Biohydrogen Production can come from Renewable Wastes such as Food Processing, Dairy, Industry Wastewater, Animal Manures and Crop Residues

The production of biohydrogen can take place with a number of different types of microorganisms, whether they be algae or bacteria. Biohydrogen production can be phototrophic or hetereotrophic, meaning one can produce hydrogen using sunlight or instead use dark fermentation, which is hetereotrophic cultivation. The method of dark fermentation for hydrogen production using microbes can use a wide variety of carbon based feedstocks, therefore much research has already been done with food processing, lignocellulosic, manure or food wastes for hydrogen production. There are a large number of industries where these types of wastes are generated. The wastes from the above mentioned sources are also considered renewable resources. Renewable wastes used for hydrogen production can come from such food processing sources such as the potato, sugar, wheat, soybean, olive and dairy industries [ 1. Ozgur et al 2010 ]. The more effective types of waste sources include those which have high sugar or carbohydrate content which is typical of crops such as sugar beets, sweet sorghum, sugarcane, wheat and potatoes. Other useful sources for dark fermentation would include many of the same wastes that would be used for producing compost, this includes food, cellulosic and manure wastes. Fruit wastes such as cranberry or apple processing types can be utilized towards compost material or converted into useful health supplements or neutraceuticals. Compost and biohydrogen would share similar waste resources due to the high carbon to nitrogen (C to N) ratio, this would include mostly carbohydrate and lipid sources. Food wastes are a great source for compost and biohydrogen but could also be used to make chemicals like lactic acid or also used to produce bioenergy [ 2. Chong et al 2009 ]. Sources such biodiesel glycerine waste are also legitimate sources that could be used for biohydrogen. Again, like other renewable waste resources, biodiesel glycerine should find a large number of uses, for fermentation purposes alone. Another area where renewable waste is utilized frequently is animal feed. The same crop or food processing wastes could be used for either animal feed or biohydrogen production, similar to the previous comparison above with compost. For example, potato processing makes food stuffs such as french fries and potato chips but also leaves a lot of waste material in the form of peels and pulp which can be used as animal feed. It can be ensilaged and processed like corn stover to make the animal food. However, as also mentioned above, potato processing waste is high in carbohydrates which makes it a prefferable fermentation source for biohydrogen.

In addition, many types of food processing wastes generate two types of fermentable feedstocks which are solid based types such as pulps, but just as importantly they generate processing effluent or wastewater. Wastewater from food processing has a good amount of carbon based chemicals such as the case with dairy wastewater. It is generated from the processing and cleaning of dairy facilities and contains waste products such as milk, lactose, fat and proteins. Dairy wastewater, like other sources are also an environmental concern and are often treated in areas such as lagoons or ponds. An excess of suspended solids can create pollution problems in fresh water bodies where chemical conditions are changed such as Biological Oxygen Demand (BOD). Companies often specialize in treatment equipment or technologies to process wastewater effluent before it reaches fresh water bodies. Adding a process such as biohydrogen production may also be another method for wastewater treatment from industry. Organic based wastewater can be generated from processing plants such as palm oil, apple, sugar and tofu. Cellulosic waste from crop residues such as sweet sorghum and corn stover is another likely candidate for hydrogen dark fermentation but could also be used to make further biofuels such as continued ethanol production. It may also be possible to reuse wood based product waste for hydrogen fermentation. Studies have been done using bioreactor sytems with a variety of the above waste feedstock sources to determine which types produce a higher volume of hydrogen production [ 3. Gao et al ]. Of most sources it was found that cheese whey waste and swine manure produced a larger amount of hydrogen per bioreactor system. It was also determined that cattle based manure produced more hydrogen than dairy manure. In summary, biohydrogen can be made from a large array of renewable waste resources. However, many of these waste resources are already implemented to make compost, animal feed, further biofuels, bioenergy and further chemicals from fermentation. For example, sugar beet waste can be used to make pharmaceutical products, livestock feed or ethanol production. Sugarbeet wastewater also already has uses such as irrigation. In other industries such as dairy, there are multiple sources of fermentation renewables in the form of manure, wastewater and whey. Wastewater effluent from industries that contain organics are a logical area for biohydrogen since they serve the dual purpose of remediation and energy production. Overall economics, practical implementation and policy decisions may determine the production of biohydrogen from renewable waste resources.

