User login

You are here

Topic 42: Potential and Safety Issues concerning Biogas

JIEFU's picture

Biogas is a mixture of various gases from organic gas methane to inorganic gases carbon dioxide, hydrogen, oxygen and so on, which can be produced from a wide range of material. Let's discuss it's potential of being a dependable energy source in the future, and the safety related issues.

Comments

JIEFU's picture

The materials which can be used to produce biogas include the biomass from agricultural and forestry residues and domestic waste etc. It is a promising way to tackle with the huge amount of domestic waste in urban area. It also shows great potential in rural areas, especially those isolated places where electricity grid can hardly reach in some developing countries. However due to the relatively un-mature techniques and lack of knowledge or carefulness, accidents happens from time to time, such as the accidents resulting from spontaneous ignition of methane and over-pressure explosion. Other potential risks also exist like exposure to the toxicity related with leak of hydrogen sulfide, and biological substances such as viruses and bacteria. But given it's potential in reducing our dependence on conventional fossil fuel and diversifying the future energy source, it worths the further research and investment. Strict regulations and guidelines are also necessary in terms of reducing the possibility of risk.  

Trevor Strawbridge's picture

Although this seems to be a popular fuel particularly amongst the farming community, and because it is produced from waste products; I am nervous about the lack of regulation particularly when this fuel can produce high levels of Hydrogen Sulphide (sour gas) which is highly toxic. There are farmers that produce biofuels without really exploring the safety issues of the product and indeed the bi-products that they produce. I wonder if they know that most bio fuels in liquid form are methanol rich, and have a tendancy to damage nitrile seals. Also Sour Gas emissions into the atmosphere produce acid rain ( H2S +H2O = H2SO4 after balancing  the equation of course). There is an official site but I'm affraid to say it paints a "rosey" picture. Its populartiy is attributable to the use of waste materials however I have less positive views until I see regulations more approprite to the refining of bio fuels. Check out the website it is endorsed by DECC.

Comments welcome as usual

http://www.biogas-info.co.uk/

Trevor

haroon latif's picture

Trevor raises an interesting point here. Biogas production clearly does produce a certain amount of hazardous waste by- products such as hydrogen sulphide. If rogue farmers are producing unregulated Biogas (on a small scale), then this will be both detrimental to the environment and potentially hazardous to the farmers as well.

However, I have been researching into this energy technology and found some interesting facts. Biogas production (from wet Biomass) via the anaerobic fermentation (AF) process is actually encouraged by the UK Government and it offers incentives for farmers or companies who produce electricity or biofuels for transport via AF. It is also strongly regulated by Health and Safety Executive, and as mentioned on both the AF and HSE website that hazard and risk assessments are carried from the design installation phase, through to the commissioning and operation phase for all chemical processes including anaerobic digestion.

Therefore surely, these regulations must be extended and imposed on farmers who do not follow them by the HSE?

http://www.biogas-info.co.uk/index.php/regulations-qa#health Accessed 22nd November 2012

Haroon Latif MSc Oil and Gas Engineering

Henry Tan's picture

H2S +H2O = H2SO4 not balanced?

Thomas Ighodalo's picture

Normal
0

false
false
false

EN-US
X-NONE
X-NONE

MicrosoftInternetExplorer4

/* Style Definitions */
table.MsoNormalTable
{mso-style-name:"Table Normal";
mso-tstyle-rowband-size:0;
mso-tstyle-colband-size:0;
mso-style-noshow:yes;
mso-style-priority:99;
mso-style-qformat:yes;
mso-style-parent:"";
mso-padding-alt:0in 5.4pt 0in 5.4pt;
mso-para-margin-top:0in;
mso-para-margin-right:0in;
mso-para-margin-bottom:10.0pt;
mso-para-margin-left:0in;
line-height:115%;
mso-pagination:widow-orphan;
font-size:11.0pt;
font-family:"Calibri","sans-serif";
mso-ascii-font-family:Calibri;
mso-ascii-theme-font:minor-latin;
mso-hansi-font-family:Calibri;
mso-hansi-theme-font:minor-latin;}

Step 1: H2S IS
liberated by the action of anaerobic bacteria on organic matter i.e. Natural
decay of organic matter

Sulphur containing Organic
matter ---anaerobes---------->H2S

Step 2: Hydrogen
Sulphide gas is oxidized into Sulphur (IV) oxide and water respectively

2H2S(g)+3O2(g)---oxidation---------->2SO2(g)+2H2O(l)

 

Step3: The
sulphur (IV) oxide is further oxidized to Sulphur (VI) Oxide over a catalyst ,
naturally this process is enhanced by particulates in the air but the quantity
produced is marginal [1] or by the presence of atmospheric hydroxyl radicals
[2].

2SO2(g)+O2(g)---catalyst----------------->2SO3(g)

 

Step 4: The
Sulphur (VI) Oxide produced reacts with water vapour in the atmosphere to form
Hydrogen tetraoxosulfate (VI) acid (sulphuric acid) which falls down as acid
rain.

