Could hydrotreated vegetable oil be an efficient fuel for automobiles?

A study that appeared in the journal Agronomy Research evaluated the effects of hydrotreated vegetable oil (HVO) when used together with commercial diesel fuel. Led by researchers from the Latvia University of Life and Science Technologies (formerly known as the Latvia University of Agriculture) and the Department of Automotive Engineering in Latvia, the paper looked at how HVO impacted automobile performance using a chassis dynamometer.

Diesel is the fuel type used in most freight trucks, trains, buses, boats, and farm and construction vehicles. In the U.S., many industrial facilities, buildings, hospitals, and even electric companies use diesel generators for backup and emergency power supply.

However, this type of fuel isn’t without its dangers. BBC report revealed that in Europe – where diesel-powered vehicles are popular – nitrogen oxide (NO2) levels exceeded the ceiling in major cities such like Athens, Berlin, Brussels, Madrid, Paris, and Rome. If a person is exposed to NO2 for an extended period of time, it increases the likelihood of having cardiovascular and respiratory diseases, particularly in the lungs. Aside from NO2, other harmful pollutants found in diesel fuel include particulate matter (PM), ozone (O3) and polyaromatic hydrocarbons (PAHs), in particular, benzo-a-pyrene (BaP).

For the study, researchers evaluated the viability of HVO as an alternative to diesel fuel. HVO, also called HVORD (hydrotreated vegetable oil renewable diesel) in other studies, can be made using various types of fats. Its production is not only limited to vegetable oils, but it can also be made using other waste materials that are rich in triglycerides like cooking oil and animal fat. Earlier studies have been made regarding the characteristics of HVO in terms of fuel consumption and performance, with positive outcomes. In addition, studies have shown that HVO reduces nitrogen oxide emissions as it reduces fuel consumption.

Two types of fuel oil were used for the test: One contained hydrogenated vegetable oil, while the other was regular fossil fuel oil. The fuel used in the study, as well as the test vehicle, was provided by Neste Lavia, Ltd.

The test vehicle, a four-wheel Mazda CX-5 2015, was outfitted with a 2.2. liter Euro 6 engine, which has a compression ratio of 14:0:1. The effective power of the vehicle – with a common-rail fuel system equipped – was recorded at 129 kW, and the rear axle drive was mechanically unlocked to accommodate the installation of the Mustang MD-1750 chassis dynamometer.

The following tests were performed to measure the power and torque on the driving axle, as well as its fuel consumption: power test, idle running test, constant speed tests (at 50 km/h, 90 km/h, and 110 km/h), IM-240 driving cycle (which simulates non-urban driving), and the “Jelgava” worked driving cycle (which simulates typical urban driving in the Latvian city of Jelgava).

Based on the results of the test, the maximum power value of the HVO fuel is 1.2 percent higher than that of regular fossil diesel. Maximum torque was recorded to be two percent higher than that of diesel, with a crankshaft speed of 1,700 per minute in power and torque values – a difference of 67 percent compared to fossil fuel. In terms of fuel consumption, the IM-240 driving cycle indicated that HVO decreased fuel consumption by 1.5 percent in the 50 km/h test, 0.7 percent in the 90 km/h test, and 3.7 percent at the 110 km/h test. It also reduced the vehicle’s consumption by up to 3.9 percent in the Jelgava test.

Researchers concluded that HVO was able to achieve a higher power and torque, as well as reduce fuel consumption in low speeds, compared to regular fossil fuel. Further studies must be done, they added, to fully explain how the physiochemical properties of HVO affect engine design, fuel system, and engine control of the vehicle.

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