What Is The Biodiesel?

What is Biodiesel?

Biodiesel is an alternative fuel similar to conventional or ‘fossil’ diesel that is made from renewable biological sources like vegetable oils, animal fats, or recycled restaurant greases (https://afdc.energy.gov/fuels/biodiesel_basics.html). It can be produced domestically and used in diesel engines with little or no engine modifications. Biodiesel is defined as a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats (https://en.wikipedia.org/wiki/Biodiesel).

Unlike fossil diesel, biodiesel is renewable and biodegradable. It is produced through a chemical process called transesterification where glycerin is separated from the fat or vegetable oil. The process leaves behind two products – methyl esters (the chemical name for biodiesel) and glycerin (a valuable byproduct usually sold to be used in soaps and other products).

Biodiesel can be used in its pure form (B100) or blended at any level with petroleum diesel. Common blends include B2 (2% biodiesel), B5, and B20. Because it shares similar properties with petrodiesel, biodiesel can function as a direct replacement for diesel fuel with few or no engine modifications.

History of Biodiesel

Biodiesel was first developed and tested in the 1890s by Rudolf Diesel, the inventor of the modern diesel engine. Diesel originally designed his engine to run on a variety of fuels, including vegetable oils. He demonstrated the use of peanut oil as fuel in his diesel engine at the 1900 World Exhibition in Paris.

The first modern biodiesel production plant was opened in Austria in 1988 by researchers at the University of Graz. This plant produced biodiesel from rapeseed oil. Commercial biodiesel production began taking off in Europe in the early 1990s as interest grew in renewable fuels. The National Biodiesel Board was formed in the United States in 1992 to promote the commercialization of biodiesel.

Biodiesel production and use saw rapid growth in the 2000s as concerns over energy security and desire for renewable fuels increased. Major milestones included the establishment of ASTM biodiesel standards in 2002 and the passage of the Renewable Fuel Standard in the United States in 2005, which mandated blending of renewable fuels like biodiesel. Global biodiesel production reached over 30 billion liters by 2016.

Key developments in the history of biodiesel include:

– 1892 – Rudolf Diesel develops engine running on peanut oil
– 1900 – Diesel exhibits engine running on peanut oil at Paris Expo
– 1988 – First modern biodiesel plant opens in Austria

– 1992 – National Biodiesel Board established in U.S.
– 2002 – ASTM biodiesel standards finalized
– 2005 – Renewable Fuel Standard passes in U.S.
– 2016 – Global biodiesel production exceeds 30 billion liters

Benefits of Biodiesel

One of the main benefits of using biodiesel is reduced emissions. Biodiesel can reduce carbon emissions by 50-80% compared to petroleum diesel, according to the U.S. Department of Energy’s Alternative Fuels Data Center. Using biodiesel also decreases emissions of particulate matter, hydrocarbons, and air toxics. The reductions in air pollutants improve air quality and public health.

Biodiesel is also biodegradable and nontoxic, meaning it is environmentally safe. Spills decompose rapidly compared to petroleum diesel. Biodiesel made from vegetable oils is renewable, since the crops used to produce it can be replanted and grown again. This renewable nature helps reduce dependence on limited fossil fuel reserves.

Since biodiesel can be produced domestically from vegetable oils, animal fats, or recycled cooking greases, it reduces reliance on imported petroleum. Higher use of biodiesel contributes to greater energy security and economic stability.

Drawbacks of Biodiesel

While biodiesel has several advantages, it also comes with some drawbacks compared to conventional petroleum diesel fuel. Some of the main disadvantages of using biodiesel include:

Lower energy density than diesel – Biodiesel contains about 8-10% less energy per gallon than petroleum diesel fuel. This means more biodiesel fuel is required to travel the same distance as with conventional diesel.¹

Higher cost – Biodiesel currently costs more to produce than petroleum diesel, which makes it a more expensive fuel option. The high production costs are due to the feedstock and conversion processes.