SO3(g)+H2O(l)-->H2SO4(aq)

References

1. http://www.eolss.net/Sample-Chapters/C09/E4-14-02-04.pdf

2. http://www.umac.org/ocp/HowisAcidRainFormed/info.html

 

 

 

 

 

 

"Everything we hear is an opinion not a fact"

Richard Sedafor's picture

Biogas is very important in most small communities in the world. It supplies
the energy needed for cooking and lighting purposes in most communities.
Analyst estimate that the biogas market may reach USD 8.98 billion in
2017.[1]Biogas is mainly made up of methane. By using methane, in this useful
way we could be saving our planet. Methane is a green house gas and has more
damaging effect than Carbondioxide. 

Anaerobic Digesters which produce the biogas have risks associated with
them. Risks associated with Biogas include explosion,hydrogen sulfide
poisoning, disease, asphyxiation( a condition of deficient supply of oxygen to
the body that result from being unable to breath normally[2]). It is reported
that several explosions on the Canadian swine farms were caused by methane gas
exploding.[3]

Because of the above risks associated with Biogas, extreme precautions
should be taken when handling biogas. These include the use of appropriate
personal safety equipments, good ventilation and engineering controls that
ensures that the right thing is done to prevent fires and disasters.

  References

[1]http://www.prweb.com/releases/biogas_plants/biomass_gobar_gas/prweb82719...

[2]http://en.wikipedia.org/wiki/Asphyxia 

[3]http://www.extension.org/pages/30311/anaerobic-digesters-and-biogas-safety

[4]http://www.thisisdorset.co.uk/Biogas-expert-shocked-death-plant-worker/s...

 

 

faizakhatri's picture

We can see many things in our life are not completely safe but by being aware of level of dangers involving to harm is good way to be a safe the same concept applies on Biogas Biogas consist higher proportion of CH4 and then CO2 along with less percentage of hydrogen sulphide (H2S) and some traces of ammonia. Since every gas has its own potential risk like methane is very explosive, CO2 affect respiration rate  and H2S gas related with smelling it has a potential to destroys (smelling) tissues and lungs,  so many factors are must takes account for handling  it during digester and storage safety is the first factor which can be at first place to follow all the procedures to ensure no harm to people and environment , correct size of storage vessel is necessary to store produces gas along with suitable  pressure with choosing better material as rough material of equipment may lead to make corrosion also there is a need of Adequate ventilation, a suitable precautions must be there at the plant to avoid any contact with these gases to operators at plant as well as to avoid create environment pollution . for safety operation hazard assessment help to cover uncertain potential to make incident/accident but it is also necessary that everyone have to understand and implement their responsibility like operators have sole responsibility for ensuring safety of operation as well as themselves and employer must make their systematic assessment to manage their system for making SAFET FIRST RULE for their employees and environment as well   Referencehttp://biomassmagazine.com/articles/5489/safety-solutions-tailored-to-bi...   Faiza khatri  M.Sc oil and gas engineering 

 

faizakhatri's picture

We can see many things in our life are not completely safe but by being aware of level of dangers involving to harm is good way to be a safe the same concept applies on Biogas Biogas consist higher proportion of CH4 and then CO2 along with less percentage of hydrogen sulphide (H2S) and some traces of ammonia. Since every gas has its own potential risk like methane is very explosive, CO2 affect respiration rate  and H2S gas related with smelling it has a potential to destroys (smelling) tissues and lungs,  so many factors are must takes account for handling  it during digester and storage safety is the first factor which can be at first place to follow all the procedures to ensure no harm to people and environment , correct size of storage vessel is necessary to store produces gas along with suitable  pressure with choosing better material as rough material of equipment may lead to make corrosion also there is a need of Adequate ventilation, a suitable precautions must be there at the plant to avoid any contact with these gases to operators at plant as well as to avoid create environment pollution . for safety operation hazard assessment help to cover uncertain potential to make incident/accident but it is also necessary that everyone have to understand and implement their responsibility like operators have sole responsibility for ensuring safety of operation as well as themselves and employer must make their systematic assessment to manage their system for making SAFET FIRST RULE for their employees and environment as well    Referencehttp://biomassmagazine.com/articles/5489/safety-solutions-tailored-to-bi...  Faiza khatri  M.Sc oil and gas engineering 

 

Michail.Sevasteiadis's picture

The final composition of biogas depends on the source of origin, for example household wastes give 50-60% vol of CH4 while agricultural waste and wastewater treatment plants sludge give CH4 60-75% vol. They also give unwanted compounds like CO2 in a significant amount which ranges from 19 to 38 % and a small quantity of H2O about 6% vol. Agricultural waste give the highest H2S amount that varies from 3000 to 10000 mg/m3, while wastewater treatment sludge gives 1000 to 4000 mg/m3 and household gives the lowest among them, 100 to 900 mg/m3. Household wastes give also a 0 to 5% of N2, aromatic 0 to 200 mg/m3 and organofluorinated or organochlorinated 100-800 mg/m3. Agricultural waste also gives 50 to 100 mg/m3 NH3.

