Diesel or Biodiesel: Which Fuel Will Keep You Going When SHTF?

The last thing you want to be doing in a disaster scenario is waiting in line at the gas station when essential services shut down. In a true SHTF scenario, gas shortages are probable, making many people wonder about using biodiesel fuel or other renewable fuel vs traditional gasoline or regular diesel. 

We'll break it down. 

Source: Andrew Winkler on Unsplash

Understanding Biodiesel, Renewable Diesel, and Traditional Diesel

Diesel is a common fuel for large trucks and boats but can also be used in some cars, trucks, and generators. This makes it a good choice for emergency preparedness, but is vulnerable to the same scarcity issues as gasoline. 

So what's the difference between traditional diesel (sometimes called petrodiesel, since it's made from fossil fuels) and biodiesel? And what's "renewable diesel?" 

• Traditional Diesel: Refined from crude oil petroleum  
• Biodiesel: Created from biomass oils, like cooking grease, plant oils, algae, or animal fat
• Renewable Diesel: Made from plant oils (mainly corn and soybean) and designed to be chemically similar to traditional diesel. 

Making it even more confusing, these different fuels are often combined in different concentrations. 

Some of the key differences in chemical composition between traditional diesel and biodiesel are:

• Biodiesel contains up to 10% oxygen, making it burn more completely. Biodiesel is a renewable resource.
• Traditional diesel contains sulfur, a highly polluting and tightly-regulated compound. 
• Biodiesel tends to thicken more quickly in lower temperatures, making it tricky for cold climates. The debate between renewable diesel vs. biodiesel is also picking up pace as one's cleaner than the other in terms of greenhouse gas emissions (more on this later).

Source:  Preston A Larimer on Unsplash

"Biodiesel" and "renewable diesel" are two terms that are often confused, but they are, in fact, different compounds.

Difference between Biodiesel and Renewable Diesel

Biodiesel is made from Fatty Acid Methyl Ester (FAME). This product is made by reacting plant fats and oils with alcohol and other chemical catalysts. The chemical reaction produces a new substance, FAME. 

While FAME can be mixed with traditional diesel (and in fact, usually is according to current U.S. regulations) it can't be used as a direct, one-to-one substitute to traditional diesel in most machines. The amount of biodiesel produced through the process also varies.

Renewable diesel is created differently from biodiesel, through a process called "hydrotreating." The resulting fuel is made of hydrogen and carbon, like traditional diesel is. Because of the chemical similarities of the final product, renewable diesel is often considered a one-to-one replacement for traditional diesel. 

Performance and Environmental Impact

If you already have a diesel engine and are interested in alternative fuel for it, there's an understandable concern about which diesel fuel will perform the best. 

Source: Hardik Jogani on Unsplash

We'll compare the three types of diesel - traditional, bio, and renewable, across key metrics: fuel economy, emissions, and environmental impacts.

Traditional Diesel

Fuel efficiency: Diesel engines are typically about 10 -15% more fuel efficient than gasoline engines, which is one reason why diesel use is popular in long-haul trucks. The better fuel economy can lead to significant savings over longer periods.

Emissions: Diesel engines produce a number of emissions that have concerns for human health, including carbon dioxide, sulfur, carbon monoxide, and particulate matter. These are what produce "smog," or the hazy cloud that can affect breathing. 

Environmental Impacts: Diesel fumes can damage the ozone and produce acid rain, which affect the water and food supply. 

Biodiesel

Fuel Efficiency: Biodiesel has slightly less energy per volume than standard diesel - about 2-5% less. Although biodiesel is slightly less fuel efficient, the difference, in most cases, is not that extreme. 

Emissions: Biodiesel doesn't contain sulfur, which removes one of the key polluting elements of diesel fuel - and that signature rotten-egg smell. It also contains more oxygen and tends to burn more fully, reducing the number of emissions. Engines may need adjustment to reduce the nitrous oxide (NOx) emissions created by biodiesel. Over time, biodiesel reduces engine wear, especially for engines that are adapted to its use.

