All that glitters is not gold… but some of what doesn’t, could very well be!

All that glitters is not gold… but some of what doesn’t, could very well be!

The value of FOG

Creating value from material we historically called “waste” – is one of the greatest trends happening in our industry today. Here is an example.

I follow the news on Anaergia because they are a local success story and because I have a few old friends that work there. A series of recent news clips have celebrated the start of a new Anaergia biogas plant in Singapore that uses anaerobic bacteria to convert wastewater sludge and food waste into biogas that can then be used to create electricity and heat

The Singapore news articles prompted me to write about the value of fats, oils and grease (FOG) taken from grease interceptors. Historically, this “waste” has been a cost to every stakeholder in FOG value chain; Food Service Establishments pay pumpers to remove FOG, pumpers pay a tipping fee for disposal, and municipalities pay for enforcement and maintenance of their sewers, lift stations and wastewater treatment plants. Some more progressive pumpers have established links to waste-to-energy facilities, but in general it is difficult for pumpers to construct waste-to-energy facilities on their own, as they lack the scale, capital or sufficient feedstock volumes. At best, they find a local facility that will accept their FOG waste. Some municipalities with waste-to-energy facilities allow pumpers to add FOG feedstock to their facility. In general, the highly fragmented pumper market and disjointed relationships between FSEs, pumpers, and municipalities prevents most cities from being able to capitalize on FOG as a resource.

A wasted opportunity

This is a shame, since I cannot imagine a more obvious waste to energy opportunity. The National Renewable Energy Laboratory estimates that the amount of FOG collected from food service establishments is 13.4 lbs/person/year. So a city such as Metropolitan Pittsburgh, for example, with a population of 2.4 million people would have access to approximately 32 million pounds of FOG collected per year.   Reviewing some published FOG-to-energy engineering feasibility studies such as a report by CH2M Hill Engineers for the City of Gresham, OR in 2011, the numbers work out something like this:

  • Depending on FOG strength, somewhere between 4 and 12 cubic feet of biogas is created from 1 lb of FOG
  • Each cubic foot of biogas produces approximately 575 Btu of fuel value
  • Each Btu of fuel value can produce at minimum 0.09Wh of energy from a cogeneration unit
(Click to enlarge) The FOGWISE ecosystem – the smarter path to a blockage free municipal sewer system

(Click to enlarge) The FOGWISE ecosystem – the smarter path to a blockage free municipal sewer system

So, a city like Pittsburgh could produce between $0.6M and $2.0M annually in electricity (@$0.10/kWh) generated from FOG if this resource was fully harvested. Naturally, the numbers would vary by city and would need to be subject to engineering studies, but surely they are compelling enough on their own to warrant consideration.   Add to this; huge GHG carbon credits for burning biogas instead of other fuels, avoidance of unsustainable landfilling of FOG where there are no other sustainable alternatives, and management of the local pumper/hauler industry (to avoid pump and dump scenarios), and the argument becomes even more compelling.

It all makes perfect sense from both an economic and an environmental perspective. What is required is the foresight of progressive communities to think beyond current practices and organize the various disjointed pumper and food service stakeholder ecosystem, and invest in the renewable energy infrastructure required.

Creating value out of waste

Ecoinsight promotes this ecosystem as our FOGWISE remote level monitor for grease interceptors plays a role in informing all of the stakeholders of the volumes of FOG in interceptors throughout the municipality in order to optimize collection and plan digester feedstock volumes.   We promote the FOG Ecosystem model shown below where FOG hauling contracts are managed by the city (similar to private waste management contracts) and the FOG resource is subsequently owned by the municipality for beneficial use under the contract.

Featured image source: New York’s notoriously toxic Gowanus Canal as seen by photographer William Miller (