Amory Lovins Misleads with Numbers

The following is a review of Amory Lovins, "More Profit with Less Carbon", Scientific American, September 2005, p. 74. In short, Lovins throws a lot of numbers around, but far too many of the ones he provides are irrelevant, meaningless, or misleading.  

The September 2005 Scientific American, a very good issue generally on "Crossroads for planet Earth" and the major near-term issues we're facing, includes an article by Amory Lovins that misleads far more than it informs. In the article's five sections Lovins pushes his two major themes of energy efficiency and hydrogen, with a nod to renewables, asserting that all we need do is take advantage of existing technologies to both save money and greatly reduce our use of oil and emissions of carbon dioxide. But the arguments and numbers he uses to make his case don't add up.

Let's start with Lovins' clearest abuse of numbers in this article, two instances where reasonable explanation is provided, as it calls into serious question the care with which the less well explained numbers have been used. The first example here is the "Compounding Losses" figure and associated discussion, which describes the energy lost on the way from a power generator to an industrial plant moving fluid through a pipeline, with less than 10 percent of the initial fuel energy delivered to the energy of fluid motion. The clearer, but quite parallel, example is the discussion following his statement that "the modern car remains astonishingly inefficient", conveying less than one percent of the energy in fuel to motion of the driver.

These may well be accurate numbers averaged over modern driving patterns and industrial fluid use. However accurate they are, they are not useful because the real purpose in both cases is not "energy conveyed to driver" or fluid, dissipated on deceleration. The important measure is the distance the driver or fluid has been moved. That's why we count "miles per gallon", not "joules per gallon". If we were launching the driver into orbit then "energy conveyed to the driver" would be a useful measure, but space travel is not the transportation sector Lovins claims to be addressing.

To better see the absurdity of Lovins' metric, imagine how one could improve it. Because the energy transfer happens only during acceleration, constantly accelerating and braking a vehicle would be one way to convey more of the fuel energy to motion of the driver. Driving at a steady speed, in contrast, conveys no extra fuel energy to the driver: 100% of the fuel input is lost to heating the air and road and other waste. Hybrid cars with regenerative braking recover the energy of the driver (and vehicle) so the net energy transfer to acceleration is much less in a hybrid than in a conventional car. Would Lovins argue on this basis that hybrids are less efficient?

In fluid flow similarly, for steady-state flow down a long pipe, ALL the energy loss goes to "pipe losses" and those further up the line and none of it goes to the energy of fluid flow, because that fluid is already flowing and we're not making it go faster. As with regenerative braking, flow energy could be recaptured by turbines at the other end of the pipe, if the fluid flow energy was that large. Just as with hybrid cars that would reduce the fraction of net input energy going to Lovins' metric, apparently making things worse by that number.

The relevant quantity that we are expending energy on in these two examples is not the energy of motion but the consequence of motion: moving things from one point to another in a given amount of time. We're turning our fuel energy into things with economic value, and the less that's lost in "energy of motion" or other side quantities, the better.

Another problem with the "Compounding Losses" figure, the "astonishingly inefficient" modern car comment, and similar statements for example on "waste heat discarded at U.S. power stations" is a neglect for the important distinctions between thermal energy and the energy available for useful work. The laws of thermodynamics imply that thermal energy (heat) is "low quality" energy and at typical temperatures (boiling water in coal-fired generators for instance) only about one third of that heat energy can even theoretically be converted to mechanical, electrical, or other forms of useful high quality energy. Some of the inevitable waste heat from such a generator can be "recycled" through co-generation arrangements, but efficiency and generating capacity numbers in those cases should be reduced because heating is a low quality application of energy. It is not evident Lovins has made this separation in the numbers associated with his "Electricity Alternatives" graph. Heat pumps can provide up to three times as much heat energy as electrical input, for instance, so thermal and electrical energy capacities and efficiencies should never be just lumped together.

So the "70%" (really 65-67%) waste in coal-electricity generation or the 75-80% waste in vehicle internal combustion engines is simply not in a territory that's available to significant efficiency improvements, as long as we're turning fuel into useful work through combustion.

There are other ways to convert the chemical energy of fuel to useful work. In particular fuel cells can have efficiencies as high as 90% when run slowly under lab conditions. But in practice when producing useful levels of power for their size, they do only marginally better than combustion. That leaves theoretical room for improvement, but we have nowhere near the technology today to recover any significant part of that wasted 50-70% of our fuel.

Nevertheless, Lovins repeatedly harks back to this inevitable waste when he emphasizes that "small reductions in the power used at the downstream end can enormously lower the required input at the upstream end", "every unit of energy saved at the wheels ... will save an additional seven units of energy now lost on route", "Europe and Japan ... are up to twice as efficient as the U.S., but they still have a long way to go." and so forth. Are these statements even relevant or informative? A 10% average improvement downstream would cut upstream energy use the same 10%; that's what we care about generally, not the exact number of kW-hrs saved by the more efficient appliance or vehicle.

