Sustainable Energy Systems Sustainable Energy Systems EngineeringEngineering

Peter GevorkianPeter Gevorkian

Ch 13: Biofuels and Biogas Ch 13: Biofuels and Biogas TechnologyTechnology

Brevard Community CollegeBrevard Community College

EST1830EST1830

Bruce HesherBruce Hesher

IntroductionIntroduction p283 p283

Biomass is the stored energy in plant and Biomass is the stored energy in plant and animal tissues and materials in chemical form.animal tissues and materials in chemical form.

The use of biomass as a source of energy The use of biomass as a source of energy dates back to the discovery of fire by humans.dates back to the discovery of fire by humans.

The Chemical Composition The Chemical Composition p283p283

The chemical composition of The chemical composition of biomassbiomass is is dependant on the various types of tissues found in dependant on the various types of tissues found in plant and animal species. In general, plant plant and animal species. In general, plant structures consist of 25% structures consist of 25% ligninlignin and 75% and 75% carbohydratescarbohydrates and sugars. Carbohydrates are and sugars. Carbohydrates are composed of many types of sugar molecules that composed of many types of sugar molecules that are linked together in long chains called polymers. are linked together in long chains called polymers. Lignin is the mortar that holds plants together and Lignin is the mortar that holds plants together and gives them physical structure.gives them physical structure.

Origins of BiomassOrigins of Biomass p284 p284

Biomass in nature is formed when carbon dioxide from Biomass in nature is formed when carbon dioxide from the atmosphere and water from the earth are combined in the atmosphere and water from the earth are combined in the photosynthetic process to produce carbohydrates and the photosynthetic process to produce carbohydrates and sugars. Energy from the sun drives the process and sugars. Energy from the sun drives the process and energy is stored in chemical bonds.energy is stored in chemical bonds.

COCO22 + H + H22O + trace minerals + solar energy O + trace minerals + solar energy biomass biomass

When biomass is burned energy is released:When biomass is burned energy is released:

OO22 + C + C CO CO22 + H + H22O + energy + ashO + energy + ash

This is a cyclic process ! This is a cyclic process !

High levels of COHigh levels of CO22 in the atmosphere promotes plant life! in the atmosphere promotes plant life!

Biomass Energy PotentialBiomass Energy Potential p285p285

The energy potential of biomass is enormous. It can be The energy potential of biomass is enormous. It can be made into electricity, liquid or gaseous fuels like ethanol, made into electricity, liquid or gaseous fuels like ethanol, solid fuels, etc. The energy density of biomass is less solid fuels, etc. The energy density of biomass is less than that of coal but it has less ash and heavy metals, so it than that of coal but it has less ash and heavy metals, so it burns cleaner. The ash content of biomass is much lower burns cleaner. The ash content of biomass is much lower than that of coal and it is relatively free of toxic metals.than that of coal and it is relatively free of toxic metals.

Ethanol fuel is ethanol (ethyl alcohol), the same type of alcohol found in alcoholic beverages. It is most often used as a motor fuel, mainly as a biofuel additive for gasoline.

See Energy Content chart on page 286.

Unintended Consequences

In the USA 40% of the corn grown in 2010 is being used for ethanol. This raises the cost of food! Corn is important for both human consumption and as a feed for livestock. Many countries are faulting the U.S. for squandering food on transportation.

There is only so much land in the U.S. that is suitable for growing corn. But there is a lot of unused land that is suited for growing other crops that can be used for biofuels; some of them are better than corn!

Benefits of Biomass EnergyBenefits of Biomass Energy p286p286

Biomass technology and the extended use of bioenergy Biomass technology and the extended use of bioenergy based fuels which maximize the use of otherwise based fuels which maximize the use of otherwise discarded agriculture, industrial, and animal waste can discarded agriculture, industrial, and animal waste can create industrial infrastructure and jobs. The U.S. create industrial infrastructure and jobs. The U.S. department of agriculture estimates that 17,00 jobs are department of agriculture estimates that 17,00 jobs are created for every million gallons of ethanol created.created for every million gallons of ethanol created.

