The Process: More Details About the Gasification Process

As mentioned in an earlier post, gasification is typically done with wet biomass or dry biomass. Usually, dry biomass is thrown into a furnace under ideal conditions and goes through a thermochemical process that forces the solid substance to release a flammable gas known as syngas. With wet biomass, there is another option of sending the material through a biochemical process where enzymes and bacteria do magical things in the absence of oxygen that create a usable liquid fuel. Just as before, we are going to focus on the thermochemical process where combustion is the name of the game.

An interesting fact about the thermochemical process is that after the flammable gas is extracted from the fuel source, it too can go through additional chemical processes and become a usable liquid fuel much like diesel or ethanol. The first embedded videos talks about this process. If not made into a liquid fuel, the other option is to burn the flammable syngas in an engine to produce electricity and/or heat. Burning the syngas onsite is the typical process of facilities being built today. This process is depicted by the second video.

The truth is that the videos can probably do a much better job of explaining the process of gasification, but I am going to attempt to list the major steps and some important details along the way.

1. Procurement- Fuel such as wood chips, switch grass, agricultural plant waste, or pellets are delivered, stored and dried as much as possible.

2. Feed system- For a large power plant, the fuel is typically automatically fed into the boiler via a conveyor system with controls allowing an operate to adjust how much fuel is going into the boiler at any time. Also, exhaust heat from later processes is often funneled to the stored fuel to reduce the moisture content and therefore increase efficiency.

3. Gasification- When the fuel is place in the gasification chamber, it is essentially closed to outside air. This is where the heart of the process lies. There is a bed of hot charcoal already in the chamber and air is let in via small nozzles around the combustion zone. In doing this, there is enough heat causing the biomass to be broken down into smaller components, but there is not enough oxygen for all of the fuel to combust (remember that fire requires oxygen). This chemical reaction is complex but the net result is a release of hydrogen gas and carbon monoxide, both of which are highly combustible. The byproduct is charcoal or ash. The amount of hot charcoal left in the reactor to heat the incoming fuel is monitored and kept at ideal volumes.

4. Cleaning & Cooling-The combustible gas is not without contaminates. The first step is to run the gas through a cyclone that essentially uses a fan to drop out solid particles via gravity. Second, water is introduced into the system often as a mist to cool the gas and to remove additional particulates. This is often called scrubbing. Different designs will begin to vary on how they cool and clean the syngas at this point. Both videos talk about different processes utilized.

5. Filters-Although the cyclone and water treatments have removed most of the contaminants, the gas still needs further cleaning. The gas is passed through a series of filters, some of which are similar to air filters you may find in your home or car, although their design is much more sophisticated. After going through the filters, you are left with a very clean usable gas.

6. Uses-As demonstrated in the Ankur Product video, the gas is piped directly to an internal combustible engine (similar to the one in your car) which is connected to a generator that converts the mechanical energy into electrical energy. In the shorter video, the end result shows the option of producing liquid fuels such as diesel, jet fuel and alcohol. These processes are possible, but are still in the development phase.

These are the main steps in a gasification facility. I think both of the videos below do an excellent job animating the process, if you can handle the background music. Both videos bring to light different ways that the process can be achieved.

Politics Aside: The Big Benefits of Biomass

If you haven’t noticed, the political world likes to categorize ideas to the left or right side of the aisle and then holds onto them until the bitter end. And if you’re on one side of the aisle, don’t you dare support an obviously excellent idea that happens to fall on the other side of the aisle! Tarred and feathered you will become! I absolutely loathe this truth about politics, but that is another story entirely. I bring this up because energy policy is political and most people develop opinions about our nation’s energy needs even though they don’t know how to flip a circuit breaker! Sad but true.

So where does biomass stand among the politically polarized masses? There is one group of people that proclaim ‘drill baby drill!’ Another group of people shout ‘global warming will kill us all!’ How do people with such strong views about energy policy feel about this renewable resource? I can safely assume that there are those who believe it’s is probably too costly simply because ‘it’s renewable’ and there are others who are for it regardless of cost because ‘it’s renewable’. I would encourage you to avoid these ways of thinking no matter what the issue. More fittingly, I will give you some useful information that I have found that will help you realize true benefits of using biomass.

