Volume 25, Number 3 July 1996
Background Paper in Support of the American Physical Society's Statement on Conservation of Helium
Gordon Dunn, Edward Gerjuoy, and Robert L. Park
This Background Paper originally was prepared by the authors (as members of the APS Panel on Public Affairs) in support of the Society's November 19, 1995 "Conservation of Helium" Statement that was published in the April 1996 issue of P&S. The present text is a slightly revised version of the Background Paper that was released to the media. The authors are indebted to Dr. Arthur W. Francis for his comments on the original version. It should be understood that neither the original nor the present version of this Background Paper has been formally reviewed or approved by the Society.
Helium properties and uses
Helium is absolutely essential to achieving the extremely cold temperatures required by many current and emerging technologies. The cryogenic (low temperature) uses of helium stem from the fact that liquefied helium has the lowest boiling point of any substance, including hydrogen. Helium boils at only 4 K (-452 Fahrenheit). On this same scale, hydrogen boils at 20 K, and at 4 K is already a solid. All other gases boil at substantially higher temperatures; nitrogen and oxygen, for instance, boil at 77 K and 90 K respectively. Since modern technologies often require extremely low temperatures, cryogenic applications of helium have risen steadily in recent years and currently amount to 25% of total usage.
In particular, liquid helium is the only cryogenic fluid that can be used to reach the low temperatures required for today's superconducting electromagnets. Helium-cooled superconducting magnets are employed in the increasingly important medical diagnostic tool known as MRI (magnetic resonance imaging). Superconducting magnets also are a standard feature of the high-energy accelerators physicists use for research on fundamental particles, and superconducting magnets will be required in the emerging transportation technology known as MAGLEV, wherein trains are to be magnetically levitated above their tracks, thereby permitting very high speed operation without the usual friction losses.
Superconducting electric power transmission lines are a potential technology that will require large quantities of helium. Such lines would avoid the wasteful energy losses in present electric power transmission Although a new unconventional class of superconductors was discovered in 1986, the so-called high-temperature superconductors which maintain their superconducting properties at temperatures well above the 77 K temperature of liquid nitrogen, it has not yet been possible to fabricate these new superconductors into wires capable of carrying large currents.
Superconductivity is also essential to so-called Josephson junctions, from which SQUIDs (superconducting quantum interference devices) are manufactured. SQUIDs can detect very minute changes in electric currents and/or magnetic fields, even permitting the mapping of brain activity. Josephson junctions also can be used in very high speed micro-electronic switching devices for possible incorporation into the computers of the future.
In addition to these technological applications, liquid helium is an essential cryogenic fluid in almost every field of modern laboratory research, and thus to the technologies of the future. Indeed, it was basic research into the unusual properties of matter at liquid helium temperatures that led to the technological uses of superconductivity. Helium is also used to cool infrared and other detectors (in modern telescopes for example) to very low temperatures to reduce background noise, permitting detection of far weaker signals. Cryogenic pumping at liquid helium temperatures produces the extremely high vacuums often required in research.
Apart from its cryogenic applications, there are also more conventional uses for helium. The second lightest gas (after hydrogen), it is also chemically inert, which makes it a safe "lifting gas," as compared to hydrogen, but less than 10% of current helium consumption is for lifting. Helium is also used to create an inert environment to prevent oxidation or corrosion in welding, which accounts for about 25% of total helium consumption. Other uses include inert atmospheres for advanced fabrication techniques, such as semiconductor crystal growth and fiber-optic production (about 12%), purging large tanks, such as NASA fuel tanks (23%), leak detection in sealed systems (2%), and medical applications (another 2%).
Supplies of helium are finite and irreplaceable. Although the atmosphere contains the vast bulk of the world's helium, about 700,000 billion cubic feet (BCF), it is at such small concentration (0.0005%) that the energy cost of recovering it is prohibitive. The remaining helium, about 1120 BCF, is a constituent of some natural gas (methane) fields. Of these fields, helium is most inexpensively recoverable from the so-called "helium- rich" fields, defined as fields containing more than 0.3% helium. Helium-rich fields are found only in the U.S. and to a small extent in Canada. About 85% of the helium-rich U.S. resources are in the large Hugoton and Panhandle fields covering parts of Kansas, Oklahoma and Texas, and in the Riley Ridge fields of southwest Wyoming.
Most of the helium in gas fields outside the U.S. is at a concentration less than 0.1%. Based on the reasonable assumption that extraction energy costs are proportional to the inverse of the helium concentration, the energy required to extract helium from a helium- rich U.S. field is considerably less than the corresponding energy for extraction from fields elsewhere in the world. The actual costs in dollars of helium extraction from the gas fields, however, are not easily compared, since those costs depend on the economic worth of the methane that contains the helium. However, the U.S. is the world's major producer, consumer and exporter of helium. Typically, exports account for about one third of total domestic production. For example, in 1992 the U.S. exported 1.09 BCF, far more than all the rest of the world produced, and consumed 2.26 BCF domestically; about 0.3 BCF of this domestic consumption is by U.S. agencies, mainly NASA and the DOD. U.S. helium sales have increased from .67 BCF in 1970, to 1.1 BCF in 1980, to 3.5 BCF in 1995.
