Cincy Science: Eat fried foods! (In moderation). UC professor & students turn waste oil into energy

CINCINNATI - About nine years years ago, University of Cincinnati engineering associate professor Ming-ming Lu and her team of students began converting waste cooking oil from the campus dining facilities into biodiesel fuel.

The process turns grease which would have been sent to a landfill into a viable resource.The team's oil extraction reactor system is currently patent-pending as commercially viable green energy technology.

According to the US Clean Air Act , biodiesel is the only alternative fuel to have fully completed health effects testing requirements. The fuel is an organic, non-toxic, biodegradable and cuts down on CO2 emissions.

From left, UC students Yang Lu and Qinshi Tu and associate professor of engineering Ming ming Lu in the lab, showing some of their research on turning used coffee grounds into a fuel source.

To help us better understand the process behind converting used cooking oil into fuel, Dr. Lu answered our questions.

1. When did you start this process and what gave you the idea?

That was 2005 -2006, we started making waste cooking oil into biodiesel using our cafeterias in the University of Cincinnati, so we tried to get some of their waste oil and make it into biodiesel.

At that time, alternative energy was pretty much starting to get a lot of people’s attention. We had an engineering student who had made biodiesel from the waste cooking oil at her home and used it in her car. She happens to be a student in our department and she helped us along to set up the reactor and showed us a lot about how to get started.

2. What are the uses for biodiesel?

The student who helped guide us uses biodiesel in her Jeep; it burns on diesel. And one of my other students, he bought a diesel car and he works with a biodiesel producer. So he uses the biodiesel they produce. The Metro buses used to use biodiesel years ago, but now they’re a hybrid. Biodiesel can be used to power vehicles and it can be used as heating oil.I think they use it for heating in New York and Massachusetts.

3. How do you turn used cooking oil into biodiesel?

If you have good oil, it’s relatively straightforward. You use the waste cooking oil, if you see a solid you have to filter it. Most of the time we do filtration and sometimes you have to repeat it a little bit if it contains water. The quality of the waste cooking oil is very important, if you get not so good quality the batch might not be successful.

You then use sodium hydroxide or potassium hydroxide, methanol and you heat it up, and then it becomes biodiesel. The final product is called glycerin. That’s basically the process.

4. How long does it take to convert cooking oil to biodiesel?

For us, we have a 50-gallon reactor, so it’s about an hour. You heat it up to 140 degrees fahrenheit and then it’s about an hour for the reaction.

5. Is it an expensive process?

Because we use waste cooking oil, the only cost is the chemical cost and the cost of electricity. We're doing research so we don’t have any labor costs in it because the students are doing the work. I would say the actual fuel costs to produce are lower than the costs that we see at the pump.

Many, many years ago, the cost of regular diesel was cheaper if you bought it from the pump, but not anymore.

According to the U.S. Department of Transportation, the national average fuel costs for April 2014: 

  • Biodiesel B20 (20% biodiesel and 20% petroleum diesel)  $4.01 per gallon
  • Biodiesel B99 - B100 (100% biodiesel) $4.23 per gallon
  • Diesel $3.87 per gallon
  • Gasoline $3.65 per gallon
  • Ethanol $3.85 per gallon

6. Could people make their own biodiesel fuel at home?

There are a lot of YouTube videos  and online information on this product. They have to be careful when using chemicals and heating the oil, and make sure these people don’t get hurt.

7. What other products are you re-purposing?

We’re thinking that coffee grounds have some oil content in it. If we use the coffee grounds somehow and make it into useful product by extracting the oil, that might be of some help so we’re not throwing all the things away. So that’s our thinking and we’re trying to extract the oil now and after extraction the coffee grounds have the potential to be used as activated carbon .

8. Do you collect waste oil from other sources besides UC?

We’re working with the Metropolitan Sewer District.  They receive a lot of high quality grease, and of course that’s a land fill. And we’re thinking if we could make the grease into useful material, that would be good. So we want to extract the oil and the energy and they want to burn whatever is left over in a large incinerator, so if we don't use it they will incinerate it.

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