The Plight of Oil and Power Electronics
by Dennis L. Feucht
Innovatia Laboratories
With record high prices at the gas pumps in a largely oil-explored world, this might be the occasion to do what engineers do best: identify technical problems and devise solutions. While some decry the demise of the ecosphere due to the burning of hydrocarbon fuels, an equal problem is the anticipated inability to supply those fuels to meet the growing world demand in the foreseeable future. This article looks at the problem, largely through comments from senior oil engineers inside the industry, and then surveys solutions.
The Plight of Oil
Glenn Morton, a geophysicist who until recently headed North Sea geophysics and reservoir engineering for a major oil company, has sized up the global oil situation. It is interesting to consider his comments as an oil-industry insider as it contrasts with what economists and oil-company CEOs are saying. The June 2004 cover story of National Geographic Magazine addresses when peak global oil production will occur. Geologists and economists are embroiled in a debate about the subject. Morton, the geophysicist, comments:
"I know a few geologists who think that oil production won't peak for a long time because we keep finding more reserves. I only know of two economists who think the world is about to peak in oil. To me it is amazing that the economist at the Hubbert's Peak Symposium at the Offshore Technology Conference in Houston [in May 2004], Michael Lynch, cited the UK as an example of a province that was continuing to gain production. But his graphs only showed production up to the year 2000, which means he is 3-4 years out of date. If he had shown the last 3 years of production, the data would not have fit his case."
The economists are merely believing Adam Smith, that a rise in prices will bring an increased supply -- like corn supplies increase when the corn price rises. But oil is not like corn. Oil must obey the laws of fluid flow which are very unforgiving.
In the 1950s, M King Hubbert devised a method of determining the flow rates of oil fields as a function of time. This method has been rather accurate for over 40 years in predicting rates of various fields, though some refinement to it has occurred.
In a recent edition of Science magazine, the argument is made that known oil reserves are huge. Morton grants them the cited number but notes that the important variable is not reserves but production. (See: http://home.entouch.net/dmd/globaloildiscoveries.jpg) He responds:
"Each year more is added to the reserves. Big deal. Reserves don't necessarily translate into PRODUCTION. The world needs PRODUCTION, not reserves. There are an estimated 4 trillion barrels of hydrocarbons in the Orinoco Tar Belts, but no one can get much of it out of the ground because it is extremely viscous -- more viscous than road asphalt. So when people are looking at articles like this, ask yourself the following question. If I put a trillion dollars in your bank account (which are monetary RESERVES), but only allowed you to get it out at $10/week (which are monetary PRODUCTION), are you rich?"
Another fact about oil supply is that the reserves estimates continue to increase. Morton comments:
"When discovered, all fields are under-reported for size. This is due to the SEC regulations which require a division of proved, probable and possible reserves. Unless you can move reserves to the proven category, you can't report them. These stringent requirements for reporting only proven oil, give a false sense that suddenly there is more oil in the world. That isn't true at all. Oil companies know the 3P numbers but are only allowed to report the 1P. Probable and Possible reserves don't get reported until they move to the 1P category."
Over the last decade, oil companies have not made a major effort to find new oil fields because essentially the entire world has been explored. The exception is Antarctica; as Morton comments:
"The real place that has had zero exploration and where I believe lie big oil fields is Antarctica. However, current technology can not get any oil out of there because you can't protect the platform and well head on the sea floor from Rhode Island sized icebergs drifting off of that continent."
With the globe essentially explored, what remains are smaller and smaller finds:
"For the past 24 years the world has been finding less oil. Take a look at the global oil discoveries averaged over 5 year intervals and think about the fact that we use about 27 billion barrels per year. In 1990-95 we [the oil industry] found about 10 billion bbl/year, but pumped 25 billion. Today we find 3 billion per year and pump 27."
Furthermore, new fields are depleted more quickly:
"Over the years, we have learned how to suck a field dry very quickly. A billion barrel field of 50 years ago is still producing. Offshore a billion barrel field today will be abandoned after only 20 - 25 years. The second half of the world's oil will be drawn down faster than the first half."
