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Advanced Biofuels, A Transformative Industry

At the recent U.S. Department of Energy (DOE)-sponsored Biomass Conference 2012: Confronting Challenges, Creating Opportunities, much of the focus was on liquid fuels from biomass. Several presenters, including U.S. Secretary of Energy Dr. Steven Chu, mentioned butanol as a highly regarded advanced biofuel.

As part of the ongoing research at the Energy & Environmental Research Center (EERC), we have been developing a catalytic pathway to convert ethanol or mixtures of methanol and ethanol to higher alcohols including butanol through Guerbet condensation reactions.  Simply stated, cellosic biomass like wood chips can be converted into a mixture of gases in a gasifier, and the resulting “syngas” can be passed over a catalyst and converted to alcohols like ethanol. The goal of EERC’ s research is to alleviate one of the major challenges and costs involved with cellulosic ethanol production, which is the coproduction of undesired quantities of methanol with the ethanol product. Current biorefinery processing technology and associated commercial catalysts render the production of unwanted concentrations of methanol unavoidable.
 
Methanol production is undesirable as it is not an ideal gasoline additive because of its water affinity, corrosive nature, volatility-raising impact when blended with gasoline, and low volumetric energy content versus gasoline. Two potential solutions to the methanol problem are to limit its production and/or separate it from ethanol. Both of these potential solutions present economic challenges.

Rather than fight methanol production during the syngas conversion process, the EERC is developing technology to capitalize on it. Utilizing an easily produced mixed-alcohol product from a biomass-derived syngas (about 60% methanol, 30% ethanol, 10% higher alcohols) as feedstock to a condensation reaction yields a mixture of branched alcohols (isoalcohols) comprising at least 65% isobutanol and significant quantities of higher isoalcohols including isohexanols and isooctanols.

According to the Argonne National Laboratory, use of cellulosic ethanol to displace gasoline reduces greenhouse gases by 85%. By extension, the use of cellulosic isobutanol and higher isoalcohols to replace gasoline should reduce greenhouse gases by a similar amount. Because isobutanol offers gasoline compatibility advantages versus ethanol, gasoline–isobutanol blends may be transportable via pipeline, which would further reduce greenhouse gas emissions.
The EERC technology will maximize the yield of mixed alcohols and subsequent isobutanol from biomass while also generating replacements for high-value normal alcohol- and isoalcohol-based chemical intermediates and solvents currently derived from fossil fuels.

The flexibility to produce fuel and higher-value normal alcohol and/or isoalcohol chemical intermediates represents a commercial advantage that should serve as an offset to the financial risk of building a cellulosic fuel plant. Propanol, butanol, isobutanol, and isohexanol have broad markets, carry a higher price, and are renewable in derivation, making them eligible for various credits and incentives worldwide. Of course there is the added branding of lower-carbon-footprint fuel and chemicals that can displace appreciable volumes of their petroleum-derived counterparts.

Additionally, this technology could take ethanol produced in current grain-based plants and react it with higher alcohols, commanding a greater return when compared to fuel-grade ethanol, enhancing profitability at these plants.

Dr. David Danielson, DOE Assistant Secretary for Energy Efficiency and Renewable Energy, believes that building a substantial, clean, renewable energy industry in the United States will be transformative and once again prove that the United States is capable of anything. The EERC plans to be part of that transformative industry.

By Bruce C. Folkedahl, Senior Research Manager, Energy & Environmental Research Center (EERC)  

"Bakken Map" proves a valuable resource

The Regional Drilling Activity in the Bakken and Three Forks Formations map, or the “Bakken map,” as it has come to be known, has proved to be a valuable resource for those with a stake in the state’s oil boom. The 2-ft × 3-ft map, which was designed and produced by the EERC with support from 22 industry sponsors, displays regional drilling activity in the Bakken and Three Forks Formations of western North Dakota. Wells are represented by dots of different colors, which signify the years in which the wells were drilled. Requests for the map have exceeded supply for both the 2011 and 2012 editions. Why are these maps so popular?

“I think people inherently like maps. Maps are a nice way for people to relate back to things they’ve seen, things they’ve experienced, and the map becomes a focal point for people to discuss items of common interest,” said EERC Associate Director for Research John Harju. “So, for anyone who has some involvement with this oil resource development in the Bakken, it’s a visually appealing and efficient means of distilling an astounding amount of information.”

