Introduction to biogas

The Canadian dairy industry is important to our economy.  Dairy products are consumed by most of the Canadian population and some, such as milk, are used in the preparation of most meals.  Due to the high consumption of these products, Canada has almost 13,000 dairy farms with over 1.4 million dairy cows (Canadian Dairy information centre). 

 What most people don’t realize is that the most valuable item obtained from the cow is not the milk, but the manure. That’s right, the cows' manure!  The manure from the cow can be collected to make a renewable source of energy called biogas, which can then be used to create electricity by anaerobic digestion, a biological process where microorganisms break down organic materials into their primary components.  With global warming, there is a pressing need for us to convert to renewable sources of energy, biogas being one of them.  Today, farmers dump the cows' manure into ponds or lagoons, wasting a valuable source of energy. Consider these facts on the value of this manure:

 Dairy cows produce on average 82 pounds of manure in one day.  With 1 429 400 dairy cows in Canada, that adds up to 117 210 800 pounds of manure a day and almost 43 million pounds of manure a year.  This would produce 57 176 mega watts of electricity every week and 20 869 240 mega watts every year - enough electricity to power all of New York City for almost 5 years!

 Now you must be wondering, how this electricity is created? All of the manure from the farm is collected and put into one end of an anaerobic digester tank.  The manure takes anywhere from 10-25 days to make it from one end of the digester to the other. Inside the tank, the manure is broken down by anaerobic bacteria, which separates the methane from the solid matter.  The methane rises to the top of the tank and is held in a different storage tank until it is ready to be used.  Since biogas is most commonly used to make electricity, it is used as fuel to power an engine which turns a generator- creating electricity. 

Diagram of the anaerobic digestion process. 

Benefits for farmers and dairy companies

For farmers and dairy companies, the motivation to produce biogas is simple.  It will reduce their costs while providing an additional source of revenue.

 First, let’s look at the opportunity to reduce costs for dairy farmers.  The use of home grown power allows farmers to become self- sufficient by using the electricity made from their cow manure to power their farm.  The amount of electricity that a dairy farm uses every week is significant, primarily because of the refrigeration of the milk and the electric milking machines.

 An example of how much electricity a dairy farm would normally use is the Haubenschilds' dairy farm that uses 9,000 kw every week.  With the electricity rates in Ontario ranging from 6,3 to 11,8 cents/ kWh they would be spending on average $900 dollars a week and $45 000 dollars a year! Not having to pay for electricity would make a huge dent in their annual costs.

Another cost reduction is heating by cogeneration.  When the generator is using the biogas to produce electricity, 60% of the energy used is lost in the form of heat.  Cogeneration projects trap the heat created by the operation of the engine and use it for various tasks such as heating water and heating rooms.  

 

The other benefit for farmers is revenue:  This biofuel provides four major sources of income:

-          Sale of electricity

-          Carbon offsets

-          Sale of livestock bedding

-          Sale of liquid fertilizer

 

The first source of income for the farmers is the production of electricity.  Because most farms use the biogas to produce electricity, the surplus can be sold to utility companies as green energy. The Ontario government has put in place a green energy price of 11 cents/ kwh (14 cents at peak hours) so that the farmers get more in return.  The farmers can also sell the biogas to gas utility companies because it is similar to commercial natural gas.

Carbon credits are another source of income for the farmers.  Companies who need to offset the greenhouse gases they’re releasing into the atmosphere want to buy carbon credits from others.  Farmers who produce biogas from manure are able to claim amounts of carbon credits by avoided methane emissions.

The last source of income is the sale of bedding and fertilizer.  In my recent post I explained that during the digestion anaerobic bacteria separates the manure in to its primary components so the methane rises and is trapped at the top of the digester.  But what happens to the rest?  Post digestion offers two different types of waste: liquid and solid.  The first type, liquid waste, can be used as fertilizer for crops.  Due to the transformation of nitrogen to ammonium in the digester, farmers are able to reduce the quantity of fertilizer applied, allowing dairy farms to sell more of it.  The solid waste that comes out of the digester can be used as bedding for animals.  By using the digester, farmers are able to eliminate most of the bacteria, making animals less prone to pathogens within the bedding. The unused bedding can then be sold to other farms.

 

The bedding here is coming out of the digester and is then being used in the farm. 