5 quadrillion Btu’s of electricity on 50 million acres of land 5 quadrillion Btu’s of electricity on 50 million acres of land could increase farm income by $12 billion annually. Note: could increase farm income by $12 billion annually. Note: the U.S. consumes about 90 billion quadrillion Btu the U.S. consumes about 90 billion quadrillion Btu annually.annually.

Should this be promoted ?If so, should government do the promoting ?

Impact of Biomass Energy on Impact of Biomass Energy on Climate Conditions Climate Conditions p287p287

Burning fossil fuels releases gasses and particles into the Burning fossil fuels releases gasses and particles into the atmosphere. atmosphere. • Carbon Di-oxide (COCarbon Di-oxide (CO22) and methane (CH) and methane (CH44) are ) are greenhouse gasses. Methane is the more powerful but greenhouse gasses. Methane is the more powerful but lasts less time. COlasts less time. CO22 is removed from the atmosphere by is removed from the atmosphere by plants. Capturing landfill gasses, waste treatment gasses plants. Capturing landfill gasses, waste treatment gasses etc. can have positive impact on CHetc. can have positive impact on CH44 in the air. in the air.• Sulfur and nitrogen oxides form fossil fuels adds to Sulfur and nitrogen oxides form fossil fuels adds to acid rain. Burning cleaner fuels can help. acid rain. Burning cleaner fuels can help. • Planting biomass crops on marginal land can help Planting biomass crops on marginal land can help prevent soil erosion and water contamination.prevent soil erosion and water contamination.

Biomass TechnologiesBiomass Technologies p288p288

Microturbine Generators use very high internal Microturbine Generators use very high internal combustion pressure to provide rotational combustion pressure to provide rotational power to the shaft of an electric generator. power to the shaft of an electric generator. They can use a variety of gas or liquid fuels They can use a variety of gas or liquid fuels including: land fill gas, natural gas, and including: land fill gas, natural gas, and hydrogen.hydrogen.

Microturbine Overview

Commercially Available Yes (Limited)

Size Range 25-500 kW

Fuel Natural gas, hydrogen, propane, diesel

Efficiency 20-30% (Recuperated)

Environmental Low (<9-50 ppm) NOx

Other Features Cogeneration (50-80°C water)

Commercial Status Small volume production, commercial prototypes now.

Economic Benefits of Using Landfill Gas Economic Benefits of Using Landfill Gas p294p294

Landfill projects benefit all parties involved. Land owners, the local utility, and community. They initially provide construction jobs then once active provide electricity with low fuel costs.

Landfill Gas Conversion to Green Energy

The gas produced by the Cocoa Landfill (methane) is extracted through a vacuum system run by LES (Brevard Energy LLC) which in turn is connected to a power grid at the FP&L Facility(Oleander Plant) and converted to Green Energy.

Land Fill GasLand Fill Gas

Environmental Benefits of Using Environmental Benefits of Using

Landfill GasLandfill Gas p294p294

Converting LFG to energy offsets the need for Converting LFG to energy offsets the need for nonrenewable resources, such as coal and oil and reduces nonrenewable resources, such as coal and oil and reduces emission of air pollutants that contribute to smog and acid emission of air pollutants that contribute to smog and acid rain.rain.

Case Study of Successful Application Case Study of Successful Application of Microgenerator Technology of Microgenerator Technology p294p294

The HOD landfill in Antioch Illinois is a The HOD landfill in Antioch Illinois is a superfund site site consisting of approx. 51 acres of landfill. In 1998 the EPA consisting of approx. 51 acres of landfill. In 1998 the EPA issued a Record of Decision (issued a Record of Decision (ROD) that required specific ) that required specific landfill closure activities. It also required the installation of landfill closure activities. It also required the installation of a LFG collection system. The system has 35 dual gas a LFG collection system. The system has 35 dual gas extraction wells that produce 300ftextraction wells that produce 300ft33/min of LFG that is sent /min of LFG that is sent to a local high school where 12 microturbines use it to to a local high school where 12 microturbines use it to produce 369KW of electricity. Together with recovered produce 369KW of electricity. Together with recovered heat it meets most of the energy needs of the high school.heat it meets most of the energy needs of the high school.

