Connect with us

Hi, what are you looking for?



The Smell of Change is in the Air with Renewable Biodiesel from Sewage

With a few hurdles to overcome, renewable biodiesel from sewage could be cheaper than petroleum dieselThe sewage-to-biofuel field is attracting interest from major companies like Waste Management and startups like InfoSpi, which are betting that renewable sewage biodiesel can become competitive with petroleum diesel on price.  Now the American Chemical Society has published an article* on sewage biodiesel that bears out this promise.  The article estimates a cost of $3.11 to produce a gallon of biodiesel from municipal sewage sludge, compared to $3.00 for petroleum diesel.


The article notes some hurdles to overcome in order to push the price lower.  Despite these reservations, considering the potential savings to municipalities in terms of reduced sewage sludge disposal costs, and the savings to the national economy in terms of eliminating the chance of another catastrophe on the scale of the British Petroleum oil spill in the Gulf of Mexico, cost-competitive biodiesel from sewage sludge sure looks sweet.

A Word about Sewage Sludge

Raw sewage sludge is a liquid heavy with suspended solids that have been separated out of sewage during the treatment process.  In municipal sludge, the solids are primarily organic matter from you can guess where (industrial sludge from factories is a different cup of tea).  Modern sewage treatment plants convert the raw sludge into an inert, processed substance by using bacteria to break down the organic material.  The processed sludge can then be dewatered and used as a soil enhancer, similar to any other yard material you might pick up at the local nursery.

Sewage Biodiesel! Errr, Not so Fast

Waste Management is a global industry giant, so its ambitious sewage biofuel project provides some indication that sewage biodiesel has a bright future; likewise for InfoSpi, which has planned a string of sewage-to-biofuel plants in the Southeastern U.S.  The American Chemical Society article notes, though, that biodiesel from sewage for the mass market has some serious obstacles to overcome.  In addition to developing a cost-effective refining process, other factors include collecting the feedstock (the sludge), ensuring quality control, and addressing regulatory issues involving traces of pharmaceuticals and other contaminants that may occur in municipal sludge.

Sewage to Biodiesel – The Big Picture

In the context of the Gulf oil spill, sewage sludge does have a significant advantage over petroleum as a diesel feedstock.  Where harvesting petroleum creates new risk and has caused catastrophic environmental and public health damage with consequent costs, “harvesting” sludge is done for precisely the opposite reason: to reduce risk and prevent harm that can lead to extreme economic burdens.  Vast quantities of sludge are already transported out of cities and disposed elsewhere, often at great expense.  Sewage biodiesel offers the potential of defraying these costs, so even if biodiesel users pay slightly more at the pump, in the big picture that could be offset by the savings to sewage ratepayers.  After all, it’s high time to take a good look at the big picture when comparing the cost of fossil fuels and renewable fuels.

*Note: The author of the article is David M. Kargbo of U.S. EPA Region III.  Mr. Kargbo specifies that the article represents his opinion and does not reflect EPA policy.

Image: Biodiesel by Laboratorio en Movimiento on

Sign up for daily news updates from CleanTechnica on email. Or follow us on Google News!

Have a tip for CleanTechnica, want to advertise, or want to suggest a guest for our CleanTech Talk podcast? Contact us here.

Autonomous Drones for Better Farming

I don't like paywalls. You don't like paywalls. Who likes paywalls? Here at CleanTechnica, we implemented a limited paywall for a while, but it always felt wrong — and it was always tough to decide what we should put behind there. In theory, your most exclusive and best content goes behind a paywall. But then fewer people read it! We just don't like paywalls, and so we've decided to ditch ours. Unfortunately, the media business is still a tough, cut-throat business with tiny margins. It's a never-ending Olympic challenge to stay above water or even perhaps — gasp — grow. So ...
If you like what we do and want to support us, please chip in a bit monthly via PayPal or Patreon to help our team do what we do! Thank you!
Written By

Tina specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.


You May Also Like

Fossil Fuels

Spot the contradiction: oil majors with record profits while lower income households struggle to pay their bills. Can Europe act to level the playing...

Clean Power

Like it or not, policymakers in some US states are unable to stem the solar power tide as Lightsource bp joins forces with leading...

Clean Power

By Miguel R.L. (aka Lambda), ETH Zürich engineer Time is fast running out to keep global surface temperatures below the 1.5°C limit we have...

Climate Change

About 25% of Alberta’s economy is evaporating over the next two decades. And with the loss of that major segment of the economy, all...

Copyright © 2023 CleanTechnica. The content produced by this site is for entertainment purposes only. Opinions and comments published on this site may not be sanctioned by and do not necessarily represent the views of CleanTechnica, its owners, sponsors, affiliates, or subsidiaries.