 

Another interesting thing that dairy companies and farmers can do is invest in community digesters.  Because most dairy famers in Canada don’t have enough cows on their farm to benefit from having a digester, the installation of one would have no economic gain.  A solution to this is installing a community digester that is centrally located so that the surrounding farms can use it. This is a benefit to dairy companies because it means that their farms can still have a place to put their manure and still allow them to be self sufficient with electricity, bedding and fertilizer.    

The savings for farmers, combined with the additional source of revenue would be an incentive for the installation of a digester.  The total cost for a farm to install one depends on how much of the work and design they do for themselves- the purchase of the actual digester only accounts for 35-40% of the total cost. Other costs are the purchase of the land, the amount and prices of material and labour input for excavation and installation.  The total price of the digester is normally around 300,000$!  However in time the digester will pay for itself.

 

Comparing a farm with a digester and one without:

 

Diagram of a farm without an anaerobic digester.

Diagram for a farm with a digester.

These are two diagrams that show the differences of a farm with an anaerobic digester and one without.  The red arrows represent all of the negative products that come from dairy farms.  The first diagram has methane emissions, odour and run off as negative products.  These are each serious consequences by themselves and when added together result in extremely high amounts of pollution.  The second diagram has no negative products because the anaerobic digester has been installed and instead has positive products that result from the digestion. 

Environment

 

This green energy is actually beneficial to the environment- unlike most other green fuels.  The first benefit is that it helps stop pollution in areas around the farm.  Traditionally, farmers would flush all of the manure in to a pit or lagoon close to the farm to be stored. But, when there was a heavy rainfall or flooding the lagoon overflows and the waste spreads, polluting the area around it.  This means that the ecosystems around the farm were being destroyed because of the pollution, killing off species and reducing the biodiversity of that area.  With the anaerobic digester being installed there would be no concern of pollution in surrounding areas so the ecosystems could continue to thrive.

 

 

 

These pictures show the overflow of a manure pit being released into open water and a different lagoon overflowing onto the surrounding area. 

 

An anaerobic digester also decreases greenhouse gas emissions in two ways. Firstly, the factories generating electricity from coal, nuclear, etc. would not have to produce as much energy, reducing the greenhouse gases that those factories emit into the atmosphere.  The other way that greenhouse gas emissions would be reduced is by trapping the methane that would normally be released into the atmosphere.  Methane is second only to carbon dioxide in the list of greenhouse gases.  It’s 21 times more potent than carbon dioxide, meaning that it’s 21 times better at trapping heat into the atmosphere than CO_2.

 Another environmental benefit of having an anaerobic digester is the result of lower odour emissions (it’s a benefit to humans too!).  When the manure is stored in a lagoon, malodorous compounds such as hydrogen sulfide and ammonia are released.  By having an anaerobic digester the air smells better and we can all breathe healthier!

 There happens to be a negative impact on the environment from the liquid effluent that comes out of the digester, which is used as the fertilizer. In it, there is high ammonia content because it is a necessary nutrient for many of the organisms in the digester. When the fertilizer is spread on to the field, the ammonia is released and if too much is breathed in, it can become toxic. Ammonia emissions are also responsible for atmospheric acidification and fragile ecosystems, but also can have a health impact on humans and animals.

Fuel companies

Biogas doesn’t have to be used only for the production of heat and electricity.  It can be used as a replacement for fuel, such as gasoline.  This means that you could technically run your car off of cow manure! First off let’s look at why this would be beneficial.

 

The most common way for fuel companies to obtain oil today is through drilling.  Drilling oil has many negative consequences like the destruction of wildlife and biodiversity, loss of fertile soil, pollution of air and drinking water, degradation of farmland and damage to aquatic ecosystems.  It is also one of the primary causes of global warming because of all the CO2 that is released into the atmosphere when the oil is used (the burning of fossil fuels).  Using biogas as an alternative for oil would completely eliminate all of these harsh environmental consequences. 

 

The Alberta oil sands have completely destroyed the ecosystems that used to be found in the areas where the drilling happens.   

 

 Oil is also going to RUN OUT.  The human race has such a huge dependence on it presently that we will not be able to survive once it is gone.  This is why it is necessary to find a sustainable, eco-friendly alternative and why this dependence on fossil fuels should further encourage the energy markets and politicians to invest in renewable energy alternatives and incentives for biogas. 

 

How could fuel companies obtain the methane?  

