One of the paths toward lower carbon-based fuel consumption in transportation is to use hydrogen as an energy carrier for fuel cells. The electricity produced by the fuel cell powers motors. One of the challenges in using hydrogen as a fuel is in accurately measuring it when dispensed into the vehicle. An H2Tech article, Billing accuracy for H2 vehicle refueling stations, highlights this challenge and an effective solution.
The article opens by highlighting the energy conversion process.
H2 reacts with oxygen in a reverse electrolysis in their fuel cells to generate the required electricity. This process is free of carbon emissions, with the only byproduct of the reaction being water.
The challenge with hydrogen as an energy carrier is that it:
…has a very high gravimetric energy density of 140 MJ/kg. This means that it stores a lot of energy relative to its weight, much more than natural gas (53.6 MJ/kg), diesel (45.6 MJ/kg) and lithium-ion batteries (< 5 MJ/kg). In volumetric terms, H2 is the least dense of any gas and takes up more space than both natural gas and diesel.
To improve hydrogen’s energy-carrying efficiency, it must be greatly compressed. This creates a lot of heat, so the starting temperatures must be cooled significantly.
H2 refueling stations are therefore required to operate across a wide range of pressures (up to 875 bar [12.7K psi]) and temperatures (–40°C–60°C). This is very challenging from a measurement perspective, since the accuracy of most flowmeter technologies is adversely affected by extreme pressure and temperature conditions, as well as the transient flow encountered for vehicle filling.
The author highlights the flow measurement technology best suited for this application.
Coriolis meters have dominated the market of H2 dispensers. They have several advantages, but the most important one might be their capability of measuring the mass flowrate directly.
The Micro Motion HPC015 Coriolis Flow Meter is well-suited for this application. It is a stainless-steel Coriolis flow meter ideal for handling high-pressure applications up to 13,960 psi (963 bar). It has high measurement accuracy for hydrogen gas flow, NMi-certified in accordance with OIML R-139 standard and ASME B31.3 process piping code.
This quick 1:20 video, Utilizing Micro Motion High Pressure Coriolis Flow Meter in the First Certified Hydrogen Dispenser, shows how it provides confidence and transparency in hydrogen fuel dispensing operations.
Visit the Micro Motion HPC015 Coriolis Flow Meter page on Emerson.com for more on specifications, selection, sizing, and detailed information.