About 6.9 BCF of helium is contained in the natural gas pumped from U.S. wells each year. About 3.3 BCF is extracted by helium producers for domestic and foreign consumption; 0.36 BCF is lost to the atmosphere during the extraction process; and the other 3.2 BCF is simply lost to the atmosphere during the burning of natural gas. Thus, the rate at which helium is depleted depends in large part on the rate of natural gas consumption. Some 10% of the total production of refined helium in the United States presently is performed by the Bureau of Mines, using facilities dating from 40 to 60 years ago; this helium production just about meets U.S. agency needs. The remaining 3.0 BCF annual helium production is extracted by private producers and sold to private consumers.
The 3.2 BCF presently being vented to the atmosphere is lost forever. Recapture from the atmosphere is made quite impractical by the enormous cost. To extract 3.2 BCF of helium from the atmosphere would require an expenditure of energy amounting to perhaps 5% of the total energy consumption of the U.S. Presumably, however, private industry would be willing to extract the helium that is now wasted if a buyer could be found. Under the Helium Act of 1960, 50 U.S. Code ' 160 ff., the Secretary of the Interior was authorized to make just such purchases, for the purpose of establishing a helium conservation program. During the years 1962-1973, 34 BCF of helium were purchased under this program and stored by the Bureau of Mines in a gas field (Cliffside) near Amarillo, TX; the Cliffside reservoir is connected via pipelines to many of the helium-producing fields in the region. This purchasing program was terminated in 1973; the government-owned helium stored in Cliffside has remained approximately constant, at 32 BCF, since 1990.
Even if the demand for U.S. helium does not grow as rapidly as might be inferred from comparison of the 1970 and 1995 sales figures quoted earlier, a rising demand for natural gas will accelerate the depletion of our helium reserves. Any unextracted helium will simply be lost during burning. The Bureau of Mines estimates that the helium-rich high BTU gas fields presently producing the bulk of this nation's helium will be depleted in about 25 years, after which the cost of helium is likely to rise greatly in constant dollars.
Legislation and policy considerations
2. The legislation requires that all but 0.6 BCF of the 32 BCF helium reserve in Cliffside be offered for sale by January 1, 2015; 0.6 BCF is just enough to meet present U.S. agency needs for a period of two years. The helium sales offering must begin no later than January 1, 2005, and continue at a rate that would minimally disrupt the private helium extraction industry. This feature of the act is seriously misguided. It is prudent to maintain a helium reserve against the not very distant day when essential high-tech helium needs must be met by extraction, if not from the atmosphere at enormous cost, then surely from gas fields which require very much greater helium prices (in constant dollars) than today in order to produce helium profitably. Moreover, retention costs are extremely small. Since the terms of the Act require that some helium be retained in the Cliffside reserve even until 2015, the government will realize little savings in its annual costs of operating and maintaining the Cliffside reserve. In any case, these operating and maintenance costs have been very modest (they are budgeted to total only $2 million in fiscal year 1996) and were just about met by the revenue Cliffside earned for storing privately extracted helium during periods when production exceeds demand (usually the winter months, when very large amounts of natural gas are used for residential heating).
3. The legislation makes no provision for saving helium that is now being wasted. Because more helium is being pumped from the ground along with natural gas than the private extractors presently can market, 3.2 BCF per year is being lost to the atmosphere. We believe the arguments for retaining the reserve make an equally compelling case for storage of this otherwise wasted helium. The helium reserve should be a very valuable asset in the coming decades. It seems likely that, during the next two decades, the market price of helium will increase at an average rate of no less than 6.5%, the approximate interest rate on Treasury bonds. The costs of extracting helium will increase enormously once our helium-rich gas reserves are exhausted. Mechanisms to finance the storage of helium against that day, such as a consumption fee, should be examined.
The helium issue has been badly muddled by claims that the selloff is required to pay off the reserve's $1.4 billion "debt". This so-called "debt" was incurred because the helium purchasing program was financed by a "loan" of $252 million from the Treasury to the Bureau of Mines, instead of by a direct appropriation; compound interest since 1960 has increased the total "owed" to $1.4 billion. From the viewpoint of the U.S. government's net worth, however, regarding this $1.4 billion as a "debt" to the Treasury, which the Treasury should collect from the Bureau, is purely illusory; any transfer of funds from one government agency to another neither reduces the Treasury's national debt nor increases the budget deficit by a single penny, as the General Accounting Office (GAO), the Office of Management and Budget (OMB) and the Department of Interior Inspector General have sought to make clear. Selling off the nation's helium reserve would be both economically and technologically shortsighted.
Gordon Dunn is at the University of Colorado; Edward Gerjuoy is at the University of Pittsburgh; Robert L. Park is at the University of Maryland.