Listed below are recent posts across all of CalRecyle's blogs.

  • Lettuce in Landfills Leads to Climate Change


    Yes, you read that right. Landfilled organic materials (like landscape trimmings and food waste) produce methane gas, which is a short-lived climate pollutant that negatively affects our environment and contributes to changes in Earth’s temperature and weather patterns.

    Wait a second—doesn’t organic material decompose into compost?

    Yes it does, but only if it’s in the right environment. Composting is a process of organic decomposition, but it requires a special recipe of nitrogen, carbon, water, and air with an extra dash of fungus and bacteria for good measure. The most basic compost recipe calls for blending roughly equal parts green or wet material (which is high in nitrogen) and brown or dry material (which is high in carbon) into a pile or enclosure. Add water and fluff the materials to add air, and then microorganisms break down the material over time.


    Landfills are not an ideal environment for composting because food waste is often enclosed in plastic trash bags, and all waste is buried, removing it from access to water and air. Organic material does decompose over time, but it produces methane gas when it breaks down outside of the composting process. In fact, landfills are the second-largest cause of methane gas in California.

    How bad is methane gas, really?

    Pretty bad. Methane gas has a short life span in our atmosphere in comparison to other greenhouse gases, but it has a stronger potency and does more damage. While carbon dioxide (CO2) is responsible for more than half the warming impact from human-caused emissions, methane is a far more powerful warming agent than CO2. Over a twenty year period, one ton of methane has the warming effect of 72 tons of CO2 . Methane emissions resulting from the decomposition of organic waste in landfills are a significant source of greenhouse gas (GHG) emissions contributing to global climate change. Methane emissions occur in the production of oil and gas, during drilling and coal extraction, and in food and agriculture waste.

    How do we reduce methane gas in our environment?

    The solution is pretty simple: divert organic materials away from landfills and into composting and anaerobic digestion facilities that produce biofuels. Organic materials account for a significant portion of California’s overall waste stream: up to 37 percent! Eighteen percent of California’s waste stream is comprised of disposed food waste, which includes waste that can be prevented, recovered for donation, or composted.

    In September 2016, Governor Brown signed into law Senate Bill 1383 (Lara, Chapter 395, Statutes of 2016) to dramatically reduce short-lived climate pollutant emissions and to steer California in a new direction for managing organic materials. The law establishes targets to achieve a 50 percent reduction in the disposal of organic waste from a 2014 baseline level by 2020 and a 75 percent reduction by 2025.

    Diverting 75 percent of organic materials from landfills will make a significant impact on California. It will help us reduce our greenhouse gas emissions, reduce the amount of trash that we bury in landfills, create new green jobs, and benefit our state’s agricultural sector with soil enriching compost.

    Posted on In the Loop by Christina Files on Mar 9, 2017

  • What is Climate Change?

    Climate change is a hot topic for our country right now. While the vast majority of the scientific community agrees that humans are having an impact on our planet, there are still some who remain skeptical that it exists and is a problem worth solving. Those paying close attention are convinced we need to reduce our impact on the planet because we can already see drastic changes to the landscape of our continents. CNN reported recently that Antarctica’s melting ice will likely lead to changes in winter storms for North America and Europe. Winter storms may be warmer and less frequent. More compelling evidence of climate change seems to unfold on a weekly basis.

    Climate Change Defined

    Climate change is simple to understand. It is a long-term change in global or regional climate patterns due to increased atmospheric temperatures. Our world is getting warmer because greenhouse gases are trapping the sun’s heat in our atmosphere for longer periods of time, intensified by anthropogenic, or human-caused, climate change fueled by various forms of industrialization that have far-reaching impacts. Snowcaps in the Arctic and Antarctic regions are melting, which causes sea levels to rise, and consequently our winter and summer storm cycles are changing.

    Climate Change in California: Cause and Effect

    California, like any society or economy, contributes to climate change by producing greenhouse gases. California cattle ranches produce manure, which emits methane gas. California’s automobiles produce carbon dioxide gas. Landfilled organic waste also emits methane gas.  We have many stationary and mobile sources of greenhouse gasses.

    Global climate change has affected California’s environment in several ways. First, irregular weather patterns have contributed to our most recent drought. Less snowpack in the Sierra Nevada Mountains and less rainfall in the valleys strain agricultural farming resources and residential water supplies. Farmlands are thirsty for water. Californians are encouraged to let their green lawns fade to gold and to take shorter showers. Additionally, drought seasons often result in higher-risk fire seasons. Dry trees are perfect tinderboxes for forest fires.

    What Are Greenhouse Gases?

