Renewable Diesel, Biodiesel, SAF: What’s the Difference?

Currently there are three types of biofuel being produced in the U.S.-biodiesel, renewable diesel and sustainable aviation fuel (SAF).

Biodiesel

Biodiesel is a renewable fuel that can be manufactured from vegetable oil, animal fats, and recycled restaurant grease as well as soybean, corn and canola oils.Biodiesel’s properties are similar to conventional biodiesel.Biodiesel is typically blended with conventional diesel for optimal performance (B5 (5% biodiesel) up to B100 (100% biodiesel)). All vehicle manufacturers allow blends up to B5 and 80% approved blends up to B20.

Older vehicles (prior to 1994) contain hoses and gaskets that can break down with heavy used of blends at B20 and higher. Cold weather performance can be an issue for some vehicles although there are workarounds such as lower blends such as flow improvers.

Renewable Diesel

Renewable Diesel is manufactured by different processes than biodiesel and is becoming the preferred fuel primarily because renewable diesel is chemically identical to regular diesel and can there be used at 100% concentration(not blended) in regular diesel engines. This is why it is sometimes referred to as a “drop-in diesel”.

Renewable diesel is more environmentally friendly than biodiesel, performs better in cold weather and can be transmitted in existing pipes and stored in existing facilities. Renewable diesel does not require any modifications to the vehicle which burns it regardless of the age and make of the vehicle.

Sustainable Aviation Fuel

SAF can be produced from a number of biomass sources the best of which given its carbon footprint is yellow grease (waste vegetable oil and animal fats).  It is a fuel used to power jet aircraft. Jet engines burning SAF produce fewer carbon emissions than conventional aviation diesel. SAF can be blended at up to 50% with traditional jet fuel. Any aircraft can use SAF blends. It has the potential to reduce the carbon lifecycle by up to 50% compared to the traditional jet fuel it replaces.

There are other benefits to biofuels such as a higher cetane number, additional power but overall it is the dramatic reduction in the total carbon footprint that makes these biofuels so important.

D&W Alternative Energy collects used cooking oil from restaurants in New Jersey and Eastern Pennsylvania and recycles it to make biodiesel. Give us a call to pickup your restaurant’s used cooking oil.

What is Driving the Surge in Sustainable Aviation Fuel?

Sustainable Aviation Fuel (SAF) is a cleaner alternative to conventional jet fuel, and its market is taking off faster than a supersonic jet. The demand for SAF is being fueled by a powerful combination of factors. First, the aviation industry faces immense pressure from governments, investors, and the public to decarbonize. The International Air Transport Association (IATA) has set a goal for the industry to achieve net-zero carbon emissions by 2050. Since electric and hydrogen-powered planes are not yet viable for long-haul travel, SAF is the most promising solution to this challenge. It’s not a future technology; it can be used in existing aircraft with little to no modification, making it a “drop-in” fuel.

Second, government policies and regulations are creating a clear market signal for SAF. For example, the European Union’s “ReFuelEU Aviation” initiative mandates a progressive increase in SAF blending, starting at 2% in 2025 and rising to 70% by 2050. Similarly, the United States is pushing for a “SAF Grand Challenge” to scale up production to at least 3 billion gallons annually by 2030, supported by tax credits in the Inflation Reduction Act. These policies are critical for driving investment and creating the confidence needed for producers to scale up production. Finally, airlines are actively seeking SAF to meet their own corporate sustainability goals and differentiate themselves in the market. Airlines are entering into long-term purchase agreements to secure future supply.

What are the Key Challenges to Widespread Use of SAF?

Despite the clear demand and policy support, scaling up SAF production faces several big challenges. The most immediate challenge is the high cost. SAF is currently three to five times more expensive than conventional jet fuel. While policy incentives and economies of scale are expected to reduce this gap, it remains a major barrier. The limited availability of sustainable feedstock is another bottleneck. SAF can be produced from a variety of sources, including waste vegetable oils and animal fats (known as yellow grease), municipal solid waste, and agricultural residues. However, the supply of these feedstocks is finite, and there is growing competition for them from other industries, such as renewable diesel.Another key challenge is the need for massive infrastructure investment. To meet future demand, the world will need to build many more SAF refineries and distribution facilities. According to a study by PwC, achieving net-zero goals by 2050 could require an estimated €1,000 billion in capital expenditure just to build the necessary refineries. The industry is also grappling with regulatory complexity and the need for a globally consistent set of standards. Standards are neededUpU to ensure that SAF is produced sustainably and that its carbon reduction benefits are accurately measured.

What Do Market Trends Tell Us About the Future of SAF?

Recent market trends highlight a clear shift toward SAF as a part of the aviation industry’s decarbonization strategy. While global SAF production remains small, representing less than 1% of total jet fuel use in 2024, the pace of growth is accelerating. The International Energy Agency (IEA) projects that global SAF use could expand by nearly 5 billion liters by 2028, with the U.S., Europe, and Japan leading this growth.

There’s a noticeable trend in feedstock diversification. While the most common SAF pathway today uses waste fats and oils (HEFA), the industry is actively exploring new, advanced feedstocks like algae, agricultural waste, and even Power-to-Liquid (PtL) fuels, which use renewable electricity to produce synthetic fuels. This innovation is crucial for expanding the total SAF supply and ensuring the industry doesn’t rely too heavily on a single source. Finally, there is a clear trend toward global policy alignment. Countries in Asia-Pacific and Latin America are beginning to introduce their own blending mandates and targets, creating a more aligned global market. This emerging international consensus, combined with technological advancements and corporate commitments,  are good signs for the future of SAF.

Tags: biodiesel, renewable diesel, what is renewable diesel?