Invention for System and Method for Integrated Waste Storage

Invented by James W. Bohlig, Douglas R. Casella, Repower Ip LLC

The Repower Ip LLC invention works as follows

Background for System and Method for Integrated Waste Storage

Fuels for transportation, heating and petrochemical production are becoming scarcer and more expensive. Energy and petrochemical industries are searching for alternative fuel feedstocks that can be used to produce these products, as well as many others. Due to the increasing cost of fossil fuels and transportation costs, fuel feedstocks for energy production and petrochemicals are rapidly increasing.

The production of electricity and heat is based on fossil fuels such as coal and oil. Synthesis gas is used to produce liquid fuels and petrochemicals.

Combustion, and gasification is a thermochemical process that releases the stored energy in the fuel. In a reactor, combustion occurs in excess oxygen or air. The combustion process is primarily used to produce steam, which is then used in steam turbines to produce electricity. The gas produced during combustion is a significant amount of pollutants due to the nature of the complete combustion. In an oxidizing environment, the combustion of coal, for instance, releases nitrogen oxides. These are precursors to ground-level ozone, which can trigger asthma attacks. The combustion of fossil fuels with high sulfur content, like coal, is the main source of sulfur dioxide, which produces very fine particles of sulfates. The fine particle pollution produced by U.S. Power Plants is responsible for the premature death of more than 30,000 people every year. “Fine particles from power plants” are responsible for asthma attacks, heart problems, upper and lower respiratory issues and cardiac problems in hundreds of thousands of Americans.

Gasification can also occur in a reactor in the absence or presence of oxygen in substochiometric quantities. The thermochemical reactions which occur in the absence or with substochiometric oxygen amounts do not lead to the formation of sulfur oxides or nitrogen oxides.

The basic reactions of gasification are:

All of these reactions can be reversed and their rates are dependent on the reaction kinetics. This is a function of the temperature, pressure, and concentration of reactants within the reactor. The endothermic reaction can be satisfied by providing heat directly or indirectly.

A number of gasifiers have been developed. Gasifiers can be classified into four main categories: fixed-bed-updraft (also known as fixed-bed-downdraft), bubbling fluidized-bed, and circulating fluidized-bed. The differences are based on how the fuel is supported in the reactor vessel. They also include the flow direction of the fuel as well as the oxidant.

The fluidized bubble bed is composed of inert, fine particles of sand, alumina or other materials that have been chosen for their size, density and thermal properties. The frictional force of the gas (oxygen or air) and particles is equalized when gas is forced through a bed of particles. This gas velocity (called the minimum fluidization speed) can cause gas to bubble and flow through the media, causing the particles to appear in a “boiling” state. Fluidized particles break up biomass and promote heat transfer in the reactor. Gasification by bubbling fluidized bed has many advantages: uniform gas product; uniform temperature distribution in the reactor; accepts fuel particles of all sizes including fines; high heat transfer rates between fuel, inert materials, and gas. High conversion is possible even with low amounts of tar or unconverted carbon. Gasification by bubbling fluidized bed has several disadvantages: lower gas-solids contact efficiency, increased dust entrainment and attrition rates. Large bubbles can result in gas bypassing the bed.

The circulating fluidized-bed gasifiers operate with gas speeds higher than the transport velocity. This results in a significant entrainment in the gas stream of particles. The entrained particles must be separated in a cyclone before being returned to the reactor. It is ideal for quick reactions, and the high heat transfer rates are possible because of the high heat capacity in bed material. High conversion rates can be achieved with low tar content and unconverted coal. The production of syngas with higher energy content is also possible, as the heat needed for gasification can easily be transferred to the outside by circulating particles that act as heat carriers. “The disadvantages of circulating liquidized-bed gasification include: temperature gradients in the direction of solid flows; smaller particles are needed; high speeds may cause equipment erosion; and less efficient heat exchange than bubbling fluidized bed.