Analyzing further as for the safety concerns, we may check each compound of the final biogas product individually for their potential danger. CH4 is not a toxic gas but it is higly flammable and any leak could cause an explosion, while it is also an asphyxiant gas and inhaling it in great amounts can cause even death. CO2 is also an asphyxiant gas and it can cause from intoxication and poisoning till death according to the amount inhaled, while oxygen presence does not play a role in treatment. Converting the above H2S quantities into ppm we can see that agricultural waste as source gives from 1999 to 6664 ppm, wastewater treatment sludge gives 666.4 to 2666 ppm and household gives 66.6 to 600 ppm. The permissible exposure limit of US Occupational Safety and Health Administration per 8 hours is 10ppm, while in 500ppm and over it causes neural stimulation and rapid breathing till death. It has the characteristic odor of the rotten egg so it can be traced by humans easily, except if its concentration is higher than 100ppm when it sets out of order the olfactory tissue. H2S and H2O are the number one factors of corrosion, a serious issue that cause major problems in the industry. NH3 is toxic for the fishes, while for the humans 66.7 to 133 ppm may cause eyes or lungs irritation. N2 has no significant effects or critical hazards on humans. Toxicity of aromatics varies according to the aromatic compound from not toxic to highly toxic the same as with organofluorinated and organochlorinated compounds.

References:
http://www.biogas-renewable-energy.info/biogas_composition.html
http://en.wikipedia.org/wiki/Methane
http://www.eiga.org/fileadmin/docs_pubs/Info_24_11_Carbon_Dioxide_Physio...
http://www.lenntech.com/calculators/ppm/converter-parts-per-million.htm
http://www.atsdr.cdc.gov/toxprofiles/tp114.pdf
http://www.ch.ic.ac.uk/rzepa/mim/environmental/html/ammonia.htm
http://en.wikipedia.org/wiki/Ammonia
http://www.airgas.com/documents/pdf/001040.pdf

Oluwatosin A. Oyebade's picture

Biogas is a combustible mixture of 50-80% methane, 15-45% C02, 5% water and some other trace gases. It is produced by biomethanation and is a self-sufficient mutually beneficial microbial process operating under anaerobic conditions at temperatures of 300c.

In terms of future energy use, I doubt its potential as a dependable energy source in the future because the economic value of methane as an energy source is only viable on a local small scale production. It's commercial large scale production has its reservations due to the following reasons:

  •  Methane is abundant in nature, especially in natural gas fields and oil fields overlays
  • Gasification of coal to produce methane is commercially more attractive than biogas production
  • Microbial production of methane (biogas) is more expensive than natural gas
  • Methane cannot be used in automobiles
  • Storage, transport and distribution costs of gaseous fuels is not cheap

As for its safety facet, I would like to point out a number of safety issues associated with biogas despite its advantages of waste removal which has positive environmental values, fertilizer production and soil conditioning. They are:

  • Fire/Explosion: Methane which is a major constituent of biogas forms explosive mxtures if it escapes and comes in contact with air.
  • Disease: Anaerobic digestion during waste treatment process depends on mixed population of bacteria of different unknown origins and causes diseases if contact is not avoided.
  • Asphyxiation: C02 and H2S present in biogas affect respiratory rate by displacing oxygen and destroying olfactory tissues and lungs in humans

Like other energy sources, biogas is not completely safe, but being aware of the dangers involved is a good step towards having it as a clean energy source.

Reference:

http://www.adelaide.edu.au/biogas/safety/

http://technologyinscience.blogspot.co.uk/2012/08/biogas-methane-product...

 

Oluwatosin Oyebade

 

Ikechukwu Onyegiri's picture

This is usually an overlooked risks but when you come down to the local farmers who sometimes carryout the process of biomas production in residential areas.

Water contamination poses a big environmental risks as improper maintenance of the pressing plants or handling of the contaminated precipitated water could lead to its penetration into the soil and even worse into the groundwater. This can be caused by corrosion of pipework, cracks in tanks or insufficient tighened ground within the plant site [1]. Polluted water could lead to diverse health issues though the main hazards arise from transporting wastes such as night soil and gray-water.

With routine maintenance, provision of better detective systems for early detection and regular staff training biogas has increasing potentials and as we all know no source of energy comes without risks.

 [1] Assessment Of Biogas Potential Hazards, Tomas ChrebetT; Jozef Martinka, International Journal Of Engineering, 2012, ISSN 1584-2665

 

Ikechukwu Onyegiri

Msc Oil and Gas Engineering

Edwin Lawrance's picture

 

As
mentioned in the above posts using biogas as it is, can cause several safety
issues due to the presence of H2S and carbon dioxide. But according to SGC
(Swedish Gas Center) a joint venture of several energy related organisations in
Sweden, it is possible to use biogas as a vehicle fuel. This is achieved by the
cleaning and upgrading of the biogas. In the cleaning section what they are
doing is the separation of water and H2S from the gas. Then in the upgrading
stage the carbon dioxide present in the gas is removed. The removal of H2S is
achieved by using adsorption utilising activated carbon and the carbon dioxide
removal by using different methods like absorption with selexol or water
wash. 

