Sunday, August 26, 2018

The Dangers of Biogas - 7 Known and 3 Unexpected AD Hazards

There are dangers of biogas just as there are dangers inherent in everything we do. The most obvious biogas dangers come from the fact that it is an explosive gas when mixed air in the right proportions.

However, there are also anticipated dangers of biogas plants which the public authorities and individuals raise during consideration of planning applications, which this article also discusses with examples, in section 2.

Finally, in section 3 below we have included three surprising unexpected dangers of biogas which few if any people have foreseen, with:

  • honey which became coloured due to an anaerobic digestion plant locally, and 
  • estrogen, antibiotics which persisted in dairy farm waste after AD treatment
  • worries about aluminium roof collapse if sulphur leaks out of the biogas.
Image - cartoon suggests the dangers of biogas.


1. Normally Accepted Biogas Hazards

The normally accepted dangers of biogas are summarized in the list of 7, below:

  1. Fire/Explosion
  2. Asphyxiation
  3. Disease
  4. Methane
  5. Carbon Dioxide
  6. Hydrogen Sulfide
  7. Ammonia.

Precautions to Limit the Normally Accepted Dangers of Biogas

Standard biogas plant safety procedures will major on the following actions to keep plant staff safe:

  • Observe All Manufacturer Warnings with Rigour, create Site Safety Policies and implement procedures to ensure all staff and each visitor is trained to avoid every biogas plant hazard which could cause injury or ill-health.
  • Conduct Safety Walk-Throughs/ Plant and Equipment Inspections Regularly
  • Use and Maintain Gas Sensors
  • Use the relevant Personal Protective Equipment via Biogas Safety

2. Dangers Raised During Biogas Plant Planning Discussions

Dangers of biogas production as an alternative energy source for rural areas

Biogas is a mixture of 55-65% Methane, 30-35% Carbon Dioxide and Moisture, Hydrogen Sulphide, Nitrogen and Hydrogen making up the balance.

Its heating value is around 600 B.T.U. per cubic feet. Biogas production is a biological process without oxygen in which organic matters are converted into biogas by bacteria, because organic matters are the food source for methane producing bacteria. About one cubic feet of biogas may be generated from one pound of cow dung at around 28°C.

This is enough to cook a day's meals for 4-6 people. In anaerobic process, the bacteria requires both Carbon and Nitrogen, but they consume Carbon roughly 30 times faster than Nitrogen.

Biogas is not poisonous, although this may be improved by filtering it through limewater to remove CO2, iron filings to absorb corrosive H2S and Ca2Cl to extract the water vapour.

The only danger is by the explosion of the plant and mixed with air and fire. Thus proper maintenance of the Biogas plant is important to prevent the leakage.

via Biogas production as an alternative energy source for rural areas

Villagers fear biogas plant in Canwick would cause ‘unnecessary danger’

February 2018: Plans for a new biogas plant in Canwick have provoked an angry response from fearful local residents, with even the Environment Agency and Lincolnshire Fire and Rescue weighing in to say that the development should not be approved in its current form. via Canwick danger’

THE Energy Regulatory Commission has not licensed any of the bottled biogas products which are ... are highly explosive, hence pose a lot of danger if not well handled. "The people bottling biogas need to get safety approval first," ERC director ... via Kenya: Traders Selling Bottled Biogas Illegally - Kenya: Traders

Anaerobic digester plans stymied in Franklin - News - Milford Daily News

After hearing the pleas of several concerned residents, Town Council on Wednesday tabled zoning changes that sited an anaerobic digester plant for a Pond Street property.

... The questions about anaerobic digestion, a biological process that converts organic waste into energy, overshadowed the positives of the burgeoning technology.

With support from the Economic Development Committee, Town Administrator Jeffrey Nutting and officials in the Department of Planning and Community Development had hoped to tweak the zoning to allow for an anaerobic digester facility on the former Pond Street sewer bed.

... a day after the Planning Board voted not to recommend the zoning changes, residents who live on or near Pond Street attended the council meeting ready to fight the prospect of an anaerobic digester in their backyard.

"I want you to take into consideration what anything seeping into the ground, or going into the air … could do to our community — the town we love so much," said Sandra Verhaegen. "Is the $500,000 to $1 million worth it? Probably not. Look to new businesses (to fill the property). Do we really want something in our community that isn’t tested?"