    A greenhouse gas is a gas that absorbs infrared radiation and radiates heat in all directions, which causes the earth’s temperature to rise. It essentially traps heat within our atmosphere.  Common greenhouse gases include methane, carbon dioxide, and nitrous oxide. Carbon dioxide is the most common greenhouse gas, and it stays in the atmosphere for a long time. We produce carbon dioxide when we drive cars, use electricity, or use industrial manufacturing methods. Carbon naturally moves through the earth via the carbon cycle, but we are currently producing carbon faster than we are able to remove or sequester it. Methane doesn’t last as long in the atmosphere, but is much more powerful than CO2 – about 70 times more potent. A significant source of methane are the state’s landfills  where, due to lack of sufficient oxygen, green waste is unable to compost and generates methane as it decomposes.



    How We Create Greenhouse Emissions

    Greenhouse gases are the result of an industrialized world that relies upon fossil fuels to make products and transport us from here to there. We know that using public transportation and driving hybrid cars help reduce greenhouse gas We can reduce our impact on the planet by reducing the amount of trash we produce.

    Californians dispose an average of 4.7 pounds of trash per person per day. California has set a goal of recycling 75 percent of trash by 2020. A significant portion of this will be organic materials responsible for accelerating climate change when landfilled. We can divert 75 percent of our current waste, and slow the harmful effects of greenhouse gases, by reducing the amount of trash we produce, reusing the materials and products we consume, and diverting the majority of our waste into recycling or composting activities instead of dumping it in the ground.

    Reduce, Reuse, Recycle

    • If you had to reduce your daily waste by 75 percent, what could you do differently?
    • Do you use a lot of plastic bags for packed lunches? Consider changing to reusable containers or recyclable materials like parchment paper.
    • Consider diverting your food waste into a green waste bin or into a personal composting bin. Compost will enrich your garden’s soil and is good for the environment.
    Posted on In the Loop by Christina Files on Mar 2, 2017

  • The Greening of Commercial Compost

    Compost happens, as they say in the biz.  It’s true that, given enough time, most natural materials will decompose.  The whole idea behind “composting” is to optimize nature’s process by providing the right mix of carbon, nitrogen, water and air. Most commercial-scale composting in California is done in long, narrow piles called windrows, which are mixed regularly by a specialized piece of equipment called a windrow turner.  These enormous, diesel-powered critters range from 200 to 600 horsepower, but you’ll be traveling in hours per mile not miles per hour.  What if there was a way to replace some of that diesel using the sun?


    CalRecycle was involved in in a project, funded by the San Joaquin Valley Air Pollution Control District, involving the Association of Compost Producers, private consultants and local partners,  to see whether large piles of green materials could be composted  using small “bounce house” blowers powered entirely by the sun to pump air into the pile instead of being mechanically turned.  The point of the project was so see whether air emissions could be reduced during the first three weeks of composting, which is the time when most emissions of volatile organic compounds—aka VOCs—occur.  VOCs are important to the air district because they mix with oxides of nitrogen (NOx) from vehicle tailpipes to form ozone, a very dangerous air pollutant at ground level. Summer ozone levels in the Central Valley are some of the highest in the country, and per the federal Clean Air Act must be reduced.

    The same sunlight that helps VOCs and NOx turn into ozone can provide more than enough electricity to power a 1.5-horsepower electric blower using only one solar panel, and that energy can be stored in batteries so that pile aeration occurs day and night. A series of pipes laid under the composting material provide a path to inject air into the bottom of the pile, and it filters up to the top, keeping things happily aerobic.  To trap more emissions, the tops of the piles are covered with a layer of finished, unscreened compost, and kept damp with sprinklers, again sparing the air because the diesel-powered water trucks so common at windrow facilities get a little rest. 


    VOC emissions were reduced in this pilot project by 98 percent, diesel use was reduced by about 87 percent during those critical first few weeks of composting, GHG emissions were reduced by about half, and the amount of water used to keep the pile moist was reduced by 20 percent.  That’s quite a savings.  

    To reach California’s goal of 75 percent recycling and composting by 2020, and ARBs draft goal to get 90 percent of organics out of landfills by 2025, many new compost facilities will be needed.  No one type of facility will fit all communities, but all new organic materials handling sites will need to have 21st century infrastructure that protects air and water quality, and they will have to be good neighbors.  The aeration system for the pilot project cost less than $15,000 per zone, which is pretty affordable considering a new diesel windrow turner would likely set you back half a mil.  

    Solar panel prices keep coming down, and efficiency is still going up, so it looks like solar-powered aerated static piles are a good option for community-sized compost sites, and probably could be scaled up quite large.  Already, several compost operators are looking at adopting this technology.  

    The full report on the project can be found linked to the very bottom of this page:

    –Robert Horowitz
    Robert Horowitz is a Supervising Environmental Scientist at CalRecycle.

    Posted on In the Loop by Robert Horowitz on May 23, 2016