Hope in better oil technology is not the answer. Morton asks why this technology hasn't worked to maintain the production rate in the UK, down 30% in 4 years, Oman down 30% in 3 years, the US down 50% in 33 years, etc. On May 18, 2004, Morton made the following observation regarding oil prices:
"In spite of OPEC saying that they would raise the quotas, the markets yesterday shrugged it off and the oil price went even higher -- a record high in current dollars (no inflation). Part of this price is terrorism fears, but part is reflecting the fact that we have an oil hungry world. China's demand for energy went up 15% from 1st quarter 2003 to 1st quarter 2004 (The Observer (business), UK, May 16, 2004, p 5). The markets are clearly saying that they don't believe OPEC has the capacity to fuel the world's energy needs."
As various factions argue about when oil will peak, the clear fact is that it is not getting any cheaper. Morton expected gas prices to fall, as they have, but over the longer run, as demand exceeds supply, prices will continue to increase. However severe the coming crisis, it poses an opportunity for long-awaited development of alternative energy methods.
Alternative Energy Solutions
As the existing large-scale solution to the problem of supplying energy falters, the prospects for alternative energy solutions grow more promising, and they all lead to a need for power and control electronics. I'll run down the list of what I see as the most interesting possibilities and provide some technical comment on them.
Solar photovoltaic (PV) panels: continuous-process "extruded" amorphous solar-panel ribbons have been projected for at least five years to reach a high-volume target price of $0.50 per W, competitive with the 1995 North American power grid. New PV panels are currently running at $3.50 per W at best. Progress is much slower than was anticipated. For a developer example see http://www.astropower.com a leading manufacturer of continuous-process PVs. Otherwise, solar cells are made using semiconductor batch processing, the original, expensive way.
Several different fuel cell technologies are being developed. Hydrogen (proton exchange membrane, PEM) technology was until recently the leader, under development by http://www.ballard.com. The fuel is still gasoline, which contains impurities that will easily foul a PEM "stack," the chemical-to-electric converter of the cell. The problem is being worked on by Detroit. A pre-conversion process is needed to filter out sulfur compounds, etc, and this is proving difficult (expensive).
Direct alcohol fuel cells (DAFCs) were stuck on a development problem that was solved a couple years ago, and now DAFCs are pulling ahead. This is particularly encouraging, as I view it, because DAFC stacks are not subject to fouling and either methanol or, preferably, the safer ethanol can be used. Ethanol is a "biofuel" and can be produced with the moderately simple chemical unit operations of sugar fermentation and distillation. Starches first must be broken into sugars by enzymes. Farmers (such as the Schroeder family in Colorado, including Gene Schroeder, the veterinarian who organized the tractorcade to Washington a few years back) have built small commercial plants in their barns, but larger corporate producers also exist, as well as grain-grower ethanol associations in the US and Canada. Sugar cane is the best source and would diversify and stabilize the sugar industry, as sugar currently gluts world markets, squeezing tropical cane growers financially.
Solid oxide fuel cells are also a leading contender and seem more suited at this time for large-scale use. They also run very hot.
The best fuel cell technical site I know of is http://www.benwiens.com the site of Ben Wiens, a former Ballard Energy fuel-cell engineer.
Biofuels: besides the "ethanol economy," other plants producing large amounts of oils, such as jetropha, sunflower, soybean, corn, canola, and crambe are under study. These organic oils are combined with hydrocarbon geofuels -- typically 20% "bio" to 80% "geo." Direct-injection diesel engines have essentially no degradation using these fuels once a few rubber parts are replaced. The 4.5 kW genset I have here at my cottage in the jungle has a Yanmar diesel engine. Similar engines have been run on discarded restaurant frying oil for years. An enzyme is used to transform it into biofuel directly burnable in the diesel engine.
Changing from gasoline or diesel fuel to ethanol is feasible, though ethanol's heating value (energy/kmol) is somewhat less. Corn oil is about 15% less relative to No 2 diesel fuel and is typical. Photosynthesis is one of the best solar conversion processes around. Why not use it? As gas prices increase, we approach an economic crossover, especially if worldwide cane production were directed at ethanol production. Temperate-zone crops are also quite suitable for biofuels, and ethanol associations have appeared in North America. (See http://www.ethanol.org)
Solar thermal: use a solar concentrator to heat a fluid stored in an insulated tank as thermal energy. Besides nuclear and chemical energy (such as ethanol in a tank), thermal storage has the highest energy density, especially if state-change materials are used. Then use thermal-to-electrical converters to produce electricity from a temperature differential.
