What is biogas?
Biogas typically refers to a gas produced by the breakdown of organic matter in the absence of oxygen. It is a renewable energy source, like solar and wind energy. Furthermore, biogas can be produced from regionally available raw materials and recycled waste and is environmentally friendly.
Biogas is produced by the anaerobic digestion with anaerobic bacteria or fermentation of biodegradable materials such as manure, sewage, municipal waste, green waste, plant material, and crops. Biogas comprises primarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulphide (H2S), moisture and siloxanes.
The gases methane, hydrogen, and carbon monoxide (CO) can be combusted or oxidized with oxygen. This energy release allows biogas to be used as a fuel. Biogas can be used as a fuel in any country for any heating purpose, such as cooking. It can also be used in anaerobic digesters where it is typically used in a gas engine to convert the energy in the gas into electricity and heat.
Biogas can be compressed, much like natural gas, and used to power motor vehicles. In the UK, for example, biogas is estimated to have the potential to replace around 17% of vehicle fuel. Biogas is a renewable fuel so it qualifies for renewable energy subsidies in some parts of the world. Biogas can also be cleaned and upgraded to natural gas standards when it becomes bio methane.
How does it work?
Biogas can be produced using anaerobic digesters. These plants can be fed with energy crops such as maize silage or biodegradable wastes including sewage sludge and food waste. During the process, an air-tight tank transforms biomass waste into methane producing renewable energy that can be used for heating, electricity, and many other operations that use any variation of an internal combustion engine, such as 2G Cenergy gas engines.
What type of excess material produces biogas?
Biogas plants can convert any type of organic material such as food scraps from households, restaurants or food processing plants. Animal waste, corn silage, sugar beets, jerusalem artichokes make for good feedstock to be digested to gain biogas. Oragics that are cellulose such as straw, sawdust clean or dirty wood are not digestable. Our upcoming wet gasification process will convert any wood product including used railroad ties to clean burning syngas that can be burned in gas engines for electricity generation.
How much biogas can I get out of my excess material?
In order to determine the amount of biogas that can be extracted from the organics, one needs to run a biogas potential test. It is typically a 21 day test in a lab digester. The resulting volume of biogas potential per given weight is the bases for biogas quantity that can be produced. There are historical numbers available for many feedstock types in order to forgo the test to estimate the biogas quantity per given feedstock weight. www.ktbl.de is a good source based on data collected from German biogas plants. Depending on what the dairy cows are fed, 300 to 400 m3 biogas per ton of manure at around 16% solids is reasonable. Biosolids have a BGP of 300, glycerine is a potent 1,000 feedstock while FOG (fat, oil and grease) is 800 and food scraps range from 500 to 700 while yard clipping are around 400 m3/t.
Where is biogas produced?
Biogas is produced in nature by the anaerobic degradation of organic waste in forest, marshes, with the permafrost in Greenland could release masses of it after the ice melt. Biogas escapes from landfills where organic food waste degrades over long periods of time. Typically landfills are capped and perforated pipes are inserted and connected to extract the biogas. It is then flared or processed in an engine to burn the methane.
Biogas production benefits.
The methane contained within biogas is 20 times more potent a greenhouse gas than carbon dioxide. Therefore, free flowing landfill gas, which escapes into the atmosphere may significantly contribute to the effects of global warming. In addition, landfill gas impact on global warming, volatile organic compounds (VOCs) contained within landfill gas contribute to the formation of photochemical smog.
Biogas energy is considered carbon neutral, since carbon emitted by its combustion comes from carbon absorbed in plants (natural carbon cycle). The decay of organic material will produce biogas over time. Rather than waiting for landfills to release biogas for the next thirty years, it will be more expedient to treat the organics in biogas plants and be able to produce renewable energy and fertilizer that is better absorbed by plants than chemical fertilizer.
When biogas is used, many advantages arise. In North America, utilization of biogas would generate enough electricity to meet up to three percent of the continent’s electricity expenditure. In addition, biogas could potentially help reduce global climate change. Normally, manure that is left to decompose releases two main gases that cause global climate change: nitrogen dioxide and methane. Nitrogen dioxide (NO2) warms the atmosphere 310 times more than carbon dioxide and methane 21 times more than carbon dioxide.