Environmental Impacts: There are some concerns that producing biodiesel can take up land otherwise used for feedstock, creating shortages. As with any chemical process, refining biodiesel does take energy and produce some of its own pollutants. 

Renewable Diesel 

Fuel Efficiency: Because its chemical structure is almost identical to petroleum diesel, renewable diesel has about the same fuel efficiency per gallon as does traditional diesel. Both fuels are hydrocarbons, and renewable diesel is considered a "drop-in fuel", or one that can replace petroleum diesel fuel on a one-to-one basis. 

Emissions: Renewable diesel lowers carbon dioxide emissions, carbon monoxide emissions, and emissions from particulate matter. Fuel made from waste products like used cooking oil tends to produce even less greenhouse gasses than raw plant matter, like corn or soybean oil. 

Environmental Impacts: Renewable diesel can be made from the same raw materials as biodiesel, but with a different manufacturing process. This raises the same concerns about using land that would be put to feed crop use instead. Some pollutants are also released through the manufacturing process, especially if regular diesel refineries are retrofitted to produce biodiesel. However, renewable diesel can be made using waste that would go to landfills, like cooking oil, animal fat, fish oil, or sub-par corn to lower emissions. This makes it a good candidate for renewable diesel production. 

Compatibility and Practicality in Existing Engines

Renewable diesel and biodiesel sound like great options for "growing" our own energy-efficient, low-polluting, renewable fuel. So why doesn't everyone use them?

Because the way we produce fuel, build engines, and distribute these goods was all built around petroleum; the newer renewable energy fuels need some adjustments to replace the existing fuel system. 

Source: Jakub Pabis on Unsplash

Engine Compatibility 

Biodiesel needs to be blended with conventional diesel to work with most engines. A blend of 20%, called B20, is generally acceptable. 

Modifications to engine components to run 100 percent biodiesel, or B100, typically include a 2-tank system. A smaller tank holds petroleum diesel which is used to start the engine and warm both tanks. Then, a built-in sensor switches over to the B100 tank and runs the engine entirely on biofuel. 

Unlike biodiesel, most engines don't need any modification to run renewable diesel. 

Blending Options

You can blend your own biodiesel to create more efficient fuel. It's important to make sure that you use clean, uncontaminated fuel. One of the benefits of biodiesel is that the refining process is fairly simple, making it possible for farmers to "grow their own" fuel. 

When blending it with petroleum-based diesel, be sure that you carefully label the concentrations of the resulting liquid fuel based on the percent petroleum diesel it contains. B20, B50, etc. so you know for sure what's in the containers. 

Cost 

Government Incentives and Subsidies 

There are a number of government incentives designed to produce renewable diesel at a higher rate. These include:

• Environmental Quality Incentives Program (EQIP)
• Advanced Biofuel Payment Program
• Renewable Diesel Investment Tax Credit
• Renewable Fuel Standard (RFS)
• Blenders Tax Credit

Production Costs 

Biodiesel has the lowest production costs as it's a relatively simple chemical process called transesterification. The chemicals used in the process - usually lye and methanol or ethanol - are cheap and easy to get. Some "home brewers" even make it at home out of used cooking oil.

Renewable diesel is chemically identical to petroleum diesel in that they are both hydrocarbons. It's manufactured using a process called hydrotreating, which is fairly similar to refining crude oil into fuel. 

While cheap materials like foodstock and cooking oil can be used to make renewable diesel, it requires high heat and pressure. This usually means an industrial factory needs to be used. 

Current Market Pricing 

The pricing for the three main fuels vary widely depending on your region. If you live near a renewable diesel plant it might be more likely to find it at a reasonable price point. 

You can track prices at the Alternative Fuels Data Center here. For example, as of April 2024,  United States national average prices per gallon were:

• Biodiesel (B20): $3.94 
• Biodiesel (B100): $4.57 
• Traditional Diesel: $4.07
• Renewable Diesel: $5.36 

While there is still an increased cost to the sustainable fuel, the reduced carbon emissions can make it a good tradeoff. 