There are two types of fuel industries that concern biogas- electrical and gasoline.  The main problem convincing fuel companies to invest in, or switch to, biogas is that it would be a waste to have centralized plants for the methane to be extracted.  To do this, the fuel companies would have to buy the manure from the farmers and transport it to the plant, using fossil fuels during the transportation, therefore defeating the whole purpose.  What the fuel companies would have to do is install the digesters on each farm to capture the methane directly from the fresh manure.  The electrical companies could either generate electricity on the farm and transport it to commercial areas through wires, or transport the gas through pipelines back to one central plant to generate the electricity and heat.

 

Then there are the fuel companies that concern gasoline.  There are two ways that a car could run off of biogas.  The first way would be to convert cars to be able to run off of upgrade biogas (bio methane).  The complicated part in this is that this gas contains 60% methane and 40% carbon dioxide.  Carbon dioxide (CO2) is the resulting waste of a combustion engine, so it would have to be extracted from the methane before it could be used for a car. 

The most practical way for Canadians to use biogas as fuel would be to convert the car to be able to start on gasoline and switch over to biogas once the engine is heated up.  The gas tank would need to be able to pressurize the gas to 3,500psi (pounds per square inch) and would have to be made out of a plastic composite core wrapped in carbon fibre.  Other than the price of the conversion, it wouldn’t be too difficult accomplish except for one thing.  Due to the large quantity of time needed by the filling station (22 hours), we Canadians would have trouble adapting to cars running on biogas. This is hugely impractical for today’s society because it would take almost a full day to fill up the car when most families and people need to use their cars multiple times a day.  Nascar is currently developing a system that can fill a car in only 8 hours which will help for the future.  Some states in the U.S. have developed and installed high-speed fueling at gas stations.  These take only 4-5 minutes (the time of normally filling up a car with gasoline), but these stations cost 750, 000 dollars each and low demand means that it would be difficult to receive the funding to install them. 

 

 

 

This is a dodge caravan that has been converted to start off of gasoline and then switch over to natural gas. 

 

The other alternative would be for Canadians to convert to electrical cars, using green electricity (generated from biogas) to run them.  Electric cars produce no tailpipe emissions and are cheaper to operate than cars running on gasoline.  Again, like the car running on biogas, the charge up time for the car takes hours which isn’t practical for Canadians. 

 

This diagram shows the differences of electric and gasoline cars. The electric cars are much cheaper and run more efficiently than electric cars without producing any pollution.

 

The government's point of view

 An important part of incorporating this biofuel into Canada today is having positive effects for the fuel industry. The fuel and electric industries today is an important part of the Canadian economy; they provide jobs for thousands of people across the country.  This is where the government comes in. If we were to incorporate this biofuel into our society, would we damage the economy?

The answer is NO.  If we integrate this gradually into our society we can transition jobs currently held by people in the fossil fuel industry to the good, green energy jobs of our future.  Biogas would also positively affect the economy of rural areas since it would be the farmers providing the electricity and earning another source of income.  This biofuel would also create many indirect jobs in the wiring and construction of natural gas pipes from the farms to commercial areas and the construction of the plants that clean the biogas. 

The governments in Ontario and Quebec are already involved in the installation of anaerobic digesters.  They offer grants to help cover the initial costs because the farms who want to install them can’t always afford it.  Quebec will pay up to 70% of the total cost (200,000$ max) and Ontario will give up to a 60,000$ grant to farmers.  The Canadian government has also put in place green electric prices of 11 cents/ kwh (14 cents at peak hours) to help these farmers pay back their grants.  The only problem with this is that without these government grants, most dairy farms couldn’t afford to install them, but the present government doesn’t have the funding to pay for the installation of an anaerobic digester at every dairy farm in Canada.  Therefore the only way for biogas to become one of Canada’s main energy sources would be to install the digesters over time. 

Integration into society

How can we integrate this biofuel into our society?

 
Integrating this biofuel in to our society is a lengthy progress in Canada. Initially, Canada would probably only use biogas as a source of electricity because of the high conversion costs for cars. 

The first goal would be for the government to provide enough grants to install digesters on as many Canadian dairy farms as possible.  We would also need the financial support for the needed infrastructures such as biogas pipelines, upgrading stations, biogas plants and heat networks to use the heat from cogeneration plants.  At the same time, the government would need to lower the green electrical prices because most consumers won’t be willing to pay extra for green electricity.   Once the electrical system for biogas is in place, there would need to be various incentives for car companies to convert their cars to be able to run off of either electricity or biogas.  The prices for these cars would have to be relatively low to for mass consumption to take place so that this green energy could make an impact.  Once this is all put in place, a cleaner and more eco-friendly planet will be assured!