1. National Security
Oil is a main factor when it comes to the sustainability of our armed forces. As the supply and demand of oil ebbs and flows with the wind, so does our national security. No war planes will protect us if they do not have fuel.

It is interesting to note that we use fossil fuels both for transportation use as well as for electricity production. Since we can make fossil fuels easily transported (ie. diesel, gasoline, liquefied natural gas, etc.) it makes more sense to use them in transportation and use other resources such as biomass and solar at stationary power plants. This will make the U.S. less dependent on other countries for oil and will shield of from the volatility of oil supplies. Utilizing biomass for electricity allows more oil and natural gas to be held in reserves for transportation and military use. Therefore, biomass can increase our national security.

2. Stabilized Energy Costs
Diversification of energy sources provides a buffer for fluctuating energy prices. It goes back to the old adage: don’t put all your eggs in one basket. For example, Florida currently relies on natural gas for 62% of its electricity production. What happens when the day comes that natural gas prices double or triple due to supply and demand? Consumers will be stuck with higher prices until more affordable options can be integrated into the system. Biomass plants that are sprinkled throughout the country can offset such peaks in energy prices from other sources by supplying localized renewable power.

3. Reliability
In step with the last point, diversification of energy sources also provides greater reliability to the grid. The picture from the U.S. Energy Information Agency states that the fuel used for electricity production in 2012 was as follows:

This is a point where I believe America has really missed it. While clean air and renewability of resources are good things, I believe the idea of diversification alone is a greater benefit than any other. You can see that the major opportunities for growing diversification in electricity production lie within the renewable sector. If a major catastrophe were to disable a large power plant or stop a fuel supply, we would experience blackouts without a back-up plan. On the other hand, if more biomass plants along with solar, wind and other renewables were incorporated into the grid, we would rely less on the major fuel sources. I think this is huge. Renewable power facilities in general are built on a smaller scale and are less susceptible to causing major disruption if they were to go offline.

4. Environmental Benefits
It is widely accepted that burning biomass is a carbon-neutral process. This means that for all of the carbon that is released during combustion, the same amount was taken out of the atmosphere originally by that very same plant through photosynthesis. The result is no new carbon introduced to the atmosphere. With fossil fuels, all of the carbon has been locked away underground and is a true addition to today’s atmosphere if burned. Other environmental benefits include large reductions in nitrogen oxide and sulfur dioxide emissions compared with burning coal. All this means that using biomass puts less pollution in our atmosphere.

So there it is, a non-political analysis of the societal benefits of biomass. The cool thing is that the cost of fuel for biomass is not far off from other sources. A study back in 2001 found at eia.gov shows that biomass fuel was at $1.25 per million Btu while coal was at $1.23 per million Btu. Now I’m not saying that there are zero negative consequences of using biomass and that my analysis is all inclusive; I can assure you it’s not. What I am saying though is that I believe the benefits listed above are significant and can serve our society well. Whether your politics lean left, right or are nonexistent, there is wisdom in keeping an open mind with energy policy. There is wisdom in considering the big benefits of biomass.

Check out this video for a cool case study of biomass increasing forest health while producing local power:

Gasification vs. Direct Combustion? Which is better?

The picture above is a new biomass plant in Gainesville, FL that was commissioned in 2013. It burns wood from local sources and produces 100 MW of electricity when running at full capacity. It does not use gasification technology, but rather the conventional method of direct combustion of the wood that is used to produce steam that powers a generator. The word on the street is that gasification is a more efficient method of producing power than direct combustion that also produces less emissions due to cleaner burning. So why would a new plant be built using old technology?

If I were to answer quickly without research, I would say that it is probably another excellent example of how society has thrown common sense out the window. However, there are more forces at play here that cause us to take a closer look at the cost/benefit analysis of each type of process.

When it comes to producing electricity from biomass, the truth is that the world has a long history of using direct combustion and it is a proven technology. There are many suppliers that have improved the processes and drive each other to reduce the cost of their systems. This lower initial cost compared to a gasification system is a major reason to go with a traditional combustion system. In addition, a direct combustion plant is easier to operate, can handle a greater fluctuation in fuel quality and higher moisture content in the fuel. In other words it carries some of the simplicity of a bonfire, just throw the fuel in and the process will work itself out. Gasification on the other hand, needs very precise monitoring of system inputs for the proper chemical reactions to take place and additional equipment or design modifications to manage emission controls. It takes highly skilled personnel to manage the process. These factors increase the operation costs of a gasification plant.
Direct combustion systems are also proven on a much larger scale. For example, the 100 MW facility in Gainesville, FL is a typical size and can be built to produce 300 MW or more. Gasification does not have much experience on that scale. Most gasification manufacturers are building significantly smaller systems on the 10 to 100 kW range. These smaller systems are often utilized at localized facilities such as at hospitals, schools, sawmills and agricultural operations that are close to the fuel source.