The idea for the map started about a year and a half ago, according to Harju, who said that the work the EERC has conducted with the support of the U.S. Department of Energy (DOE), and specifically the National Energy Technology Laboratory, allowed the EERC to accumulate a great degree of knowledge regarding the Bakken System through its oil and gas programs.

“Based on the demand we had for some smaller Plains CO2 Reduction (PCOR) Partnership maps focused on oil fields in the Williston Basin and in conjunction with the work we’d been doing in the Bakken System,” said Harju, “we decided to approach producers and service companies who were active across the Bakken System in the Williston Basin with the idea of a sponsored map that would illustrate where activity was occurring and the magnitude of that activity.”

In addition to the oil wells drilled in the state, the first version of the map in 2011 highlighted what Harju called “notable wells”: wells that were really successful, those that had large numbers of completion stages, or those that were very historic or prolific in terms of production. The map included the Bakken “discovery well”—the well drilled on land owned by a farmer named Henry Bakken in 1951 that tapped into oil and was part of the first oil boom in western North Dakota.

The map was revised in 2012 to include wells beyond western North Dakota into the neighboring areas of Canada and added a stratigraphic column of the Williston Basin in general and a more specific breakout of the Bakken System. Two other key modifications to the new map are the addition of all gas-processing plants in the state and an annotated graph of historical oil production for the state of North Dakota. The annotations call out notable points in time and their incumbent influence on production, and the graph illustrates the remarkable increase in production in the region as a result of the Bakken oil play.

Well data for both maps were obtained from the North Dakota Industrial Commission’s Department of Mineral Resources and the respective state and provincial oil and gas resource offices for Montana and Saskatchewan and Manitoba, Canada.

The 5000 maps printed for the 2011 edition were sent to all attendees of the Williston Basin Petroleum Conferences (WBPCs) for 2010 and 2011, all members of the North Dakota Petroleum Council, map sponsors, state legislators, and local governmental officials. Inquiries from people who had seen the map soon flooded the EERC. The 2012 printing was increased to 7500 and again sent to all attendees of the growing WBPC and other former recipients. Although 50% more maps were printed for 2012, it was still not enough to meet demand, and an additional 2000 were ordered.

In addition to its value as an informative resource, Harju said the map has also been a great way to showcase the logos of some of the companies that have sponsored this effort and, in many cases, other EERC research.

“Some of our sponsors have had the map matted and framed and proudly feature it up on their walls,” said Harju. “It is a very rewarding experience when I walk into a client’s office and see that.”

For more information on obtaining a copy of the map, go to www.undeerc.org/bakken/Purchase-a-Bakken-Map.aspx. 

Water: Reducing Our Use

More freshwater is now used for thermoelectric power production than for agricultural irrigation in the United States—41% to 37%, respectively (U.S. Geological Survey Circular 1344, 2005). Much of this generation operates according to the steam-driven heat engine process known as the Rankine cycle. In a Rankine cycle-based power plant, heat generated from the combustion of conventional fuels (e.g., coal, gas, oil) and renewable fuels (e.g., biomass, waste-to-energy), or through the use of concentrated solar energy and geothermal energy, or through nuclear fission is used to boil water to make high-pressure steam that is expanded through a turbine to generate power. The exhausted steam must be condensed by dissipating heat to the environment before being returning to the boiler to complete the cycle.

For many years, the most popular cooling option for thermoelectric power was once-through cooling (or openloop cooling) because it requires the lowest capital costs. In this system, the water is withdrawn from a body of water and diverted through a heat exchanger (typically called a condenser) where it absorbs heat from and condenses the turbine exhaust steam. The water is then returned directly to the water source with minimal water consumption. However, open-loop cooling does require large water withdrawals and returns water to the source at a higher temperature.

At the high flow rates utilized for open-loop cooling (~30,000 gal/MWh), water intake structures can remove aquatic organisms through impingement and entrainment, causing direct kills of fish and eggs at the intake; aquatic ecosystems can also be altered as a result of the elevated water temperatures near plant water discharge, according to the U.S. Environmental Protection Agency (EPA). These systems are no longer considered to be a viable design option for new plants, and existing installations are under increased regulatory pressure to switch to technologies with less environmental impact. For example, EPA is currently proposing to update regulations that would require implementation of a closed-loop cooling technology or another design change equivalent (e.g., reducing intake flow rates, installing fish deterrents, etc.) to the entrainment reductions associated with closed-loop cooling.

