Beer brewing wastes to energy, Part 2

So not only does the brewing process produce a large spent grain waste stream, but brewing also produces large amounts of carbon dioxide.  Carbon dioxide is a by product during the fermentation step of brewing as the yeast eat the sugars present in the wort and turn it into alcohol.  So how can this waste stream be used to generate energy, Solix Biofuels of Fort Collins, CO thinks that it has come up with a way.  Solix Biofuels is a new biofuels company that has partnered with Colorado State University to research and find a way to implement energy from algae.  What make this process so exciting is that algae only need sunlight and carbon dioxide to grow.  Sunlight is not hard to come by and neither is carbon dioxide when you are next door to New Belgium Brewery in Fort Collins.  Solix Biofuels is conveniently located next door to New Belgium Brewery, where almost 5,000 metric tons of carbon dioxide are produced a year from the brewing processes.  So with the carbon dioxide from New Belgium, Solix Biofuels has come up with a technology that will grow and harvest the lipid rich algae produced.  When algae grow they produce large amounts of lipids or oils for their overall size.  By injecting carbon dioxide into the a water algae mixture contained in a transparent bioreactor the algae can grow and produce oils.  After a certain period of time the algae can be harvested.  After harvesting the algae can be squeezed and pressed to extract all of the oils contained within each algae.  These oils can then be further refined into liquid bio-diesel.          

Beer brewing wastes to energy, Part 1

This last month me and my father brewed our third batch of beer.  The past two batches we brewed were extract beers.  This simply means that the malting, mashing, and sparging process had already been done for us, which makes it a whole lot easier on us just being beginners.  As many of you know who have went through the whole Coors tour and not just the short tour, malting is the process of germinating the grains used to brew the beer.  This is done in a temperature and humidity controlled environment.  Once the grain starts to germinate the process is stopped and then the malted grain is mashed.  Mashing can be thought of as making a giant batch of tea.  The malted grains are first lightly crushed and mixed with hot water.  The hot water extracts the nutrients and sugars from the grain making a sweet sugary "tea".  The grains contain many complex sugars and carbohydrates that much be broken down into smaller and smaller sugars so that the yeast used to brew the beer can utilize them.  Mashing is the process that breaks down these sugars. By just draining off the "tea" many of the sugars stay trapped in the grains, so sparging is utilized to get the remaining sugars out of the grains.  Sparging can be thought of as just rinsing the grains until mostly all of the sugars are extracted.  So after all of that processing you are left with wort, the brewing technical word for the "tea".  For many beginner home brewers all these steps can be skipped by brewing an extract beer.  The extract is just concentrated wort that looks about like molasses.  This extract is mixed with water and the then the beginner home brewer can continue on with the brewing process to make beer.  So this time my father and I decided to step it up and we tried brewing an all grain beer.  An all grain beer is one that is brewed by doing all of the steps talked about earlier, except for malting.  So after we mashed and sparged our malted grains we had nearly 20 pound of spent grain.  This twenty pounds of grain was used to brew just five gallons, can you imagine how much grain is used at Coors.  So what are we to do with all of this spent grain.  I got on the internet and did a Google search and found that people have done many creative things with their spent grains.  One that I thought was very interesting was making dog biscuits.  But anyways after reading about many different ways to use this spent grain, I got to thinking about anaerobic digestion and if energy could be extracted from the spent grains in this way.

Spent Grain Dog Treats!

So after another Google search I found an article in Biomass Magazine that talked about a Germany brewery that has done just this as an demonstration.  The article says that most breweries around the world do already have anaerobic digester to treat their wastewater streams, but this brewery has claimed to be the first to demonstrate that a digester for spent grains can be done.  One big obstacle that digesting the spent grains brings about is that in the past the spent grains have been sold to the agricultural industry as animal feed.  Bringing $9 to $18 a metric ton, digesting spent grain may not always be economical.  The brewery that has implemented this demonstrational anaerobic digestion process says that its been more of a marketing strategy that shows those around them that they can be self sustaining and not use fossil fuel energy.  Convincing the rest of the brewing industry to implement such a technology may be very difficult, but this might just make it possible for home breweries or craft breweries to lead the way!  

