Which statement about hydrogen storage tanks is true?

• A. Stored as liquid and cooled to -423F
• B. Compressed and stored with pressures of 3600, 5000 and 10,000 psi
• C. Chemically combined in hydride form
• D. Stored in microscopic pores of carbon nanotubes

Answer: (A)

Hydrogen storage in cryogenic liquid form is defined by keeping hydrogen at very low temperatures so it stays liquid rather than gas. The boiling point of hydrogen at atmospheric pressure is about -423°F (-252.8°C), so tanks that store hydrogen as a cryogenic liquid rely on extreme cooling and excellent insulation to maintain that temperature. This approach yields a much higher energy density per unit volume than storing hydrogen as a compressed gas, which is why it’s a common method in many storage systems. Other storage methods, like high-pressure compression or theoretical concepts like hydrides or adsorption in porous materials, exist but are not the standard cryogenic liquid storage method described by the statement.