1. Technical Field
This invention relates generally to a method of transportation of energy and more specifically to a method of transportation of energy and a high-energy transport gas that increases the amount of energy in a pipeline or transportation vessel designed to carry methane and other gases with low heats of combustion. This invention further relates generally to a high energy transport product and more specifically to a high energy transport gas having a higher heat of combustion than methane.
2. Prior Art
Natural gas, often commonly referred to as methane, is a worldwide source of energy. Natural gas varies in composition from country to country as well as from region to region within a specific country. A natural gas composition at the wellhead typically contains over 85% methane. Some natural gas compositions at the wellhead can contain over 96% methane. Although the terms natural gas and methane often are used interchangeably, typically, natural gas will contain some ethane (a C2 hydrocarbon), propane (a C3 hydrocarbon) and Butane (a C4 hydrocarbon). Table 1 illustrates common compositions of natural gas exports of various countries.
TABLE 1Natural Gas Export Compositions from Select CountriesTrinidadAlgeriaOmanN. AmericaNorwayQatarNigeriaHHV1048110311681096108711321125BTU/SCFCompositionMethane96.13%89.57%86.52%92.77%91.94%89.18%89.07%Ethane3.40%8.61%8.3153.36%5.44%7.07%7.67%Propane0.39%1.18%3.32%1.51%1.97%2.50%2.98%Butane0.07%0.31%1.70%0.88%0.2351.1550.34%
In Table 1, HHV is the high heat value of the gas that is measured in British Thermal Units per standard cubic feet (Btu/scf). The high heat value is determined by the natural gas compositions. Natural gas composition that contains relatively large amounts of ethane, propane and butane have greater high heat values (HHV) compared to natural gas compositions that are richer in methane.
Depending upon national policy, local economics and contractual agreements for natural gas purchases, the component gas of ethane, propane, butane and other compounds with a greater heat of combustion than methane may be removed from the wellhead natural gas composition prior to export. The ethane, propane, butane and other compounds can be used to manufacture other petrochemical products and plastics. For example, in Table 1, Trinidad removes much of the ethane, propane and butane for Trinidad's local petrochemical and plastics industries, and a natural gas mixture of greater than 96% methane with a HHV of 1048 (Btu/scf) is exported. Similarly, the North American market removes some ethane, propane and butane prior to transporting and distributing a natural gas mixture to the market place. Processed North American natural gas typically contains over 96% methane and has a HHV of 1029 (Btu/scf). Other countries such as Japan use a gas for commercial distribution having a HHV of over 1330 (Btu/scf). The economic differences for natural gas transport between Japan and North American are discussed below.
In recent years, natural gas has been a growing source of energy for the in the world economy. The future consumption of natural gas for energy needs is projected to grow at a fast pace. For example, the United States Department of Energy (USDoE) stated that the projected use of natural gas as an energy source in the US would grow dramatically as a fuel for the production of electricity. Demand for natural gas for electricity production is expected to rise 90% between 2001 and 2020. However, many bottlenecks exist in natural gas pipelines throughout the US and the world and natural gas pipelines between the US and Canada are at capacity. See “Reliable, Affordable, and Environmentally Sound Energy for America's Future”, Report of the National Energy Policy Development Group of the US. Many nations including Japan, the European Union (EU) and the US are developing transportation vehicles fueled by hydrogen. The demand for natural gas and hydrogen is driven by current and future environmental, economic and national security concerns.
Electricity generation in the world is dominated by coal; however, the future of electricity generation is projected to have a growing demand for natural gas. Today, electricity generation in the US is approximately 52% coal, 20% nuclear, 16% natural gas, 7% hydroelectric, and the balance from oil and renewable energy sources such a wind, solar and biomass. By 2020, the USDoE projects that the US will become more dependent on energy from natural gas for electricity, transportation, industrial processing, and home heating. Electricity from natural gas will increase from today's 16% of generation to 33% of the generation by the year 2020.
