+ Fuel Cells: What are They and How do They Work?
With an ever growing need for an alternative energy source, one of the newest, most promising technologies is the modern fuel cell. While licenses for fuel cell patents were purchased for use in NASA space programs back in the 1960’s, recent advances are making fuel cell technology a serious near future contender for general commercial purposes. However, with all of this recent talk of these breakthrough devices, one may wonder, what exactly is a fuel cell and how does it work?
How Does It Work
I checked out How Stuff Works to get a basic understanding. In the most basic sense, a fuel cell utilizes a chemical reaction to produce electricity, much like the standard batteries we are all familiar with. While there are many different types of fuel cells, let’s take a look at a polymer exchange membrane fuel cell (PEMFC) for the sake of simplicity.
In the basic construction, we basically have two plates with grooves or channels, one negative (called the anode) and one positive (called the cathode), much like the terminals on a battery. Between these two plates is a thin layer of material called a proton exchange membrane. Then, two “fuels” such as hydrogen and oxygen are sent down the channels on either side of the membrane. On the negative anode, molecules of a fuel like hydrogen are split into electrons (electricity) and protons (positively charged particles). The membrane allows the protons to cross the barrier in-between the two fuels while the electrons are forced to travel around an electrical circuit, generating a current, before rejoining the protons on the other side of the membrane and completing the chemical reaction, forming a byproduct such as water (in the case of hydrogen and oxygen) or carbon dioxide.
What About the Hydrogen?
In a world that relies upon naturally occurring and refined fuels such as gasoline, ethanol, propane, etc., how do we effectively produce the hydrogen necessary for fuel cells? While research continues in the pursuit of a long term, fully hydrogen sufficient solution, the answer for the transitional period from fossil fuels to hydrogen seems to lie in a process called “Steam Reforming.” Fuels like readily available methane (natural gas), ethanol, propane and even gasoline are reacted with steam at high temperatures (700 -1000ºC) and in the presence of a catalyst (a material that speeds up a chemical reaction) produces hydrogen and carbon monoxide. Then, in another process called the "water-gas shift reaction," the carbon monoxide from the previous reaction is reacted with water and another catalyst and water, producing more hydrogen and carbon dioxide.
After saying this, I’m sure some red flags have gone up. Aren’t we trying to reduce greenhouse gas emissions? Isn’t that the point of using a fuel cell over conventional combustion? Won’t this just switch our dependence on imported oil to a dependence on natural gas? However, according to the U.S. Department of Energy,
“Producing hydrogen from natural gas does result in some greenhouse gas emissions. When compared to ICE (internal combustion engine) vehicles using gasoline, however, fuel cell vehicles using hydrogen produced from natural gas reduce greenhouse gas emissions by 60%... Current estimates indicate that using natural gas to produce hydrogen during the transition period to a hydrogen economy would increase overall U.S. natural gas consumption by less than five percent… [The Department of Energy] is not funding research activities for large-scale central production of hydrogen from natural gas. DOE efforts are focused on distributed natural gas reforming for the transition period only. Large-scale hydrogen production from natural gas reforming is a mature technology, and natural gas resources in the United States are limited—15% of the natural gas we use is imported. Producing large amounts of hydrogen from natural gas in the long term would only trade U.S. dependence on imported oil for U.S. dependence on imported natural gas.”
In addition, natural gas pipeline infrastructure already exists, reducing costs associated with needing new equipment, facilities and additional maintenance. Again, according to the department of energy, “Today, 95% of the hydrogen produced in the U.S. is made via natural gas reforming in large central plants. (The hydrogen produced is used predominantly for petroleum refining and ammonia production for fertilizer).”
High Efficiency
Another question that might arise is why do we even care about fuel cells? For one, they have incredible efficiency over standard batteries and combustible fuels alike. For two, they create less waste and/or pollution. Typical batteries are completely closed systems, meaning that when their internal chemicals are finished reacting (and cannot be reversed in the case of rechargeables) the battery is completely “dead” and must be replaced, generating landfill waste and possibly environmental hazards while fuel cells will generate electricity as long as the proper fuels are continuously supplied. Additionally, in terms of engines taking advantage of fuel cells, typical byproducts are water, carbon dioxide or other eco-friendly compounds.
Although fuel cells have advanced incredibly far since their first applications in NASA space programs, manufacturers still face many challenges in production. Equipment costs and sheer cost of materials (one material often found is platinum) used in the fuel cell must be overcome in order to make hydrogen cheap enough to be able to compete with current alternatives. Key research areas include reducing these costs with more effective catalysts/manufacturing methods and combining the many manufacturing processes required into several larger steps.
Despite these challenges, many companies are taking fuel cell technology to the next level, integrating them into various prototype consumer devices, vehicles and power generation devices. Among those companies are Honda with their FCX Clarity, their latest fuel cell vehicle, planned for availability to a limited number of customers in summer 2008. Other companies include Horizon Fuel Cell Technologies, whose remote control car runs completely on hydrogen, and Medis Technologies with their 24/7 Power Pack, producing portable power for a wide range of handheld devices.