Cal Poly Biogas Case StudyCal Poly Biogas Case Study p299p299

An interesting application of biogas in farming. Done by Cal An interesting application of biogas in farming. Done by Cal Poly Univ. in California. Converts animal waste to heat and Poly Univ. in California. Converts animal waste to heat and electricity using a microturbine. A farm with 300 cows and electricity using a microturbine. A farm with 300 cows and other animals kept the cows in a barn with a concrete floor. other animals kept the cows in a barn with a concrete floor. The manure is periodically washed into covered lagoons The manure is periodically washed into covered lagoons where it creates methane gas by anaerobic digestion. where it creates methane gas by anaerobic digestion. Digested biogas from the lagoon is compressed and dried in Digested biogas from the lagoon is compressed and dried in a desiccant tank and is then used by a Capstone 30KW a desiccant tank and is then used by a Capstone 30KW 440V microturbine that is connected to the grid. 440V microturbine that is connected to the grid.

The project cost $225K and The project cost $225K and produces $16K annually in the produces $16K annually in the value of electricity and heat it value of electricity and heat it produces.. This gives it a produces.. This gives it a financial payback of about 14 financial payback of about 14 years.years.

Biomass Energy Biomass Energy p301p301

For thousands of years people have used biomass in the For thousands of years people have used biomass in the form of burning wood for heat and to cook food without form of burning wood for heat and to cook food without impact to the environment. Plants remove CO2 and impact to the environment. Plants remove CO2 and replenish O2 and the system was in balance. The rate at replenish O2 and the system was in balance. The rate at which CO2 and other gasses are being produced in which CO2 and other gasses are being produced in modern times may be a source of concern. The use of modern times may be a source of concern. The use of biomass energy such as plants, agriculture waste, forestry biomass energy such as plants, agriculture waste, forestry and lumber residue, commercial and industrial waste help and lumber residue, commercial and industrial waste help to offset theses concerns.to offset theses concerns.

Biofuels ProductionBiofuels Production p302p302

There are several processes used to create Biofuels:There are several processes used to create Biofuels:

Pyrolysis: a method of processing a base fuel to produce a : a method of processing a base fuel to produce a more efficient one. Involve the heating of the original fuel more efficient one. Involve the heating of the original fuel material in the absence of air to temps of 300-500°C until the material in the absence of air to temps of 300-500°C until the volatile matter has been evaporated. The residue is often volatile matter has been evaporated. The residue is often charcoal which has about twice the energy density of the charcoal which has about twice the energy density of the original material and burns at a higher temperature.original material and burns at a higher temperature.

A thermal degradation of carbonaceous material in an A thermal degradation of carbonaceous material in an oxygen-free reactor. Pyrolytic oils, fuel gas, chars, and ash oxygen-free reactor. Pyrolytic oils, fuel gas, chars, and ash are produced in quantities that are highly dependent on are produced in quantities that are highly dependent on temperature, residence time, and the amount of heat applied.temperature, residence time, and the amount of heat applied.

GasificationGasification: based upon the extraction of flammable gas : based upon the extraction of flammable gas mixtures of hydrogen, carbon monoxide, methane, and mixtures of hydrogen, carbon monoxide, methane, and other nonflammable by-products from coal and wood. The other nonflammable by-products from coal and wood. The process involves partially burning and partially heating the process involves partially burning and partially heating the biomass in the presence of charcoal. When produced, biomass in the presence of charcoal. When produced, gases are compressed and liquefied a d used as a gases are compressed and liquefied a d used as a substitute for gasoline. Such fuels generally reduce the substitute for gasoline. Such fuels generally reduce the power output of a car by about 40%!power output of a car by about 40%!

