From Farm to Fork to Fuel

In the world’s most productive region of agriculture, food waste is being transformed into natural gas.

by / January 24, 2014

Who are we? It’s a question residents of Sacramento, Calif., have long grappled with. Aside from serving as the hub of state politics, the city has been in the midst of a seemingly perpetual identity crisis. For decades, residents and visitors alike saw Sacramento as little more than a way point between San Francisco and Lake Tahoe. About two hours from either destination, Sacramento was merely a place to gas up and grab a bite.

Sacramento is a place steeped in history. It was the western terminus of the Transcontinental Railroad and was at the heart of the California Gold Rush. Aside from the state capitol, the city’s historic district, which houses one of the world’s finest railroad museums, was for decades one of the only other draws for tourists. 

In 1985, however, the city landed a professional sports franchise – the historically beleaguered Kings of the NBA, which since its inception as the Rochester Royals in 1923, made its way west with stops in Cincinnati, Omaha, and Kansas City. Since arriving in Sacramento, the city’s status as a destination began to rise.

Yet even a NBA basketball team, which in the early 2000s was the darling of hoops fans, wasn’t enough for the city to shake the perception that it was nothing more than, as the Los Angeles Lakers’ former coach Phil Jackson once said, a “cow town.”

Over the last decade, however, Sacramento’s stock has been trending upward. First, the city gained international fame as a part-time home to celebrity governor Arnold Schwarzenegger. More recently, native son and former NBA star Kevin Johnson was elected mayor. Perhaps to a fault, Johnson has been a tireless promoter of his home city, most recognizably for fighting and winning a number of uphill battles to retain the city’s basketball team and build a new arena in the heart of downtown.

Less well known, at least outside the city, has been Johnson’s effort to brand Sacramento the nation’s premier “Farm-to-Fork” destination. Blessed to be surrounded by some of the most productive agricultural lands in the world, Johnson’s vision coincided with Sacramento’s burgeoning culinary scene. The city is now home to hundreds of diverse restaurants that take full advantage of the region’s food resources. Some restaurants in Sacramento – such as Mulvaney’s and The Kitchen – have received national acclaim from food critics.

Last September, the city held its inaugural Farm-to-Fork Festival to celebrate its food scene and the utilization of the region’s many farms, ranches and vineyards that are making high-end restaurants a centerpiece of – and city leaders hope a tourism draw to – Sacramento.

But within the Farm-to-Fork initiative lies what is perhaps an even more compelling identity. What if all of Sacramento’s agricultural riches could not only make it a foodie destination but also one of America’s greenest cities? What if instead of just being the Farm-to-Fork capital, Sacramento was also the Farm-to-Fork-to-Fuel capital? With a rich food supply also comes a bounty of high-quality organic waste. As cities scramble for ways to be greener and incorporate renewable energy, organic waste in Sacramento is being used to create renewable natural gas that is fueling everything from garbage trucks to street sweepers.

In 2010, Johnson launched an initiative called Greenwise that aims to develop green business for both economic development and environmental sustainability. The initiative, as Governing reported last year, involved 275 leaders who together created the Greenwise Regional Action Plan. The plan includes doubling the number of green jobs to 28,000 by 2020; investing $1 billion in the clean-technology sector; promoting green urban design (such as by retrofitting buildings and planting trees); and increasing the locally produced food supply from 2 percent to 20 percent. The plan also calls for the city to remove 100 percent of organics from landfills by 2020.

“One of our signature projects that the mayor really talked about in the State of the City in January 2011 was to create a biofuels industry where we take organic waste and turn it into transportation fuel,” said Julia Burrows, President and Executive Director of Greenwise. “The long term goal is a zero waste solution and also reduced emissions in transport and adding renewables to the grid.”

According to Burrows, the biofuel idea stemmed from Gary Simon, a founding co-chair of the Sacramento Regional Technology Alliance’s CleanStart program. CleanStart is tasked with helping “accelerate the development” of clean technology companies in the greater Sacramento region.

Last year, Gold River, Calif.-based CleanWorld partnered with Sacramento-based Atlas Disposal on the construction of the Sacramento BioDigester, an anaerobic digestion system that converts organic waste into natural gas. The system is connected to a compressed natural gas fueling station and pumped its first gallon of natural gas in May 2013. Initially, Atlas was the primary consumer of the natural gas, using it to fuel its fleet of garbage trucks. But in October, the city of Sacramento’s fleet manager, Keith Leech, took notice.

“We learned about what CleanWorld was doing here and we got all excited about that,” Leech recalled. Leech said Sacramento’s fleet of heavy vehicles, such as pavement patching trucks, compressor trucks, and street sweepers, were perfect candidates for natural gas because the city has been using natural gas to fuel its fleet for a decade.

“We’ve been doing natural gas trucks here in Sacramento for over 10 years,” Leech said, noting approximately 100 vehicles in the fleet run on natural gas. “We were one of the first pioneers with Sacramento Regional Transit. They went the compressed natural gas route on their buses and we went the liquefied natural gas route on our garbage trucks mainly for the heavier payloads and to run the longer routes. We’ve been doing it a long time and we’ve saved a lot of money. We’ve consistently saved $1 million a year by using liquefied natural gas as opposed to diesel.”

The city’s commitment to using natural gas to power its fleet lead in part to it being named the greenest fleet in North America at last October’s Green Fleet Conference. Leech said now that the city has access to the BioDigestger, it will be acquiring more natural gas vehicles, the first of which are to arrive this month.

