uncertainty associated with usual flat plate solar collector efficiency tests performed with solar simulator. For this purpose, tests were performed according indoor method in order to estimate uncertainty associated with efficiency determination. Uncertainty evaluation included the contributions of instrumentation, temporal stability of environmental test conditions and statistical regression used to determine collector's efficiency curve. Additional tests and evaluations were also carried out to investigate solar simulated irradiance and air speed influence on estimated uncertainty and to validate the results from comparison with uncertainties derived from two other laboratories. more...