Electric vehicles have been given a significant amount of attention in recent years. Due to the rising demand for action against pollution and climate change caused by fossil fuel-powered vehicles.

As public transit is one of the most important modes of transportation in large cities, it is important to consider the available alternatives for cleaner transit.

As an advocate for clean transit, the Canadian Urban Transit Research and Innovation Consortium (CUTRIC) has focused on helping transit agencies to adopt zero-emission transit solutions like battery electric buses (BEBs) and hydrogen fuel cell electric buses (FCEBs).   

However, there is a less explored, yet promising alternative that exists. Renewable natural gas (RNG) can be used to operate compressed natural gas (CNG) buses.

What is Renewable Natural Gas?

Renewable natural gas (RNG) is an energy source with a potentially negative carbon intensity (this depends upon the source of organic matter and method of production). It is the gaseous product of decomposed organic matter under anaerobic conditions. Anaerobic conditions often occur during  the processing of organic matter coming from different sources like:

• Food waste
• Agricultural waste
• Manure
• Municipal organic waste
• Landfills

RNG is an innovative energy source that can play a huge role in reducing greenhouse gas emissions. With future goals set on achieving zero-emission transit, RNG offers an alternative solution that can be net-zero or even negative carbon intensity.

Renewable Natural Gas as a Transit Fuel Solution

Using natural gas to power vehicles actually dates back to the early 1930s in Italy. However, it wasn’t until the 1970s that scalable efforts started to convert gasoline vehicles to natural gas vehicles (NGV).

Recently, there has been a shift towards transit and non-transit NGVs. As concerns regarding rising greenhouse gas emissions increase, RNG is gaining traction as a promising fuel alternative. RNG buses have a potential savings of $250,000 per bus over a 16 year lifecycle. Compared to diesel buses, RNG buses are an average of 10 decibels quieter, making them a favourable option for noise reduction within cities.

RNG also poses the possibility to realize savings during implementation. Transit electrification with BEBs and FCEBs requires investing in new infrastructure, whereas RNG can be directly injected into CNG pipelines. This means that introducing RNG does not require a complete shift in technology or operations.

Using Renewable Natural Gas Buses in Alberta

In the last decade, cities within Alberta have been testing CNG buses as a replacement for diesel fleets.

For instance, the City of Calgary and Calgary Transit introduced CNG powered buses in 2013. This was a part of a pilot project to test vehicle performance under diverse weather conditions. After years of positive results, the city decided to add 40 new CNG buses to its fleet in 2019. To support their efforts in transportation decarbonization, Calgary recently opened the Stoney CNG Bus Storage and Transit Facility. This state-of-the-art facility has the capability to house 450 buses and can support the maintenance, operation and fuelling of CNG buses. 

The City of Red Deer received 17 new CNG buses to replace retired diesel vehicles in 2017. This decision was based on extensive environmental and economic analysis that shows CNG buses produce fewer harmful emissions and noise. Medicine Hat recently added six CNG buses. In the coming years, they plan to move its entire fleet to CNG buses.

All this to say, cities in Alberta that have invested in converting diesel fleets to CNG fleets, can easily operate CNG buses with RNG. As previously mentioned, RNG can easily replace CNG without the need for a complete overhaul of the infrastructure. This means that RNG is a promising alternative for cleaner, greener transit.