The USA produces over 70 million tons of organic waste every year. Though reduction of the source and feeding the needy are important to reduce needless wastage of food, organic wastes are several and include non-edible items too such as livestock excretion, agricultural wastes, uneatable food waste and water waste.
If these wastes are poorly managed, it may pose a threat to the health of people and the environment. Chemicals, pathogens and antibiotics present in them can infect the groundwater and surface of the earth during runoff or via leaching. It may lead to algal growth, harmful wildlife and bad quality drinking water. Drinkable water with nitrate may cause hyperthyroidism and blue baby syndrome.
Organic waste produces methane in large quantities during decomposition. It is a strong greenhouse gas which traps the heat of the atmosphere better than Carbon dioxide. Methane is said to absorb 86 times more heat than carbon dioxide in 20 years. To lower greenhouse production and organic waste, you can use it to produce biogas which will further lessen emission. Because of the several benefits of organic waste usage, such as environmental safety, low pollution to waterways, job creation, USA has thousands of operational biogas systems.
What is biogas?
They are produced when the organic materials are broken by bacteria without oxygen, through a procedure known as anaerobic digestion. Biogas systems use anaerobic to recycle the organic waste and transform them to biogas.
Anaerobic digestion takes place in landfills, nature and livestock manure, and can be controlled and stored in an aerobic digester. Biogas has 50-70% methane, 30-40% carbon dioxide and some amount of other gases. Some wastes such as fats, oils and greases are simple to break down while livestock wastes are a little difficult. Mixing all the waste together in a digester helps in increasing biogas yields. Once biogas is trapped, it produces heat and electricity for engines, fuel cells and micro-turbines.
Advantages of biogas
Trapped biogas can offer a safe, renewable and reliable source of power as a substitute of coal or natural gas. Just like natural gas, biogas can be utilized as a source of high power which can quickly be ramped up. The stored biogas usage limits the amount of methane emission in the atmosphere and lower reliability on fossil fuels. The fall of methane emissions taken from trapping all prospective biogas in the US is equal to the yearly emissions of 800,000 to 11 million cars. According to waste to wheel evaluation, compressed natural gas extracted from biogas lowers greenhouse gas emission to 91% in comparison to petroleum gasoline.
Along with it, it also yields climatic benefits. Anaerobic digestion reduces the cost linked with waste remedies and helps local economies. Anaerobic digestion also lowers foul smell, pathogens and potential risk of water pollution. The residual matter after the digestion procedure can be used as fertilizers, thereby lowering the requirement of chemical fertilizers.
Biogas Feedstocks
Food waste
Around 30% of worldwide food supply is wasted every year. To address this waste, the EPA’s Food Recovery Hierarchy prioritizes reduction of source first then uses extra food for the hungry people, animal feed as well as production of energy. Lastly, the food is sent to landfills. With just 5% of food waste being recycled as fertilizer, the rest is sent to landfills where it breaks down to produce methane.
Though the landfill may trap biogas, landfilling organic waste offer no chance to recycle the nutrients from source organic stuff. Hence, more and more food is now being sent to anaerobic digester to increase biogas production.
Landfill gas
Landfills have same anaerobic bacteria available as in a digester which breakdown organic matter to produce biogas. Once this LFG is trapped, it can be used as energy to power electricity in the house and natural gas pipelines.
Livestock waste
The manure of livestock produces methane when decomposing and contributes to nutrients in waterways. When livestock manure is placed in an anaerobic digester, it produces biogas and reduces greenhouse gas emissions and foul odor, thereby lowering 99 percent of manure pathogens.
Waste water treatment
The on-site anaerobic plant is useful to treat sewage sludge. The wastewater treatment plant with anaerobic digester produces biogas and reduces annual carbon dioxide emissions.
Crop residues
It involves plant trimmings, straw as well as stalks. Left on the field, they are helpful in retaining soil organic content and moisture. With higher crop production, you have higher residues and hence a removal of some of their part is important. Crop residues are joined with other organic waste because of the high lignin amount they have.
End uses of biogas
Raw Biogas and Digestate
With no to little processing, you can use biogas to heat buildings and power boilers. You can use biogas for heat and power operations and turn it to electricity with the help of a combustion engine, gas turbine or fuel cell.
Digestate is a liquid or solid compound left after the digestion procedure. It has the recycled nutrients which were available in the original organic matter. Liquid digestate can be used as a spray fertilizer. Solid digestate can be used as livestock bedding.
Renewable natural gas
RNG or biomethane is used to remove carbon dioxide, water vapor and additional gases so that it abides by the natural gas industry standards. You can inject RNG in natural gas grid pipelines as well as to produce electricity. You can also use them for industrial purposes.
Compressed and liquefied natural gas
You can use compressed natural gas or liquefied natural gas for vehicles. It can be used in light to heavy duty vehicles. CNG and LNG are recommended for fleet vehicles.
Verdict
Biogas systems have transformed the price of waste management to an income making opportunity for nations. Ductor is a global biotech company that has taken initiative to produce renewable energy and to resolve waste accumulation challenges. You can click here to learn more on it. The company develops products which help in the regeneration of agriculture and boost production of renewable energy. The company allows a sustainable production of organic fertilizers and converts renewable energy to biogas.