REFERENCES

1. "Potential Use of Thermophilic Dark Fermentation Effluents in Photofermentative Hydrogen Production by Rhodobacter Capsulatus", Journal of Cleaner Production Vol 18 No 1 pgs S23-S28 [2010] by E. Ozgur, N. Afsar, T. Vrije, M. Yucal, P. Clausen, I. Eroglu

2. "Biohydrogen Production from Biomass and Industrial Wastes by Dark Fermentation", International Journal of Hydrogen Vol 34 pg 3277-3287 [2009] by M. Chong, V. Sabaratnam, Y. Shirai, M.A. Hassan

3. "Hydrogen Production from Agricultural Waste by Dark Fermentation", International Journal of Hydrogen Energy Vol 35 Issue 19 SI pgs 10660-10673 [2010] by X. Gao, E. Trably, E. Latrille, H. Carrere. J.P. Streyer

Photos taken from Picasa Web Album and NASA photo archive

KEYWORDS: Hydrogen Generation from Renewable Wastes, Crop Residues, Cellulosic and Lignocellulosic Wastes, Dairy and Cattle Manure, Dark Fermentation, Biohydrogen Production, Food Processing Waste, Dairy Wastewater, Biodiesel Waste Glycerine, Cheese Whey, Carbohydrate Based Food Processing Wastes, Sugar Beets, Potato Processing Waste, Sweet Sorghum, Tofu, Fruit & Citrus Wastes

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Corn Stover Most Abundant Crop Residual that can be used for Vehicle Fuels, Electrical Energy and Chemicals

Corn stover is the residual crop material left over after the harvesting of corn which consists of the other parts of the corn plant which are the stalks, leafs, cobs and husks. Some of these plant residuals are left to lie on the corn fields to help mulch the soil before the next planting period. However, corn stover has been collected after corn harvests in the past and reused to produce other chemicals and products. For example, due to the fiber content of corn stover, some of it was processed as non-wood fiber pulping which can be converted into other products. Even currently, the fiber processed from corn stover is being considered as use in particleboard manufacturing. Under current farming conditions and practices, corn stover is collected or produced at around 100 million tons per year. According to the USDA and DOE, this figure could increase dramatically within the next decade if corn yields are increased and farming technology is improved. The government estimates that at least 170 - 256 million tons of corn stover could be produced every year according to the USDA billion ton study, corn stover would definitely be the largest plant crop residual renewable resource in the United States. There are certain obstacles that make the use of large amounts of corn stover not as realizable. For example, since corn stover can only be collected once per year, it must be transported and stored properly before it can be bioprocessed. One of the challenges involved is ensuring that it is dry. The use of corn stover has now expanded into energy and fuels production as well as the continued production of chemicals. This essay attempts to demonstrate some of the practical uses of corn stover. One method that corn stover can be stored and partially processed into useful chemicals or energy is the ensilage process. Ensilage packs corn stovers into silos and fermentation of the stover then proceeds with the natural microorganisms. Ensilage is a method that is being used to produce hydrogen for a 1.5 kW fuel cell power plant in Germany. The ensilage process allows the corn stover to be converted into biogas through anaerobic fermentation, the biogas is then converted into hydrogen. Ensilage is also a method that could produce adequate amounts of a chemical called lactic acid which can then be further converted into poly lactide plastics or ethyl lactate. This is usually done with regular corn starch which is full of sugars which lactic acid bacteria need to make lactic acid.

