In the movie “Oppenheimer” one of the key plot points is the discussion of the development of the hydrogen bomb vs. the original atomic bomb. While the atomic bomb operates on nuclear fission, the hydrogen bomb is both a fission and hydrogen fusion device, greatly increasing the potential release of energy. Despite the infancy of hydrogen technology in the 1940’s, scientists understood the potential of the universe’s most abundant element as a weapon, but even they couldn’t see the promise of hydrogen as the ulitmate green energy source.
Fuel cells represent one of humanity’s best chances to use hydrogen not as a weapon, but as one of the worlds most efficient and non-polluting energy sources. Due to their chemistry, fuel cells are very clean. Fuel cells that use hydrogen as fuel, are completely carbon-free, with their only byproducts being electricity, heat, and water. Some types of fuel cell systems are capable of using hydrocarbon fuels like natural gas, biogas, methanol, and others. Because fuel cells generate electricity through chemistry rather than combustion, they can achieve much higher efficiencies than traditional energy production methods such as steam turbines and internal combustion engines. To push the efficiency even higher, a fuel cell can be coupled with a combined heat and power system that uses the cell’s waste heat for heating or cooling applications.
Today the focus of hydrogen based fuel researched is on how to produce it and use it as a fuel source in an environmentally friendly way. Currently 95% of the hydrogen produced for fuel is made from non-renewable natural gas, and the by-products of this hydrogen extraction process generate large amounts of CO2. The careful management of heat and pressure is another key factor in the hydrogen extraction, regardless of the method used. Some of these newer methods show the promise of extracting and storing hydrogen fuel in ever more environmentally friendly ways.
CPI is excited about this promising technology and even more excited that fuel cell manufacturers are choosing CPI thermal switches as key components in their evolving solutions.
What is a Fuel Cell and How does it Work?
A fuel cell is an electrochemical device that combines hydrogen fuel and oxygen to produce electricity, heat and water. Fuel cells operate without combustion, so they are virtually pollution free literally producing water as a by-product. Since the fuel is converted directly to electricity and heat, a fuel cell’s total system efficiency can be much higher than internal combustion engines, extracting much more energy from the same amount of fuel. Some modern fuel cells have an overall efficiency of almost 65% compared only 20% of a gas engine. The fuel cell itself has no moving parts, making it a quiet and reliable source of power.
Of course challenges exist with fuel cells because hydrogen is not a naturally occurring element. Hydrogen must be separated from other compounds that contain hydrogen, and breaking these chemical bonds requires energy that is mostly coming from fossil fuel sources. Until renewables provide a much higher percentage of the energy grid, it is fair to say that fuel cells aren’t entirely emissions-free. And of course, in this electrochemical reaction heat is produced along with electricity and water. This heat must be managed carefully as the temperature of the fuel cell is a significant performance changing factor. That’s where CPI comes in.
Managing Thermal Performance of Fuel Cells.
Solid Oxide Fuel Cell (SOFC)
SOFCs are the highest temperature fuel cells, operating at about 1800 degrees Fahrenheit. SOFCs use a dense layer of ceramic as an electrolyte, which at high temperatures allows for the conductivity of oxygen ions. SOFCs use a non-platinum catalyst utilizing internal reformation, and are commonly fueled by natural gas. Through this process, SOFCs can achieve electrical efficiencies of 50% to 60%, and 70%-80% in CHP applications. SOFCs are being used in a range of applications, from small residential auxiliary power units supplying heat and power to homes, to large-scale stationary power generators for larger buildings and businesses.
One CPI thermal switch already seeing use in fuel cells is our AD173 bimetallic thermal switch. This switch is a small form factor switch that can detect temperatures from –18C to 148C with tolerances as tight as 2.8C. The under-clamp mounting tab makes this switch perfect for pipe or exhaust mounting and the small size and custom lead lengths mean it can fit into a tight space. Another feature of the AD series appropriate for fuel cells is the fact that it is hermetically sealed and can be deployed inside or exposed to the elements without issue. The switch is also impervious to shock and vibration for vehicle mounted cells and will not fail even under highly challenging environmental conditions.
Controlling the temperature of fuel cell reactions is critical to the overall efficiency of its operation and the AD series of thermal switches has been used for both high and low temperature detection in fuel cells for different monitoring applications.
Low Temperature Fuel Cell Detection & Prevention
Given that water is such an important part of fuel cell operation, careful precautions must be take to ensure that the water in a cell is not allowed to freeze. For this our AD series turns out to be a perfect solution as well. Deployed at a 35F set point, our AD series switches have been used to initiate anti-freeze protection extending the useful temperature range of outdoor fuel cells.
Our AD series also offers flexible off the shelf mounting options as well as customizable lead lengths. And for those who need something more, our engineering team is able to handle custom features.
Please call our team today for a consultation on your Fuel Cell Application.
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