Which hydrogen production method is most common and emits carbon dioxide?

Which hydrogen production method is most common and emits carbon dioxide?

• A. Steam methane reforming (SMR).
• B. Electrolysis using renewable electricity.
• C. Biological fermentation.
• D. Photocatalytic splitting with solar energy.

Answer: (A)

Hydrogen production methods differ in feedstock and emissions. Steam methane reforming, which uses natural gas as the feedstock, is the most widely used due to mature technology, established infrastructure, and low production costs. In reforming, methane reacts with steam at high temperatures over a catalyst, and the overall process converts methane and water into hydrogen and carbon dioxide. The net reaction is CH4 + 2 H2O → CO2 + 4 H2, so carbon dioxide is produced as a byproduct unless captured. Electrolysis powered by renewable electricity can make hydrogen with near-zero direct CO2 emissions, but it is currently less common because of higher energy requirements and cost, depending on electricity prices. Biological fermentation and photocatalytic solar splitting are not yet deployed at scale and thus contribute far less to total hydrogen production.

Hydrogen production methods differ in feedstock and emissions. Steam methane reforming, which uses natural gas as the feedstock, is the most widely used due to mature technology, established infrastructure, and low production costs. In reforming, methane reacts with steam at high temperatures over a catalyst, and the overall process converts methane and water into hydrogen and carbon dioxide. The net reaction is CH4 + 2 H2O → CO2 + 4 H2, so carbon dioxide is produced as a byproduct unless captured.

Electrolysis powered by renewable electricity can make hydrogen with near-zero direct CO2 emissions, but it is currently less common because of higher energy requirements and cost, depending on electricity prices. Biological fermentation and photocatalytic solar splitting are not yet deployed at scale and thus contribute far less to total hydrogen production.