Biogas FAQ

7/28/2019 Biogas FAQ

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Biogas FAQ

Q. Since when has biogas been used by humans?

The formation of biogas is a natural phenomenon that naturally occurs in wetland,

manure stack, human and animal intestines. For centuries, humans have harvested the

power of bacteriological digestion, by recovering naturally formed biogas to use

for lighting, cooking, heating or to power mechanical engines.

In Asia, millions of family digesters were built to provide cooking fuel and

lighting in rural areas. During the Second World War, German army trucks were

fueled with biogas collected from farmers manure (gas engine).

Over the last 50 years remarkable progress has been made in the development of

anaerobic digesters (bioreactors) to increase methane (CH4) yield and improve its

process flow technologies.

Nowadays, there are thousands of projects around the world, from small dairy farms

to large municipal waste water treatment plants. All of them are demonstrating that

biogas generating systems are environmentally and economically sound. In Europe,

villages are entirely supplied in electricity and heat from their local centralized

biogas pant.

Currently in China there are said to be over one million biogas digesters in use.

In Germany there are nearly 10 thousand, Sweden 1 to 2 thousand. All of Europe has

around 15 thousand biogas plants. World-wide there are nearly 1.5 million biogas

plants in use. It is the ultimate renewable energy source.

Q. What is biogas?

Biogas is a byproduct of the decomposition of organic matter by anaerobic bacteria.

Biogas is typically composed of 60% methane and 40% CO2. It is similar to natural

gas which is composed of 99% methane.

Biogas is a clean and renewable energy that can be substituted to natural gas tocook, provide light, hot water or to generate electricity.

At room pressure and temperature biogas is in gaseous form, not liquid like LPG

(propane).

Q. How does it work?

Organic waste is put into a tank called a digester or bioreactor. In the absence of

oxygen anaerobic bacteria consume the organic matter producing biogas as their

waste.

Q. What type of waste produces biogas?

Any organic waste has the ability to produce biogas: human and animal manure (solid

and urine), animal slurry, fruit and vegetable waste, slaughterhouse waste, meat

packing waste, dairy factory waste, brewery and distillery waste, so on. Any animal

or plant matter that was once living or natural waste by-product can be used in the

process to produce biogas (methane).

Fiber rich wastes like wood, leaves, so on make poor feedstocks for digesters as

they are difficult to digest. Not to say their couldnt it would just take a much

longer time.


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The only type of waste that can not be converted is anything made from fossil

fuels: plastics, oils, paints, medications, and so on. It its origin is from a

fossil fuel then it is useless in a biogas digester.

Q. How much biogas can I get out waste?

The amount of biogas you can extract from your organic waste depends on the type of

waste itself and the design of the digester system.

Some digesters can yield 20 m3 of biogas per ton of waste while others can yield as

much as 800 m3 per ton.

It all depends on the type and quality of the waste quality, and proper operation

of the system.

Q. Where is biogas produced?

Biogas is normally produced in nature by the anaerobic degradation of organic waste

in soil, marshes, bogs, ocean, or lakes. It only has to be moist and free of

oxygen.

Biogas is also produced in landfills where organic waste degrades in anaerobic

conditions.

Biogas can be produced digesters (tanks) ensuring full biogas recovery.

Since methane is a potent greenhouse gas, isnt it stupid to produce biogas?

Methane has a greenhouse gas (GHG) heating factor 21 times higher than CO2.

Combustion of biogas converts methane into CO2 and reduces the GHG impact by over

20 times.

By extracting methane out of waste and using it to produce heat and/or electricity

we ensure that the waste will not degrade in an open environment therefore reducing

direct methane atmospheric emissions. Moreover, the energy provided by the biogasis likely to displace fossil fuel which is the main contributor to GHG emissions.

Biogas is carbon neutral as what carbon dioxide is release is taken up by plants

and reabsorbed which closed the loop: carbon dioxide used by plant which are then

eaten and excreted which goes into the digester to make methane that is burned once

again releasing the carbon dioxide.

Q. 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 electricgenerator, we get about 2 kWh of useable electricity, the rest turns into heat due

to inefficiencies in the generator and the transmission of electricity. The heat

energy could be used for heating applications.

2 kWh is enough energy to power a 100 W light bulb for 20 hours or a 2000 watt hair

dryer for 1 hour.

[ No one has every done an exhaustive study on just how much biogas could be

generated from all the waste society generates: household food waste, farm waste,

food processing waste, food wholesale and grocery store waste, yard waste, human


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and animal waste, etc. All this waste could generate more than enough biogas for

every household and still have enough for storage. ]

Q. What happens to the waste after digestion?

Despite popular belief, the amount of waste going in the digester is almost equal

to the amount coming out. However the quality of the waste is greatly improved for

the better - much less odor, a high quality fertilizer, organic load reduced, less

polluting.

Waste coming out of the digester can be separated into a solid and a liquid: the

solid part can be composted or turned into a dry pellet, flakes or cake that can be

applied directly to the a garden or farm and the liquid part can be used as a

liquid fertilizer.

Q. So why make biogas?

It always costs money to get rid of waste. If it doesnt cost you anything, you are

probably creating an environmental hazard. By putting a digester in your waste

treatment chain you introduce a potential revenue center.

For example:

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.

In an agro-food industry the digester can be used as a primary waste treatment unit

where the biogas is used to offset energy costs in the plant and to reduce the size

of the secondary waste treatment.

Q. How much does it cost and how much can I make?

Biogas plants can take various shapes and forms.

Every project is different small household units to huge industrial units on farms.A typical payback on a biogas plant is between 5 and 8 years.

Biogas systems are a significant capital investments that require careful planning

to maximize biogas production for maximum sucess.

If you feel exposed to energy price fluctuation and you have an environmental

conscience about your waste then a biogas plant could be a sustainable solution for

you.

There are biogas systems that are customized to fit specific needs or mass produced

household units. Every biogas system is unique, because everyones waste quantity

and quality is different. Also, there are above ground and below ground biogas

options availble.

Q. Can I build a biogas plant myself?

Yes, if you have the resources you can setup your own. You will have to educate

yourself on the intricacies of a biogas plant design, build a plant, research the

equipment needed, find suppliers, hire contractors, get permits, put the financing

together, do the construction, register your project for greenhouse gas credits,

etc. Or you can hire an established biogas plant contractor.

Q. How long does it take to build a biogas plant?


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That all depends on how big it is, is it above ground or below. Some biogas plants

designed for the home are nothing more than two tanks, one fitting inside the other

and the tubing to pipe the biogas into the home for use. As small tank system for

the home may cost around $300 and can be installed in a day.

Q. How difficult is it to run a biogas plant?

A biogas plant is like you it needs to be fed every day. Just like you if you donttake good care of it, it will become ill and will yield poor results.

Q. Could the U.S. ever see the application of Biogas?

Yes, but only if the current establishment is removed, dismantled. As long as

billions of dollar in subsides are paid to the oil, coal and natural gas industries

the U.S. will never see at the scale possible the creation of renewable energy,

like biogas. Building biogas plants for maximum methane generation would mean at

least a million plants built around the country to accommodate all the waste and

turn it into methane and a high quality fertilizer that can be put directly on the

farm.

In the U.S. industrial, medical and biological waste needs to be separated so the

organic material, poop, plant and animal waste can be used to generate methane and

fertilizer while the non-organic petro-chemical based stuff is treated separetely.

Doing so will allow for the maximum methane production which has the potential to

supply all of our needs.


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Biogas FAQ