For electricity production, natural gas (methane) is considered an abundant source of energy, is environmentally advantageous over coal, is more energy efficient for electricity production with lower-capital equipment costs and shorter construction lead times for electricity plants, and is favored by power generation companies due to changes in the economics of electricity generation. Natural gas (methane) is an abundant natural resource for energy within the US and around the world. Estimates of natural gas reserves around the world are large. Estimates of quantities of known stranded gas reserves have been identified by synthetic fuel manufactures such as Syntroleum, Inc., which places the quantity of these stranded gas reserves to be equivalent to the oil reserves of Saudi Arabia, if these reserves were converted from methane gas to hydrocarbon liquids fuels. These reserves would provide hydrocarbon liquid fuel from Fischer-Tropsch synthesis methods that could provide fuel for all the cars and trucks in the US for over 80 years. Other methods for methane production include reacting hydrogen with coal.
Besides its abundance for an energy source, natural gas (methane) is sought after for environmental, economical and energy efficiency reasons. Shifting energy sources for electricity generation to natural gas (methane) provides many environmental advantages compared to coal and nuclear sources. When methane is used as a primary source for electricity and energy produced by gas turbines, electricity generation produces fewer emissions that lead to pollution and poor air quality, compared to coal. Unlike coal, electricity generation from natural gas fired gas turbines produces low emissions of nitrogen oxides (NOx) and sulfur dioxides (SO2) and virtually no emissions of organic particulates, chloride, fluorides, mercury, hazardous metals, and other pollutants. In addition, electricity production from methane produces less carbon dioxide (CO2) emissions than coal. Carbon dioxide emissions are considered among many in the scientific community to cause global warming. Generation of electricity from nuclear energy produces no pollutant or carbon dioxide emissions, but the byproducts from fuel preparation and spent fuel creates environmental hazards. The nuclear fuel manufacturing process introduces a large number of environmentally hazardous chemical and isotopes into the environment, and spent fuel contains highly radioactive byproducts that can last thousands of years.
Another environmental advantage of electricity production from methane compared to coal is that electricity is produced more energy efficiently from natural gas turbines. Electricity generation from natural gas can be very energy efficient. Natural gas fired turbines can produce electricity with and without cogeneration. Cogeneration can produce either steam or steam and electricity from steam turbines. Cogeneration, also known as combined heat and power (CHP), can achieve efficiencies of greater than 80%, whereas the newest coal-burning power plant can achieve efficiencies of only slightly over 40%. However, most conventional coal fired power plants operate at approximately 30% efficiency.
The future demand for natural gas (methane) energy is not just being driven by electricity demand. Energy consumption from methane accounts for 24% of the total energy used in the US. Natural gas is a feedstock for many products and a source of energy for many manufacturing processes. These products include textiles, chemicals, rubber, and furniture. Manufacturing processes that rely heavily on natural gas include brick making, glass making, and paper production. Residential heating produces a great demand for energy from natural gas, also.
According to the Report of the US National Energy Policy Development Group:                Between 2000 and 2020, US natural gas demand is projected by the Energy Information Administration to increase by more than 50 percent, from 22.8 to 34.7 trillion cubic feet. Others such as the Cambridge Energy Research Associates expect gas consumption to increase by about 37 percent over that period. Growth is projected in all sectors—industrial, commercial, residential, transportation, and electric generation. More than half of the increase in overall gas consumption will result from a rising demand for electricity generation.The report further cites current and future problems associated with getting methane's energy to the market place:        To meet this long-term challenge, the United States not only needs to boost production, but also must ensure that the natural gas pipeline network is expanded to the extent necessary. For example, although natural gas electricity generation in New England is projected to increase by 16,000 MW through [2020], bottlenecks may block the transmission of necessary supplies. Unless pipeline constraints are eliminated, they will contribute to supply shortages and high prices, and will impede growth in electricity generation.The report further cites that:        The current domestic natural gas transmission capacity of approximately 23 trillion cubic feet (tcf) will be insufficient to meet the projected 50 percent increase in US consumption projected for 2020. Some parts of the country such as California and New        
England, already face capacity shortage. . . . [D]elays have constrained the ability to transport natural gas to California, contributing to high prices. In addition, the natural gas pipeline connections from Canada are near capacity, so any greater US reliance on Canadian natural gas will require increase pipeline capacity.