How Does It Work
I checked out How Stuff Works to get a basic understanding. In the most basic sense, a fuel cell utilizes a chemical reaction to produce electricity, much like the standard batteries we are all familiar with. While there are many different types of fuel cells, let’s take a look at a polymer exchange membrane fuel cell (PEMFC) for the sake of simplicity.
In the basic construction, we basically have two plates with grooves or channels, one negative (called the anode) and one positive (called the cathode), much like the terminals on a battery. Between these two plates is a thin layer of material called a proton exchange membrane. Then, two “fuels” such as hydrogen and oxygen are sent down the channels on either side of the membrane. On the negative anode, molecules of a fuel like hydrogen are split into electrons (electricity) and protons (positively charged particles). The membrane allows the protons to cross the barrier in-between the two fuels while the electrons are forced to travel around an electrical circuit, generating a current, before rejoining the protons on the other side of the membrane and completing the chemical reaction, forming a byproduct such as water (in the case of hydrogen and oxygen) or carbon dioxide.
What About the Hydrogen?
In a world that relies upon naturally occurring and refined fuels such as gasoline, ethanol, propane, etc., how do we effectively produce the hydrogen necessary for fuel cells? While research continues in the pursuit of a long term, fully hydrogen sufficient solution, the answer for the transitional period from fossil fuels to hydrogen seems to lie in a process called “Steam Reforming.” Fuels like readily available methane (natural gas), ethanol, propane and even gasoline are reacted with steam at high temperatures (700 -1000ºC) and in the presence of a catalyst (a material that speeds up a chemical reaction) produces hydrogen and carbon monoxide. Then, in another process called the "water-gas shift reaction," the carbon monoxide from the previous reaction is reacted with water and another catalyst and water, producing more hydrogen and carbon dioxide.
After saying this, I’m sure some red flags have gone up. Aren’t we trying to reduce greenhouse gas emissions? Isn’t that the point of using a fuel cell over conventional combustion? Won’t this just switch our dependence on imported oil to a dependence on natural gas? However, according to the U.S. Department of Energy,
“Producing hydrogen from natural gas does result in some greenhouse gas emissions. When compared to ICE (internal combustion engine) vehicles using gasoline, however, fuel cell vehicles using hydrogen produced from natural gas reduce greenhouse gas emissions by 60%... Current estimates indicate that using natural gas to produce hydrogen during the transition period to a hydrogen economy would increase overall U.S. natural gas consumption by less than five percent… [The Department of Energy] is not funding research activities for large-scale central production of hydrogen from natural gas. DOE efforts are focused on distributed natural gas reforming for the transition period only. Large-scale hydrogen production from natural gas reforming is a mature technology, and natural gas resources in the United States are limited—15% of the natural gas we use is imported. Producing large amounts of hydrogen from natural gas in the long term would only trade U.S. dependence on imported oil for U.S. dependence on imported natural gas.”
In addition, natural gas pipeline infrastructure already exists, reducing costs associated with needing new equipment, facilities and additional maintenance. Again, according to the department of energy, “Today, 95% of the hydrogen produced in the U.S. is made via natural gas reforming in large central plants. (The hydrogen produced is used predominantly for petroleum refining and ammonia production for fertilizer).”
High Efficiency
Another question that might arise is why do we even care about fuel cells? For one, they have incredible efficiency over standard batteries and combustible fuels alike. For two, they create less waste and/or pollution. Typical batteries are completely closed systems, meaning that when their internal chemicals are finished reacting (and cannot be reversed in the case of rechargeables) the battery is completely “dead” and must be replaced, generating landfill waste and possibly environmental hazards while fuel cells will generate electricity as long as the proper fuels are continuously supplied. Additionally, in terms of engines taking advantage of fuel cells, typical byproducts are water, carbon dioxide or other eco-friendly compounds.
Although fuel cells have advanced incredibly far since their first applications in NASA space programs, manufacturers still face many challenges in production. Equipment costs and sheer cost of materials (one material often found is platinum) used in the fuel cell must be overcome in order to make hydrogen cheap enough to be able to compete with current alternatives. Key research areas include reducing these costs with more effective catalysts/manufacturing methods and combining the many manufacturing processes required into several larger steps.
Despite these challenges, many companies are taking fuel cell technology to the next level, integrating them into various prototype consumer devices, vehicles and power generation devices. Among those companies are Honda with their FCX Clarity, their latest fuel cell vehicle, planned for availability to a limited number of customers in summer 2008. Other companies include Horizon Fuel Cell Technologies, whose remote control car runs completely on hydrogen, and Medis Technologies with their 24/7 Power Pack, producing portable power for a wide range of handheld devices.
Labels: Alternative Energy, Energy, energy storage, Transportation
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posted by Ryan McIntire on Friday, January 25, 2008
