Biomass Gasification co-products breathe new life into gasification power applications.

By Jim Beck, Project Manager/Engineer, Precision Energy Services, Inc.

Biomass as a renewable energy source faces challenges in current regulatory markets in the US and abroad, due to current legislation focusing on energy storage for wind and solar renewable energy.  Biomass as a renewable energy resource needs an advantage when competing for investment capital for new projects.  Co-products formed when gasifying biomass is that advantage.

Gasification is the process that occurs when fossil or biomass fuel is heated without sufficient oxygen, which occurs between 550 C and 650 C in a fluid bed gasifier.  The process self-sustains temperature by fully reacting a portion of the fuel into carbon dioxide and water.  This heat causes the remaining biomass to break down in the absence of oxygen into primarily carbon monoxide and hydrogen, as well as lesser fractions of biochar and tar.  By tuning the fluid bed gasification process, up to 40% of the carbon present in biomass can be captured in the biochar, and prevented from fully converting into CO2.

Fluid bed gasifiers create a high-carbon biochar byproduct, (char produced from biomass).  Historically, this byproduct of gasification has been a waste stream, is extremely hard to handle and required disposal.  New research into using biochar has shown its applicability as a soil amendment, filtration medium, long-term carbon sequestration medium, feedstock for activated carbon production and many others.  These uses of biochar could not come at a more opportune time.  The world’s growing population creates constant need to improve the productivity of agricultural land, reduce the contamination of (or) improve the quality of rainwater runoff from roadways, reduce carbon emissions from power plants, and find more carbon neutral raw materials.

This recent evolution of biochar is changing the value of gasification systems. Historically, an energy plant had to justify the economics strictly on a single product, such as electricity, or heat. Given the global need for the power industry to reduce its carbon footprint, this char byproduct reduces the carbon footprint of biomass power plants, as well as produces a valuable byproduct to the plant’s energy output.  If this biochar is captured and marketed, it has the potential to generate a revenue stream which could match or exceed the value of the primary energy sales.   Depending on the properties of the biochar (carbon content, porosity, size distribution and others) the value of this product can range from $70 per short ton to as high as $2,500 per short ton.

Biomass as a renewable energy source also brings other benefits to the region in the form of providing a value to proper forest maintenance practices.  Normally, there is little motivation to remove this fuel from the forest, and given the difficulty to harvest timber in large areas due to political opposition, it accumulates until a wildfire occurs.  After a fire starts, the high concentration of fuel strengthens that fire, reduces air quality to dangerous levels, increases the damage to home and property, and drastically increases the cost to control that fire.  There have been many successful examples of proper harvesting practices which lower the risk and reduce the severity of forest fires, simply by the plant operating within normal conditions.

Biomass gasification power plants are key to the power industry of the future. There are numerous benefits that stem back to the use of biomass as a renewable energy resource using responsible and ecological methods.

There are a large number of beneficial and valuable uses of biochar, but it has not been commercialized to the fullest extent because of other products, primarily originating from the petroleum and petrochemical industry.  Biorefineries, which process the oils and tars created during biomass gasification into useable compounds, are subject to the economic roller coaster and control of competing crude oil prices.  Biomass has a high entry cost, and even when it is paid, it is usually only a matter of time for the cycle of crude oil and energy pricing to remove any economic incentive for these facilities to keep operating.  Therefore, to assure these biomass plants have the longevity to fulfill the needs of the power industry, they need more streams of revenue that are independent of the fluctuating price of crude oil.  Biochar provides that stream, but only if we recognize its potential and prioritize implementation of this model.