The ensilage process could also make large amounts of lactic acid if other enzymes from fungi are seeded with the corn stover. Fungi such as Trichoderma Reesei or Aspergillus Niger could be grown and placed with the stover as it is going through the fermentation process to ensure that sugars from its cellulose and hemicellulose content are hydrolyzed [ 1. Ren et al 2007 ]. PLA based platics are one of the fastest growing biobased plastics on the market made from lactic acid. Another valuable chemical that can be extracted from corn stover are furfurals. These compounds are oftentimes extracted from wood and other materials that have hemicellulose content where the pentose sugars are extracted and converted into furfurals through processes like steam distillation. Furfurals constitute a large subset of plastics that are made partially from natural sources. Furfurals are mixed with a number of other chemicals such as acetone, other ketones, alcohol, phenol and aniline to make furfural based resins [ 2. Brady 1991 ]. Corn stover can also be densified in the future to produce fuel and further power and heat known as combined heat and power (CHP). The University of Minnesota is working with densified corn stover which are in the form of pellets, to show it is a legitimate fuel that can be gasified to produce electricity and heat. Corn stover is also being experimented by the government in large bioethanol refineries that can produce multi million gallons of ethanol per year along with other sources such as switchgrass. Corn stover can also be used to produce butanol, which has been considered as another alcohol based fuel source for vehicles. Butanol can be made through a process known as ABE (Acetone Butanol Ethanol) Fermentation. Other companies may also use corn stover in order to gasify it as a Fischer-Tropsch process to make biobased alternative fuels such as jet fuel. Overall, there are numerous alternative products that corn stover can produce that have not been mentioned, the uses outlined in this essay are not an exhaustive list. It is meant to provide information on how useful corn stover will become in future generations to help produce electricity, heat & power, plastics and vehicle fuels - all areas in which renewable resources such as crop residues can help solve our alternative product and energy needs when replacements for petroleum are needed.

REFERENCES

1. "The impact of enzyme characteristics of corn stover fiber degradation and acid production during ensiled storage", Applied Biochemistry and Biotechnology Vol 137 pgs 221-238 [2007] by H. Ren, K. Moore

2. Materials Handbook 13th Edition [1991] pg. 361 by G. Brady, H. Clauser

Photos taken from one of NREL photo archives

KEYWORDS: corn stover, poly lactic acid, furfurals, ethanol biorefineries, butanol ABE fermentation, ensilage of corn stover, ensilage fermentation of corn stover with fungi, Fischer-Tropsch, Combined Heat and Power with corn stover, fuel cell power with corn stover, USDA billion ton study, crop residues as renewable resources, corn stover use for energy and fuel

Petroleum Coke is a good Resource for Electrical Energy Generation due to its Price, Availability and its Ability to Produce Hydrogen

Petroleum coke is the residual material from the processing of heavy oils at refinery plants. The petroleum coke is a byproduct of the oil cracking process which converts the heavy oils into further fuels or products. However, in addition, sometimes the heavy oils must be pre-processed by other manufacturing stages known as Flexicoking or Delayed Coking unit operations [ 1. Trommer et al 2005 ]. The use of Petroleum Coke used as fuel in electrical power plants has been steadily increasing since 1995 according to the figure shown above [ 2. EIA 2009 ]. In fact, the use of petroleum based liquids such as distillate oils or diesel has declined markedly during this time period also, maybe due to the fact that alternative carbon based power sources are being used instead. The combustion of petroleum liquids causes more pollution, carbon dioxide emissions and particulates than other means of electrical generation such as Gasification. Although petroleum coke does have some metal content as well as a good amount of sulfur content (~ 5 %), but is still good to use due to its in gasification technology along with calcinization that may help to alleviate the high sulfur content. Coal and other carbon sources have been used in cleaner electrical generation from the use of Circulating Fluidized Bed CFB Boilers. Petroleum coke has also been used in mills such as Pulp and Paper as well as Cement and Brick kilns [Same Internet Reference as Above]. In order for Petroleum Coke to be used effectively in CFB units it must be sold in its Pulverized form, like what is required with coal to operate in CFB's. Even though Petroleum Coke may not be considered a renewable resource by many since it is produced by the Petroleum industry, it is cheap carbon source that should be taken advantage of to produce electrical power.