In this carbon dioxide removal
using water wash is preferred because it doesn't involve any chemicals but for
the selexol method chemicals are used for absorption. This method of upgrading
biogas to a vehicle fuel has many advantages like the presence of H2S and carbon
dioxide which cause possible issues can be avoided, but there are some
disadvantages as well they are the loss of methane due to the removal of carbon
dioxide and the upgrading process is a bit expensive. Even so high hopes are
there in this field because several new methods are being introduced, by which
the loss of methane and the initial cost can be reduced. 

 

OKECHUKWU CHUKELU's picture

Biogas can be
just as dangerous as other sources of fuel if not handle in an appropriate
manner. In operating biogas systems certain precautions must be observed so as
to avert the worst possible outcome of an explosion. Biogas can form an
explosive mixture when it comes in contact with air. For this it is always
necessary to put in place specific measures like ensuring that there is no
ignition source when a situation like this is to occur. We look at the concept
of a fire triangle, which involves having an ignition source, fuel and oxygen.
Eliminating one of the three will advert the risk of an explosion and therefore
safety guarantee safety.

In the case of a
biogas leak, the presence of H2S can act as a safety measure as its rotten egg
smell will alert any individual that there is a leak. H2S on the other hand can be extremely toxic even in low concentrations and can result in poisoning
or asphyxiation symptoms and possibly a fatality.

 

Okechukwu Chukelu (51231798)

Michail.Sevasteiadis's picture

We have already discussed about the general safety concerns around biogas and analyzed its composition and some of the potential dangers with its use. We could also add some procedures and measures someone has to follow in order to assure a safe environment.

Firstly, we have to inspect frequently the biogas system for leakages to prevent loss of production, fire, explosion, etc. We have to ventilate the areas where the gas piping is crossing to avoid a possible gas concentration after leakage. We have to control the system’s pressure continuously. We have to build the power station room above the surface and keep it exposed to air, in order to prevent a concentration of gases that are denser than the air. Also its rooftop must have ventilation to drive out those gases that are less dense. The metallic digesters and the storage tanks have to be electrically grounded to prevent a possible danger from lightnings. The gas piping should have condensation traps to collect the humidity. Lastly, the surrounding areas of the digester, the piping and the storage tanks should not be exposed to any fire source like flames or cigarettes.

Reference:
Michael Arnott. The biogas/biofertilizer business handbook. 3rd Ed. Washington: Peace Corps.

Ikechukwu Onyegiri's picture

My colleagues have elaborately explained the risks and safety issues involved with biogas but an interesting aspect I would want to diverge into are the sketchy regulations surronding its production. Because of the "little technicality" people feel is involved in its production almost everybody indulges in its production. Proper regulatory bodies should be put in place tp ensure that local farmers are properly educated on the safety issues involved in its production as most cases of H2S poisoning/suffocation, body burn accidents and bacterial infections have been recorded in locally operated plants.

I feel safety legislations should be enforced to cover these local farms as though the process for biogas production might be relatively straight-forward, underlying risks usually abound as have been stated in previous posts.

 

Ikechukwu Onyegiri

Msc Oil and Gas Engineering

Ikechukwu Onyegiri's picture

Safety measures thrive to reduce risks in our daily lives. This applies also to industries and processes. Some basic safety measures that can be applied to reduce safety issues associated with biogas systems include:

1.  No smoking or open flames should be allowed near biogas digesters and gas storage tanks, especially during gas leak inspection.

2. Lightning protection systems must be installed on metal digesters and gas storage tanks [1].

3. The engine room floor must be at or above ground to avoid the build-up of gases which are heavier than air

4. Proper ventilation must be provided all through the process opration modules.

5.  Establishment of 'no-leak' conditions by  routinely inspection and use of external protective coating materials such as PVC on gas lines.

6. Also drainage systems should always be online with back-up remedy in case of gas line blocking by water condensate.

 

[1] Biogas Problems: The ABCs of safety http://werkgroepterlinden.be/Biogas.html

Ikechukwu Onyegiri

Msc Oil and Gas Engineering

Craig Donaldson's picture

Something which I think may have been overlooked is the waste used as a feedstock for anaerobic digestion often contains various pathogenic viruses, bacteria and parasites. Since the digestate (by-product) is usually used as fertiliser there is the possibility of these pathogens entering the animal or human food chains.

Utilisation of digestate as a fertiliser means application on the fields of several different
farms, with the risk of spreading pathogens from one farm to another, but it doesn't necessarily mean new routes for pathogen and disease transmission will appear.

It is possible to prevent any transfer and control the distribution of pathogens by following some simple standards:

•Livestock health control - No animal wastes should be supplied from livestock with health problems.

