Biomass Energy Generation:
In the process of composting, microorganisms break down organic matter and produce carbon dioxide, water, heat, and humus, a relatively stable organic end product.
Organic decomposition is essentially a natural, biological process that compares somewhat to the raising of plants or animals. The rate of composting, like the growth rate of plants or animals can be effected by many factors. Four key factors to establishing and maintaining active organic decomposition are:
a) nutrient balance
Nutrient Balance is determined largely by the ratio of carbon to nitrogen in the compost mix (C/N ratio). It is like balancing carbohydrates and protein in a diet. Bacteria, fungi and actinomycetes require carbon and nitrogen for growth. These microbes use 30 parts carbon to 1 part nitrogen. Composting is usually successful when the biomass contains 20 to 40 parts of carbon to 1 part nitrogen. However, as the ratio exceeds 30, the rate of composting decreases. As the ratio decreases below 25, excess nitrogen is converted to ammonia which is wasted into the atmosphere and results in undesirable odors.
Moisture Content of compost should ideally be 60 % after organic components have been well mixed. As moisture content exceeds 60 %, the structural strength of the compost deteriorates, oxygen movement is inhibited and the process tends to become anaerobic. Low C/N ratio materials putrefy when anaerobic. High ratio materials ferment. Both processes produce undesirable odors. As moisture content decreases below 50 %, the rate of decomposition decreases rapidly. A mixture of organic wastes that contains 60 % moisture feels damp to the touch but is not soggy.
Temperature increase which occurs during composting is a result of the breakdown of organic materials by bacteria, actinomycetes, fungi and protozoa. The temperature range can be from freezing to 180 F . Starting from ambient temperature, compost can reach 150 F in less than 2 days. Applying heat to compost from external sources serves no purpose; heat is generated from within the compost medium.
Aeration is a key element in composting. Proper aeration is needed to control the environment required for biological processes to thrive with optimum efficiency. A number of controllable factors are involved. Carbon dioxide is a product of the biochemical reactions that are part of composting. This gas must be removed from the compost micro-environment to avoid toxic concentrations that inhibit the process.
Under normal circumstances, the basic principles of composting are quite simple and adhering to them will result in an efficient and successful outcome. Composting has become an excellent way to manage certain wastes responsibly, prevent the wasting of a natural resources, and produce a value-added, inexpensive soil amendment product. Composting also generates another valuable resource that may be recaptured and re-used:
However, harnessing this energy source for commercial use such as greenhouse heating, presents new challenges to Agrilab. This form of energy is unlike any standard within the heat transfer industry. To heat a greenhouse structure from this energy source, it must be viewed in three separate components:
a) heat energy generation,
Agrilab has an abundance of experience in heat transfer and, although challenging, this goal is achievable. Heat distribution and use within a greenhouse facility is well documented with much information and data available. However, modifications should be pursued to enhance heat retention and use within these structures to maximize the heat re-capture benefits.
The most critical and difficult challenge of this project comes in the heat energy generation phase. It has been proven that temperatures, in the best enhanced aerobic composting situations, can reach up to 180 F by intensive aeration (oxygen replenishment) on a continual basis; this methodology is commonplace in the production of compost as a growing media used in mushroom operations. These temperatures are a requirement for the safe destruction of any contained pathogens within the organic composting components. However, this particular method of composting may not be practical for the purpose pursued in this application because of the constant need to mechanically aerate by turning and fluffing the piles or windrows. This form of composting is very rapid, causing the components to be "consumed" very quickly.
The underlying challenge for Agrilab in each case, is to establish composting systems that will function within the designed confinement criteria, presenting a consistent temperature range of 140 - 160 F, sustainable for a practical time frame of up to 20 weeks, while mitigating the negative effects of the generated by-products. Compost component selection, means of aeration, moisture content maintenance, and by-product management are all of great importance to the development of a satisfactory biomass heat generation system, which can present a suitable and affordable alternative to traditional heat energy sources, while demonstrating a positive effect on the environment. Further, engineering designs of the heat transfer and distribution systems are to be customized to the structural applications and parameters as per client needs. This technology is essentially transferable, enabling Agrilab to provide this service to a vast array of structural heating applications.