Source: Alternative Fuels Data Center 

Long Term Maintenance 

Biodiesel has a higher concentration of oxygen than either traditional or renewable diesel. This helps it burn cleaner, reducing tailpipe emissions and limiting certain chemical deposits in your engine. 

 It also has a higher lubricity, which means it acts as an engine lubricant. This can be a good thing, as it reduces wear and tear on the engine. 

Because of its higher cloud point, biodiesel can start to gel, or partially solidify, in lower temperatures. This can clog engine filters and mean that they need to be cleaned more quickly.

The quality of the biodiesel plays a huge role in the amount of maintenance. Higher quality biodiesel will produce fewer maintenance problems than lower-quality biodiesel. 

Fuel Performance in Extreme Conditions

Biodiesel is produced from feedstock like corn and soy, which solidifies at a higher temperature than traditional petroleum diesel. This can create problems for using pure biodiesel in cold climates. 

This leads to "gelling" or "cloudiness" where the fuel becomes too thick to pump. This makes it hard to pour or pump at low temperatures. The exact temperature varies widely but can be as high as 35 degrees, making it a concern for a significant portion of the United States. 

Source: mali maeder from Pexels: 

Some adjustments can help with this problem:

• Heating storage tanks 
• Using biodiesel blended with petroleum diesel 
• Additives that prevent gelling 
• Using lower levels of saturated fats in the biodiesel production 
• Mixing with kerosene and petroleum diesel in cold climates

Storage

Different fuels have a different shelf life:

• Traditional diesel and low biodiesel blends (like B5) can be stored for up to a year
• Higher concentrations - like B20 - are generally good for about 8 months
• Pure biodiesel (B100) should be checked for quality or used up within two months
• Renewable diesel has a much longer shelf life even compared to petroleum diesel - up to 10 years

Energy and Power Biodiesel vs. Diesel 

One drawback of biodiesel is that its higher oxygen content makes it slightly less energy efficient in situations demanding high power output. 

Biodiesel contains roughly 120,000 to 130,000 BTUs of energy per gallon, while renewable diesel and petroleum diesel each contain around 130,000 -140,000 BTUs. 

This isn't a huge energy difference, but under stressful conditions like pulling heavy loads, petroleum and renewable diesel can perform slightly better. 

In colder climates, the gelling issues need to be addressed to ensure good performance from renewable fuels. 

In the classic movie Back to the Future, Doc Brown fuels his futuristic car by shoving trash into an on-board processor. While we're not quite there yet, the advances in using food waste for biofuel make it seem less like science fiction and more like a real possibility. 

Source: Wikimedia commons 

Bonus: A Look at Vegetable Oil and Other Potential Fuel Sources 

Biofuel can be made from food mass like corn, soy, and palm oil or even from waste products, like used cooking oil or even animal fat waste from butchering.

In the United States, corn is usually the cheapest source of biofuels. In other parts of the world, sugarcane is more economical. 

SHTF (Survival) Scenario Considerations

So which is the best fuel type for a survival scenario? 

Obviously, any of the three fuels will require some preparation and advanced knowledge. While biofuels can be grown and processed locally, crops take a long time to grow and are dependent on the weather. 

You can set up a biodiesel making system in your home, but it will take a little chemical know-how and some supplies. Here's a good explainer. 

If you are an experienced biodiesel home brewer, you can carry on with production even in a crisis situation. If you use it consistently and continuously, you can keep an emergency vehicle and a generator going. 

One drawback to this is that biodiesel isn't a drop-in substitute for traditional petroleum diesel. So you will still need a stockpile of regular diesel to make a blend that is usable. 

Renewable diesel is a good option because of its long storage life. It's more versatile, since it's a drop-in substitute for traditional diesel. So if you need to fuel up a neighbor's vehicle or generator it will work.

The drawback to renewable diesel in a SHTF scenario is that it can't really be easily produced at home. It requires a refinery process similar to traditional diesel.