•Feedstock control - Biomass types with high risk of pathogen contamination must be excluded.

•Separate pre-sanitation - Certain specific feedstock categories must be sanitised before use, as described by European Regulation EC 1774/2002.

•Controlled sanitation - For feedstock categories which, according to the aforementioned regulation, do not require separate pre-sanitation, the combination of high temperatures and a minimum guaranteed retention time used in the process will provide effective pathogen reduction.

•Control of pathogen reduction efficiency - An accredited indicator organism method must be used to verify the efficiency of pathogen reduction.

 

References:

http://www.lemvigbiogas.com/BiogasHandbook.pdf

http://www.eu-vri.eu/filedown.aspx?file=7032 

Keqin Chen's picture

 

Produced by the breakdown of organic
matter
 in anaerobic fermentation process,  By transforming all kinds of biodegradable
materials e.g. biomass, manure, sewage, municipal waste, green
waste, plant material, and crops to valuable energy,
biogas has caused increasing attentions and will be an important renewable energy in the future.

 

But it is still the start stage of production and several limitations in
production and utilization of biogas are listed below:

 

1.     
Sometimes the production will cause the campaign with
crops and food.

 

2.     
Compared to other biofuels, it is relatively difficult
to enhance the efficiency of biogas systems. Meantime, the process of biogas is
not very attractive economically, especially on large industrial scale.

 

3.     
Because biogas contains some impurities gases e.g. H2S
and ammonia which cause obnoxious smells could affect devices, human and environment. 

 

With the development of biogas technology in the future, I believe the limitations
above will not be the troubles. And ATT in Germany has become a successful
company in the processing plant design and manufacturing. [1]

 

Reference:

 1.     
ATT http://www.aat-biogas.at/en/news/

 

 

Keqin Chen


Msc of Oil and Gas Engineering

ID:51126368

sreehariprabhu's picture

As discussed by my friends, biogas is produced through anaerobic digestion of slurries, animal waste and from a wide range of other organic wastes thus converting to renewable energy. This can be used as a natural fertilizer for agricultural purposes. The good things about biogas is that it emits less green house gases like carbon di oxide, methane and nitrous oxide when compared to fossil fuels. Also it helps in reducing the organic waste.

Even if these are the advantages of biogas, there are also certain risks associated with it. It can lead to an explosion if proper safety measures are not taken. If the biogas gets mixed with air and if it finds any source of ignition, it can lead to an explosion. Next risk involved is poisoning. If we inhale biogas more than a certain period of time, it may even lead to death. There are also non-desulphurised biogas plants. In these plants Hydrogen Sulphide which is a very toxic gas gets leaked, it may lead to death even if we breath a small concentration. So necessary safety measures should be adapted in the biogas plant to make it safer. Since it is a renewable energy source, it will a be a great source of energy in future if operated safely.

http://www.renewableenergymagazine.com/article/60-percent-of-biogas-plan...

Sreehari Ramachandra Prabhu 

Tianchi You's picture

Biogas is consited of several kinds of gas, which is CH4,CO2,O2,N2,H2,H2S. Normally if there was 8.6% of biogas in the air, then it will be exploded. Biogas is clean, convenient and efficient in some ways; however, there are some other disadvantages of biogas, not only in safety sector but also in other functions.

  • Biogas is toxic, which is harmful to environment and people
  • It is relatively clean, but the CO2 in biogas will definitely aggravate the greenhouse effect
  • It is efficient in a family-size, but not in an industrial size, which means it is not economically attractive in industrial ways
  • It is hard to enhance its efficieny in industries
  • It is not fesible to construct biogas facilities everywhere, which means it has limited location

Reference: http://ecovillage.org.in/ecopedia/alternate-energy/advantages-and-disadvantages-of-biogas

Regards,

Tianchi You

51233959

Oil&gas engineering

Angelos Hadjiantoni's picture

Hello everyone,


I think that we all agree on the mentioned risks associated with biogas.
In my point of view, people should not develop a negative opinion about this technology since many safety measures
have been developed to ensure proper operation of the plants.
ATEX  is the name for the European Directives for Controlling Explosive Atmospheres and includes the ATEX 137 and 95.
These 2 directives set a minimum safety level for working in explosive environments.
Also a biomass plants are separated into Zones in respect to the danger of explosion or gas mixtures.
In addition the plants have specific fire protection measures with regulation about the distances of bioreactors, gasholders etc.
There are measures fore reducing the noise from the plant like sound absorbers in the exhaust systems.
Sure accidents might happen but modern technology and new regulations try to minimize that
in order to increase the productivity of this sector.