According to the Environmental Protection Agency, the "biogas" or gas produced when the anaerobic digester breaks down waste is comprised of methane, hydrogen sulfide, a highly toxic and flammable gas with a distinct rotten egg smell, and carbon dioxide.

Residents worried that problems [of the dangers of biogas] with the plant, such as a fire or leak, could put them in immediate danger. And they feared the increased truck traffic that would accompany the plant.

Councilors expressed the same concerns. via Anaerobic digester plans stymied

3. Unexpected Dangers of Biogas

Waste from M&M's Candy Causes Honey to Turn Green in France

M&M candies come in every color of the rainbow – but what if honey came in the color of M&Ms?

Distraught beekeepers in Northeastern France are facing just that conundrum, as honey from their apiaries has been turning up in shades of green and blue.

After weeks of perplexing investigation, the farmers found the candy colored honey to be caused by waste from nearby Agrivalor biogas plant, which has been processing M&M’s waste.

The farmers in Ribeauville, Alsace are just 2.5 miles away from the biogas plant, a short jaunt for their bees to travel and pollinate before returning to the hive. In the past the biogas plant threatened no danger to their business, but since processing waste from the colorful shells of M&M’s, the beekeepers felt an immediate effect. Bees from around twelve apiaries have been returning to the hive with blue and green debris, which gets directly transferred to the honey they yield.

Honey appearing in colors other than amber is needless to say, unsellable. The murky blue and green sweet stuff isn’t being packaged as a new M&M flavor, but instead is being thrown in the trash.

These beekeepers are already facing adversity, with increasing bee mortality rates killing off many of their producers they can’t afford to lose the honey they do make. Coupled with the effects of harsh winters, the apiaries are already in a jam.

[The AD plant operator] has been notified and has begun cleaning up the mess, but the beekeepers are still stuck with green honey. via Honey Green

Estrogen, antibiotics persisted in dairy farm waste after advanced treatment, study finds

When University at Buffalo chemists began studying waste disposal at a dairy farm in New York State, they thought that the farm's advanced system for processing manure would help remove estrogens and antibiotics from the excrement.

Instead, the scientists found that the chemicals largely persisted in the treated materials, which are typically reused as fertilizer and animal bedding on the farm.

The waste management process—an advanced anaerobic digestion system—also converted a less harmful form of estrogen in the manure into a form that may pose a greater ecological threat.

The study underscores how far waste treatment techniques have fallen behind the times.

Hormones and antibiotics, if not removed from waste, can migrate into the environment and threaten wildlife. Estrogens, for example, can enter rivers and lakes, causing male fish to develop female traits—a phenomenon that can harm reproduction. Rogue antibiotics pose a different kind of challenge, encouraging the spread of antibiotic resistance, in which disease-causing bacteria stop responding to drugs.

... "One of the messages of our work is that even anaerobic digestion, an advanced treatment, doesn't totally remove these chemicals which may pose a danger to the environment. We need to start looking closely at additional treatment techniques to identify better practices."

The research, funded by the New York State Pollution Prevention Institute, was published in two recent papers. via Estrogen, antibiotics persisted

Waste Not, Pollute Not 

This is part of IEEE Spectrum's special report: Critical Challenges 2002: Technology Takes On

Cow Power - Danger of Sulphur Precipitation to Aluminium Roof Corrosion and Potential Eventual Collapse

...each of DDI's three barns will be warmed by water pipes running under the concrete floor. The hot water, which will be heated by biogas power, will keep the manure flowing into the digester even in the dead of winter. So the electricity will keep flowing, too.

That electricity will be generated by four microturbines from Capstone Turbine Corp., Chatsworth, Calif. [see "Networking Assets," IEEE Spectrum, January 2001, p. 84]. ...DDI will still scrub the gas before it goes to the microturbines by passing it through iron-impregnated wood chips...

If the biogas is not scrubbed, the sulfur could precipitate out of the exhaust as an acid, a danger for surrounding equipment as well as the farm's 12 000 m2 of aluminum roofs.

via Waste Not, Pollute Not

Well there you have it! Biogas Dangers never imagined!

No comments:

Anaerobic Digestion Community Website