Energy IQ: What is a solid oxide fuel cell and how fuel cells work

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July 20, 1969 might not immediately ring a bell, but what if we were to give you a hint by saying the word "Apollo?" 

Yes, that was the date humans first landed on the moon as a part of the Apollo 11 mission. Most of us remember details such as the images of astronauts on the Moon’s surface, and Neil Armstrong’s reaction, “That's one small step for [a] man, one giant leap for mankind.” Yet many don’t know how the spacecraft obtained its electrical power through this historical mission.

Fuel cells were NASA’s answer to this challenge, as Apollo spacecraft carried three hydrogen-fuel cells to provide electricity for all the equipment. Each of these fuel cell modules had 31 individual fuel cells stacked together 1.

Over 50 years later, fuel cells today are used in a variety of applications ranging from vehicles to data centers. Let’s focus on solid oxide fuel cells and answer four common questions to boost your energy IQ.

Question No. 1: What is a solid oxide fuel cell?

Simply put, all fuel cells are energy converters; they convert energy from one form to another. More specifically, fuel cells convert the chemical energy stored in the fuel to electric and thermal energy (heat), without the need for combustion. Engines and power plants also convert energy from one form to another, but they rely on combustion, which reduces the overall efficiency of the energy conversion.

Solid oxide fuel cells are one of the many types of fuel cells and produce electricity, water, heat and small amounts of carbon dioxide using natural gas as the fuel.  

Question No. 2: How does a solid oxide fuel cell work? 

Electricity is the movement of electrons, and all elements (hydrogen, oxygen and others) have varying numbers of electrons. 

Solid Oxide Fuel Cells - Electricity
Solid oxide fuel cells produce electricity, movement of electrons. 

A solid oxide fuel cell utilizes the movement of electrons and generates electricity in few basic steps.

  1. Natural gas goes through a steam-reforming process. This chemical reaction produces hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2) and steam (H2O). There will be some unreformed natural gas left in the mix as well.
  2. The mix of elements from the reformer enter the fuel cell at the anode side. Meanwhile, air (including oxygen) enters the fuel cell at the cathode side. 
  3. Oxygen in the air combines with free electrons to form oxide ions at the cathode. Oxide ions with free electrons travel from the cathode to the anode through the electrolyte.
  4. At the anode, oxide ions react with hydrogen forming water (steam) and with carbon monoxide (CO) forming carbon dioxide (CO2).  
  5. Reactions covered on Step #4 release free electrons. These free electrons travel to cathode through the external electrical circuit, producing electricity.

Question No. 3: What are the differences between solid oxide and proton exchange membrane fuel cells?

Proton exchange membrane (PEM) fuel cells, also known as hydrogen fuel cells, and solid oxide fuel cells share the same basic operating principles yet have many differences. Here are two of these differences impacting how these technologies are being used today. 

Types of fuel cells
Comparison of four primary types of fuel cells. 
  • Fuel : PEM fuel cells use pure hydrogen (H2) as fuel. Meanwhile, solid oxide fuel cells can use hydrocarbon fuels such as natural gas, methane and propane to produce electricity. 
  • Size: While a single cell of a PEM fuel cell and a solid oxide fuel cell don’t differ significantly in size, the size difference comes into play when a fuel cell module is assembled together. A typical PEM fuel cell module would be smaller than a solid oxide fuel cell module. This makes PEM fuel cells a good candidate for transportation applications ranging from trucks and buses to trains and boats. 

Question No. 4: Why do we need solid oxide fuel cells?

The benefits of solid oxide fuel cells vary depending upon the application but two benefits remain consistent across applications. 

  1. High efficiency delivers environmental and financial benefits: Electrical efficiency of solid oxide fuel cells reach up to 60% 2. This means 60% of the energy stored in the fuel is converted to useful electrical energy. This is much higher than the efficiencies of coal power plants. Moreover, the use of excess heat produced by the fuel cell for heating purposes in a cogeneration application will further increase the overall efficiency over 80%. Additionally, since fuel cells could be located locally, they eliminate the inefficiencies associated with distribution losses from large central power plants.

    This high efficiency delivers financial benefits and minimizes the environmental footprint, since solid oxide fuel cells commonly use natural gas as fuel in comparison to traditional power plants using coal as fuel. Solid oxide fuel cells also don’t emit sulphur oxides and particulate matter.
     
  2. Modular design brings scalability: The individual fuel cells are bundled together to form a stack. These stacks are then combined with other equipment to form modules. These individual power generation modules can be paralleled to form the fuel cell power system. You can add more fuel cell modules to the overall system as you need. This provides financial flexibility for the user to align the power generation investments with business needs.

Microgrids and fuel cells to energy storage devices, our energy future includes a diverse set of technologies and fuels, and Cummins is committed to innovating and delivering a variety of power solutions to meet these diverse needs of customers. 

Sign up below for Energy IQ to periodically receive relevant insights and trends about energy markets. To learn more about distributed generation solutions Cummins offers, visit our webpage.

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References: 

1 Smithsonian National Air and Space Museum. (n.d.). Apollo to the Moon, About the Spacecraft [Web page]. Retrieved from https://airandspace.si.edu/
2 U.S. Energy Department, Office of Energy Efficiency and Renewable Energy . (n.d.). Comparison of Fuel Cell Technologies [Table]. Retrieved from https://www.energy.gov/

 

Aytek Yuksel - Cummins Inc

Aytek Yuksel

Aytek Yuksel is the Content Marketing Leader for Cummins Inc., with a focus on Power Systems markets. Aytek joined the Company in 2008. Since then, he has worked in several marketing roles and now brings you the learnings from our key markets ranging from industrial to residential markets. Aytek lives in Minneapolis, Minnesota with his wife and two kids.

