Curtis Robbins

Biodistillate Transportation Fuels 1. Production and Properties

Biodistillate transportation fuels include biodiesel (produced via transesterification of animal fats and vegetable oils) and renewable diesel (produced via catalytic hydroprocessing of the same feedstocks). Production and use of biodistillates are increasing dramatically, both in the U.S. and globally. This paper describes the policy drivers prompting growth of biodistillate fuels in the U.S., Europe, and selected other countries. Trends in fuel production volumes and feedstocks supplies are presented for these fuels. Current feedstocks are dominated by soybean oil in the U.S. and rapeseed oil in Europe. However, there is much interest in developing alternative, non-edible feedstocks such as jatropha and microalgae. Currently, biodiesel is the dominant biodistillate in use, though interest in renewable diesel is increasing. This paper describes different conversion processes used to manufacture these fuels, and discusses the pros and cons of each. Chemical and physical properties of biodistillates are presented, along with a discussion of the relevant fuel specifications established by ASTM and other organizations. Measures to assure satisfactory fuel quality are explained. Finally, in-use handling and performance of biodistillates are discussed, focusing on issues such as fuel stability and low-temperature operability where special precautions may be necessary to ensure satisfactory quality.

Empirically Driven Computer Simulations of Solar Thermal Systems for Space Heating and Domestic Hot Water

The Desert Research Institute (DRI) has developed a Renewable Energy Deployment and Display Facility (REDD) which utilizes solar and wind to create a net zero energy residence for research, education, and outreach. The facility is a demonstration of the integration of many renewable energy technologies into a residential setting such that technology developers can show proof-of-concept, students and trade workers can get hands-on experience, and public organizations can see renewable energy components implemented into a residential setting. A major technological aspect of the facility is the use of solar thermal energy to provide space heating, Domestic Hot Water (DHW), and solar cooling. Data are monitored from three separate solar thermal systems, each with their own hot water storage, to evaluate optimized utilization of solar thermal energy into residential applications.The three solar thermal systems differ in their working fluids. System 1 uses a conventional mixture of glycol and water in 200 ft2 of ground mounted collector area, System 2 uses DHW in 210 ft2 of roof mounted collector area, and System 3 uses air in a 578 ft2 collector built into the roof. Each system is configured to be used for space heating and DHW. Systems 1 and 2 are built into the HVAC system of the 1200 ft2 house, and System 3 is built into the HVAC system of the 600 ft2 detached workshop. Data collected from each system provide the basis for year-long energy and economic simulations using TRNSYS for comparison. The results from the simulations are used to demonstrate the effectiveness of site-built solar air collectors, which have the advantage of using conventional materials, and avoid the issues of liquid collectors associated with boiling and freezing. This paper describes the experimental setup of the solar thermal systems, how the data are used as inputs to the computer simulations, and the configuration of the computer simulations.The REDD Facility, as well as the use of TRNSYS will continue to be used by DRI researchers to investigate not only the most feasible integration of components for a solar thermal residential system, but also as a tool to properly size and implement solar thermal systems.Copyright

Development of the Renewable Energy Deployment and Display (REDD) Facility at the Desert Research Institute

The Desert Research Institute (DRI) has developed a Renewable Energy Deployment and Display (REDD) Facility as an off-grid capable facility for exploration of integration, control, and optimization of distributed energy resources (DER) with an emphasis on solar and wind energy. The primary goal of the facility is to help grow DRI’s capabilities and expertise in areas of renewable energy research, development, demonstration, and deployment. The facility is powered by four solar PV arrays (6 kW total) and two wind turbines (3 kW total) during off-grid operation. Energy storage is achieved via two 2.5 m3 hydrogen storage tanks and a 9 kWh battery bank. The hydrogen is produced via a 5 kW electrolyzer and is used to fuel an internal combustion engine (ICE) with an alternator when needed.The REDD Facility consists of a 111.5 m2 residence and a 56 m2 workshop. The REDD House features over 37 m2 of solar thermal collectors used to provide hot water to either a 15.9 kW heat exchanger or a 17.6 kW absorption chiller. The REDD Workshop features a 54 m2 solar collector air heater and thermal storage via water and air in the floor. Also housed in the REDD Workshop is a modified 3-cylinder 950cc naturally aspirated renewable gas engine connected to a 5 kW generator to be used for future biomass-related research.Future research at the REDD Facility will include continued investigation into the use and regulation of site-built solar air collectors, solar cooling technologies, and the advancement of hydrogen as energy storage for residential applications. The facility is also continually used for education and outreach purposes. Lastly, DRI encourages the use of the REDD Facility as a test bench for new technologies; whether for proof of concept or demonstration.© 2014 ASME

Enhancing Engine Operations in Off-Grid Renewable Energy Applications Through the Additional Use of Hydrogen

The current renewable energy transformation taking place around the world has led to drastic advances in technology that relates to the issue of climate change. Although many solutions have been found and/or created, there has yet to be one that can, on its own, solve the problem of finding an environmentally friendly energy source. This leads to the challenge of creating an integrated system which relies on several components with different types of energy. It has been the goal of this study to further enhance an off-grid renewable energy power system to supply economical, secure, and continuous electrical power, in an environmentally conscious way, for various types of loads. The previous power system consisted of a mobile unit with inverters, batteries, hydrogen generator, hydrogen storage, propane storage and an internal combustion engine generator that was connected to photovoltaics and wind turbines while being controlled and monitored by a single computer unit. The only pollutants emitted from this power system were the result of the use of propane as a backup fuel, when renewable energy was insufficient. Even though propane is a fossil fuel, its use in this study allowed the system to be simpler and more cost effective. With the assistance of Southwest Gas Corporation, a more efficient and reliable internal combustion engine was acquired. The three cylinder engine, with a 10,000 hour maintenance interval, was converted from natural gas to combust either hydrogen or propane. The engine provides mechanical power to a belt driven alternator supplying electricity to the load and other components of the system. Initial testing of the engine achieved engine dynamometer efficiency of over 40% using propane at wide open throttle and 45% using hydrogen at wide open throttle. The output under these conditions was roughly 20 HP using propane and 10 HP using hydrogen. The current system is not mobile but has the potential to be mobile by using an existing KOH electrolyzer for hydrogen generation with a larger output and hydrogen storage capacity.© 2010 ASME