Burning gasoline, diesel or any hydrocarbon causes a handful of undesirable emissions. This can include greenhouse gases (GHG)—like carbon dioxide (CO2) and nitrous oxide (N2O)—and other potentially toxic substances like carbon monoxide (CO), nitrogen oxides (NOx), and particulate matter (PM).
A true indicator of a fuel’s emissions is the life-cycle fuel emissions, which measures the total gases and substances emitted from when the oil is pulled out of the ground (or crop planted) until the fuel is pumped into a vehicle and burned as a motor fuel. This is also known as well-to-wheel emissions. Reducing any of these emissions throughout the life-cycle of the fuel is a step towards responsible environmental stewardship.
Renewable diesel is nearly chemically identical to petroleum diesel, which makes it directly compatible in engines that are designed to run on conventional diesel fuel, with no blending required. It can also be mixed with other types of diesel fuels with no noticeable differences.
Like biodiesel, renewable diesel is derived from a mixture of animal fats, vegetable fats and waste products. The difference lies in how the fuel is processed. Renewable diesel uses a hydrogen process that removes all the oxygen out of the fuel. Since the end product doesn’t contain oxygen, users don’t encounter challenges related to freezing temperatures and storage. Renewable diesel also has a higher cetane level than petroleum diesel which burns cleaner, helps with cold starts, provides more energy per gallon and withstands longer periods of storage.
According to CARB, using renewable diesel provides a 40 – 50 percent reduction of GHG from well-to-wheel emissions and produces specific measurable reductions in tail-pipe emissions versus fossil-based diesel. Renewable diesel provides both immediate and long-term benefits for the local community and the environment, including reductions in both carbon dioxide (CO2) and nitrogen oxides (NOx). The reduction of NOx is particularly advantageous with renewable diesel due to the fact that other biofuels tend to increase the amount of NOx emitted into the air compared with petroleum based fuels.
To test if renewable diesel performed better than regular petroleum-based fossil fuels, we started using it on both projects.
Our teams used renewable diesel in all applications that they would use petroleum-based diesel fuel, from various pieces of heavy equipment to on-highway tractor trailers and crew trucks. Two significant differences they noticed right away were the lack of odor from tailpipe emissions and a reduced frequency of diesel particulate filter (DPF) cleanings in their vehicles. Reducing the frequency of DPF cleanings is an indicator the fuel is burning cleaner and producing less particulate matter.
At Skanska, we’re a leader in Care for Life, and this particular improvement supports our culture, which includes caring for the communities in which we live and work. It also improves our position in the eyes of our clients, many of our employees and our local communities.
"Metro has been encouraging its community of constructors, designers and stakeholders to work together with us in creating innovative solutions to reduce impacts of our construction, specifically in communities where we are expanding our system,” said Cris Liban, LA Metro’s chief sustainability officer. “By policy, our projects are already set up to be most protective for any environmental impacts. Having an organization like Skanska work in solutions that go beyond our sustainable strategies is very commendable and should set an example for others who are working with us in our capital programs."
Renewable diesel is a stepping stone in Skanska’s path towards carbon neutral, and there are many advantages to using this type of fuel on project sites; so, it’s hard to find any challenges worth noting. Throughout the two and a half years that our project teams have used renewable diesel, the benefits have far outweighed any small issues they’ve overcome, including a one-time stint of limited availability for the renewable diesel. Even the cost of renewable diesel is directly comparable to that of petroleum diesel. Renewable diesel has cost a very minimal premium, with a negligible cost difference.
Thanks to the creativity of our LA Metro and Skanska Los Angeles’ equipment teams, they’ve been able to leverage biodiesels to decrease our carbon emissions, which will help push Skanska toward its ambitious global goal of achieving net-zero carbon emissions by 2045.