Like coal, Petroleum Coke may usually be transported by rail not far from the place of its generation. In fact, it appears that only around less than 20 states implement the use of Petroleum coke for power generation according to the EIA. This may mostly be due to the fact that it is not transported far from the places of its generation, which are oil refineries. Petroleum coke also has the advantage in that it can be used to generate hydrogen for electrical fuel cell generation, which is also a cleaner renewable energy based technology. In most of these systems, petroleum coke would also be gasified and then steam reformed into synthesis like gas where hydrogen is then produced. Hydrogen produced from the synthesis gas from petroleum coke has been experimented with solar reactors as well as molten carbonate type of fuel cells [ 3. Trommer 2005 & Cherepy et al 2005 ]. There has also been mention for the use of petroleum coke based power plants in sequestering carbon dioxide by putting it underground near oil wells. This would help to replenish an existing oil well that is partially depleted. Since many oil refineries may be near oil wells, it may make sense to use petroleum coke as an energy source near oil wells and oil refineries. An advantage of petroleum coke is that it is a cheap source of energy and it may be abundant. It is said that petroleum coke is less expensive as an energy source than natural gas. It is uncertain by the author what other products petroleum coke is used as other than electrical energy generation. It is known that coal based coke is used in producing other types of products, somewhat from the tars that are generated. Even though petroleum coke is derived from the petroleum industry, it is a potential energy source that can be used in electrical energy generation, whether it drives turbines or produces hydrogen for fuel cells. The fact that it is cheap and abundant makes it an ideal energy source to help solve our sustainable energy needs.

REFERENCES

1. "Hydrogen Production by Steam-Gasification of Petroleum Coke using Concentrated Solar Power - I. Thermodynamic and Kinetic Analysis", International Journal of Hydrogen Energy Vol 30 No 6 pgs 605-618 [2005] by P.Trommer, F.Noembrin, M.Fasciana, D.Rodriguez, A.Morales, M.Romero, A.Steinfeld

2. "Net Generation by Energy Source", Energy Information Administration (EIA) [2009]

3a. Same as Reference #1

3b. "Direct Conversion of Carbon Fuels in a Molten Carbonate Fuel Cell", Journal of the Electrochemical Society Vol 152 issue 1 pgs A80-A87 [2005] by NJ Cherepy, R. Krueger, AF Jankowski, JF Cooper

KEYWORDS: Petroleum Coke, Sulfur and Metal Content in Petroleum Coke, Hydrogen Generation from Petroleum Coke, Heavy Oil Refinery, Carbon Sequestration in Underground Wells, Solar Generators of Synthesis Gas, Price and Abundance of Petroleum Coke, Circulating Fluidized Beds, Pulverized Petroleum Coke, Pulp and Paper Mills, Cement and Brick Kilns, Products from Petroleum Coke, Electrical Generation from Petroleum Coke

Photos taken from Picasa and graph generated from EIA source 2009 data

Three types of Biofriendly Solvents can use Renewable Resources, are Biodegradable or are Good Cleaning Solvent Candidates

Several types of alternative solvents may be favorable in the future due to environmental factors, practical applications and the use of renewable resources that could be used to produce them. Many different types of solvents can be made from renewable carbon based feedstocks, but overall it comes down to economics or whether bio-based solvents can be made just as cheaply. Many years ago, this wasn't even a consideration as biobased solvents cost at least several times more than petroleum based solvents. Advancements in process technologies and materials are allowing bio-based solvents to be made a bit more cost competitive. In this essay, three types of eco-friendly alternative solvents are examined towards practical applications that will be very much in demand. These solvents are also compared as to their biodegradability and reuse of renewable resources. These three types of solvents are proplene carbonate, ethyl lactate and methyl soyate. The first two can be made from renewable resources and the last is made from plant sources. While the last two are mainly biodegradable, therefore their practical usage could be meant for cleaning purposes with solvents. Soy esters and ethyl lactate can be used in formulations for various types of cleaning products, where usually just a component is made from one of these types of biosolvents. Products using these solvents are sold on the markets, the other day I found cleaner advertised to contain ethyl lactate that was an epoxy & adhesive cleaner. Ethyl lactate could be used in more cleaning products but it's cost of production is fairly high compared to other cleaning solvents. For example, methylene chloride costs around 30-35 cents per pound while it costs around $1.50 - $2.00 per pound to make ethyl lactate [ 1. K. Watkins 2002 ]. Of course, this was several years ago and it has been claimed that improvements in technology are cutting these costs by close to half. Ethyl lactate can be made with carbohydrate renewable resources that produce lactic acid from fermentation. Ethyl lactate is very non-toxic and friendly towards the environment and human health. For example, even though it is a volatile organic chemical it would not cause atmospheric pollution such as ozone depletion, in addition, the FDA considers Ethyl Lactate so non-toxic for human consumption that it could be used as an ingredient in food products [ 2. S. Aparacio et al 2009 ].

