One of the biggest hurdles to widespread hydrogen use is the capital cost required to produce the fuel from natural gas in large facilities. Distribution of the hydrogen to users of fuel cell vehicles is another key challenge. A team of Virginia Tech researchers discovered a way to create hydrogen fuel using a biological method that greatly reduces the time and money it takes to produce the zero-emissions fuel. This method uses abundantly available corn stover – the stalks, cobs, and husks – to produce the hydrogen. Arrival of the hydrogen-powered vehicles in a way that is inexpensive and has extremely low carbon emissions. Joe Rollin, a former doctoral student of Zhang’s at Virginia Tech and co-founder with Zhang of the start-up company Cell-free Bioinnovations, is the lead author on the paper.
The researchers have demonstrated the most important step toward a hydrogen economy – producing distributed and affordable green hydrogen from local biomass resources.
This work represents a revolutionary approach that offers many new advantages,” said Lonnie O. Ingram, director of the Florida Center for Renewable Chemicals and Fuels at the University of Florida, who is familiar with the work but not associated with the team. These researchers have certainly broadened the scope of our thinking about metabolism and how it plays into the future of alternative energy production.This work builds upon previous studies Zhang’s team did with xylose, the most abundant simple plant pentose sugar, to produce hydrogen yields .
Unique features in new discovery
The Virginia Tech team used dirty biomass — the husks and stalks of corn plants — to create their fuel. This reduces the initial expense of creating the fuel and enables the use of a fuel source readily available near the processing plants, making the creation of the fuel a local enterprise.
Rollin used a genetic algorithm along with a series of complex mathematical expressions to analyze each step of the enzymatic process that breaks down corn stover into hydrogen and carbon dioxide. He also confirmed the ability of this system to use both sugars glucose and xylose at the same time, which increases the rate at which the hydrogen is released. Typically in biological conversions, these two sugars can only be used sequentially, not simultaneously, which adds time and money to the process.
Rollin’s model increased reaction rates by threefold, decreasing the required facility size to about the size of a gas station, which reduces associated capital costs. The dominant current method for producing hydrogen uses natural gas, which is expensive to distribute and causes fossil carbon emissions.
To produce distributed hydrogen at affordable costs, product yield, reaction rate, and product separation must be addressed. In terms of product yield, the use of cell-free artificial enzymatic pathway not only breaks the natural limit of hydrogen-producing microorganisms by three times but also avoids complicated sugar flux regulation.
The team also increased enzymatic generation rates. This reaction rate is fast enough for hydrogen production in distributed hydrogen-fueling stations. The achieved reaction rate is at least 10 times that of the fastest photo-hydrogen production system.
The reaction the researchers studied takes place at modest conditions. This means that hydrogen can be easily separated from aqueous reactants and enzymes. Also, enzymatic reactions such as those being used in this system generate high-purity hydrogen, perfect for hydrogen fuel cell vehicles.The modest reaction conditions also indicate the feasibility of low-capital requirements for building distributed hydrogen generating and fueling stations based on this technology.
“We believe this exciting technology has the potential to enable the widespread use of hydrogen fuel cell vehicles around the world and displace fossil fuels,” Rollin said.
Their findings have been published in PNAS.