Transportation of natural gas (methane) energy is cited as one of the major hurdles for meeting the projected demands for natural gas. The expected increase in the demand for methane energy is expected to require 263,000 miles of distribution pipelines and 38,000 miles of new transmission pipelines. Construction of these miles of pipelines will face obstacles. These obstacles include, but are not limited to, encroachment on existing rights-of-ways and heightened community resistance to pipeline construction.
Liquefying methane is one method to increase methane energy density for transportation of the methane energy. By liquefying natural gas, the energy that is contained in one thousand cubic meters (1000 m3) of methane gas at standard temperature and pressure (STP) is compressed into approximately a volume of one cubic meter (1 m3) in the liquid state of methane. Liquefied natural gas (LNG) can be transported through pipelines or transported by specially designed ships. Such ships commonly transport liquefied natural gas. Transportation by ship uses liquefied natural gas to increase the energy density of the storage volume of the ship increasing the amount of energy that the ship can carry. This above stated increase demand for methane energy to generate electricity could require a substantial demand for LNG imports. The current demand for methane energy has begun to demonstrate this trend. The current US market in the New England region has seen a 350% increase in imports of LNG by ship between 1998 and 1999. Several companies have considered reopening terminals in the state of Georgia and the state of Maryland to import LNG. Other petroleum companies have announced plans for creating terminals to import LNG.
Conventional facilities for liquefying methane tend to be quite large and expensive to build. Hundreds of millions of US dollars are typically required to build a LNG process facility. Newer technology has decreased the cost of LNG processing facilities. One such new technology is small, natural gas driven compressors invented by the USDoE at Los Alamos National Laboratory (LANL). The technology is called thermoacoustic natural gas liquefaction. Among patents for this technology are U.S. Pat. No. 4,953,366 and U.S. Pat. No. 4,858,441. This technology is also known as Thermoacoustic Sterling Hybrid Engine Refrigerator (TASHER).
The USDoE and its industrial partners have spent over US$20 million to demonstrate this thermoacoustic technology. The technology is quite small and effective for liquefying natural gas. The main markets for this technology are liquefying methane on drilling platforms at sea for transporting by ship, liquefying stranded coal bed methane for transportation by pipeline, rail car or truck, and liquefying natural gas at the end of pipe, end of line or at the market locations to increase the energy content of fuel containers that are used for vehicle transportation that operate on methane energy.
Another prior art method to transport methane energy is to convert methane gas to liquid fuel using steam reforming with Fischer-Tropsch catalysts and autocatalytic oxidation of methane. This method is quite common to transport stranded methane gas and is sought after to increase the pressure on oil pipelines to transport oil from mature oil fields where oil production is declining. Stranded methane gas is methane gas that has no common economic means to be transported from remote locations to the market place. For example, locations where no pipelines exist to transport the natural gas to ports or the market place.
Gas to hydrocarbon liquid (gas to liquid, g to l) technologies and processes have received much attention by the USDoE to supplement the constant decline in oil from State of Alaska's North Slope with Fischer-Tropsch methods. The hydrocarbon liquid fuels derived from methane are intended to keep the pressure on the Alaskan Pipeline great enough to transport the remaining oil in the North Slope as production continues to decline. Other companies, such as Syntroleum, Inc., use autocatalytic oxidation of methane to produce liquid fuel with ultra-low sulfur contents as additive to common gasoline to meet new US Environmental Protection Agency (USEPA) sulfur standards for gasoline and conventional diesel fuels. Syntroleum, Inc. has received many US patents in this area, including U.S. Pat. No. 6,344,491 for a high-pressure autothermal oxidative catalytic process for methane and U.S. Pat. No. 6,085,512 for other Fischer-Tropsch technology.
Other methods and technologies to transform and transport methane energy by converting methane gas into a liquid hydrocarbon fuel by the USDoE and their industrial and university partners include Ion Transport Ceramic Membrane and Steady State and Transient Catalytic Oxidation and Coupling of Methane. See, for example, <www.fe.doc.gov/fuel/gas-to-liquids.shtml>.