Soybean based esters like those used in biodiesel are made from crushed soybean oil. Soy esters like Methyl Soyate can then be produced and be used in a number of cleaning product formulations such as those used in cleaning applications like degreasing parts, concrete & graffiti surface cleaners, ink & adhesive removers and parts washing. Since methyl soyate is made directly from soybeans it is not considered as produced from renewables, but it is an attractive solvent because it has low eco-toxicity and may have other environmentally friendly applications such as it's use as a specific lubricant. Propylene carbonate is a solvent that can be partially made from renewable sources. It has many favorable properties as use for a solvent such as a high boiling point. Propylene carbonate can be made from the combination of an epoxide and carbon dioxide produced over a catalyst [ 3. Z. Bu et al 2010 ]. Carbonates in general could be used in helping to make products from organic synthesis reactions when used as a supporting solvent or even chemical feedstock. For example, DMC (dimethyl carbonate) - can replace Phosgene in chemical synthesis reactions. Phosgene is known as a toxic chemical. Carbonate solvents themselves can serve as starting materials for the production of plastics called polycarbonates which are used in a large number of goods which include automotive materials and electronic parts [ 4. J. Parrish et al 2000 ]. Most of the these eco-friendly can be used in a variety of applications such as those mentioned for carbonate solvents. In fact, several types of carbonates are used as electrolyte material in batteries. Ethyl lactate also has a variety of purposes in the semiconductor and electronics industry, as it can be used to exclusively clean electronic parts replacing the need to use halogenated type solvents it can also be used as a solvent to produce various electronic devices. These environmentally friendly solvents can help drive forth the use of renewable resources towards the end of sustainable products which do not solely rely on petroleum resources. The practicality towards their use comes down to overhead costs and experimental imagination towards their practical application. For example, the biomedical and pharmaceutical areas also have great if not greater needs to implement the use of 'Green Solvents' towards production. A large goal of these industries is to become very eco-friendly in a matter of decades. The use of soybeans for alternative products other than food products becomes a questionable issue, however, the author feels that they should be acceptable for overall use until better natural products are invented towards similar product purposes.

REFERENCES

1. "A Solvent Business: Ethyl Lactate Seeks to Replace Work horses like Acetone and Methylene Chloride" Chemical and Engineering News vol 80 no 2 pgs 15-16 [2002] by K. Watkins

2. "The Green Solvent Ethyl Lactate : An Experimental & Theoretical Characterization" Green Chemistry vol 11 pgs 65-78 [2009] by S. Aparacio, R. Alcalde

3. "Synthesis of Propylene Carbonate from Carbon Dioxide using trans-dichlorotetrapyridine-ruthenium III as catalyst" Applied Organicmetallic Chemistry vol 24 issue 11 pgs 813-816 [2010] by Z.Bu, Z.Wang, L.Wang, S.Cao

4. "Perspectives on Alkyl Carbonates in Organic Synthesis", Tetrahedron vol 56 pgs 8207-8237 [2000] by J.Parrish, R.Salvatore, KW Jung

KEYWORDS: Ethyl Lactate, Methyl Soyate, Soybean Ester Solvents, Propylene Carbonate, Dimethyl Carbonate, Carbon Dioxide used to Produce Solvents, Cleaning Solvents, Degreasing and Parts Cleaning Solvents, Solvents in Electronic Industry, Polycarbonates, Production of Solvents using Renewable Resources, Eco-friendly Solvents, Biodegradable Solvents, Non-Ozone depleting Solvents