By converting cow manure into methane biogas via anaerobic digestion, the millions of cows in the United States would be able to produce one hundred billion kilowatt hours of electricity, enough to power millions of homes across the United States. In fact, one cow can produce enough manure in one day to generate three kilowatt hours of electricity; only 2.4 kilowatt hours of electricity are needed to power a single one hundred watt light bulb for one day. Furthermore, by converting cow manure into methane biogas instead of letting it decompose, global warming gases could be reduced by ninety-nine million metric tons or four percent.
How much energy is in biogas?
Each cubic meter (m3) of biogas contains the equivalent of 6 kWh of calorific energy.
However, when we convert biogas to electricity in a biogas powered electric generator, we get about 2 kWh of useable electricity per ton of biogas, a nearly equivalent amount of heat which can also be used for heating applications and some 20% of the energy is lost in the conversion process. Check out www.ktbl.de that allows you to calculate the energy output per volume of many feedstock types.
What happens to the access material after digestion?
The amount of organics fed into the digester produces about 90% digestate. However the quality of the input organics gets improved during digestion (less odor, better fertilizer, organic load reduced, less polluting, better absorbed by plants).
The digestate from the digester is typically sepaarted (solid/liquid) using a screen or belt press in order to make transportation more cost effective: the solid part becomes a fertilizer or compost and the liquid part is partially used to dilute the feedstock with the rest becoming liquid fertilizer.
So, why make biogas?
It always costs money to get rid of excess material. If it doesn’t cost you anything, you are probably creating an environmental hazard.
By putting a digester in your waste treatment chain you introduce a revenue center.
On a farm, the manure is not considered to be a waste but a fertilizer. By installing a digester the farmer can profit from the biogas by reducing odors and enhancing the fertilizing value of the manure and supplement its revenue stream by producing electricity for internal use or sale.
In an agri-food industry, the digester can be used as a primary excess material treatment unit where the biogas is used to offset some energy cost in the plant and to reduce the size of the secondary waste treatment.
How much does it cost and what is my return?
Biogas plants can take various shapes and forms.
A simple agricultural plant could cost as low as $3,500 per electrical kW installed. A municipal food waste plant can cost more than twice as much! Costs come down with scale or size of the operation.
Every project is different. A typical payback on a biogas plant is 4 to 7 years depending on complexity, location, subsidies, grants and tax credits received.
Biogas systems are significant capital investments that require careful planning to maximize the chances for economic success.
Because of ever increasing energy cost combined with an environmental conscience about access material, a biogas plant is a sustainable solution.
How long does it take to build a biogas plant?
For a moderate to large scale digester (10,000 tons/year +) it will typically take, from the first call to a running biogas plant, 8 to 10 months for negotiations and permitting plus 6 months for construction.
How difficult is it to run a biogas plant?
A digester operation using feedstock of manure and corn silage takes a person to load a container with waste twice a day. Once every other day, processed material needs to be picked up. Monitoring the system is typically done remotely and if a valve or actuator fails, a maintenance person gets automatically alerted.
The labor intensive part is to have clean and consistent organic material to achieve high output yields. If the feedstock is food scraps and yard waste, the process requires more investment and employees. Sophisticated storage, sorting equipment for plastics and metals will be required and maintained. The cleaner the feedstock is upon arrival at the plant the more cost effective the operation becomes. Close communication and training of food waste suppliers is required to have a happy digester. Sand, dirt and rocks need to be trapped prior to entering the digester. Particle size nees to be less than one inch.
BIOGAS Equity 2 together with its partners has expertise in financing, designing and building biogas plants. Our German sister company owns and operates plants. Our engineering partner has designed and built many plants in Germany and completing the design and permitting of a UDR plant in Lowell, Michigan awaiting financing. A large facility is being engineered for SWACO in Ohio.
BIOGAS Equity 2 has selected the best wet process technology and together with its engineering partner has the rights for North America to install the patented UDR system. Standard Upflow and Downflow tanks will be manufactured in Ohio. We will guide you in your biogas project planning. Or, if you do not want to own the plant, we will assess your situation of organic feedstock, raise the capital based on your credit worthiness and long term guaranteed feedstock agreement and electricity nd heat take off agreement, design and build an optimized plant, maintain and operate it.
With the UDR process we focus on feedstock of food waste, manure and biosolids from waste water treatment plants. Low solid percentage biomass is ideal for this technology. The UDR technology focus will benefit you in a faster, more efficient and profitable solution to convert your excess material into renewable energy and by products.