Note: The system described above has been submitted for patent protection and has currently been designated as "patent pending" by the U.S. Patent Office.
In this undertaking, energy generation is the first and perhaps the most technically unpredictable variable to be studied. A number of biomass materials and mixtures were tested for biological properties with the primary focus on heat generation capacity and process longevity. The organic materials tested for greenhouse biomass energy generation consist largely of greenhouse waste materials and matrixes from crop production such as waste tomato leaves and vines. Energy generation, process longevity, response to various levels of biological culture catalysts were determined over a wide range of products in the formation of "biomass recipes". The goal is to customize a blend with available and compatible materials for specific applications. This testing was undertaken in a controlled environment to maximize biomass performance and mitigate the effects of any undesirable byproducts of decomposition such as odor, methane, ammonia, carbon dioxide, etc.
The normal duration of the heating process for biomass decomposition occurs within a 42 day time period, establishing a high temperature range of 130 - 150 degrees F. With very specific parameter definition of the biomass micro-environment within this test apparatus, Agrilab has extended the heating period for its "recipe" biomass beyond 150 days at temperatures above 130 degrees F, while simultaneously extracting heat energy from the biomass: an extraordinary achievement!
The heat transfer testing consisted of the modification and customization of a series of heat pipes that remove the heat energy created in the natural decomposition of the biomass materials. Apparatus "A" contains 2 separated chambers equal in size; one containing the biomass, the other empty to be heated by heat pipes from energy contributed by the biomass decomposition. The biomass/heat pipes system was challenged in extreme conditions by the addition of dry ice into the heated chamber; the response was observed and computer monitored to provide for the development of the most efficient energy transfer system. The passive and self-regulating nature of the heat pipe repeatedly demonstrated extraordinary compatibility with heat energy generation from the biomass decomposition process.
A very specific design of heat distribution system was employed in the greenhouse apparatus to distribute the heat throughout the entire greenhouse facility. The heat was extracted from the decomposing biomass (located in the pit adjacent to greenhouse) by means of heat pipes inserted into the sub-floor area where the heat is permitted to rise by convection to warm the internal atmosphere of the structure. The entire system functions without the use of any external energy source whatsoever!
In Energy Generation experimentation, Agrilab's "recipe" biomass has surpassed, by a wide margin, the normal decomposition heating time period of 42 days before the biomass enters the cool down phase. By controlling the air and moisture conditions within the biomass environment, Agrilab has extended the duration of energy generation to almost 4 times the expected time period, while consistently yielding temperatures in excess of 130 degree F. Agrilab has established "recipe" biomass mixtures that will decompose rapidly at very high (+160 F) temperatures, or slowly to provide a predictably consistent moderate to high (130 -140 F) temperature for up to 5 months.
In Heat Transfer experimentation, Agrilab has successfully modified and customized its heat pipe technology to suit the application of biomass heat extraction. The gentle, passive and self regulating nature of the heat pipe demonstrated an extraordinary compatibility with the energy generating biomass. When the biomass was challenged through the heat pipes (with extreme cold of dry ice), the biological reaction remained a constant because of the gentle nature of heat extraction by the heat pipe.
In the Heat Distribution study, it was determined that the heat pipes surrendered the biothermal energy extracted from the biomass into the greenhouse interior through the concrete block matrix, gently by convection. To retrofit into existing greenhouse water or steam distribution system, an array of heat pipes can be assembled to preheat the water supply.
Traditional heating sources in the energy intensive greenhouse industry have always represented a high percentage of the operating costs of vegetable production. In the recent past, the unit energy costs of fossil fuels have risen significantly, thereby rapidly eroding grower profitability. At the same time, millions of kilowatts of heat energy from organic waste decomposition can be recaptured and used as a valuable resource. It is projected that Agrilab's technique of biomass heat generation combined with heat pipe transfer technology functioning in a commercial greenhouse operation could, in some instances, reduce dependency on fossil fuel supplies by up to 70%.