Best regards,
Angelos Hadjiantoni,
MSc Renewable Energy
http://annals.fih.upt.ro/pdf-full/2012/ANNALS-2012-2-03.pdf

t01sik12's picture

Biogas typically refers to a gas produced by breakdown of organic matter in the absence of oxygen. Organic waste such as dead plant and animal material, animal feces, and kitchen waste can be converted into a gaseous fuel called biogas. Biogas originates from biogenic material and is a type of bio fuel. The most important impurity or toxicity is hydrogen sulfide(H2S), this gas can be corrosive and can produce SO2 when not properly burned, because H2S is highly toxic, it can cause damage to central nervous system, metabolism and gastrointestinal tract. Long exposure to small concentrations can be irritating  to eyes and respiratory system & eventually result in Pulmonary Oedema. The Risk of explosion is always present in a biogas plant because of  mixture of Air/Biogas.

 

Necesasary measures should be adapted in the biogas. Biogas is not completely safe, Information is a good step towards having it as clean energy source.

 

Reference

1)  http://en.wikipedia.org/wiki/Biogas

2) http://biowasterecoveryplant.files.wordpress.com/2010/10/paper_safety.pdf

 

Samuel Kanu

Msc Subsea Engineering

amaka.ikeaka's picture

 

Biogas is produced from the process of anaerobic
digestion of wet organic waste, producing carbon dioxide, methane and a
digestate which can be used as fertilizer. From a safety perspective, the three
main dangers to property and workers that must be considered during
installation and use are: toxicological dangers due to poisonous gases, fire due to
combustible gases, physical dangers due to system operation. The following
equipment are recommended for safe biogas practices:

Pressure
Relief Valve: Prevents biogas leakage in the event of the over pressurization
of seals and averts injury to the workers due to rupture.

Vacuum
Breaker: While draining liquid in digester, ensures that the walls and roof of
the digester does not collapse

Combustible
Gas Sensor: Helps in the early detection of biogas leakage which could become
an explosion hazard if not detected

Hydrogen
Sulfide Sensor: Helps in the early detection of hydrogen sulfide, which could
become a potential toxicological danger to workers.

Reference

Walsh, J. L., Ross, C. C., Smith, M. S., & Harper, S. R. (1989). Utilization of biogas. Biomass, 20(3), 277-290.

 

Sineenat Kruennumjai's picture

Topic 42: Potential and Safety Issues concerning Biogas

 In the future, the non-conventional sources of energy, that will commonly play major role, are Solar, Wind, Biomass and also Biogas. Biogas can generate a clean and controllable energy from organic waste. The energy produced from biogas can  replace fossil fuel.  The main processes of biogas generation are scalable and have been applied globally. The main hazardous associated with this kind of energy resource are explosive and flammable, health effects, noise pollution, and water pollution.
- Explosion and Flammable might occur in workplaces because biogas contains lots of hazardous gas, such as methane (can explosive), H2S (flammable gas).
- Health effects which might cause from the inhalation of inert gas, as well as displacing oxygen in workplace. Hydrogen sulphide for example, 0.03-0.15 ppm of its concentration can cause irritation of eyes and airways, vomiting, headache, and unconsciousness. 
- Noise pollution which can occur near gas engines.
- Water pollution occur when water from plants which is penetrated into surrounding.

 Consequently, such hazardous have to be assessed in order to make sure the processes are safe. Moreover, during operation, it is important to do a regular check and keep records of the operational safety features. 

Sources; http://annals.fih.upt.ro/pdf-full/2012/ANNALS-2012-2-03.pdf
http://www.adelaide.edu.au/biogas/

Posted By
Sineenat Kruennumjai
ID 51126536

Biogas is consider to be a renwable and clean energy. Still it have some safety issues. As my friends said at certain conditions, when biogas combine with air it form explosive gas mixture. There is high risk for fire and explosion near digesters and gas resevoirs. Therefore specific measures should be taken for its safety. Biogas which contain more than 50% of methane are combustible. 

 

Waste treatment procees should be given extra care in order to reduce the spreading of odour and the number of pathogenic bacterias. This will help to reduce the diseases caused by this type of bacterias. Biogas mainly contain CH4 and CO2. A small amount of H2S is also found. These gas have thereown problems. So adequate ventilation and proper precuation and protective equipments should be consider inorder to reduce the risk.   

 

 

Liu Yishan's picture

Compared with other fuels such as coal, gasoline, biogas is relative less dangerous than others. I think the most risk issue is biogas can hurt human when it burns. Biogas can be explosive when mixed with air in the proportion of one part biogas to 8-20 parts air in an enclosed space. This situation can occur when a digester is opened for cleaning, when biogas is released to repair a gas storage tank, or when there is a gas leak in a poorly ventilated room. A biogas leak can be smelled if the hydrogen sulfide has not been removed from the biogas. It smells like rotten eggs. As the widely use of biogas in family and factory, it will help people to identify the leakage of biogas as soon as possible to avoid casualty. Therefore, I believe for safety reason, there is no necessary to remove the hydrogen sulfide from biogas.

