December 6, 2012
Synthetic Fuel Could End US Reliance On Crude Oil
Lawrence LeBlond for redOrbit.com - Your Universe Online
The United States has been relying on crude oil for more than a century. While it has played a vital role in driving modern innovation–transportation, plastics, detergents and even clothing–crude oil has also contributed to dangerous global warming. With the burgeoning threat of climate change, researchers from Princeton have outlined how the US could end reliance on petroleum and move to synthetic fuels.
The US could use a combination of coal, natural gas and non-food crops to produce synthetic fuel, the Princeton team explained. Besides the economic and national security benefits such a move could herald, the move could also be environmentally advantageous. Because plants absorb carbon dioxide to grow, the US could cut automotive greenhouse gas emissions by as much as 50 percent by the 2080s using non-food crops to create fuel.
The synthetic fuel idea comes from professor Christodoulos Floudas and graduate students Josephine Elia and Richard Baliban. The trio developed a comprehensive system for optimizing the production of synthetic liquid fuels as an economical replacement for petroleum-based fuels. These synthetic fuels would be an easy replacement in the transportation sector because they can replace modern fuel without any special modifications to engines as they are nearly identical to refined crude oil.
Such a development is a smarter option than biofuels, the team said, as these organic fuels still need to be mixed with gas or require specially modified engines to work.
Floudas and his colleagues spent the better part of the last year evaluating scenarios in which US vehicles are run using synthetic, rather than petroleum-based fuels. Producing a series of scholarly articles, the team analyzed the impacts that synthetic fuel plants were likely to have on local regions and also identified locations that would not overload electric grids and water supplies.
"The goal is to produce sufficient fuel and also to cut CO2 emissions, or the equivalent, by 50 percent," said Floudas in a statement. "The question was not only can it be done, but also can it be done in an economically attractive way. The answer is affirmative in both cases."
But accomplishing this feat is no easy task, nor is it a quick one, said Floudas. He said a realistic approach would call for a gradual implementation of synthetic fuel technology, estimating it would take up to 40 years for the US to fully adopt such a fuel system. And while it could be a savior for the environment, it won´t be easy on our wallets. He said such a system could cost upwards of $1.1 trillion to implement.
But if the cost is a driving factor in keeping the technology from taking off, it should be noted that the costs of coping with climate change could be far greater. As it stands, it would be likely that such a system would not curb climate change in the near term, but would present a positive trend for future generations, potentially saving the world from climatic catastrophe.
Princeton´s research has been an important part of another paper produced by the American Institute of Chemical Engineers (AIChE), the nation´s largest chemical engineering association. In their paper, the engineers call for a greater integration of energy sources and urge lawmakers to consider chemical conversion processes as a potential method to produce cleaner energy.
"Right now we are going down so many energy paths," said June Wispelwey, the institute's director and a 1981 Princeton alumna. "There are ways for the system to be more integrated and much more efficient."
Vern Weekman, one of Floudas' co-researchers, and author of the AIChE paper, said the main reason the industry has not embraced synthetic fuels has been cost. But with crude oil prices continuously rising, a move to synthetic fuel production could be far more viable than before.
Weekman, a Princeton lecturer and former director of the Mobil Research Laboratories and past AIChE president, said: "The main reason we wrote the paper was to get the planning agencies – the national academies, the Department of Energy, the Environmental Protection Agency, the Defense Department – thinking about this."
He added that it was important that the agencies consider "this key link of using chemical processes to produce conventional fuels."
In the Princeton research, Floudas and his colleagues found that synthetic fuel plants could produce gasoline, diesel and jet fuels at competitive prices, depending on prices of crude oil and feedstock used for synthetic fuel production.
"Even including the capital costs, synthetic fuels can still be profitable," said Baliban, a chemical and biological engineering graduate student from Princeton. "As long as crude oil is between $60 and $100 per barrel, these processes are competitive depending on the feedstock," he said.
The technique would implement the use of heat and chemistry to create gasoline and other liquid fuels from high-carbon feedstock ranging from coal to switchgrass, a native North American grass common in the Great Plains. This technique, called the Fischer-Tropsch process, is a 1920s German-developed method that converts coal to liquid fuels.
The process takes carbon and hydrogen from feedstock and reassembles them into complex chains that make up fuels like gasoline and diesel. The feedstock is super-heated to temperatures over 1,800 degrees Fahrenheit and converted to gas, and through the Fischer-Tropsch process, the gas is converted to chains of hydrocarbon molecules. These hydrocarbon chains are then processed over catalysts such as nickel and iron. The end product includes fuel, wax and lubricants normally made from crude oil.
Floudas and his colleagues added an extra step to recycle CO2 through the process to reduce the amount of emissions produced by the plants. Baliban said there is a limit to how much CO2 can be economically recycled, although such plants could also trap unused CO2 emissions for later storage.
Over the years, the Fischer-Tropsch process hadn´t gained much attention due to low crude oil prices and the high cost of building new synthetic plants, making synthetic fuels too expensive to gain widespread acceptance. But as crude oil prices increase, the synthetic fuel prospect is becoming a more practical approach.
With skyrocketing crude oil prices, the US government has recently looked into a number of projects involving the process to see how feasible the synthetic approach would be.
In a July paper, published in the AIChE Journal, the Princeton researchers said the US could meet its entire demand for transportation fuel by building 130 synthetic fuel plants around the country. Elia, that paper´s lead author, said the country should build 9 small, 74 medium and 47 large plants producing 1 percent, 28 percent and 71 percent of the fuel, respectively.
The researchers found that the largest contributor to the price of synthetic fuel will be the cost of building these plants, followed by the purchase of biomass and electricity. They estimate that the nationwide average cost of producing the synthetic equivalent of a barrel of crude oil would be $95.11. However, the cost would vary regionally, with some areas of the country paying more, and others less. Kansas, where the researchers believe the most production would occur, would average $83.58 for the equivalent of a barrel of crude oil.
The cost could be much lower if plants used coal and natural gas rather than biomass, said Floudas, but that would also eliminate most of the environmental benefit.
"If you want to have a 50 percent reduction in emissions, you need to have the biomass," he said.
The team noted that synthetic fuels are a much greener option than petroleum-based fuels. The heavy metal and sulfur contaminants of petroleum fuels can be captured in synthetic plants before the fuel is even shipped out. Synthetic fuels can also be used in both gasoline and diesel engines with no modifications needed. Synthetic fuels would also greatly reduce transportation´s carbon footprint.
Even if the entire country were to switch to zero-emitting electric or fuel cell vehicles immediately, millions of internal combustion vehicles would still be on the road, emitting carbon into the atmosphere. By switching to synthetic fuels, Floudas said the country could drastically reduce emissions, at least from the transportation point-of-view.
"This is an opportunity to create a new economy," Floudas said. "The amount of petroleum the U.S. imports is very high. What is the price of that? What other resources to do we have? And what can we do about it?"