Let’s continue on our journey to discovering alternative energy processes that can be utilized to replace fossil fuels. As many of you know by now, this blog has specifically been delving into types of alternative energies. This week’s blog discusses and illustrates the natural gas reformation process of producing hydrogen.
We are currently standing in an economic and political standstill because we keep producing the necessary hydrogen that we need from fossil fuels and other crude materials. For example, many of you would know that this typically occurs at an oil refinery. Nevertheless, there must be ways of producing hydrogen from renewable resources so that the United States can cut down on the amount of greenhouse gas emissions and pollution into the environment. How does it work?
Hydrogen is a versatile energy carrier in today’s transportation sector and in industry. For example, many of you may realize that hydrogen could be a viable energy carrier in hydrogen fuel cell electric vehicles, as illustrated by the very first blog post. Now, where can the United States efficiently make enough hydrogen for today’s demand?
About 95% of today’s hydrogen is produced in a process known as steam-methane reformation (U.S. Department of Energy, 2012). This is a process that utilizes high-temperature steam around 700 degrees Celsius to 1000 degrees Celsius. The overall mechanism of natural gas reformation undergoes three steps: the steam-methane reformation (or other natural gas reformations), water-gas shift reactions, and pressure-swing absorption.
Hydrogen can be produced from natural gas, such as methane, in the steam-methane reformation process. This process utilizes a catalyst that allows methane and other natural gases to react with steam in order to produce hydrogen, carbon monoxide, and a small byproduct of carbon dioxide. Comparatively, a small byproduct means that the substance makes a minor contribution to the total amount of product formed. As a result of forming vast amounts of hydrogen in stream-methane reforming, the stream of carbon dioxide produced is very significant!
Overall, the steam-reforming process is endothermic. An endothermic process is a particular reaction or mechanism that requires heat to be supplied in order for the reaction to move forward, that is, from reactants to products.
Water-Gas Shift Reaction
Here is where the overall reformation process can get interesting. The water-gas shift reaction reacts the carbon monoxide and steam left over from the preceding the steam-methane reformation process using a catalyst in order to produce carbon dioxide and more hydrogen. This cuts down on wasting the unnecessary byproducts of the previous reaction. This essentially extends and increases the amount of hydrogen that can be produced in order to optimize the amount of desired product.
At this point, the amount of hydrogen is maximized in the product streams of the two steps in the natural gas reformation process shown above. You may be wondering about what engineers and scientists have done about the undesired products, and this subject is worthy of discussion. In a process known as pressure-swing absorption, carbon dioxide and other impurities are removed from the gas stream (U.S. Department of Energy, 2012). Essentially, all you have left is hydrogen, which is the only desired product in this overall process.
Not only methane is used in steam-reforming processes. Fuels, such as ethanol, propane, and gasoline, are utilized to their fullest extent to produce massive amounts of hydrogen. Here are several of them illustrated below, along with the water-gas shift reaction:
Methane: CH4 + H2O (+ heat) –> CO + H2
Propane: C3H8 + 3H2O (+ heat) –> 3CO + 7H2
Gasoline: C8H18 + 8H2O (+ heat) –> 8CO + 17H2
Water-Gas Shift: CO + H2O –> CO2 + H2 (+ small amount of heat)
Why Does This Technology Matter?
As illustrated above, 95% of today’s hydrogen in the United States comes from natural gas reforming technology. This hydrogen is utilized in the petroleum refining and ammonia production for fertilizer (U.S. Department of Energy, 2012).
This amount of hydrogen could help stimulate the hydrogen economy that could drive our nation from our economic dependence on foreign oils. The hydrogen economy generally illustrates how hydrogen could be the major energy carrier in today’s society if it can be mass-produced on a nationwide scale. Hydrogen fuel could be utilized in revolutionizing hydrogen fuel-cell electric vehicles that use hydrogen as their primary carrier of energy to produce the necessary amount of electricity from electrochemical reactions to power the vehicle.
Like most technological innovations, there are some drawbacks. Many areas of improvement can be made into intensifying the process, developing better designs to lower equipment manufacturing and maintenance costs, and increasing efficiency by using better catalysts and heat processes (U.S. Department of Energy, 2012). As these areas are being further developed through research and experimentation, the public must be informed about using hydrogen so that we can make the transition from fossil fuels to alternative energy sources.
U.S. Department of Energy. (2012). Hydrogen Production. Energy Efficiency & Renewable Energy. Retrieved from http://www1.eere.energy.gov/hydrogenandfuelcells/production/natural_gas.html.