Reference: http://werkgroepterlinden.be/Biogas.html

Abdulazeez Bello's picture

Biogas is a
form of renewable energy which can be produced by treatment of by products
(waste activated sludge) from biological waste water using anaerobic methods. Other
organic materials that can be used includes: Municipal, Industrial and
Agricultural waste (Athanasoulia et al., 2012). These wastes are produced from
our everyday activities and being able to convert it into energy should be a
plus to the society. Farmers also produce this biogas locally using waste from
plant, swine slurry and other animals.
Use of biogas can reduce the CO2 and CH4 emission from
conventional fuel combustion and natural decomposition of organic substances
respectively (Iglinski et al., 2012)
 In conclusion, Energy production processes
have a degree of inherent risk associated with it. The onus is on the
regulatory body concern to ensure that biogas production process follow an
established safety code like the Control of major accident hazard (COMAH) regulation
of 1999 and environmental pollution is reduced to barest minimum.

 

Reference
1.         Athanasoulia, E., Melidis, P.,
Aivasidis, A., (2012) ’Optimization of biogas production from waste activated
sludge through serial digestion’ Renewable Energy, SciVerse [Online] Available
at http://www.sciencedirect.com/science/article/pii/S0960148112002790
[Accessed on 09 December 2012]

2.         Iglinski,B., Buczkowski, R., Iglinska,
A., Cichosz. M., Piechota, G., Kujawski,W., (2012) ‘Agricultural biogas plants
in Poland: investment process, economic and environmental aspects, biogas
potential’ Renewable and Sustainable energy Reviews , SciVerse [Online]
Available at http://www.sciencedirect.com/science/article/pii/S1364032112003127
[Accessed on 09 December 2012]

 

OKEKE FRANCIS's picture

Like every other energy source, Biogas is not completely safe.  It consists mainly of 60% methane and 40% CO2 with trace amount of H2S and other gases. It can be explosive when mixed with air and can result to poisoning and asphyxiation symptoms or death if inhaled in high concentration. 

In handling Biogas, the manufacturer warnings must be strictly adhered to, safety precautions which help determine hazards and preventive measures should be put in place, gas sensors must be put in place in order to detect poisonous gas hazards, adequate training of personnel involved with Biogas should be of importance and also ensuring the right PPE is worn at all times.

http://www.extension.org/pages/30311/anaerobic-digesters-and-biogas-safety

http://www.adelaide.edu.au/biogas/safety/ 

 

OKEKE FRANCIS
OIL AND GAS ENGR.

I would like to note some safety issues regarding the production of biogas and safety measures which can be taken to avoid them. The first and foremost issue is the potential of explosion since it contains a large amount of methane. If you look at MSDS(Material Safety Data Sheet) of Methane, you can see that it is explosive. If biogas is diluted by air to 10%-30%, there will be explosion hazard. So,the digester of biogas should not be exposed to flames or any potentially explosive material or equipmnt. There are also health risks associated with biogas. From previous reports, it is shown that there is risk of suffocation.In addition, some diseases can be resulted since animal manure(in manure digestion) contains bacteria and virus, etc which are harmful for health. Also, it contains Methane, Carbon Dioxide, Hydrogen Sulfide which can cause death if not used properly.

Maxwell Otobo's picture

Biogas is a renewable fuel produced from waste treatment and best used directly for cooking and heating. The raw gas is typically composed of methane 50-85%, carbon dioxide 5-50%, hydrogen 0-1%, hydrogen sulphide 0-3%, nitrogen 0-5% and oxygen 0-2%.

Biogas is not completely safe but a good knowledge of the dangers involved would be of great importance to the safety of lives and the environment.

The safety issues to be considered when working around a biogas system include;

  • Fire/explosion - Methane which is present and a major constituent of biogas forms explosive mixtures in air and explosion occurs if there is a light match or fire nearby.
  • Diseases - Since the biogas system relies on waste material, a mixed population of bacteria of unknown origin are present. To carry out the waste treatment, enough care should be taken to avoid contact with these waste materials and clean up thoroughly after working around the biogas system (digester).
  • Hydrogen sulphide toxicity - H2S is know to be a poisonous gas that destroys the olefactory tissue and lungs. Dangerous to life and health at 300ppm
  • Carbon dioxide toxicity- a slightly value high can affect the respiration rate. 11% concentration leads to unconciousness for a minute and at concentrations of 25-35%, convulsions would occur.

A good ventilation, adequate protective equipment and suitable precautions will minimize the above listed dangers, making biogas a good servant rather than a bad master to the society.

References

1. http://www.adelaide.edu.au/biogas/safety/

Maxwell Otobo - 51122742

MSc. Oil and gas engineering

 

Connie Shellcock's picture


Many of the previous posts have mentioned that one
of the negatives of Biogas formation is that hydrogen sulphides and nitrogen
are produced as a result of biogas production, however in my research I have
come across a novel way of removing these substances. Swine waste water was used
as a source. During anaerobic digestion of swine wastewater hydrogen sulphide
is produce and accumulates in the biogas produced. As previous posts have
rightly pointed out hydrogen sulphide is corrosive and this limits the use of
biogas as a renewable fuel. When placed in a series of specialised reactors, it
was found that hydrogen sulphide can be removed from the biogas, eliminating
the problem. This process also has less environmental impact compared to
previous methods of hydrogen sulphide removal.


