A lot of motivations prompt companies to look for new sources of fuel. As of right now, petroleum-based fuels are great, but the supply is limited. In addition, a large percentage of that fuel supply is controlled by a small group of countries in an unstable part of the world. Costs can go up for a variety of reasons, and we don't have many alternatives if prices go sky high or another embargo happens. So even people who don't consider themselves environmentalists can agree there are valid reasons to find ways to reduce our dependency on petroleum. Enter DME.
DME, or dimethyl ether, could be a way to solve several problems with one product. It is a clean-burning fuel -- said to burn cleaner than diesel -- producing next to no soot or nitrogen oxides. No DPF is necessary. When DME is made from biogas, the fuel's well to wheel CO2 emissions are 95 percent lower than with diesel. It also inherently contains no sulfur. In addition, it is similar to propane, so it doesn't require high-pressure (with DME, it would be stored at 75 psi as opposed to 3600 with CNG) or cryogenic storage.
Instead of having petroleum as the basis for fuel, DME can be made from anything that contains methane. That can be natural gas or biomass sources like sewage wastewater, plant waste, landfill gas, and animal by-products. Trash could become fuel. Since there are so many potential sources for DME, this is a sustainable fuel. As long as there are animals that expel waste, there is a fuel source. And it's non-toxic and not a carcinogen, and is safe to handle and store. There are companies that can take a farm's waste products and convert them to fuel.
DME can be made from anything that contains methane. It's non-toxic and is safe to handle and store.
The biggest reason DME hasn't been established as an alterative fuel is the high cost of establishing a nationwide infrastructure. Oberon Fuels in San Diego, California, has come up with a way around this, by looking at the fuel source as a regional supply. The company can create smaller modular production units to supply a smaller area with DME. One station could supply a few farms.
Because there can be so many sources that get broken down into methanol to become fuel, the quality and makeup of the resulting fuel is consistent, wherever it's produced. Oberon is already working on setting up the first regional small-scale production center, in the farmland-rich Imperial Valley in California. The company is also going to supply DME made from biogas for Safeway grocery stores' big-rigs. The expectation is that once the infrastructure is established, fuel will be comparably priced to diesel.
The idea of DME isn't a new one. It's been used in developing countries, where it's mixed with propane for cooking fuel. It's also used as a propellant in aerosols around the home and in inhalers for asthma patients.
With all these potential advantages, it's no wonder multiple truckmakers have become interested in DME as an alternative to diesel. Nissan and Isuzu are working on developing engines that run on DME, and Volvo has already announced it is going to produce DME-powered heavy-duty commercial vehicles for the North American market. Volvo has already conducted 650,000 miles of testing with DME-powered vehicles, and has been very happy with the results. So happy, in fact, that the company has announced it will make a limited production of DME vehicles starting in 2015. These will be powered by Volvo's D13 engine, the best-selling heavy-duty engine in the world. While current diesel engines can be retrofitted to run on DME, Volvo is making a separate version of the engine, and has not yet offered retrofitting for current diesels. The engine will be backed by the company's automated manual transmission, called I-Shift. The trucks use compression ignition, which have a 10-15-percent higher efficiency than spark ignition and use a 17:1 compression ratio in the Volvos.
We had the special opportunity to drive a Volvo truck that runs on DME. We admit we don't have a Commercial Driver's License, but the drive was not on public roads, so we were neither breaking the law nor putting anyone's life at risk. The drive took place in a safe, private, controlled environment.
The truck we drove was a VNL 300, with Volvo hauling equipment on a flatbed. There isn't much that's visibly different from a typical diesel big-rig, though it uses a different fuel storage tank. Yes, the idea of driving a truck this size was intimidating, but we knew there was only so much trouble we could get into. After all, this was essentially on an autocross course, on a much larger scale. The only thing we could really hit were
We had to take three steps to climb into the cab, and once there, we realized the gauge layout and center console weren't completely foreign. There were definite similarities to the setup you would see in a smaller truck. With a representative from Volvo in the passenger seat telling us how to get moving, we were on our way. Not having to shift gears allowed us to focus more on the drive itself.
The route was uncomplicated -- each driver did only a couple laps, but there were 90-degree turns involved. Acceleration was better than we thought it would be, and braking was much more sensitive than in a pickup. As is the case with driving a large vehicle, you plan ahead for turns and try not to make any sudden, jerky changes of direction. The initial anxiety of driving such a massive truck quickly vanished, and what was left was the fun of it, as well as the realization that we were getting only a quick glimpse of what long-haul truckers do -- and we didn't have to park, or deal with uncooperative traffic. The truck sounded no different from a regular big-rig, and it certainly wasn't slow. But our time behind the wheel went by way too quickly.
Driving the DME-powered truck showed that while using the fuel is a relatively new idea, it makes sense and it doesn't really change the day-to-day driving experience. This fuel has a lot of potential, and it wouldn't take much for it to grow popular in North America. What if, at some point in the future, we could have DME sources based on household waste? What if each home's trash could be put into a tank and sent off to a production company to be turned into fuel? It isn't exactly like the Mr. Fusion setup in the DeLorean in "Back to the Future," but the idea that it could even be possible is certainly exciting.
How Dimethyl Ether (DME) Works
DME can be made from multiple sources, including animal "waste," biogas, plant matter, and basically anything that contains methane. First, methane and oxygen are converted to syngas, which is then converted to methanol. The methanol is then dehydrated through a dual-catalyst process producing the DME and water. Each of Oberon's regional processing units produces 3000-10,000 gallons of fuel per day.