I am currently working on a design for a Solar Thermal Electric System (STES) because it looks quite promising and nobody seems to be doing it. (I'm looking for a mechanical/chemical-oriented partner for this.) Here's why it appears to be cheaper and better than solar PV. First, storing heat in a tank is less costly and has less maintenance than storing charge in a battery bank. Second, by separating energy collection from conversion, the additional degree of freedom allows optimization of system sizing, which reduces cost.
The thermal-to electrical converter possibilities are:
Thermocouple stacks = thermoelectric modules (TEMs), used in Igloo-brand car coolers for example. Hi-Z is a leader in optimizing TEMs for electric power generation. Efficiency is the issue. It is increasing but is currently around 4%. Even so, it beats solar PV at 15% at a system level because collecting and storing heat is relatively cheap. The expensive TEMs are sized for desired peak power, while the lower-cost collector size is determined by the maximum storage requirement. TEMs are relatively inefficient because thermal and electrical transfer is done by electrons diffusing through semiconductor material. It's an ugly way to move electrons.
Thermionic devices: I know of no commercial work but research looks promising.
Reference:
"Multilayer Thermionic Refrigerator and Generator", G D Mahan,
J O Sofo, and M Bartkowiak, Dept of Physics and Astronomy, University of
Tennessee, Knoxville, TN, 37996-1200, and Solid State Division, Oak Ridge
National Laboratory, Oak Ridge, TN 37831-6030 ; arXiv:cond-mat/9801187 v1
19 Jan 1998
In thermionic conversion, electron transport is ballistic instead of diffusive, and efficiency figures (which can be calculated to about 1% accuracy on the basis of solid-state physics) are 2 to 5 times higher than thermoelectric devices. That's very encouraging, though it hasn't seemed to attract commercial interests yet.
Thermotunneling devices: place two metal plates 10 nm apart and electrons will tunnel across them. Tunneling is a quantum phenomenon that requires this close spacing. (Thermionics requires about 100 nm spacing.) http://www.powerchips.gi is the leading company, funded by Rolls Royce, headquartered in the tax haven of Gibraltar, with actual development in Canada. Using existing semiconductor processes and some novelties, prototype devices show an efficiency of 15%. This is sufficient to compete with the internal combustion engine. It would eclipse ordinary solar PVs too.
Low differential-temperature Stirling engines: The Stirling heat engine has been around for well over a century though it fell out of use due to the unavailability of stainless steel in the 1800s. It is making a comeback and several commercial concerns are working on product development. The free-piston design has one moving part. Efficiency is 40% or more, rivaling large steam turbines, and it is essentially maintenance-free. The Swedish submarine builder, Kockums, uses them in subs because they are nearly silent. At present, they are unaffordable, but mainly due to a lack of high-volume commercialization. Inventor Dean Kamen is working on a patented design (US patent 6,062,023).
Thermophotovoltaics (TPV): An enhancement to PV uses an optical frequency converter film in front of the PV layer to convert more thermal solar to the frequency conversion range of silicon panels. This approach might keep PV competitive with solar thermal. It is in the research stage of development.
Wind, ocean waves, ocean thermal, geothermal, etc: I see these as augmenting the more direct solar methods. In his Foundation sci-fi trilogy, Isaac Asimov had a whole planet running off of the geothermal temperature difference. A mine a mile deep is well above ambient surface temperature. Wind is feasible on or near large bodies of water and on hilltops. Ocean-wave energy has been attempted and is still in its early stages of development.
In summary, of the alternatives there are several promising energy developments with a 1 to 10 year time frame for mass commercialization. The alternatives result in a distributed and not necessarily centralized approach, which reduces the need for more copper distribution lines, and relies upon an energy source in the sky that will be available for the foreseeable future (and then some). The key question is whether enough interested inventors, developers, financiers, and entrepreneurs will arise in time to maintain continuity of the global energy demand. I hope this article contributes to that end.
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