Synthetic FuelsSynthetic Fuels: Made by a : Made by a gasification process that involves gasification process that involves oxygen rather than air. Produces oxygen rather than air. Produces mainly H2, CO, and CO2. When mainly H2, CO, and CO2. When the CO2 is removed the the CO2 is removed the remaining is synthetic gas. remaining is synthetic gas.

Ethanol: A very high energy fuel used as a direct substitute Ethanol: A very high energy fuel used as a direct substitute for gasoline. The fuel that is produced from fermentation of for gasoline. The fuel that is produced from fermentation of the sugar solution left over in the sugar cane or beet the sugar solution left over in the sugar cane or beet harvest; has been successfully produced in large quantities harvest; has been successfully produced in large quantities in Brazilin Brazil

Some Interesting Facts About BioenergySome Interesting Facts About Bioenergy p306p306

According to the CEC, California produces 60 million tons According to the CEC, California produces 60 million tons of biomass each year, only 5% of which is burned to of biomass each year, only 5% of which is burned to generate electricity. If all of it were burned; 2000MW or generate electricity. If all of it were burned; 2000MW or enough energy for 2 million homes would be produced.enough energy for 2 million homes would be produced.

As of 2010 biomass provides about 3-4% of the U.S. As of 2010 biomass provides about 3-4% of the U.S. energy needs. By 2020 this is expected to be 7%.energy needs. By 2020 this is expected to be 7%.

BiodieselBiodiesel p307p307

Considered one of the most promising alternatives to petroleum based Considered one of the most promising alternatives to petroleum based diesel fuel. Looks like yellow cooking oil. It is made from vegetable oil or diesel fuel. Looks like yellow cooking oil. It is made from vegetable oil or animal fats. Chemically it is a combination of long chain fatty acids known animal fats. Chemically it is a combination of long chain fatty acids known as monoalkylesters. The process of producing biodiesel is called trans-as monoalkylesters. The process of producing biodiesel is called trans-esterification, which involves removal of esters or fatty acids. Upon esterification, which involves removal of esters or fatty acids. Upon completion of the process biodiesel becomes combustible!completion of the process biodiesel becomes combustible!

Biodiesel has a flash point Biodiesel has a flash point of 150°C. Gasoline has a of 150°C. Gasoline has a flash point of 45°C, and flash point of 45°C, and petroleum has a flashpoint petroleum has a flashpoint of 64°C. OSHA classifies of 64°C. OSHA classifies biodiesel as a non-biodiesel as a non-flammable liquid.flammable liquid.

Fluidized Bed BoilersFluidized Bed Boilers p309p309

Based on a mixture of limestone and coal. The limestone acts Based on a mixture of limestone and coal. The limestone acts as a sponge to absorb the sulfur and other pollutants in the coal. as a sponge to absorb the sulfur and other pollutants in the coal. As coal burns in a fluidized bed boiler. It releases sulfur; As coal burns in a fluidized bed boiler. It releases sulfur; however the tumbling action of the limestone around the coal however the tumbling action of the limestone around the coal captures the sulfur. The chemical process of the limestone captures the sulfur. The chemical process of the limestone capturing the sulfur results in calcium sulfate powder that can be capturing the sulfur results in calcium sulfate powder that can be removed from the boiler. The calcium sulfate can then be used removed from the boiler. The calcium sulfate can then be used in the production of drywall for construction. Fluidized boilers in the production of drywall for construction. Fluidized boilers can burn very “dirty” coal and remove 90% of the sulfur and can burn very “dirty” coal and remove 90% of the sulfur and nitrogen pollutants. nitrogen pollutants.

Over 300 installations of fluidized boilers are in use in the Over 300 installations of fluidized boilers are in use in the U.S.U.S.

See this DOE article on fluidized bed boilersSee this DOE article on fluidized bed boilers