The "Compounding Losses" figure also misleads in another rather subtle way. While in the text Lovins usually makes numerical comparisons on a total energy basis, in the figure the percentages quoted are losses at that stage relative to input to the stage, not losses relative to the original fuel input. For instance, the 9% quoted loss to transmission and distribution is not 9 units out of the 30 units of energy delivered to the grid, but only 2.7 units of those 30. The graphic design makes this clear enough, but from the numbers some readers might end up thinking grid-related losses are much more significant than in reality.

Further on, Lovins strangely attacks gas turbine generators, which are actually more efficient at converting fuel to useful work than both conventional steam turbines and practical high-power fuel cells, with waste reduced to perhaps 40-45% of the input energy. Gas turbines manage this feat by creating both mechanical and heat energy when burning instead of just heat; coal gasification can allow coal to take advantage of this technology as well as natural gas, possibly extracting 50% more energy out of each ton of coal. Nevertheless, Lovins in a bout of illogic states that gas turbines are "so wasteful ... saving 1 percent of electricity would cut ... consumption by 2 percent and its price by 3 or 4 percent". The alert reader will note that the sizes of those percentages are not increased by the wastefulness of gas turbine generators, rather the reverse: the fact that gas turbines are so efficient makes natural gas that much more valuable when electricity is needed.

The cause of Lovins' attack on use of natural gas for electric power production seems to be a conviction that it can be more useful for vehicle fuel - preferably by converting it to hydrogen. Use for electric power drives up the fuel price, making hydrogen that much more expensive. But surely, for somebody promoting efficiency, isn't it better to have natural gas converted to useful work where it can be done with the highest efficiently, ie. at a gas turbine power plant?

Lighting is certainly one area where there is great room for efficiency imrpovements, and some promise: Lovins rightly points out the position of compact fluorescent bulbs now. There's little excuse for anybody to buy incandescent bulbs for most purposes, though defects in earlier generations of these bulbs have likely made many consumers shy away so far. LED lighting should improve things even more in the near future.

There certainly is also room in transportation for efficiency improvements. It's odd that Lovins makes no mention of expanding mass transit - rather he talks about the utopian "New Urbanism" where all you need is within a five-minute walk. The specific vehicle highlighted, the 5-passenger concept SUV "Revolution", is touted as being capable of tripling average fuel efficiency through "ultralight" materials. Strangely Lovins first talks about carbon-fiber composites capable of absorbing 6-12 times more crash energy per unit weight than steel, and allowing factories to be 40% smaller with no need for painting, and then states that "new ultralight steels" could subsitute if the composites "prove unready". How could less steel provide higher crash protection and smaller factories again? In any case, Lovins' SUV design is claimed to achieve a fuel economy "equivalent to" 114 mpg, and with a small fuel cell requires "only one third as much hydrogen" in "off-the-shelf" components to travel 530 kilometers (in a quick switch to metric, Lovins was perhaps trying to hide the rather low 330 mile range).

One would think that the fact hydrogen requires an "ultralight" vehicle to even achieve that limited range would suggest something is wrong here. How efficient would a hybrid power train be in such a vehicle? And if efficiency is the only goal, why not push for purely electric (battery-powered) vehicles, which can have net efficiencies two to six times that of hydrogen?

Some of Lovins' other discussion, on renewables and nuclear energy, and on savings from efficiency, seem fine if a little on the overly rosy side. In reality there's a lot of effort and probably government investment required to make any of the steps he mentions a significant factor in energy use, but that's all swept under the rug here.

Lovins also repeatedly compares our energy intensity (energy use per dollar of GDP) with that from 30 years ago, or the improvements from 1977 to 1985 or 1978 to 1987 in a couple of cases. As we should all remember, that brief period of the late 1970s was rather exceptional due to the oil shocks and perhaps also thanks to Jimmy Carter's presidential leadership on energy issues. With oil prices rising to similar levels again today there may be hope of a similar set of improvements in store; oddly however Lovins opposes European-style high fuel taxes to accelerate such progress, as these "cut driving more than they make new cars efficient". Is that really a problem?

Lovins does quote an EPA official who claims a 2.1 percent annual improvement in US energy intensity over the past ten years, attributed to "prudent choices ... with the shift to a more information- and service-based economy", indicating we have been making real progress recently. But even if the number is correct, it is meaningless on a world-wide scale, as the shift in our economy has just exported energy-intensive industry elsewhere.

Lovins throws a lot of numbers around, but unfortunately too many of the ones he provides are irrelevant, meaningless, or misleading. There are some good points in here, but missing are the really important numbers on real-world costs and realistic adoption rates. Those numbers would show that in reality we have a very difficult road ahead of us, far more so than the complacent picture of technological readiness Lovins portrays.

Created: 2005-09-17 04:32:34 by Arthur Smith
Modified: 2005-09-17 04:37:39 by Arthur Smith