Technological Change In The Future

It has been clear since the mid-1950s, if not longer, that economic growth is largely driven by technological change, at least in a broadly defined sense. Economic forecasting - a very important activity - concerns the understanding and extrapolation of economic growth from the past to the present and into the future. This consequently implies a need for technological forecasting. Yet economists have largely avoided this topic, although there is a very large literature (already cited) on the closely related subjects of innovation, diffusion, imitation, substitution, returns to R&D, returns to adoption ('lock-in') and evolution. Most of this literature, except that subset which deals with R&D and diffusion case histories, is essentially theoretical, dealing with change processes as such. Few economists have considered technological change in terms of the specific technologies that characterize and enable various economic sectors - as defined by products and service outputs - still less their inherent limits and changing functional capabilities over time.

This persistent avoidance of the specifics has its obvious justification, in terms of the need to find or create broadly defined variables with explanatory power. Examples of such variables include capital stock, labor supply, money supply, agriculture and forestry, industry, commerce, transportation, energy services (electricity, gas, etc.), communication services, production, trade, and consumption. Each of these, and many other standard variables used by economists, are really an aggregation of heterogeneous elements, each one of which is likely - on inspection - to be revealed as an aggregation of subsidiary elements. The disaggregation process can be continued to lower and lower levels, with further proliferation of elements at each level. The similarity to biological classification into phyla, sub-phylae, families, genera, and species is obvious (and intentional).

Thus, industry can be subdivided into mining (extraction), manufacturing, construction, transport, and so forth. Manufacturing can be further subdivided into primary processing of raw materials (agricultural products, forest products, metal ores, fossil fuels, etc.), secondary refining and processing into finished materials and finished fuels, tertiary processing into shapes and simple components, combination and assembly into subsystems, assembly of subsystems into structures, vehicles, etc. Similarly, transport can be subdivided by modes (air, sea, road, etc.) and each mode can be further subdivided into components, like vehicles, guide-ways (if appropriate), terminals, fuel distribution, traffic control, and so forth. Systems can also be defined by attributes such as distance, speed, load, schedule, route structure, propulsion system, fuel economy and others.

Evidently each level and branch of this 'tree' structure is characterized by its corresponding technology. Many of these technologies - but not all - can be assigned to a specific economic sector. Thus underground mining is essentially a generic technology that differs only in minor respects from coal mines to silver mines, but has little relevance elsewhere. Surface mining is also generic, but utilizes different earth-moving and physical concentration techniques. Drilling through earth and rock is recognizably similar, whether the object is water, oil, gas or to build a tunnel. Furnaces converting fuel to heat are similar; they differ only in minor ways depending on the fuel, the ignition, and the way in which the heat of combustion is utilized. Carbo-thermic reduction of metal ores is essentially the same whether the ore (concentrate) is an oxide of iron, copper, lead, zinc, phosphorus, silicon or some other metal. The same holds for electrolytic reduction: the technology is very similar for aluminum, chlorine, phosphorus or magnesium, although electrolytes and voltages differ. Grinding mills are similar whether the material being ground is limestone, iron ore or wheat. Rolling mills are quite similar, whether the material being rolled is metal (hot or cold), paper pulp or some plastic. Pumps and compressors are similar, except for size and power, whether they are used to pump water, crude oil, natural gas, air or refrigerants.

Prime movers (engines) differ in terms of power output and on whether the fuel combustion is external (that is, steam engines) or internal, whether ignition is by spark (Otto cycle) or by compression (diesel), whether the working fluid is steam, some other working fluid (like helium) or exhaust gases, or whether they utilize pistons and cranks or turbines. But most prime movers convert heat from combustion (or nuclear reactors) into rotary mechanical work. Electric motors differ in detail depending on the configuration of windings, load patterns and whether the electric power supply is AC or DC, but they all convert electric power into mechanical work, usually in the form of rotary motion.

It is important for what follows to emphasize that, while all of these different technologies depend on design, the possibilities for design, in the case of physical systems, depend upon, and are limited by the specific properties of materials. As already mentioned, some technologies, such as prime movers and many metallurgical reduction and synthesis processes, depend on the temperatures, and in some cases, pressures, achievable in a confined space. These are limited by the strength and corrosion resistance (chemical inertness) of structural materials at elevated temperatures. The performance of engines, whether turbines or piston, also depends upon the pressure gradients that can be utilized and the rotational speeds that can be sustained - also limited by the tensile strength of metals. Turbine efficiency also depends, in turn, on the precision with which turbine blades, piston rings, gears and bearings can be manufactured, which depends - again - on the properties of the materials being shaped and the properties of the ultra-hard materials used in the cutting and shaping of tools.

In short, the limiting efficiency of all metallurgical, chemical and electronic processes depends essentially on the properties of structural materials. Some technologies are limited by the precision of metal cutting and shaping, as noted above. Some technologies are limited by the properties of hard materials, others by ferromagnetic materials, diamagnetic materials, superconductors, semiconductors, photo-conductors, photo-electrics, photo-voltaics, thermal conductors, thermal insulators, electrical insulators, optical conductors, optical reflectors, elastomers, long-chain polymers, chemical solvents, catalysts, lubricants, surfactants, flotation agents, adhesives, . . . the list is nearly endless.

Evidently materials have become more and more specialized over the years. This trend has enabled machines of all kinds to become more efficient and functional. But increased functionality almost always entails more complicated processing and more complex, and costly, capital equipment. The apparent and highly touted trend toward 'dematerialization' is an illusion. (We discuss the material requirements of industrial society in greater detail in Chapter 3.)

While it is true that high strength alloys may reduce the weight of aircraft or trucks - plastic containers weigh less than glass containers, modern raincoats are lighter than their rubberized predecessors, and so on - lightweight products based on light metals or composites invariably require much more complex pre-processing than the materials used in similar products a century ago. An extreme case, perhaps, but nonetheless suggestive, is the transistor. A silicon computer chip of today may only weigh a gram or two, while embodying the capabilities of literally millions of the vacuum tube triodes that were employed in the early electronic computers. However, precisely because of their power, today's ultra-advanced chips are produced by the billions and employed in hundreds of millions of products each year. Moreover, the weight of materials embodied in the chips is but a tiny fraction of the mass of materials that must be processed (and almost entirely discarded) in the manufacturing process.

However the key implication of the points already made is that specific processes depend upon the properties of specific materials. It follows that the capabilities of virtually every technology utilized by our industrial society is also limited by the properties of existing materials. As technologies approach these limits, it is occasionally possible to find or develop a substitute material that will enable superior performance and surpass the prior limitations. For example, all kinds of turbo-machinery effectively reached the temperature and pressure performance limits allowed by alloy-steel turbine blades nearly half a century ago. Super-alloys have permitted gas turbines to reach somewhat higher performance, but at much higher prices. For several decades, researchers have attempted to surpass these limits by substituting ceramics for metals, but - up to now - ceramics have proven to be too difficult to manufacture with sufficient purity and to shape with sufficient accuracy. In effect, turbine design is up against a materials-based limit that it may, or may not, be possible to overcome.

The point is that particular technologies - as contrasted with technology in general - always have limits. When a limit is approached, it can be characterized as a barrier. When the barrier is overcome, it is a breakthrough. Technological change in the past can be characterized quite accurately as a sequence of barriers and breakthroughs. But not every material has a viable substitute and not every process can be replaced by another, cheaper one. This is also an illusion fostered by oversimplified economics.

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