Diversificación y modernización de las actividades económicas

aluminium goods, against a projected doubling of demand. The project has received funding of £1.5 million, comprises a team of seven researchers, and is backed by a consortium of 20 global com-panies. The research will firstly, evaluate all existing options for carbon emissions reduction, ranging from low carbon energy sup-plies (renewables, nuclear and Carbon Capture and Storage (CCS) to energy and material efficiency. Secondly, radical new options will be explored—such as non-destructive recycling (the reuse of materials without remelting), light-weighting, and single-step heat processing—to deliver much greater carbon reductions. The work will combine physical and economic modelling, development and demonstration of new technologies, and ongoing interaction with industry built around a portfolio of fact sheets, case studies and workshops on wider themes. Two key publications will be released over the five year project: a mid-term project report that will be widely distributed to stakeholders, and a final book to be used as a reference guide for future work in this area.

ap-§6.3

pear, and some of the upstream oil supply would be displaced by electricity generation. Thus, the rubber sheet would become a tool for exploring alternative energy supply options and different tech-nology pathways—for assessing large-scale changes to the energy network, rather than just improvements.

During the last century, abundant supplies of inexpensive fos-sil fuels have proved significant in shaping and driving the global economy. For this reason, the conversion of chemical energy to heat using combustion is the dominant conversion process, being present in 90% of energy conversion pathways. It is not surpris-ing therefore that much of the current energy efficiency research is focused on around improving combustion processes. Although al-ternative conversion pathways are available—for example electro-magnetic radiation to electricity (in solar panels), nuclear energy to heat (in fission reactors), and kinetic energy to electricity (in hydro and wind turbines)—these technologies play only a minor role in energy conversion.

In contrast to the dominance of fossil fuels, concerns over cli-mate change and energy use reduction are still relatively new. Yet, at some point in the future, perhaps in 100 to 200 years, the domi-nance of fossil fuels energy supplies will likely end (due to excessive environmental damage or because the fossil fuel supplies dwindle) making alternative options more cost effective. During this tran-sition, alternative conversion processes will become increasingly important.

Energy can be divided into 6 different forms: radiation, chem-ical, nuclear, thermal, mechanchem-ical, and electrical. This gives 36 possible energy transformations for a single conversion process. In 1969, Zwicky¹⁹¹ proposed creating a matrix of all possible energy conversions, which he called the ‘Morphological Box of Energy Transformations’. The idea was to identify and explore alterna-tive pathways for converting energy, however the work was not completed. The concept of an energy conversion matrix has been revisited several times, but only in outline form, for example

Sum-mers,82(pp.150–1) Smil^{40 (p.14)} and Ashby.^164(p.21)

With the current pressures on fossil fuel supplies, it seems an opportune time to revive Zwicky’s idea, quantify the current energy conversions using an input-ouput framework and begin a comprehensive and fundamental search for alternative energy con-version routes. This would begin by reviewing all known tech-nologies for converting energy, whether used in practice or still in the conceptual stage. Then using the morphological approach, a structured search of potentially new conversion pathways could be explored. Based on future projections of the fossil fuel avail-ability and public acceptance, scenarios could be developed and a roadmap described for large-scale changes to the energy network.

6.3.2 Passive systems: reduce, conserve and recover

The analysis of passive energy systems separate from conversion devices, has led to a new perspective on saving energy. This new view originates from the concept of material efficiency, where the demand for materials can be decreased by: reducing the mate-rial in the product (reduce), extending the service-life of prod-ucts (conserve) or recycling and reusing prodprod-ucts (recover). It is proposed to apply these concepts to useful energy—motion, heat, light, cooling and sound—in passive energy systems.

The ‘reduce’ approach aims to deliver the same amount of final service, using less useful energy. This includes measures such as:

increasing the passenger loading in cars, turning off light bulbs when not in use, and ensuring electric motors and drives are matched with the required load. The underlying aim is to elimi-nate over-deisgn and use systems to their full capacity. (Energy savings in passive system, should not be confused with reductions in energy use through efficiency gains in conversion devices.)

The ‘conserve’ approach involves modifying passive systems to extend the lifetime over which useful energy is applied. Examples include: insulating and sealing buildings to conserve heat;

reduc-§6.3

ing vehicle aerodynamic drag and tyre-to-road friction to maintain momentum; designing electronic displays that require no power to maintain text on the screen.

The ‘recover’ approach requires improving the design of passive systems to recover useful energy following its application. Motion in vehicles can be recovered using regenerative braking, a tech-nique already commonly used in electric motor systems. A possi-ble alternative is the transfer of momentum to another moveapossi-ble body, as is observed in a Newton’s cradle. Interestingly, if a signif-icant proportion of motion in vehicles could be recovered, it would negate the need to light-weight vehicles.

The recovery of heat follows the same principle as down-cycling of materials in products. Currently, most of the thermodynamic availability of fossil fuels is wasted because it is used for low tem-perature applications, such as heating air and water. However, waste heat from an application is not lost (conservation law), in-stead only its quality is degraded. Thus if the waste heat from a high-temperature application can be used at a slightly lower temperature, and so on, then a cascade of reducing heat quality is formed. This concept is not new and is employed in industry, using optimisation tools such as the ‘pinch analysis’ methodology developed by Linnhoff and Hindmarsh.¹⁹² However, the theoreti-cal potential to cascade heat at a national or global level has only briefly been explored (see Lovins³⁷ and Nakicenovic and John¹⁹³), and is an area that warrants further investigation.

Table 6.2 gives examples of reduce, conserve and recover for the passive energy systems. The time scales for useful energy in pas-sive systems are typically short. Light will be absorbed within less than a second, sound over a few seconds, kinetic energy perhaps lasts a few minutes, whereas heat or cooling is available for hours.

In contrast, the long service life time for materials in products—

from days to centuries—makes them an ideal area to pursue the strategies of reduce, conserve and recover. Allwood, Cullen and Milford¹²⁵ have discussed such ideas under the topic of material

Examplesofreduce,conserveandrecoverinpassivesystems ServiceReduceConserveRecover Transportfullpassengerloadaerodynamicdesignregenerativebraking enginematchedtovehicleimprovedtrafficcontrolmomentumtransfer Structurelowenergymaterialsservicelifeextensionmodulardesign light-weightingre-configurabledesignreuse/recycle Sustenancelesssupply-chainwasteadvancedpackagingnutrientrecovery? lessconsumerwastelong-lifeproducts Hygienetanklesshotwaterinsulateequipmentwaste-waterheatrecovery Thermalcomfortheat/coolonlypeopleinsulateair-tightnessventilationheatrecovery usesolarheatgainreduceairleakagethermalmass Communicationprintlessonpaperstaticimagedisplaysun-photocopying Illuminationimprovedluminairedesignreflectivesurfaces?photovoltaicsurfaces? illuminateonlytaskarea

§6.4

efficiency for the five most energy intensive materials: steel, crete, paper, plastics and aluminium. However, the reduce, con-serve and recover strategies are yet to be examined in detail.

Having ascertained in this research that large opportunities exist for reducing energy use in passive systems, the next step required is to identify the specific technical breakthroughs required to deliver these gains. The field of energy efficiency would benefit from a structured analysis which explores this potential using the three different approaches: reduce, conserve and recover.