For a typical commercial 10 acre greenhouse farm in Essex County, experiencing annual heating costs of $500,000, the projected return on investment for an Agrilab heating system, in an average weather growing season, is 2-3 growing seasons.
The decomposition of organic materials is a process that exists in nature and occurs every day in the forest floors, farmers fields, and even in your garden. The materials projected for use in greenhouse structural heating through biomass decomposition, will undergo the same natural process wherever they may land.
However in Agrilab's process, the regulated decomposition occurs over a longer period of time, in a controlled environment and with the usual byproducts passing through biofilters to minimize the effects of nuisance odors, ammonia and methane. Because of the aerobic activity, if methane production occurs at all, the volume is minimal. Reducing dependency on fossil fuels diminishes the volume of harmful exhausts gases from fuel oil or natural gas boilers.
The Agrilab system can, in effect, reduce the overall waste stream by composting, reduce the volume of organic wastes entering landfills, and reduce the volume of gases produced by burning fossil fuels, which are believed to contribute to global warming.
The possible applications of using energy from biomass decomposition are all but endless. From severe cold climates to a much more temperate region, this system will provide economic and environmental relief from traditional reliance on the world's diminishing fossil fuel supplies to any heating application conceived. Greenhouse structures, livestock barns, farm workshops, and even rural residential dwellings could be considered as logical applications for biomass heating. In Eastern Europe, many fodder rich but energy starved countries may be able to alter living standards by using this type of energy for greenhouse food production and shelter heating. Shelters in cold climates can provide areas for winter overnight truck parking, permitting engine shutdown, thus reducing atmospheric emissions. The forestry industry which produces a huge quantity of biofuel could heat many of its facilities with its own waste products without burning it. Manufacturing facilities, food processors, even in semi-urban areas can effectively take advantage of biomass heating.
Application options present almost limitless potential!!
Biomass is often referred to as an alternative energy source. Most often this material is burned in a controlled environment in what appears to be an efficient manner.
However, estimates have been made that up to 80% more heat energy is captured from the same volume of organic material when extracted as biomass decomposition, than is recovered when a rapid burn occurs.
Composting is an established method employed in the waste management field with the ultimate goal to reduce volumes of organic waste entering landfills while producing humus, a soil enhancement product. Few have successfully attempted to manage organic decomposition with the expressed purpose of energy generation and extraction. Agrilab has established some significant benchmarks in temperature generation, active residency time, and environmental controls in its efforts to date. Thousands of tonnes of quality biomass decompose in piles, on farm fields and in the forest each year; this biomass can be used as an economical alternative fuel source by capturing the heat of decomposition.
Agrilab has successfully extracted this heat energy from the biomass by employing heat pipe technology to heat a small greenhouse structure, its pilot project.
Agrilab continues its research efforts to modify and monitor all aspects of its heating system to enhance performance in heat generation, transfer, and distribution for consistency and reliability in field operations.
Parabolic Trough Solar Heating System:|
In order to enhance this system and to take full advantage of the natural resources that are available, Agrilab has developed a solar heating system. Agrilab�s Parabolic Trough Solar Heating System amplifies sunlight much like a magnifying glass, but, instead of forming a very hot focal point, the parabolic trough forms a high intensity focal line. An Isobar super-thermal conductor is placed along this heat focusing line, raising it to remarkably high temperatures. The Isobar then transfers this energy directly to a water circulation heat exchanger that pumps water from the insulated water tank, through the heat exchanger and returns it to the tank.
On sunny days, even in the coldest days of mid winter the insulated water tank is heated by the high intensity sunlight, precision focused by the parabolic mirror trough. During those all too familiar dull cold winter days, the biomass system continues to produce energy that heats the water in the insulated retention tank 24 hours a day, seven days a week.