Biomass Energy Prof Park UTI 111 Essex County College How Biomass Energy Works To many people the most familiar forms of renewable energy are the wind and the sun But biomass plant material and animal waste supplies almost 15 times as much energy in the United States as wind and solar power combined and has the potential to supply much more There are a wide variety of biomass energy resources including tree and grass crops and forestry agricultural and urban wastes It is the oldest source of renewable energy known to humans used since our ancestors learned the secret of fire What is Biomass Biomass is a renewable energy source because the energy it contains comes from the sun Through the process of photosynthesis chlorophyll in plants captures the sun s energy by converting carbon dioxide from the air and water from the ground into carbohydrates complex compounds composed of carbon hydrogen and oxygen When these carbohydrates are burned they turn back into carbon dioxide and water and release the sun s energy they contain In this way biomass functions as a sort of natural battery for storing solar energy As long as biomass is produced sustainably with only as much used as is grown the battery will last indefinitely How Biomass Energy Works From the time of Prometheus to the present the most common way to capture the energy from biomass was to burn it to make heat steam and electricity But advances in recent years have shown that there are more efficient and cleaner ways to use biomass It can be converted into liquid fuels for example or cooked in a process called gasification to produce combustible gases And certain crops such as switchgrass and willow trees are especially suited as energy crops plants grown specifically for energy generation Types of Biomass Energy Crops Trees Grasses Other crops Oil plants Biomass Residues Forestry Agriculture Cities Energy crops Energy crops also called power crops could be grown on farms in potentially very large quantities just like food crops Trees and grasses particularly those that are native to a region are the best crops for energy but other less agriculturally sustainable crops such as corn tend to be used for energy purposes at present Converting Biomass to Energy The old way of converting biomass to energy practiced for thousands of years is simply to burn it to produce heat This is still how most biomass is put to use in the United States and elsewhere The heat can be used directly for heating cooking and industrial processes or indirectly to produce electricity The problems with burning biomass are that much of the energy is wasted and that it can cause some pollution if it is not carefully controlled Converting Biomass to Energy An approach that may increase the use of biomass energy in the short term is to burn it mixed with coal in power plants a process known as co firing Biomass feedstock can substitute up to 20 percent of the coal used in a boiler 3 The benefits associated with biomass co firing include lower operating costs reductions of harmful emissions and greater energy security Co firing is also one of the more economically viable ways to increase biomass power generation today In 2000 the Chariton Valley Biomass Project a joint effort including Alliant Energy the U S Department of Energy and local biomass groups began testing the co firing of switchgrass with coal at Alliant s Ottumwa Generating Station in Iowa The project has proved so successful that in 2005 Alliant received permission to build a permanent biomass processing facility at the plant capable of co firing up to five percent of its energy with switchgrass 4 Converting Biomass to Energy A number of non combustion methods are available for converting biomass to energy These processes convert raw biomass into a variety of gaseous liquid or solid fuels that can then be used directly in a power plant for energy generation The carbohydrates in biomass which are comprised of oxygen carbon and hydrogen can be broken down into a variety of chemicals some of which are useful fuels This conversion can be done in three ways Thermo chemical Bio chemical Chemical Thermo chemical Conversion When plant matter is heated but not burned it breaks down into various gases liquids and solids These products can then be further processed and refined into useful fuels such as methane and alcohol Biomass gasifiers capture methane released from the plants and burn it in a gas turbine to produce electricity Another approach is to take these fuels and run them through fuel cells converting the hydrogen rich fuels into electricity and water with few or no emissions Biochemical Conversion Bacteria yeasts and enzymes also break down carbohydrates Fermentation the process used to make wine changes biomass liquids into alcohol a combustible fuel A similar process is used to turn corn into grain alcohol or ethanol which is mixed with gasoline to make gasohol Also when bacteria break down biomass methane and carbon dioxide are produced This methane can be captured in sewage treatment plants and landfills for example and burned for heat and power Chemical Conversion Biomass oils like soybean and canola oil can be chemically converted into a liquid fuel similar to diesel fuel and into gasoline additives Cooking oil from restaurants for example has been used as a source to make biodiesel for trucks A better way to produce biodiesel is to use algae as a source of oils McNeil Power Station In 1998 the first U S commercial scale biomass gasification demonstration plant based on the SilvaGas process began at the McNeil Power Station in Burlington Vermont 5 The SilvaGas process a particular form of biomass gasification indirectly heats the biomass using heated sand in order to produce a medium Btu gas The McNeil power station is capable of generating 50 MW of power from local wood waste products One persistent myth about biomass is that it takes more energy to produce fuels from biomass than the fuels themselves contain In other words that it is a net energy loser In fact most of the studies done over the past 10 years confirm that the production of ethanol has a positive energy balance According to a 2002 U S Department of Agriculture study technological advances in ethanol conversion and efficiency increases in farm production have caused the net energy value NEV of corn ethanol to increase gradually over time 6 7 This study states that every British thermal unit BTU of energy used in the