With all of this talk about the glory of old-school direct combustion, why even bother with gasification? The answer is that if it is done correctly, we can get more energy out of a ton of wood via gasification versus direct combustion due to more efficient burning. During direct combustion one of the byproducts is carbon dioxide which is noncombustible. The chemical bonds inside of the CO2 molecule is energy that cannot be recovered. With gasification, one of the byproducts in synthesis gas is carbon monoxide. This chemical bond can be broken and releases additional energy. This is just one example of how we get more energy out of the same amount of biomass if gasification is used.

So here is the breakdown: Gasification is a more efficient, cleaner burning process that is a better option from an efficiency and emissions standpoint. It is also a more complicated system having higher initial costs and operating costs. These higher costs currently offset the greater efficiency of the system. Since this currently makes direct combustion and gasification systems similar economically, many customers are choosing to go with the system that is tested, proven and simpler. Also, let’s not forget that gasification systems have not been built on a large scale as of yet.

Moving forward, I see the gasification process becoming much better understood and much more accepted in the next 10 years. I envision gasification plants being utilized on a smaller scale thus reducing the transportation costs of the fuel. The new technology will be perfected and provide us with greater energy yields and less emissions. The benefits of using gasification of biomass keep adding up. It won’t be long before the cost benefit analysis will tip in the favor of gasification compared to direct combustion.

Check out this video produced by a major gasification equipment manufacturer in Europe that depicts the gasification process:

The Confusing Question: What is Gasification?

Technology is moving swiftly in the biomass industry and there are plenty of resources out there that will easily confuse you. If not you, then definitely me. Many articles and videos will leave you with more questions than answers. This is precisely what happened to me as I scoured the web trying to understand the process of gasification of biomass. So now I will share with you some of the questions in my head for which I have found answers.

First of all, let me start with the fact that gasification typically falls under two categories based on whether you are utilizing a wet biomass (i.e. manure, food waste, slaughter house waste) or dry biomass (i.e. wood waste, crop residue, urban solid waste). If it is wet, typically it is more advantageous to go through a biochemical process to extract energy out, typically as a liquid fuel. This is how the ethanol is produced that is in your gasoline right now. If you have dry biomass, the biomass process is typically a thermochemical conversion. That is a fancy way of saying that you heat up the biomass, which is a solid, and convert it to a combustible gas that is much more useful. So if you were tricked into thinking that biomass conversion was only from a solid to a liquid via a biochemical process or solid to a gas via a thermochemical process, you now know that biomass can be converted through either of these processes. Biochemical and thermochemical processes are completely different in every way, but they are both considered gasification and produce a useful fuel out of biomass as an end result. Confusing? Yeah me too.

So now that we have a grip on the different types of gasification process, we are going to safely put aside the biochemical process used on wet biomass and talk only about the gasification process of dry material. This process is similar to just burning wood or straw or whatever you have, but there is added complexity to the system. With gasification, the end goal is not to get thermal energy (heat) out of the wood. The end goal is to get the biomass to releases combustible gases contained within itself that can be captured, cleaned and able to be used much like natural gas is used today.

In order to get these gases to be released from the material, we apply heat that will break down the components of the material until you are left with carbon as a solid (approximately 20% of material by weight) and volatile gases (mostly hydrogen and carbon monoxide). The gases released are captured and can be used to create liquid fuels, to run engines, turbines for electricity, or simply for heating.

I am leaving out a lot of technical details about the gasification process, but if you watch the embedded video, you can learn about the very specific chemical reactions that are taking place inside of the combustion chamber. It’s a lengthy video but well worth it.