Gasifiers are designed to produce a specific product using a fuel that is constant and unchanging. Gasifiers today use wood, coal and biomass as fuels. Energy and petrochemical companies are looking for alternative fuel feedstocks because some fuel sources are becoming more expensive.

Waste is a potential source for a large quantity of feedstock. Waste, such as municipal waste, is currently disposed of in incineration process to produce heat and/or steamed for use in turbines. The incineration process is a form of combustion, and its negative effects have been discussed above.

The release of greenhouse gasses (GHGs), into the atmosphere, is one of the greatest threats to the environment. GHGs, such as carbon dioxide (CO2), methane (CH4), nitrous dioxide, water vapor, nitrogen oxide, ozone and carbon monoxide absorb heat from solar radiation, but they do not allow the long-wave radiation back into space. The presence of GHGs causes the heat absorbed by the earth to be trapped and the surface of the planet to warm. In the U.S. GHG emissions are primarily caused by energy consumption, which is largely driven by economic growth, fuels used to generate electricity, and weather patterns that affect heating and cooling requirements. Carbon dioxide emissions from energy, such as petroleum and natural gases, account for 82 percent (or the total) of all human-made greenhouse gas emissions in the United States. Methane is another greenhouse gas that comes from landfills and coal mines. It also comes from oil and gas operations and agriculture. The burning of fossil fuels, the use of fertilizers and certain industrial processes emit nitrous oxide, which accounts for 5 percent of all emissions. Carbon dioxide emissions in the world are expected to rise by 1.9 per cent annually between 2001-2025. The majority of these emissions will be generated in developing countries where fossil fuels are used to drive economic growth in emerging economies such as China and India. The emissions of developing countries are expected to increase above the global average by 2.7 percent per year between 2001 and 2025, and surpass those of industrialized nations near 2018.

Landfills are also significant sources of GHG emission if there is no system in place to connect landfill gas. This is mainly due to the methane that is released when waste such as municipal solid waste decomposes. Methane has a twenty-onefold higher GHG rating than carbon dioxide. Landfills account for 4% of anthropogenic CO2 emissions. By burning waste and collecting methane in landfills, it is possible to reduce methane emission by a significant amount. Methane from landfills can be either used to produce energy directly or flared off. Combustion Of Waste Can Reduce Greenhouse Gases, Science Daily (8 Dec 2007).

The carbon footprint is a measure of human impact on the environment, as measured by the amount of greenhouse gases produced. It is expressed in carbon dioxide units (CO2). Carbon footprint is the total amount released by a product over its entire lifecycle. Carbon footprints are usually expressed in CO2 equivalents (usually in kilograms and tons) which account for the global warming effects of various GHGs. Carbon footprints are calculated by using the Life Cycle Assessment method or they can be limited to emissions directly attributable from fossil fuel energy use.

An alternative carbon footprint definition is the total CO2 attributable by an individual’s actions (primarily through their energy consumption) over the course of a year. The personal carbon calculators are based on this definition. Originating from the notion that an individual’s footprint is the result of their activities, the term was coined. Carbon footprints are either limited to direct emissions, such as those from home energy use and travel (including cars, planes, trains and other public transportation), or they can include indirect emissions, which includes CO2 emissions resulting from goods and services purchased, and the waste generated.

The carbon footprint can be effectively and efficiently reduced using the following steps: Carbon offsetting and investments in projects that reduce CO2 emissions are the last steps.

The purchase carbon offsets are another way to reduce your carbon footprint. A carbon offset is equal to one tonne of CO2-equivalent. Carbon offset companies invest in renewable energy, landfill gas capture and tree planting.

The purchase and withdrawal of emission trading credits occurs as well, creating a link between the voluntary markets and regulated carbon market. Emissions trading schemes offer financial incentives for corporations and organizations to reduce their carbon footprint. These schemes are part of cap-and trade systems where total carbon emissions in a country, region or sector are limited to a specific value. Organizations are then issued permits for a fractional share of those total emissions. Organisations that emit less than their target amount of carbon can sell the ‘excess’. “Organizations that emit less carbon than their emission target can then sell their “excess