Cummins Custompaks are being used for water management as Thailand struggles with its water crisis

CustomPak on site

Water crisis

Sixty Cummins Inc. CustomPaks are in service in Thailand as part of a critical water management plan aimed at easing the country’s water crisis – a crisis that has caused enormous economic and social damage and stirred conflict among communities.

Over the past several decades, Thailand has continually faced water problems caused by severe drought. Water reserves in dams and reservoirs are insufficient while water resources are often contaminated with toxins caused by urban communities and the industrial and agricultural sectors.

Severe flooding is a threat, too, at a time when the realities of climate change are hanging over the country.

As a result, the allocation of precious water resources, which must be shared among various stakeholders including new and existing industry, large and small agriculture, and cities and villages has become a flashpoint.

Kittithanapat Engineering Co. (KTP), has been involved in the water management system since 1996, working closely with authorities such as the Royal Irrigation Department, Department of Water Resources, Bangkok Metropolitan Authority and others.

CustomPaks on site

600 hp CustomPaks

To help KTP meet its often urgent requirements, Cummins DKSH (Thailand) has recently supplied 60 Australian-built CustomPaks – 45 powered by Cummins’ X15 engine rated at 600 hp, and 15 powered by the QSL9 rated at 325 hp. These fully self-contained powerpacks are emissions certified to Tier 3.

The CustomPaks are coupled to hydraulically-driven, large-volume submersible water pumps sourced by KTP from US company Moving Water Industries (MWI); KTP is the exclusive distributor in Thailand for these MWI Hydroflo pumps.

Prior to Cummins’ involvement, KTP was using another diesel engine brand but service support wasn’t up to the standard required.

Long-serving KTP engineer Kittisak Thanasoot says Cummins DKSH’s reputation for technical and aftersales support along with the reliability of the Cummins product were a key reason behind KTP’s decision to specify the CustomPaks for the Royal Irrigation Department.

The ability of Cummins DKSH to respond to short delivery times was also important.

“Supplying large quantities of high horsepower diesel engines for emergency situations such as flash flooding can be a challenge for KTP,” says Kittisak Thanasoot.

“Responding to the needs of the government agencies to manage such problems in a timely manner and with least impact on communities, KTP has found the answer in our partnership with Cummins DKSH.”

Power, pride and passion

Parked semi truck

The switch back to Cummins power has been beneficial for iconic New Zealand company Uhlenberg Haulage. It's all about whole-of-life costs.

Uhlenberg Haulage is closing in on 60 years in business, having been founded in 1966 by Mike and Carol Uhlenberg.

Based in Eltham, Taranaki, in New Zealand’s North Island, the operation is today owned and operated by their sons Chris, Daryl and Tony Uhlenberg.

Describing the Uhlenbergs as “old school family truckies”, Daryl talks about the company’s time-honored journey with a definite tone of pride, especially the work of his parents in laying the foundations for what is today an iconic fleet in its own right.

Cummins Inc. made its debut in the Uhlenberg fleet in 1971 with an NH250 powering a second-hand Kenworth K923 used in logging. A second Kenworth, a new W924 with a Cummins NTC335, followed soon after hauling an LPG tanker.

The Uhlenberg operation today comprises 40 prime movers and a variety of trailing gear to cater for the myriad of a jobs the fleet is involved in.

A number of Peterbilts feature in the fleet although Kenworth is now the brand of choice with six new units to be delivered over the next 12 months to cater for business growth.

Cummins’ X15 Euro 5 engine rated at 550 or 600 hp is the preferred power specification, with 18 red engines currently in the fleet.

Uhlenberg family in front of truck

Whole-of-life support

“The switch to Cummins has been a very good experience for us. We have nothing but praise for the Cummins organization,” says Daryl.

“The whole-of-life picture is the key thing for us and we’ve got that nailed with the support we get from Cummins – parts availability, scheduled maintenance, life expectancy and in-frame rebuilds.

“So the red engines turn up, we run them to life, which is 900,000 to 1.2 million kilometers, and then Cummins does an in-frame overhaul in a timely manner. If there’s an issue, parts and support are close by.

“The support we get from Cummins Palmerston North is fantastic, second to none.”

Daryl recently looked under a Kenworth that was in the workshop for a service and was surprised to see no oil leaking from the one-million-kilometer X15. “I remember when I was a fitter we had to wear a raincoat when working under a truck,” he jokes.

Fuel agnostic

Acknowledging that the push to decarbonize is now “very real”, Daryl likes the idea of Cummins’ fuel agnostic concept where one base internal combustion engine, optimized to run on diesel, can also be customized to run on ultra-low and zero-carbon fuels like renewable natural gas and hydrogen.

“My father was a pioneer of linehaul trucking in New Zealand and he always embraced new technology. He was never scared of it,” he says.

“I tend to be a little more cautious but I can see where a 500 hp natural gas or hydrogen engine would work for us in short haul applications,” he admits. “We’re certainly willing to look closely at these alternative fuel technologies when suitable infrastructure is in place.”

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