Closed-loop wet cooling systems recirculate water through a condenser and a cooling tower. The cooling tower rejects the heat from the steam to the atmosphere via evaporative cooling using mechanical or natural draft airflow. Although closedloop systems recirculate a majority of system water, evaporative losses need to be continuously replaced; therefore, significantly less water is withdrawn but more water is consumed (~750 gal/MWh) compared to open-loop cooling systems.

Water-based cooling is cost-effective and efficient, but lack of water availability frequently makes water-based cooling a contentious issue because cooling needs are often perceived to be in conflict with sustainability of water resources.

“Two EERC projects are focused on reducing water use for thermoelectric power,” according to EERC Director Gerry Groenewold. “One is a novel dry cooling technology that can eliminate the need for cooling water. The second project involves a new hybrid cooling system that will economically decrease water requirements.

“Optimizing cooling systems used in power generation to increase water use efficiency is key to long-term sustainable energy development and economic development,” said Groenewold.

Novel Dry Cooling
Dry cooling options reject heat directly to the atmosphere, but they are more costly than wet systems and do not work as efficiently or produce as much electricity during hot weather. Conventional dry cooling systems cost 3.5 to 4 times as much as a wet cooling system. Particularly in those hot, dry areas of the country where water is scarce, there is a unique need for a dry cooling alternative.

The EERC has developed a novel new dry cooling technology with support from DOE and the Wyoming Clean Coal Technologies Research Program that is applicable to all Rankine-based power plants and similar heat rejection loads. The project also has in-kind assistance from SPX Cooling Technologies. This unique system uses a hygroscopic fluid as a coolant, which is nonvolatile and does not evaporate. This eliminates the continual need for cooling water, making the technology most suitable for locations without adequate water.

“One of the most remarkable aspects of the technology, to me, is that the coolant absorbs moisture from the air at night when temperatures are lower and, as the day heats up, evaporates the excess water, which is a benefit for cooling and helps to moderate performance,” said Research Engineer Chris Martin. Martin invented the technology and serves as project manager for its evaluation.

In late 2011, the EERC designed and built an experimental validation test facility at its research complex in Grand Forks, North Dakota. Testing in early 2012 showed that the initial feasibility concerns can be overcome and that the process dissipates heat to the atmosphere efficiently. Evaluation testing will continue in  2012 to demonstrate that the EERC technology offers improved cost vs. performance compared to conventional dry cooling methods. Future developments could include a long-term outdoor demonstration at a power facility with industry support.

Improved Hybrid Cooling
Systems that integrate both wet and dry cooling components are referred to as hybrid cooling systems. Hybrid systems generally have a lower capital cost than a dry cooling system and use less water than a completely water-cooled system. There are various configurations to achieve hybrid cooling, including a system that consists mainly of 1) a wet stream–surface condenser plus a wet cooling tower and 2) a dry  stream–jet condenser plus a natural or mechanical draft air-cooling tower.

The EERC and GEA Heat Exchangers, Inc. (GEA), with DOE support, partnered to build and evaluate a first-of-its-kind hybrid condenser, which combines the operations of a jet condenser and a surface condenser. The hybrid condenser was designed by GEA to maintain the benefits of a hybrid system, while further reducing costs.

A prototype module of the hybrid condenser design was fabricated and tested at the EERC to validate its potential to more economically reduce water consumption in electricity generation applications. GEA conducted the testing with the EERC to ensure operations and data were representative of conditions seen in  commercial industry. Data and economic evaluation is currently under way.

“This project reflected, to me, the best of the EERC, such as working in partnership with commercial, global companies like GEA, as well as using our pilot-scale fabrication and system-testing capabilities,” said Research Engineer Kerryanne Leroux, who, as the project’s principal investigator, oversaw the initial testing in the summer of 2012.

There is a growing market for the hybrid condenser, specifically at existing power plants with water-based cooling where water availability is becoming limited. The ability of the hybrid condenser to be retrofitted into these power plants’ existing footprints and the resulting water savings realized during operation make the hybrid condenser an attractive solution.