Landfill gas to energy statistics

Here are some quick statistics on the number of landfill gas to energy plants by state. California has 77 operational plants, Illinois has 32, Texas has 27, and Colorado has 1.  Granted we have a much smaller population than all of these other states, but with over 30 landfills in the state of Colorado there should be more of these plants in operation.  The only landfill gas to energy plant in operation is located at the Lowery Landfill in Aurora.  The gas gathering system consists of 218 wells and collects LFG from both the Lowery Landfill and the Denver Arapahoe Disposal Site (DADS).  Between the two landfills, Lowery being closed and DADS still in operation, they collect enough gas to produce 3.2 megawatts of electricity.  This is enough electricity to power nearly 3,000 homes.  In April of last year, a new LFG to energy plant broke ground at the Larimer County Landfill, located in Fort Collins.  This plant is expected to produce 1.6 megawatts of electricity.  Both the Lowery Landfill/DADS and Larimer County Landfill have plant sized below the average size of simlilar plants in the United States, which is 3.4 megawatts.  The largest LFG to energy  plant is located in Puente Hills, CA and produces 50 megawatts.  

How much methane does a landfill produce?

I have been doing a lot of research to try to determine how much methane or LFG an actual landfill can produce.  Many factors go into the production of the LFG and include, age of garbage, temperature, moisture level, and type of garbage.  In general the more organic the garbage the more methane and carbon dioxide that is produced.  Also, the warmer the better and the higher the moisture content the better. As for the age of the garbage there are wide ranges of time periods where many experts say the LFG production is at its peak.  Gas production normally starts around the 1 to 3 tears after the garbage has been covered, and after 5-10 years gas production is at its peak.  There are many different suggestions to when the landfill stops producing gas ranging from 10 - 40 years.  And many times the life of gas production varies depending on the conditions of the landfill and its contents.  Here is a quick video that show LFG being emitted from a bore hole drilled into a garbage layer.  Sure does seem like a lot of LFG being produced!

Landfill Gas, does this sound familiar

Making the shift from anaerobic digestion to other types of waste to energy technologies will be easier if we look into a process that is nearly the same.  This type of technology is known as landfill gas.  Landfill gas is produced in almost all landfills and many times the landfill gas that is produced is lost to the atmosphere.  Landfill gas is made up of 50% methane(CH4) and 50% carbon dioxide(CO2).  Sound familiar, this is the nearly the same composition of biogas.  Landfill gas (LFG) is also produced in the same way.  Microbes deep under the layers of trash in landfills eat away at the trash and transform the garbage into it most basic form, which happens to be both methane and carbon dioxide.  One major difference in this process is that while nothing special needs to be done for the LFG to be produced, such as buying a digester and then agitating and heating it (as in anaerobic digestion), but collecting the :LFG is more difficult.  In order for LFG to be captured the garbage is first covered with a layer of soil that both contains the garbage but also helps create an environment suitable for the naturally occurring microbes to begin their work.  Once the LFG is produced it slowly makes it way up through the layers of garbage until it is emitted to the atmosphere.  When the LFG is lost to the atmosphere, it is known as fugitive emissions.  Collecting the LFG to use in productive ways is accomplished by drilling wells into the garbage.  Lining these wells with PVC pipe gives the LFG a path to take to get to the surface.  Just like most things in this world, the LFG will take the path of least resistance and that is the PVC pipe.  An array of these wells are drilled and connected to a central LFG collection line.  This raw LFG also contains some other gases that are non desirable such as ammonia (NH3) and hydrogen sulfide (H2S).  Therefore, the LFG is treated to remove these gases.  Once the LFG has been cleaned up, it can be used just as biogas or even natural gas would be used.  Here is a diagram that may help you visualize what a LFG system looks like.

Back to the Future!

How long has the idea of using trash for energy been around?  At least since the the movie "Back to the Future" came out in 1985.  In "Back to the Future," Doc fills his time machine with garbage to power a trip back to the future.  Mr. Fusion, the name given to this garbage to energy generator, may have seemed like some science fiction idea that may never become reality, but it has.  A larger scale Mr, Fusion has been created and has proven to turn everyday garbage into energy.  This technology consists of a tank that contains plasma arcs that reach almost 6000 degrees Fahrenheit.  Simply put a plasma arc is a  lightning strike.  The high temperatures of the plasma arc cause anything within the tank to break apart into smaller and smaller particles until a gas is produced, that can be burnt just as natural gas is burnt, to create mechanical energy.  This mechanical energy can be used to power a car, or to make electricity.  So if this type of technology can convert any type of garbage into energy why did Doc pick through the trash and then pour a beer into Mr. Fusion?  I'm sure it was done that way just to make the scene more interesting and to grab the attention of the audience.  By the way pouring liquids into a fusion gasifier ( the technical name of this "lightning tank") would cause big problems. But isn't it great when seeming out of this world ideas in movies become reality.

  

DIY Anaerobic Digester