A liquid nitrogen (LN₂) economy is a hypothetical proposal for a future economy in which the primary form of energy storage and transport is liquid nitrogen. It is proposed as an alternative to liquid hydrogen in some transport modes and as a means of locally storing energy captured from renewable sources. An analysis of this concept provides insight into the physical limits of all energy conversion schemes. General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... LH2 is an acronym used in the aerospace industry, which stands for Liquid Hydrogen. ... Renewable energy (sources) or RES capture their energy from existing flows of energy, from on-going natural processes, such as sunshine, wind, flowing water (hydropower), biological processes, and geothermal heat flows. ...

Typically, the demise of the petroleum-age is presented as a catastrophic collapse. The Liquid Nitrogen Economy is a proposal to initiate an energy diversification, an alternative to the typical collapse scenario.

Description

Currently, most road vehicles are powered by internal combustion engines burning fossil fuel. If transportation is to be sustainable over the long term, the fuel must be replaced by something else produced by renewable energy. The replacement should not be thought of as an energy source; it is a means of transferring and concentrating energy, a "currency". A colorized automobile engine The internal combustion engine is a heat engine in which the burning of a fuel occurs in a confined space called a combustion chamber. ... Coal rail cars in Ashtabula, Ohio Fossil fuels, also known as mineral fuels, are hydrocarbon-containing natural resources such as coal, oil and natural gas. ... Renewable energy (sources) or RES capture their energy from existing flows of energy, from on-going natural processes, such as sunshine, wind, flowing water (hydropower), biological processes, and geothermal heat flows. ...

Liquid nitrogen is generated by cryogenic or Stirling engine coolers that liquefy the main component of air, nitrogen (N₂). The cooler can be powered by renewable generated electricity or through direct mechanical work from a hydro or wind turbines. Cryogenics is the study of very low temperatures or the production of the same, and is often confused with cryobiology, the study of the effect of low temperatures on organisms, or the study of cryopreservation. ... A Stirling engine and generator set with 55 kW electrical output, for combined heat and power applications. ... Hydraulic turbine and electrical generator. ... Horizontal axis wind turbine, the Enercon model E-66 wind energy converter, in Germany. ...

Liquid nitrogen is distributed and stored in insulated containers. The insulation reduces heat flow into the stored nitrogen. Heat from the surrounding environment boils the liquid. Reducing inflowing heat reduces the loss of liquid nitrogen in storage. The requirements of storage prevent the use of pipelines as a means of transport. Since long-distance pipelines would be costly due the insulation requirements, it would be costly to use distant energy sources for production of liquid nitrogen. Petroleum reserves are typically a vast distance from consumption but can be transferred at ambient temperatures. Dewar can mean: Dewar flask James Dewar Rt. ...

Liquid nitrogen consumption is in essence production in reverse. The Stirling engine or cryogenic heat engine offers a way to power vehicles and a means to generate electricity. Liquid nitrogen can also serve as a direct coolant for refrigerators, electrical equipment and air conditioning units. The consumption of liquid nitrogen is in effect boiling and returning the nitrogen to the atmosphere. Refrigeration (from the Latin frigus, frost) is generally the cooling of a body by the transfer of a portion of its heat away from it. ... A fan blowing at a CPU heatsink. ... Note: in the broadest sense, air conditioning can refer to any form of heating, ventilation, and air-conditioning. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... Layers of Atmosphere (NOAA) Air redirects here. ...

Political argument

The adaptability of thermal-engines and a diverse means of production is likely to lead to the diversification, localization and stability of the energy market. Possible energy diversification includes the hydrogen economy, solar and biofuel alternatives. A hydrogen economy is a hypothetical future economy in which the primary form of stored energy for mobile applications and load balancing is hydrogen (H2). ... Solar Panel (photovoltaic array) A Solar panel is a flat collection of solar cells or solar thermal collectors used for converting solar energy into electricity or heat. ... Biofuel is any fuel that derives from biomass — recently living organisms or their metabolic byproducts, such as manure from cows. ...

The dependence on the petroleum economy has a significant global influence. Petroleum reserves represent political and monetary power. Considerable effort is focused on managing a stable supply, shaping global politics. The environmental impact from the carbon dioxide discharge is currently unsustainable. Alternatives are a matter of necessity. Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ...

Criticisms

The approach has been criticized on the following grounds, which can also be seen as the engineering challenges that must be overcome.

Cost of production

Liquid nitrogen production is an energy-intensive process. Currently practical refrigeration plants producing a few tons/day of liquid nitrogen at about 50% of Carnot efficiency ^[1]. The Carnot heat engine uses a particular thermodynamic cycle studied by Nicolas Léonard Sadi Carnot in the 1820s and expanded upon by Benoit Paul Émile Clapeyron in the 1830s and 40s. ...