Cold flow issues – One of the major drawbacks of biodiesel is that it gels and solidifies at lower temperatures than petroleum diesel. This can make biodiesel unsuitable for use in cold weather conditions without additional treatments or blending with conventional diesel.²

Potential engine compatibility issues – Biodiesel can impact rubber hoses and seals over time. It also acts as a solvent that can clog fuel filters initially by cleaning residue from tanks and lines. Engine modifications may be needed to accommodate biodiesel blends above 5-20%.

Lower energy density and cold flow properties are the two biggest technical challenges facing widespread adoption of biodiesel as a diesel alternative. Research is ongoing to optimize biodiesel feedstocks and fuel additives to help overcome these disadvantages.

Biodiesel Production Process

Biodiesel is produced through a chemical process called transesterification, where oils and fats are reacted with an alcohol (usually methanol) in the presence of a catalyst (such as sodium hydroxide) to form methyl esters (biodiesel) and glycerol as a byproduct. This process converts the long chain fatty acids found in oils and fats into shorter chain methyl or ethyl esters that make up biodiesel fuel.

Common feedstocks used for biodiesel production include soybean oil, canola oil, animal fats, and used cooking oil. The yield of biodiesel depends on the type of feedstock, with some oils containing more unsaturated fatty acids that produce higher yields. For example, biodiesel yields from soybean oil are around 1 gallon of biodiesel per gallon of oil, while yields from animal fats are typically 0.85-0.9 gallons per gallon of fat.

The transesterification process consists of mixing the oil/fat feedstock with methanol and a catalyst, then heating the mixture to speed up the chemical reaction. Glycerol separates from the biodiesel and the mixture is washed with water to remove impurities. Excess methanol is recovered and recycled back into the process. The finished biodiesel is then tested to ensure it meets fuel quality standards.

Biodiesel Feedstocks

Biodiesel can be produced from a variety of feedstocks, but the most common ones are:

Soybean oil – This is the most widely used biodiesel feedstock in the United States, accounting for over half of all biodiesel production. Soybean oil is readily available and cost effective. The con is that relying too heavily on soybeans could lead to problems with food supplies and deforestation.[1]

Canola oil – Canola is the second most common biodiesel feedstock in the US after soybeans. It produces high quality biodiesel efficiently. The drawback is that canola production requires a lot of fertilizer.[1]

Used cooking oil – Recycled waste vegetable oil is an appealing biodiesel feedstock because it reduces waste and is very low cost. However, impurities can cause problems with biodiesel quality.[2]

Animal fats – Tallow from beef, pork, and poultry industries can be converted into usable biodiesel. This helps utilize waste material. But it can solidify in cold weather.[3]

Other less common biodiesel feedstocks include palm oil, corn oil, cottonseed oil, and algae oils. The optimal feedstocks depend on availability, cost, quality, and sustainability factors.

Biodiesel Standards

Biodiesel standards help ensure quality control and specifications for biodiesel blends. The main biodiesel standard in the United States is ASTM D6751, which covers specifications for pure biodiesel (B100) intended for blending with petroleum diesel. The ASTM D6751 standard includes tests and requirements for properties like flash point, cloud point, oxidation stability, sulfur content and more.

For biodiesel blends, ASTM D7467 covers specifications for blends from B6 (6% biodiesel) to B20 (20% biodiesel). Key requirements include cetane number, sulfur content, flash point, and more. According to ASTM D7467, B6 to B20 blends must meet ASTM D975 petroleum diesel fuel specifications.

In Europe, the main biodiesel standard is EN 14214, which is similar to ASTM D6751. It specifies requirements for pure biodiesel (B100) before blending with petroleum diesel. The key differences between ASTM D6751 and EN 14214 relate to differences in climate and refining processes between the U.S. and Europe.

Using Biodiesel

Most diesel engines can operate on biodiesel blends up to B20 (20% biodiesel, 80% petroleum diesel) with little to no modifications. However, there are some guidelines and maintenance considerations when using biodiesel blends.

