CNG to Hydrogen  

Americans today are more conscious of their fuel usage and the environmental effects of transportation than ever before. The last few years have taught us that partial dependence upon imported petroleum leaves us vulnerable to enormous fluctuations in fuel prices. Additionally, this same petroleum that we are reliant upon is responsible for worsening air quality in urban centers. We have now awakened and looked for alternatives. Fuel technology has improved to the point where there are several options available.

CNG has emerged as the clear leader by corporate and governmental fleets. They have shown that it can be used efficiently and economically. The fuel supply infrastructure is already in place, readily and widely available to receive the compressors and fuel-delivery equipment necessary to transfer it to our vehicles.

In the long term, these CNG fueling stations can be converted to produce hydrogen (H2) from natural gas using a process called Steam Methane Reformation (SMR). This process is the most accessible and cost-effective method of producing hydrogen and is used to produce about 95% of the hydrogen in use today.

Steam Methane Reformation (SMR)

1. Reformation of Natural Gas:

The first step of the SMR process involves methane reacting with steam at 750-800°C (1380-1470ºF) to produce a synthesis gas (syngas), a mixture primarily made up of hydrogen (H2) and carbon monoxide (CO).

2. Shift Reaction:

In the second step, known as a water gas shift (WGS) reaction, the carbon monoxide produced in the first reaction is reacted with steam over a catalyst to form hydrogen and carbon dioxide (CO2). This process occurs in two stages, consisting of a high temperature shift (HTS) at 350ºC (662ºF) and a low temperature shift (LTS) at 190-210ºC (374-410ºF).

Eventually, hydrogen fuel cells will provide the cleanest and most efficient source of clean power for all of our energy needs. For most applications, there are technological and economical hurdles that must be cleared before this can become a reality. For example, hydrogen fuel cells are currently used to provide backup power for hospitals, banks, and telecommunications networks, but advances in production, storage, and distribution technologies must be made before it is cost-effective to use hydrogen to significantly fuel the national power grid.

In the case of hydrogen vehicular fueling, SMR technology applied to a well-developed CNG fueling infrastructure will help eliminate the production obstacles. CNG stations will be able to convert their equipment to produce hydrogen and offer HCNG (a hydrogen-cng blend) and Hydrogen fuels to their customers.