How to Recycle Used Cooking Oil : From Restaurant to Biodiesel

What Is Biodiesel?

Biodiesel is liquid fuel derived from various types of cooking or vegetable oils and fats. It has similar combustion properties to regular petroleum diesel fuel.  Because it is produced from cooking oils and fats, biodiesel is non-toxic and biodegradable. When burned, It produces significantly fewer emissions than petroleum-based diesel fuel which makes it much more environmentally friendly

Cooking Oils From The Kitchen

It is no surprise that restaurants use endless amounts of cooking oil each year to support their menus and their businesses. Various types of cooking oils are used in restaurant kitchens, and each type serves a different purpose based on the cooking practice or style being used. Deep fryers cook at very high temperatures, on average of 350 to 375 degrees. Many oils will burn at such high heat, so the most commonly used oils for deep frying include peanut oil, soybean oil, canola oil, and lard (animal fats). In specialty and higher-end establishments, duck fat can also be used in deep fryers to add more bold and savory flavors. When it comes to sautéing, it is not necessary to have an oil that can withstand such high temperatures as frying. Typically a more neutral-flavored, moderate-burning oil is used such as canola, grape seed oil, coconut oil, and olive oil. Sesame oil is often used for sautéing in Asian cuisine because it adds a particular flavor to the dish. Other types of oils have a lower heat tolerance burn when used with high or even medium heat. These types of oils include, but are not limited to, extra virgin olive oil, truffle oil, flaxseed oil, and walnut oil. Oils with low heat tolerance are most often used for making dressings, sauces, and marinades. With the seemingly endless amounts of cooking oils used in food service establishments around the country, it begs the question, "Where does it all go after it's used?"

Used Cooking Oil Disposal

"Grease dumping" is the improper disposal of used cooking oil by pouring it down a drain that leads to a sewer or waste management facility. Grease dumping is illegal in the United States because it damages sewer and plumbing systems, causing backups in the restaurant as well as in local streets and sewage lines. Additionally, there is major fire potential associated with grease.

What happens to these oils after restaurants have used them in their cooking practices?

Luckily, grease collection and restaurant grease pickup is a big industry. Most restaurants partake in cooking oil recycling and waste oil pickup services provided by companies that specialize in dispose of used cooking oil, pickup, and recycling.  According to the United States Environmental Protection Agency (EPA), "Hotels and restaurants in the United States generate 3 billion gallons of waste cooking oil per year." With the help of grease collection services, used cooking oil can be collected from restaurants and food service establishments to be processed and then refined into biodiesel.

What is the best practice for recycling used cooking oil?

Contact a licensed collector for a consultation. Grease collection companies help restaurant and food service establishment owners recycle used cooking oil through supplying bins for proper used cooking oil disposal. They will help determine the proper size grease collection bin for your establishment and also help set up a regular pickup schedule. There is also an option for will-call pickup with most companies as long as the minimum gallon amount is met... To find out more about restaurant grease pickup and grease collection service, see our blog post: "Grease Collection Service: What is it?"

Processing Used Cooking Oil

When grease collection bins get full, the grease collection service drains the bins to be taken to processing, or rendering facility. Waste cooking oil must be treated to remove impurities before it can be converted into biodiesel. "Rendering" is the purification process of the used fats, oils, and grease (F.O.G.). The first step is to sample all recycled F.O.G. to ensure it is free of pesticides and other harsh chemicals or contaminates. Next, the sampled F.O.G. will be filtered. The filtration process begins by placing all material into setting tanks to remove all solids. The last step of the rendering process involves a high-temperature cooking and drying procedure used to decontaminate and separate useable and recyclable fat. It is heated in a vacuum to help volatile impurities. Upon completion of the rendering process, the purified and usable bi-product can be refined into biodiesel.

Refining Processed Cooking Oil Into Biodiesel

Processed cooking oil that has been treated and filtered in the rendering process is ready to be converted into biodiesel through a process of refinement called "transesterification." According to Oilgae.com, "The transesterification process reacts alcohol (like methanol) with the triglyceride oils contained in vegetable oils, animal fats, or recycled greases, forming fatty acid alkyl esters (biodiesel) and glycerin." For a more in-depth look into the transesterification and refinement process, see an article published by the Energy Systems Research Unit (ESRU) of the University of Strathclyde: "What is Biodiesel?" The final step after transesterification is the separation of the two bi-products from the process: biodiesel and glycerin. Once the biodiesel has been tested and analyzed to meet commercial use requirements, it can then be packaged and distributed for use as fuel.