Biodiesel has excellent lubricating properties but can act as a solvent, cleaning debris out of fuel lines and tanks. This can initially clog fuel filters, so it is recommended to replace fuel filters after first switching to biodiesel, and monitor them closely afterwards. Some rubber components may experience swelling or degradation with biodiesel, so hoses and seals may need to be replaced with biodiesel-compatible materials (Diesel Vehicles Using Biodiesel).

Because biodiesel blends can absorb more water than petroleum diesel, extra care must be taken to prevent water accumulation in storage tanks. Fuel filters should have water-separating capabilities. In cold weather, blends higher than B20 may start to gel and clog filters, so lower blends are recommended. Storing vehicles in a garage, using fuel additives, and switching to winterized biodiesel can help (How Biodiesel Cars Work).

With proper fuel management and maintenance, many diesel vehicle owners experience minimal issues when using approved biodiesel blends.

Biodiesel Applications

Biodiesel has a wide range of applications, both currently in use today and with potential for expanded use in the future. The transportation sector is the largest current user of biodiesel, where it can be blended with petroleum diesel or used as a pure biodiesel (B100) fuel in diesel engines. Biodiesel blends of up to 20% (B20) can be used in most diesel engines with no modifications required. Higher blends may require certain engine components to be upgraded to be compatible with biodiesel.

Biodiesel is also commonly used as a heating oil for residential and commercial buildings. Blends up to B20 can generally be used as a direct replacement for conventional heating oil in existing systems and appliances. Biodiesel heating oil burns cleaner than petroleum-based fuels, producing less air pollution.

Electricity generation is another key application for biodiesel. Biodiesel can be used to fuel generators and in co-generation systems that produce both electricity and usable heat. Biodiesel offers the benefits of reducing greenhouse gas emissions compared to fossil fuel-based electricity.

In the future, biodiesel has the potential to be used in even wider applications as production volumes increase and costs decline. Marine vessels, mining equipment, and agricultural machinery are examples of additional heavy-duty transport sectors that could adopt biodiesel. Biodiesel could also play a role in air transport, with some commercial flights already demonstrating flights using blended biodiesel fuels.

With further research and development, biodiesel may also find new applications that go beyond direct fuel uses. For example, biodiesel can be converted into bioplastics or used to produce organic chemicals like paints, solvents, and personal care products. The versatility of biodiesel feedstocks gives it substantial potential as a sustainable bio-based alternative to petroleum.

Overall, biodiesel usage as a transportation fuel, heating oil, and electricity source account for most of its applications today. But in the future, biodiesel production volumes may support greatly expanded use across many sectors of the economy.

Future of Biodiesel

The future looks bright for increased biodiesel production and adoption, but there are also some challenges. As the world looks to transition to more renewable energy sources, biodiesel is poised to play an important role.

One major driver for biodiesel growth is increasingly stringent emissions standards and carbon reduction goals being set by governments around the world. Biodiesel can help reduce particulate emissions from diesel engines. Several countries have already implemented biodiesel blending mandates to reduce emissions. For example, the US has a nationwide Renewable Fuel Standard that sets annual volume requirements for biodiesel blending (The Future of Biofuels: A Global Perspective).

Advancements in biodiesel production technologies and expanded feedstock options will also aid growth. Researchers are developing ways to convert waste oils and non-food crops like jatropha, algae and mustard seed into biodiesel more efficiently and cost-effectively. Genetic engineering of oilseeds could further increase crop yields down the road (The Future of Biofuels: Getting the Balance Right).

However, vegetable oil and animal fat feedstocks are in limited supply. As demand grows, feedstock sustainability and price spikes could hamper biodiesel expansion. More research is needed to commercialize advanced biofuels from non-food sources (IEA Biofuels Report).

Overall, biodiesel is expected to continue displacing petroleum diesel, especially in transportation, as long as costs can remain competitive. Strong policy support will likely be necessary to enable biodiesel to reach its full potential as part of the renewable energy mix.