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Densification of Biomass May Aide in Manufacture of Fuels and Chemicals in Thermochemical Biorefiniries

The densification of biomass involves the grinding, separating and compacting of biomass into small pellets or cubes. This technology is already being used to densify biomass into pellets for use in stoves that have the ability to create electricity and heat, also known as combined heat and power (CHP). The densification of biomass can also be applied towards the biochemical conversion of biomass into fuels, chemicals and electrical energy through the use of related gasification technologies, of which there are several to choose from. Some gasification technologies include Pyrolysis, Fischer-Tropsch and Mixed Alcohol production. Densification may be the favorable form to produce biofuels through gasification. For example, one type of gasification technology called pyrolysis can convert biomass into several different chemical fractions that can be separated and used towards electricity, chemicals or fuels. In one pyrolysis study, three types of chemical fractions were produced from cellulosic materials, those being 1)synthesis gas components, 2) Light condensables which consist of acids, ketones and alcohols and 3) tar like fraction that consists of furan compounds, phenolics and other chemicals [ 1. E. Soltes 1988 ]. Densification of biomass could be applied towards the simultaneous production of electricity and other chemicals such as mixed alcohols and hydrocarbons from synthesis gas, which are emerging production methods. Sythesis gas produced from gasification can also be converted into Naptha or diesel fractions through the use of Fischer-Tropsch technology. Thermochemical processing of biomass into fuels should also allow the production of cellulosic ethanol to reach around $1.00 per gallon. In fact, the use of thermochemical based biorefineries may be needed in order to produce ethanol at very high quantities as well as becoming energy efficient by producing heat and power for related refining processes.

If large enough biorefineries are built such as those that can process 100 + Mega Million (MM) Gallons of ethanol per year, they should be able to make enough electrical power that can be put back into the electric grid. There are various other benefits to densifying biomass. It is easier to transport and store biomass when it is densified, this helps to deliver and transport biomass to thermochemical processing plants effectively. This is due to the fact that biomass in its loose, original form is irregular shaped or spatially scattered which makes it difficult to collect and store [ 2. J. Singh et al 2010 ]. In addition, densification reduces moisture content and reduces material waste in handling. However, the cost of densification into pellets or other forms makes it impractable currently for its use in biorefineries. For example, a densification plant that uses corn stover may be able to produce pellets at around $60 per ton but large biorefineries such as those operated by the government, may be able to purchase corn stover at a cost of only $35 per ton [ 3. Aden 2007 DOE ]. The ideal crop residues to use for densification may be corn stover as well as straw residues like wheat, barley, oat and canola and energy crops such as switchgrass [ 4. S. Mani et al 2006 ]. It is however, more difficult to use lignocellulosic based residues due to the tar material that must be cleaned as it is gasified. The conversion of municipal waste into electricity, fuels and chemicals may also be another source of potential fuels from refuse derived fuel (RDF) that must also be densified in order to be processed thermochemically. Municipal waste processing plants are already being built that can convert around 2000 tons of RDF per day into mixed alcohols using thermochemical gasification.

REFERENCES

1. "Pyrolysis Oils from Biomass : Producing, Analyzing & Upgrading" - E.J. Soltes, T.A. Milne - ACS 1988

2. "A Mathematical Model for Transporting the Biomass to Biomass Based Power Plant", by J. Singh, BS Panesar, SK Sharma, Biomass and Bioenergy - Vol 34 pgs 483-488 [2010]

3. "Biomass & Biofuels : Technology & Economic Overview" NREL - by Andy Aden [2007]

4. "Economics of Producing Fuel Pellets from Biomass" by S.Mani, S.Sokhensanj, X.Bi & A.Turhollow, Applied Energy in Agriculture - Vol 22 No 3 pgs 421-426 [2006]

KEYWORDS: Densification of Biomass, Mixed Alcohol Production, Pyrolysis, Fischer Tropsch Synthesis, Refuse Derived Fuel, Thermochemical Biorefineries, Cellulosic Ethanol, Crop Residual Waste, Combined Heat and Power, Furfurals, Phenolics, Synthesis Gas

Images are taken from the Picassa Web Album

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