Energy density of liquid nitrogen

Liquid nitrogen as an energy store has a low energy density. Liquid hydrocarbon fuels by comparison have a high energy density. A high energy density makes the logistics of transport and storage more convenient. Convenience is an important factor in consumer acceptance. The convenient storage of petroleum fuels combined with its low cost has lead to an unrivalled success.

The maximum energy density that can be realised from liquid nitrogen at atmospheric pressure is 213 Watts-hours per kilogram(W-hr/kg). This compares with about 3,000 w-hr/kg for a gasoline combustion engine running at 28% thermal efficiency, 14 times the density of liquid nitrogen used at the Carnot efficiency ^[2]. A colorized automobile engine The internal combustion engine is a heat engine in which the burning of a fuel occurs in a confined space called a combustion chamber. ...

For an isothermal expansion engine to have a range comparable to an internal combustion engine, a 350 litre onboard storage vessel is required ^[2]. Add to that the fact the container would need to be insulated. A practical volume, but a noticeable increase over the typical 50 litre gasoline tank. The addition of more complex power cycles would reduce this requirement and help enable frost free operation.

Frost formation

Unlike internal combustion engines, using a cryogenic fuel require heat exchangers to warm and cool the working fluid. In a humid environment, frost formation will prevent heat flow and thus represents an engineering challenge. To prevent frost build up, multiple working fluids can be used. This adds topping cycles to ensure the heat exchanger does not fall below freezing. Additional heat exchangers, weight, complexity, efficiency loss, and expense, would be required to enable frost free operation ^[2].

See also

• Energy storage
• Energy crisis
• Future energy development
• Hydrogen economy
• Methanol economy
• Lithium economy
• Zinc economy
• Solar power

Energy storage is the storing of some form of energy that can be drawn upon at a later time to perform some useful operation. ... An energy crisis is any great shortfall (or price rise) in the supply of energy resources to an economy. ... Energy development is the ongoing effort to provide abundant and accessible energy, through knowledge, skills and constructions. ... A hydrogen economy is a hypothetical future economy in which the primary form of stored energy for mobile applications and load balancing is hydrogen (H2). ... The methanol economy is a hypothetical future economy in which methanol fuel has replaced fossil fuels as a means of transportation of energy. ... The Lithium Economy is a concept analogous to the Hydrogen Economy, Methanol economy, Ethanol economy or Liquid Nitrogen Economy but where the energy vector is Lithium instead of Hydrogen, methanol or ethanol. ... The zinc economy is a concept analogous to the hydrogen economy, methanol economy, ethanol economy, lithium economy or liquid nitrogen economy. ... Solar power describes a number of methods of harnessing energy from the light of the sun. ...

External links

• Liquid Nitrogen Economy - Similar overview with diagrams. (License GFDL)

• L2N Vehicle 1 - A liquid nitrogen powered car using a Cryogenic Heat Engine at the University of North Texas.

• L2N Vehicle 2- Another liquid nitrogen powered car at the University of Washington.

• WhisperGen - Domestic stirling generators.

• Cryogenic Coolers - Small, rapid, compact cooling.

• Discussion on L2N vehicle feasibility at How stuff works

• Thermodynamic Properties of various fuels - Tabulated data.

GNU logo (similar in appearance to a gnu) The GNU Free Documentation License (GNU FDL or simply GFDL) is a copyleft license for free content, designed by the Free Software Foundation (FSF) for the GNU project. ...

References

1. ^ J. Franz, C. A. Ordonez, A. Carlos, Cryogenic Heat Engines Made Using Electrocaloric Capacitors, American Physical Society, Texas Section Fall Meeting, October 4-6, 2001 Fort Worth, Texas Meeting ID: TSF01, abstract #EC.009, 10/2001.
2. ^ ^a b c C. Knowlen, A.T. Mattick, A.P. Bruckner and A. Hertzberg, "High Efficiency Conversion Systems for Liquid Nitrogen Automobiles", Society of Automotive Engineers Inc, 1988.

• C. A. Ordonez, M. C. Plummer, R. F. Reidy "Cryogenic Heat Engines for Powering Zero Emission Vehicles", Proceedings of 2001 ASME International Mechanical Engineering Congress and Exposition, November 11-16, 2001, New York, NY.

• Kleppe J.A., Schneider R.N., “A Nitrogen Economy”, Winter Meeting ASEE, Honolulu, HI, December, 1974.

• Gordon J. Van Wylan and Richard F. Sontag, Fundamentals of Classical Thermodynamics SI Version 2nd Ed.