By: Yang Yan
Fuel cell (FC) is an electrochemical device that can directly convert the chemical energy of hydrogen, natural gas, methanol and other fuels into electricity. In addition to its applications in new energy vehicles such as Toyota Mirai, the fuel cell train manufactured by Alstom has entered commercial operation in Germany in September 2018. Depending on the material used and operating temperature, FCs can be divided into several types. A comparison of major classifications is shown in Table 1.
Solid Oxide Fuel Cells (SOFCs) are one of the main focuses in FC research. In 2010, Bloom Energy Inc. (NYSE: BE) in the US introduced an SOFC mini-power station that will provide US households with low-cost and environmentally-friendly power 24/7. The company is now the SOFC provider for Google, Walmart, FedEx, AT&T, Panasonic and many more fortune 500s. In 2017, Kyocera Japan Ltd. (OTCMKTS: KYOCY) introduced the first commercial 3 kW SOFC system. The system achieves a standalone efficiency of 52% and, through waste heat cycle, the overall system efficiency can reach 90%. The system integrates four small stacks with a power of 700 W and can deliver 3 kW of power externally.
SOFC has many unique advantages. At present, SOFC has application prospects in large, medium and small distributed power stations, portable power bank, military, aerospace and other fields. Significant advantages are:
1. High efficiency. The power efficiency can reach more than 60%; with waste heat and gas turbine combined use, the total efficiency can reach up to 90% or more;
2. Reliability. achieves operating times more than 90% and power available more than 99.99% of the time. This is the main reason why computer facilities, call centers, data processing centers and high technology manufacturing facilities choose SOFC:
3. All-solid-state structure, leading to easy assemble and cell amplification;
4. Use of common, low-cost catalysts, which can effectively control manufacturing costs;
5. A wide range of fuel options; In addition to the use of hydrogen, natural gas, liquefied petroleum gas, ethanol and even biological waste gas could be used. This is useful in waste treatment plants, as the cell can convert biomass gases to electricity with minimal environment impact.
6. Low cell noise, less pollutant emissions; This is useful in urban areas, industrial facilities, airports, and zones with strict emissions standards.
7. Long cell life, up to 10 years.
Given that SOFCs can directly use hydrocarbons as fuel, its large-scale application can promote the efficient and clean utilization of coal, natural gas and biomass.