The one thing I want to leave you with is the biggest thing I learned about gasification. If you are as clever as I am, you might say to yourself, ‘If I have to supply energy (heat) in the first place to get the gases to be released in a gasification system, isn’t that counterproductive? After all, if the goal is to get usable energy as an end product, Why would I want to spend a bunch of energy to get it?’ Excellent question. This stumped me for days. Here is the answer: When you begin a gasification process, you must at first supply heat to get the process started. What many resources fail to mention is that the charcoal that is produced inside becomes very hot and eventually self-sustaining based on the chemical reactions taking place. At that point, an external heat source is no longer needed. The inputs become fuel and air and the outputs become a blend of combustible gases (known as syngas) and water. If you run the process efficiently, all the tars and other impurities are completely burned up and you are left with very little residue.

Hopefully I have given you some insight into your learning about gasification and what it is and cleared up some confusion. There are many processes and designs out there. The biochemical processes that we did not talk much about is a newer technology and is ever evolving. The thermochemical process is much better known. In fact, you can see a bunch of do-it-yourselfers creating gasifiers in their garages on YouTube videos. Both processes have a place in the energy needs of tomorrow and are guaranteed to become more efficient with time.

How can biomass be a cost effective alternative energy source?

Biomass has been used as an energy source for centuries.  Unfortunately though, starting fires to keep warm and for boiling our water is not going to help today’s energy needs.  Today’s energy demands are more complex and need a more sophisticated approach than just building a bonfire.  Even still, those chunks of trees can be just as useful today in producing our electricity as coal, petroleum, natural gas or any other energy source.  Let’s talk about how it can work.

Let’s put our focus in the comparison of biomass products versus traditional fossil fuels.  Today we rely heavily on fossil fuels for electricity production mostly due to the fact that it has been the most cost effective source of energy.  Why is it cost effective?  Well, the answers to that question are many, but there is one of great importance:  The energy per unit volume in fossil fuels is very high!  Coal has nearly twice as much energy per kilogram and natural gas has nearly 7 times more energy in 1 cubic meter than 1 kg of firewood.  That means you have to transport a lot more ‘firewood’ to get the same amount of energy output.

This leads to the fact that there will be a lot more transportation and storage costs for biomass compared to other energy sources because you need to use such a large quantity of it.  This has made biomass less appealing and is a large part of why it is not used as much as traditional fossil fuels for electricity production. This is not the sad ending of the biomass story and where the book gets closed.  On the other hand, we ask ourselves:  What does biomass have going for it?  The answer is that a) it is renewable b) it is very abundant in many areas and c) it’s free!

Okay not completely free.  But the truth is that in many places like my home state of Florida, there is a ton of biomass waste produced by tree service contractors, municipalities, forestry operations, and land development operations.  Unfortunately, a lot of this material gets buried, is burned on site, or taken to incinerators at nearby facilities.  I worked in the tree care industry for 10 years and have become very aware of the hassle and cost of hauling tree debris and paying disposal fees.  The cool thing about biomass plants is that they can be built on a smaller scale on a more local level.  It has been my understanding that the costs for transporting biomass for energy purposes increases greatly after about 75 miles.  What that means is that we can build biomass plants that pull in biomass material in a radius of 75 miles around itself.  This will keep the cost of transportation down, and there will be a steady flow of biomass into these plants on day one.  All of these contractors will gladly dump for free compared to paying dump fees at the local landfill.

Now I know that many places utilize wood waste more effectively and there are other markets that rely on wood waste such as mulching operations.  So in the future I recognize that there may come a time where the local biomass plant may need to purchase this same material simply due to supply and demand.   In the meantime, there is simply way to much material being discarded to ignore its potential.

So even though biomass is a bulky material that has not been cost effective compared to traditional sources, the truth is that we can overcome this barrier with a little bit of common sense.  In places like Florida,  there is so much tonnage of material produced everyday just to keep the trees from growing over roofs, into power lines, roadways and everything else.  Building smaller, more localized biomass plants could be an excellent option for keeping costs down and utilizing a readily available energy source.

-Josh

http://www.wbdg.org/resources/biomasselectric.php

Welcome! What are we doing here?

If you’re anything like me, you want to know a lot about a lot!  It’s possible that your the odd person who would rather do a quick search to learn something scientific than play Doodle Jump when you have a few extra minutes.  Well, be comforted and know that you are not alone.  I am dedicating this blog to my research into biomass technology and how much it can benefit society in the near future.  Check back soon for excellent information along with some attempt at humor….no guarantees.

-Josh