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: