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Making Every Dollar Count – How South Carolina Is Saving Money While Meeting Sustainability Goals

As the Director of Transportation for the South Carolina Department of Education (SCDE), I’m tasked with the unique opportunity of overseeing the logistics for thousands of students across South Carolina.

And, although the number of buses and students that I’m responsible for may outnumber your typical school district, managing a fleet of any size takes the combination of great people, operational excellence and an emphatic focus on safety. It also requires a thoughtful strategy when it comes to replacing school buses and exploring opportunities with in-service diesel school buses.

Diversification – The Key to Success

A common theme across the country is exploring ways to reduce operating expenses and finding “cleaner” and more sustainable options for your fleet. Unfortunately, these two goals are often at odds with each other. South Carolinians take the preservation of the state’s environment seriously, and over the last few years we have been able to leverage grant funding to increase and provide alternative options for our school bus fleet without burdening taxpayers with additional costs.

The conventional alternative fuel options range from electric to propane to CNG. They all have varying degrees of benefits including reduced emissions, lower maintenance costs and a quieter ride for students. However, they can come with their challenges such as cost, range and infrastructure needs. As with all alternative fuel and technology options, there is no silver bullet.

At the SCDE, we are exploring all options and taking an “all the tools in the toolbox” approach. Initiatives by the SCDE include plans to deploy 160 electric school buses in districts across the state through funds from the EPA’s Clean School Bus Program. The state also used the Volkswagen Environmental Mitigation Trust to fund a plan to deploy 453 propane buses.

While the industry pursues alternative vehicle strategies for new vehicle purchases, the options are limited, if non-existent for existing diesel school buses, which account for a whopping 80% of the total US school buses on the road. Exacerbating the issue, elevated diesel prices often put pressure on already-tight school budgets and these existing assets don’t necessarily align with sustainability initiatives outlined by many school districts. So, while we are working on new vehicle purchase strategies, this leaves a glaring question of what to do with those vehicles that will be in service for the foreseeable future.

An Economic Benefit & Net Zero Solution for In-Use School Buses

After doing our research and exploring our options, the SCDE decided to pilot the DEMI-NeuFuel school bus platform on several of our in-service diesel buses. The platform, branded as the “CowFartBus” because of its use of low-carbon renewable natural gas (RNG), provides a cost-effective and viable solution for existing diesel vehicles.

One of the features that attracted us to the CowFartBus is that it’s a “dual fuel” vehicle, meaning that if the RNG tank is empty it automatically shifts back to running on full diesel, eliminating the range anxiety seen with other types of alternative fuel vehicles and alleviating any compromises in terms of utility, functionality or performance – something that our drivers really value.

And from a budget standpoint, the low-cost school bus conversion and fueling appliance, was especially attractive to us. The price to convert a bus was cheaper than buying a new alternative fuel vehicle and it created the opportunity to immediately reduce our fuel costs by switching from 100% diesel, which is running at roughly $4.02/gallon on a national basis, to the low cost of natural gas at our utility service rate, and the use of RNG at no incremental cost.

Moving to the DEMI-NeuFuel platform was a logical step for us at the SCDE. We have spent the last several years diversifying our fleet and incorporating alternative fuel vehicles through the use of grants and other funding. The CowFartBus allowed us to reduce the carbon footprint of our in-service, diesel buses in a cost-effective way. Knowing that these vehicles are able to remain in-use and help us cost-effectively meet our budget and sustainability goals is fantastic and something we didn’t think was previously possible.


Mike Bullman is Director of Transportation for the South Carolina Department of Education. For more than forty years, Mr. Bullman has been recognized for his leadership and commitment to the transportation safety of South Carolina students, reflecting South Carolina’s twin mottos of hope that propels hard work. This culminated in being awarded the inaugural Spirit of South Carolina Award in November 2023.

The DEMI-NeuFuel system is made available through a partnership with Ingevity and American CNG. Ingevity is an automotive and sustainability leader as a Tier 1 & 2 supplier to the US and global auto industry. They harnessed their 40-years of expertise in activated carbon to develop and commercialize the DEMI-NeuFuel platform in tandem with strategic partner American CNG, who as a leader in the Natural Gas Vehicle Industry with over 15 years experience, provides its diesel displacement platform for a variety of heavy-duty vehicles. The DEMI-NeuFuel platform operates at a lower pressure (900 psi), compared to higher pressure CNG (3,600 psi), enabling convenient, private fueling with a low-cost and small (2’x2’) fueling appliance that can be installed on-site at the fleet location with access to natural gas.

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