Reducing a Carbon Footprint by Turning Trash and Manure Into Power

For the state of California, taking a bite out of climate change is a high priority.  In recent years, more legislation has sought to bolster long-time efforts, across the board – and for some – solidified the notion that one person’s trash could be another’s treasure.

James Moore/Director – Merced County Regional Waste Management Authority: “I think the landfill industry has a vested interest in seeing better opportunities for the use of the methane we generate.  It’s definitely a fact that California does typically set the standard, and then other states follow in the successive years.”

Merced County Regional Waste Management Authority Director James Moore says his Central Valley utility now annually diverts 25-thousand tons of green-waste material they would previously bury.  Subterranean decay does act as a carbon sink, but anerobic conditions underground also produce volatile methane, a greenhouse gas 28 times more potent at trapping heat in the atmosphere than CO² - according the U.S. Environmental Protection Agency. 

Under Senate Bill 1383, approved by former Governor Jerry Brown in 2016, and in effect as of 2022, residents and businesses are required to compost food and other organic waste in utility-provided carts.  The goal is a 75 percent reduction in entombed organic waste by 2025. 

The action has opened the door for contractors and jurisdictions like Merced County to not only produce compost commodities for landscaping and soil development, but capitalize on existing mitigation systems.

James Moore/Director – Merced County Regional Waste Management Authority: “For the last 20-25 years or so, landfills have put in – based on regulations -  methane collection systems.  In the last 20 years, it’s become quite economical to capture that gas, and use it for either energy generation, or under the new regulations today, renewable fuel standards – rather than just environmental control – burning it off or burying it.  So, there’s an economic advantage to being able to put in these power plants, or conversion plants, and transform that methane into a renewable natural gas that can either be injected into the pipeline, and used just like natural gas, or be used to create fuel.”

The Renewable Fuel Standard has benefited U.S. corn growers by requiring a percentage of biofuels, like ethanol, be blended into the nation’s fuel supply.  But the federal mandate also covers biogas, a cellulosic, or next-generation source – which also qualifies to generate Renewable Identification Numbers or RINs.  These credits are sold to major polluters like the oil and gas industry to keep their emissions in check.

California’s Low Carbon Fuel Standard, a similar state program, may be stacked with RINs to provide a dual windfall – an enticing incentive for a state at the forefront of the shift from gasoline to electric vehicles.  Some say biofuels can help bridge the gap.

Dr. Sarah Kurtz – Distinguished Professor – School of Engineering/Department Chair for Electrical Engineering Dept. – University of California – Merced: “I think there is a real opportunity for biofuels – largely because they can be stored.  If we shut down all the fossil fuel, right now, the world would come to a screeching halt.  We would starve, we would freeze.  That’s not the way we are going to be able to build a better world.”

University of California – Merced Distinguished Professor, Dr. Sarah Kurtz, spent more than 30 years working at the National Renewable Energy Laboratory in Colorado.  Her tenure in Merced has focused on integrating various energy sources to collectively drive down costs, with a focus on choice, as opposed to government mandates.

Dr. Sarah Kurtz – Distinguished Professor – School of Engineering/Department Chair for Electrical Engineering Dept. – University of California – Merced: “California is definitely a leader.  They are doing some things very, very well.  I do want to raise a concern, that one of the ways they’ve done it, is to say, we want to do it at whatever cost.  And we end up…then we have some of the most expensive electricity in the nation.  If electricity prices go sky-high, then who wants to electrify?”

UC Merced staff are tackling today’s challenges from various angles.

Dr. Gerardo Diaz/Professor of Mechanical Engineering/University of California – Merced:

“This area, where we are, in the Central Valley – there is a lot of generation of biomass.  Not only in the Sierras, for the forest type of waste, that is available, but also, agricultural waste.” 

Dr. Gerardo Diaz says bio-circular economies keep money on the farm - and proper composting techniques, like livestock bedding use, can heavily reduce methane and other objectionable by-products.

Dr. Gerardo Diaz/Professor of Mechanical Engineering/University of California – Merced:

“We were able to show that there’s a reduction in odor from the dairy production.  That really helps to improve the quality of life of some of the surrounding communities, for instance.  Sometimes, people don’t consider those things.  But, we have a large community of people that are either rural, or disadvantaged communities, or low income, that are affected by some of these aspects.” 

Entrepreneurs who’ve worked with UC-Merced are harnessing the rising tide of energy incentives to help float dairy operations of all size and scale.

Omar Ramirez/General Manager – Aligned Digesters: “It’s not super-sophisticated technology.  It’s a natural process.  You know, it doesn’t get more simple than this.  It’s a covered lagoon capturing the methane that is being released from the microbial activity within the manure.  Takes about 30 days for the biogas to be generated underneath the cover.”

Aligned Digesters General Manager Omar Ramirez says after purchasing the proper equipment, similar systems can generate power at 9¢ per kilowatt hour, as opposed to up to 22¢ from a local utility.  He adds this dairy in Chowchilla, which milks 6,500 head, feeds his setup roughly 350,000 gallons of liquid waste daily – which can generate around 2 megawatts of power.  Net metering can further offset inputs, while even more potential remains.

Omar Ramirez/General Manager – Aligned Digesters:

“On the plus side, if you’re doing renewable natural gas, you could also power your fleet, onsite, to haul your milk, to haul your feed, and so it’s really easy to create a circular loop.”

Critics charge this bevy of benefits encourages booming herds and exponential greenhouse gas, but Ramirez sees it as a hedge.

Omar Ramirez/General Manager – Aligned Digesters: “The dairy market is very volatile.  In our mind, it’s dairy first and how are we going to help the dairymen generate that additional revenue stream while helping the environment - and also putting a little bit more money into their pocket for the hard times.”

For Market to Market, I’m Josh Buettner.

contact: Josh@iowapbs.org