Sunday, February 15, 2009

From Grease Trap to Fuel Pump

The city of San Francisco recently announced its plans for a grease-to-diesel plant [CNET]. Through the program SFGreasecycle, the city had already been collecting “yellow” grease from restaurants and other establishments for no charge, which it processed and sold to bio-diesel producers. Now, the city will expand its program to include pickup of “brown” grease, which is tougher to process. This brown grease will be processed into three grades of biofuel: high-grade American Society for Testing and Materials (ASTM) certified biodiesel for vehicles, lower grade biofuel source for running sewage treatment plant turbines and pumps, and rich energy for cogeneration – the process of capturing methane gas at the sewage plant and converting that to heating/electrical needs [SFWATER.ORG].


Although I don’t know much about biofuels and associated technologies, my general preconception is that the fuels suffer from horrible inefficiencies. I have heard and read a lot of criticism of the food for fuel cycle, and so am usually hesitant to get excited about biofuels. However, I like the approach of recycling a waste product such as grease to create fuel. San Francisco is able to claim several advantages from their program. Because the city picks up waste for free, business owners benefit directly from saved costs of disposal. In addition, the city can mitigate cleanup costs associated with illegal dumping from owners who pour out grease rather than pay to dispose of it properly.


The scope of the SFGreasecyle program is relatively small, with a daily production expectation of 500 gallons of fuel [CNET]. The program will also receive over $1 million from the state of California to fund the plant’s development. I am definitely interested in seeing how this development plays out. If SF can produce these fuels economically, I would love to see other cities implement a similar system. I think this is an excellent example of how policy can affect multiple problems with innovative solutions.

http://reviews.cnet.com/8301-13746_7-10158246-48.html

http://www.sfwater.org/detail.cfm/MC_ID/18/MSC_ID/114/C_ID/4018

4 comments:

Michael E. Webber, Ph.D. said...

Brodie, biofuels are very inefficient to produce from scratch (because photosynthesis has such a poor efficiency), as you noted, but the efficiency of recycling a waste product is a different story altogether. I like the grease-to-fuel concept because it turns an environmental hazard into a useful commodity, and so we should do it, but there's not enough grease in total to offset all our consumption, so we'll need other solutions, too.

koh said...

I agree with what Professor Webber said. I was about to make the same exact comment he did. I just wanted to add that because of the fact that there isn't enough grease to offset our consumption completely, I personally think it should be a "DIY" thing with a cult following (therefore offering free fuel for the weekend mechanics). I personally think by limiting free biodiesel sources, it would decrease interest in it (i.e. the city collecting "yellow" grease). However, I think collecting "brown" grease is a great idea.

SC_Tang said...

I agree with what you said. I think it is a wonderful program that the city of San Francisco can take advantage of transforming a waste product into biofuel. I recently read an article about how Walmart has currently developed a pilot program for its truck fleet. There are four green trucks that Walmart are testing. One of them runs on waste reclaimed grease biofuel. Walmart transformed 15 trucks in its Buckeye Arizona center to run on reclaimed Grease fuel made from brown cooking grease. The rest of the trucks at the same center is running on 80/20 blend of biodiesel made from reclaimed yellow grease. I think if Walmart is doing it. It must have a significant trade off.

David Wogan said...

Using waste grease is a great idea, especially since most companies pay someone to take it away. Using waste grease has been, for the most part, more of a cult following as koh mentioned. I looked into collecting waste grease for my diesel car at one point, but it requires some work to get a fuel that will not clog your fuel lines.

As Brodie mentioned, the fuel ultimately has to meet ASTM standards if it's going to be used on a scale larger than someone's garage.

Using waste grease is a perfect example of small steps people can take to reduce their use of traditional fossil fuels.