FOG Co-Digestion

Bioenergy Potential from Food Waste in California Hanna M. Breunig,*,† Ling Jin,† Alastair Robinson,† and Corinne D. Scown†,‡

†Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States ‡Joint BioEnergy Institute, Emeryville, California 94608, United States

*S Supporting Information

ABSTRACT: Food waste makes up approximately 15% of municipal solid waste generated in the United States, and 95% of food waste is ultimately landfilled. Its bioavailable carbon and nutrient content makes it a major contributor to landfill methane emissions, but also presents an important oppor- tunity for energy recovery. This paper presents the first detailed analysis of monthly food waste generation in California at a county level, and its potential contribution to the state’s energy production. Scenarios that rely on excess capacity at existing anaerobic digester (AD) and solid biomass combustion facilities, and alternatives that allow for new facility construction, are developed and modeled. Potential monthly electricity generation from the conversion of gross food waste using a combination of AD and combustion varies from 420 to 700 MW, averaging 530 MW. At least 66% of gross high moisture solids and 23% of gross low moisture solids can be treated using existing county infrastructure, and this fraction increases to 99% of high moisture solids and 55% of low moisture solids if waste can be shipped anywhere within the state. Biogas flaring practices at AD facilities can reduce potential energy production by 10 to 40%.

■ INTRODUCTION Inefficiencies occur at all stages of the food supply chain, linked to complex factors ranging from market conditions and weather to consumer preferences, and these inefficiencies translate to an abundance of food waste. The U.S. generated approximately 38 million tonnes of municipal food waste in 2014, approximately 95% of which was landfilled.1 An enormous amount of energy, water, land, and other resources go into producing nutrition for humans.2 A recent analysis of food waste estimated that $218 billion is spent in the U.S. on growing, processing, transporting, and disposing of food and byproducts that go uneaten.3

Furthermore, because food waste biodegrades four times faster than typical paper products and 10 times faster than wood waste, it releases methane from landfills more quickly than most other organic waste, with 34−51% of generated methane escaping typical landfill gas capture systems.4−6 Landfilling uneaten solid organic material not only contributes to climate change and occupies land resources, but also eliminates the possibility of cycling the valuable nutrients and energy in food back into the economy. First and foremost, policy measures are necessary to ensure

source-reduction through changes in consumer behavior and improved harvesting, processing, and transportation methods.7

However, source-reduction alone will not be a sufficient strategy. Americans consume raw produce and livestock that have both edible and inedible parts, from local and nonlocal sources, and in quantities that require some level of centralized production and distribution. These biological materials can only be used for their original purposeto provide nutrition and

sustenance to humansfor a short window of time, and maintaining the value of food is not always possible. Food waste-to-energy strategies can help meet renewable energy targets, greenhouse gas (GHG) reduction targets, air quality standards, and divert waste from landfills.8

In this paper, the potential for converting California’s food waste to electrical and thermal energy is analyzed, including organic waste from the food supply chain: agricultural production, postharvest handling and storage, processing and packaging, distribution, consumption, and end-of-life. The objectives of this study are to determine the quantity, locations, and temporal variation in food waste generation, use these results to model regional and subannual electricity and heat generation potential, and gain insight into the roles of policy and technology in overcoming challenges associated with food waste utilization. California serves as a useful starting point for building an analysis framework that can be applied to the U.S. or globally because of its diversity and significance in national food production (40% of U.S. vegetables, 20% of dairy, and 70% of fruits, tree nuts, and berry production by revenue).9,10

Although previous assessments have estimated the total annual energy potential from food waste from retail and consumer waste streams and from food processors in California,11−14 this study is the first to assess food waste production at the

Received: September 9, 2016 Revised: December 23, 2016 Accepted: January 10, 2017 Published: January 10, 2017

Policy Analysis

pubs.acs.org/est

© 2017 American Chemical Society 1120 DOI: 10.1021/acs.est.6b04591 Environ. Sci. Technol. 2017, 51, 1120−1128

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