(Deng, Chen et
al. 2009)


ADENG, L.,
CHEN, H., CHEN, Z., LIU, Y., PU, X. and SONG, L., 2009. Process of simultaneous
hydrogen sulfide removal from biogas and nitrogen removal from swine
wastewater. Bioresource technology, 100(23), pp. 5600-5608.


 

Ojo Oluwayimika Joseph's picture

Acknowledging the previous posts and comments, the safety concerns of biogas can be fully understood and risks mitigated. Anaerobic digestion has proven to be a dependable method for biogas generation.The digested sludge from anaerobic digesters can be used to enhance soil fertility. This is a success story of  the biogas potential from the sewage generated in four public universities in Ghana for the 2008/2009 academic year. The estimation of sewage used in this exercise was generated from the four universities taking into consideration both residential and non-residential staff and students. The population of the universities varied throughout the year due to the vacation periods hence the sewage generated varies accordingly. The estimated population for the four universities was 100,313 when insession and 20,903 on vacation and the estimated daily sewage generated is 1379.9 cubic meters and327.8 cubic meters when the universities were in session and on vacation respectively. It was discovered that an yearly biogas potential of about 815,109 m3 could be obtained which is equivalent to about 4,891 MWh of energy or can replace about 4532 tonnes of firewood or 326.4 tonnes of LPG which can reduce the pressure on the forest and the use of LPG.

ReferenceRichard Arthur, Martina Francisca Baidoo, Abeeku Brew-Hammond,Edem Cudjoe Bensah. Biogas generation from sewage in four public universities

in Ghana: A solution to potential health risk

Ojo Oluwayimika Joseph   

Oil and Gas Engineering 

 

Ojo Oluwayimika Joseph's picture

Acknowledging the previous posts and comments, the safety concerns of biogas can be fully understood and risks mitigated. Anaerobic digestion has proven to be a dependable method for biogas generation.The digested sludge from anaerobic digesters can be used to enhance soil fertility. This is a success story of  the biogas potential from the sewage generated in four public universities in Ghana for the 2008/2009 academic year. The estimation of sewage used in this exercise was generated from the four universities taking into consideration both residential and non-residential staff and students. The population of the universities varied throughout the year due to the vacation periods hence the sewage generated varies accordingly. The estimated population for the four universities was 100,313 when insession and 20,903 on vacation and the estimated daily sewage generated is 1379.9 cubic meters and327.8 cubic meters when the universities were in session and on vacation respectively. It was discovered that an yearly biogas potential of about 815,109 m3 could be obtained which is equivalent to about 4,891 MWh of energy or can replace about 4532 tonnes of firewood or 326.4 tonnes of LPG which can reduce the pressure on the forest and the use of LPG.

Reference

 

Richard Arthur, Martina Francisca Baidoo, Abeeku Brew-Hammond,Edem Cudjoe Bensah. Biogas generation from sewage in four public universities

in Ghana: A solution to potential health risk

Ojo Oluwayimika Joseph   

Oil and Gas Engineering 

 

As a renewable form of energy, the potentials of biogas when duly applied following strict regulations and safety precautions outweigh the related concerns. Like other fuels such as wood, gasoline and cooking gas, biogas also has its potentials for being dangerous. In the world we find ourselves in today where economies are looking towards greener ways of producing energy towards a sustainable ecosystem we should be willing to explore alternative sources of energy.
Biogas is a gas whose primary elements are about 65% of methane (CH4) and about 35% of carbon dioxide (CO2). It is a product of the natural decomposition of any organic substance of animal or plant origin due to the activity of anaerobic (functioning in a non-oxygen environment) bacteria. Major sources of methane are all animal excrements, waste landfills, and any other organic material which is left untreated.
Although biogas is used mostly in rural areas by farmers and as stated by Oluwatosin, the potentials of biogas as a dependable energy source are not encouraging for the reasons she outlined. However, the production of biogas on the local scale should be encouraged especially as a means of waste management in crowded cities as well as farming communities.
The safety issues of biogas such as explosions (due to the presence of methane forming 60% of biogas composition), asphyxiation (biogas in an enclosed space with poor ventilation), and disease (animal manure contain bacteria, viruses and possible parasites) can be prevented under strict safety precautions, regulations by concerned authorities and adequate sensitization on the hazards associated with biogas production.

References:

"Anaerobic digesters and Biogas Safety." Extensions, April 12, 2012. http://www.extension.org/pages/30311/anaerobic-digesters-and-biogas-safety

"What is Biogas?" Biogas Nord. 2012. http://www.biogas.de/en/technology/what-is-biogas.html

Kuma Mede
51126022

Subscribe to Comments for "Topic 42: Potential and Safety Issues concerning Biogas"

Recent comments

More comments

Syndicate

Subscribe to Syndicate