A friend of mine asked me the other day why the US doesn’t invest in passenger cars that run on natural gas since we now have so much of it. He pointed out that New York City has been purchasing vehicles such as buses that do. Since I’ve had my head buried in research of the burgeoning electric vehicle (EV) industry, I didn’t really have an educated answer at hand. My gut reaction was that it’s still a non-renewable fossil fuel, albeit cleaner burning, so why would we do that? To my knowledge, there was little to no investment (especially federal) being made in developing Natural Gas Vehicles (NGVs). His persistence on the issue had me guessing he’s probably somehow invested in the booming US natural gas industry (it turns out he’s not). However, it was an intriguing question given today’s abundance of domestic natural gas, the relative ease with which current vehicles can be converted, and the reduced greenhouse gases they emit compared to both diesel or gasoline. So I did some research on the subject and found some surprising answers, many of which parallel that of EVs.
Most folks are probably aware that the controversial process of fracking has helped propel the US to the number one producer of natural gas surpassing both Russia and Saudi Arabia with domestic supplies forecasted to last us at least 100 years. Currently, 98 percent of the natural gas consumed in the US is from domestic sources (making me ponder the remaining 2%). By comparison, only 52% of the oil we use is domestically sourced. While most Americans think of natural gas for household use and maybe for newer power plants, many may not realize that NGVs have been cruising on highways in other parts of the world for decades. According to NGV Global, there are over 15.2 million NGVs on roads worldwide yet there are only about 142,000 in the US. So with so much domestic natural gas now available, why is the US lagging behind other countries in utilizing it to power vehicles?
First and foremost, as with the electric vehicle industry, there is no comprehensive nationwide infrastructure to support refueling NGVs. Investment has been made in some locales to refuel truck and bus NGVs such as those for garbage collection and local mass transit but most of those facilities are strictly for private use. According to the Department of Energy, there are currently only 708 compressed natural gas stations and 54 liquefied natural gas stations for public use in the US. That’s far less even than electric stations, of which there are 8,170 that now dot the landscape, never mind gas stations. Though liquefied natural gas (LNG) has 2.5 times better energy density (energy per unit of volume) than compressed natural gas (CNG), CNG is favored because it is easier to store and pump. Liquefied gas must be stored at -260 deg F and vehicle fuel tanks will vent evaporating LNG (methane) into the atmosphere when the engine’s not running. In contrast, CNG is compressed at ambient temperature to 3600 psi shrinking it to less than half of the volume it would otherwise occupy. In either case, fuel tanks are big and bulky making natural gas better suited to power larger vehicles. Indeed, visits to websites dedicated to the NGV industry nets you a plethora of truck and bus photos. According to NGVAmerica, 50% of all newly purchased garbage trucks in the US are NGVs. One fifth of all current transit buses in the US are NGVs. All of the buses in Los Angeles and indeed many in New York City are now NGVs.
Like electric vehicles, one would think you could fuel up your NGV at home since natural gas is available in so many households. It can be done but currently the cost to install a CNG fueling system is about $5000 plus installation. This is prohibitive compared to the $200-500 cost to install a Level 2 (dedicated 240 VAC) electric charging system for your EV at home. Eaton and General Electric are purportedly developing home CNG refueling units to be priced around $500.
A significant disadvantage of CNG is that its energy density is lower than gasoline or diesel. An equivalent gallon of CNG has little more than 25% of the energy content in a gallon of gasoline. Combined with the hefty fuel tank requirements, this limits NGVs to less than two thirds the driving range of gasoline cars (roughly 220 miles versus 350 miles) before having to refuel. While certainly much better than EVs (with the possible exception of Tesla), range anxiety may actually be worse since there are even fewer locations to refuel. Similar to EVs at this point in time, NGVs are best suited for localized applications where they operate within nominal daily mileage and return “home” afterward to refuel. One other note, vehicles using gasoline achieve full power until the tank is empty while vehicles using CNG will experience some decrease in power as the fuel tank pressure decreases.
As alluded to earlier, NGVs emit 25-30% less tailpipe greenhouse gases than their gasoline-powered counterparts. Interestingly, this cleaner burning fuel means NGV engines require fewer oil changes. However, well-to-wheel (or lifecycle) analysis of emissions, which takes into account emissions occurring during production and transport of the fuel, lowers the numbers somewhat. According to a study by Argonne National Laboratories, natural gas well-to-wheel emissions, though still better, are only 6-11% better than comparable emissions from gasoline or diesel. This is mainly due to methane, one of the worst greenhouse gases, escaping during natural gas production. Much work is being undertaken to mitigate and recover the escaping methane. Similarly, electric vehicle emissions must include those used in the generation of the electricity needed to charge the EVs.
Due in large part to the hefty fuel tank requirements, NGVs can cost thousands more than gasoline-powered vehicles as do EVs. They can also be somewhat slower to accelerate than gasoline-powered vehicles while EVs on the other hand accelerate faster than even their gasoline counterparts. On the flip side, natural gas is lighter than air and dissipates should the fuel tank be ruptured in an accident creating a safer scenario than gasoline as well as Lithium batteries that are used in most EVs. Additionally, some states allow lone drivers to use HOV lanes if they are driving an NGV, which is also true for EVs. A big advantage of natural gas over gasoline may be the cost at the pump since natural gas is currently only one half the cost of gasoline per gallon. However, EVs are quite a bit less than even natural gas especially when charging overnight during off-peak hours. Another potential issue stems from competing uses for domestic natural gas such as electrical power generation, heating, and other industrial applications that have made natural gas prices more volatile since the early 2000’s. Adding a thriving NGV industry to the mix is not likely to lessen that volatility.
It turns out there has been some federal investment made in NGV research as the US Department of Energy awarded a total of $30 million in 2012 to 13 research firms to look for breakthrough technologies aimed at introducing NGVs to the general public. However, in the newly released Department of Energy 2014-2018 Strategic Plan, natural gas use for vehicles is not even discussed while EVs are mentioned eleven times. Further development of hydrogen burning fuel cell technology is also mentioned in the plan for EV power generation. The private sector has more significant investment activity for the development and promotion of NGVs including from the likes of T. Boone Pickens. But the level of NGV investment is still quite small compared to what is currently being spent on EV research while both are miniscule compared to that being spent on perpetuating gasoline-powered vehicles.
So my research begs the question: “If we are to invest in the next generation infrastructure of personal and public transportation, should it be one around yet another limited non-renewable supply even if it is abundant for the next 100 years? Or should it be one such as the electric car industry where multiple sources (both renewable and non-renewable) will continually be developed and used to power the grid that fuels EVs?” The answer becomes even more difficult when biogas enters the discussion. Biogas is a so-called renewable or sustainable natural gas that is produced from a myriad of organic waste conjuring up images of the methane refinery in the Underworld of Bartertown (see the movie Mad Maxx: Beyond Thunderdome). The potential for biogas, as disconcerting as the prospect of sustaining organic waste may seem, makes it tempting to give NGVs a second look. However, NGVs will still require significant investment in a nation-wide support infrastructure while still emitting greenhouse gases unlike an EV charged from a solar power station or possibly an onboard fuel cell. A better alternative may be to use our limited investment dollars to continue pursuing a thriving EV industry while converting more electrical power plants to cleaner burning natural gas in order to charge those EVs.