“We’re the first government customer that I’m aware of across the country that’s actually putting renewable biomethane, compressed natural gas into their trucks,” Leech said. “If you compare it to diesel and you use conventional petroleum-based natural gas you save about 30 percent in carbon. Then when you go to renewable natural gas from a landfill or a digester you’re saving about 90 percent or sometimes it’s even a negative score [when factoring in carbon credits for cleaner gas and landfill avoidance].”

The way the BioDigester works, at a very simple level, is like that of composting, only writ very large. But such a description doesn’t do justice to what actually takes place. At Sacramento’s South Area Transfer Station, organic waste is hauled in by Atlas trucks. The waste is often still in cardboard or other packaging. But the machine CleanWorld designed is capable of automatically separating the organic from the inorganic. The piles of waste are moved onto a conveyor belt and into a pulverizer, which chews and splits packaging and separates organic and inorganic material. Inorganic material is shredded and removed while organic material is mashed into a slurry of less-than-pleasant appearance and smell. This slurry is introduced into a settling tank. It is then moved through three more tanks that hold the material at about 130 degrees, which is ideal for microbes to breakdown organics. During the breakdown process is when methane is captured. At end of process the resulting gases are 60 percent methane [natural gas is primarily composed of methane]. The methane is then transferred to a machine called the BioCNG 100 which cleans it of most of the remaining impurities, resulting in a gas that is about 90 percent methane. The methane then goes into two 20,000 low pressure tank system for storage.

“Cleanworld’s process is really good at developing this gas through this microbial process in a very short period of time,” said Andrea Stephenson, Atlas’ Director of Sustainability. “What might take composting two to three months would take this system, because it’s anaerobically digested through liquefaction, seven to ten days. The other thing that is important about their process is because it’s so good at breaking down the organic fraction is that what you get at the other end has far fewer residuals than what you would get in a traditional composting process.”

The BioDigeser, according to Stephenson, is currently processing about 25 tons of “feedstock” each day, which results in natural gas that is the equivalent of 500 gallons of diesel fuel. By the end of March Stephenson anticipates they’ll be processing close to 100 tons of feedstock.

In addition to the city of Sacramento’s fleet, other local organizations – such as Sacramento State University, Sacramento City Unified School District, Mission Linens and Super Shuttle – have also begun filling up with natural gas generated by the BioDigester.

So while the BioDigester is fueling vehicles in Sacramento, where does the fuel for the BioDigester come from? This is where Farm-to-Fork-to-Fuel fits in. Many of the restaurants that participated in the city’s Farm-to-Fork program were also the first organizations to contribute organic waste to be used for fuel.

“There’s a boutique program we started out with taking [food waste] from called GRAS – the Green Restaurant Alliance of Sacramento,” Stephenson said. “What they were very good at was teaching people in the kitchen how to separate their food scraps at a post-consumer level.”

GRAS was founded by Jason May, and aquatic ecologist at the U.S. Geological Survey and David S. Baker, who works for the Selland Family of Restaurants (owners of the aforementioned The Kitchen). GRAS’s mission is to make Sacramento a leading sustainable food community and help restaurants initiate green procedures and coordinate related infrastructure. To that end, GRAS helped organize a cluster of Sacramento restaurants to feed the BioDigester the organic waste it requires.

“Our foremost program is kitchen scrap collection for restaurants, where we began collection in 2010 from thirteen of Sacramento's finest restaurants that went to local farms for compost,” Baker said. “Partnered with Atlas Disposal, this program developed proper kitchen procedures with restaurants and haulers.”

Since the BioDigester came online, some of that organic waste is now used to create natural gas.

“The fact that there is an anaerobic digester is a true asset that opens a whole new dimension and scope in how this region can divert and utilize its organic waste,” Baker said. “Our kitchen scrap collections from the thirteen restaurants were the first loads of organic waste to feed the anaerobic digester and still do feed the digester with its purest organic material.”

GRAS is no longer the only contributor to the Farm-to-Fork-to-Fuel system. In addition to area restaurants, grocery stores, food manufacturers and suppliers, schools and institutions are beginning to add their organic waste as well.

“Everything that is going to the anaerobic digester is commercial waste,” said Sarah Leddy, Project Manager at Greenwise. “We’re trying to divert all the waste and participate in the emerging economy that is in waste – tapping into the value there to create jobs.”

CleanWorld has already begun construction on another anaerobic digester on the campus of the University of California, Davis – which is about 15 minutes to the west of Sacramento. Plans are being drawn up for a second digester to be built in Sacramento as well.

While Farm-to-Fork-to-Fuel is a bit of a mouthful, in truth a better term would be Farm-to-Fork-to-Fuel-to-Farm. Remember that slurry that eventually yields the natural gas? Once the gas is captured, it just so happens that the remaining solids are an excellent composting material that is being sold back to the very farmers who grow Sacramento’s food. 

In response to Phil Jackson’s slight against the city, Sacramento Kings fans were known for a time to bring cowbells to the arena to ring while the opposing team had the ball. It was their way to mockingly embrace the “cow town” moniker. Now, with a state-of-the-art arena slated to begin construction this year and innovative, renewable energy programs like Farm-to-Fork-to-Fuel, Sacramento seems ready to shed its inferiority complex and reinvent itself as a city that understands how everything is connected and how it can leverage those connections to make the city a better place to live. That’s an identity any city would be proud of.


Chad Vander Veen

Chad Vander Veen is the former editor of FutureStructure.