Other methods to increase the amount of natural gas (methane) energy available to the market place use prior art that is associated with current energy policy and conventional energy transportation methods. These methods provide a reasonable, conventional solution to addressing the constraints of delivering methane energy to the market place. One method is to build more pipelines—distribution pipelines and transmission pipelines. One other is to increase the energy content of a natural gas pipeline by increasing the pressure of the gas in the pipeline. These conventional approaches would, as stated in the Report of the US' National Energy Policy Development Group, call for increasing the amount of energy supplied from natural gas (methane) by building tens of thousands of miles of new transmission pipelines and hundreds of thousands of miles of new distribution pipelines. The cost for the new infrastructure to transport the energy of methane is estimated to be well over US$10 billion.
Another method to transport the energy associated with natural gas (methane) is to convert the methane in natural gas to methanol. Methanol, a liquid alcohol, can increase the energy density of a pipeline, but a methanol energy economy would require drastic changes to a countries' energy infrastructure. Additionally, methanol is not an environmental friendly chemical. Methanol can poison ground water.
Other prior art contains end of the pipe, end of the line or at the market technology to process natural gas (methane). These technologies convert natural gas (methane) to chemical species for feedstock to other process for an end use. Such uses include feedstocks such as ethane and ethylene for plastics such as polyethylene and polypropylene. Other technologies are used to convert methane to acetylene as well as to use methane for gas to hydrocarbon liquid processes. These technologies employ processes that use catalysts, electromagnetic energy, non-thermal plasma and plasma initiators. Some technologies use these processing in combination with each other. These technologies use methane, coal, carbon sources, water and hydrogen as input chemicals species for producing feedstock chemical for industrial process. Methane can be processed with coal, a carbon species, or a carbon containing species. Methane also can be processed alone, with water, or with hydrogen or oxygen. Coal can be processed with hydrogen, water, or hydrogen with water.
These other end of the pipeline or at the market technology prior art processes include U.S. Pat. Nos. 5,328,577 and 5,277,773, which disclose the use of plasma initiators exited by microwave energy to convert methane and hydrogen to acetylene, ethylene, and ethane. U.S. Pat. No. 5,972,175 discloses the use of a catalyst heated with microwave energy to convert gaseous hydrocarbons, methane and propane, with char to synthesize higher order organic species including ethylene and acetylene. U.S. Pat. No. 4,574,038 discloses processing 100% methane with microwave energy and a metal catalyst to produce a product mixture of 51.3% ethylene, 21.8 methane and 26.7 hydrogen. U.S. Pat. No. 5,472,581 discloses the use of microwave energy to heat activated charcoal to react the charcoal with methane to produce ethane, ethylene and acetylene. Also, U.S. Pat. No. 5,472,581 discloses the use of microwave energy to heat activated charcoal with water to produce methane, ethane, ethylene and acetylene. U.S. Pat. No. 5,900,521 discloses creating a metal catalyst that uses a conventionally heated catalysts bed to convert methane to ethylene and hydrogen. U.S. Pat. Nos. 5,131,993 and 5,015,349 disclose the use of a non-thermal plasma, catalyst and microwave energy to synthesize higher order hydrocarbons from methane. Bool et al. have used microwave energy as a catalyst to react oxygen and methane to form ethylene, carbon monoxide and acetylene. Bool, C. J. et al, “The Application of Microwaves to the Oxidative Coupling of Methane over Rare-Earth Oxide Catalyst”, source unknown, pp. 39-42, School of Chemistry, University of Hull, Hull, North Humberside, United Kingdom, HU67RX.
These many processes produce higher energy gases from methane, methane and coal, methane and water, methane and oxygen, methane and hydrogen, coal and hydrogen, and coal and water that have higher heats of combustion compared to methane and that have higher boiling points compared to methane. Compared to natural gas (methane) alone, these mixtures of gases have a lower number of moles if the hydrogen is removed from the mixture.
Even with these methods, there is a need for a more efficient method of transporting methane and other gases so to as to provide a higher energy content in a smaller volume of gas. It is to this need and other needs that the present invention is directed.