The Metropolitan Transportation Authority (MTA) issued a request for proposals (RFP) to purchase ultra-low-carbon renewable natural gas (RNG) to fuel some 800 New York City buses currently running on CNG.  It represents the first step any heavy duty vehicle fleet in New York City has taken toward adopting RNG. To run MTA’s CNG buses on RNG, MTA must replace the equivalent of 12 to 14 million gallons of CNG a year with RNG.

RNG is chemically the same as CNG, but better in other respects. Its production requires no fracking or other types of drilling. It is a renewable fuel made from a renewable resource: organic wastes such as food waste or municipal wastewater.  By capturing and refining the methane biogases emitted as organic materials decay, RNG production prevents these gases from escaping into the atmosphere, where they would have a powerful climate-warming impact.

According to the California Air Resources Board (CARB), RNG is the lowest carbon vehicle fuel available today.  In fact, when made in anaerobic digesters from food wastes or manures, and used as a transportation fuel, CARB found RNG is net carbon-negative over its lifecycle. That means making and using RNG is a net gain for the climate, resulting in less greenhouse gas in the atmosphere than if it were never made or used in the first place.  As a transportation fuel, RNG can reduce emissions up to 300% compared to diesel.

The RNG that MTA plans to purchase will put over 650,000 tons of organic waste to beneficial use:  reducing lifecycle carbon emissions of MTA’s CNG buses by some 40,000 tons a year, and helping New York State meet its climate goal of cutting greenhouse gas emissions 80% below 1990 levels by 2050.

The benefit comes at no added cost to the fleet and may save it money, since RNG requires no conversion of buses, engines, or fueling infrastructure. RNG MTA purchases will be transported through existing natural gas pipelines. Depending on the price of the winning bid for an RNG purchase agreement, it will either cost the same as conventional CNG, or possibly, less.