Chapter 3
The Importance of Energy Efficiency Measures
3.1 Traditional Extrapolation of Future Energy Demands or Alternatively “The Same or with Renewables Even Better Quality of Life with Much Less Energy”
There is a very simple calculation which is easy to remember and which demonstrates the false but often heard assumption that renewables are not able to power the future world energy demands. Using approximate numbers this goes as follows: Only one quarter of today’s global population – about 1.5 billion in OECD countries – is using three quarters of today’s primary energy – which is about 105 PWh. That also implies that today, three quarters of our global population only have one quarter of the primary energy left – clearly an unfair situation which has to change! As we would like to allow everyone in a future world to live in an environment with the same quality of life as we have, there is this simple calculation: At today’s quality of life, 70 PWh of primary energy is needed per one billion people. If we assume that the global population will have risen to 10 billion people at the end of this century, this would quite simply mean that we would have a primary energy need of 700 PWh! This 5 fold increase in 90 years is often described in terms of a small annual increase, in this case only 1.8% per year, which seems little but underestimates the real challenges in the long term. It is often argued that such a huge energy content of 700 PWh cannot be delivered by renewable sources. This is wrong for three reasons: firstly, as will be explained later, when using renewables, we do not have to take the losses of converting primary energy – which is contained in solar energy, wind, geothermal and many more forms of energy – to secondary energy into account, secondly, it simply neglects the huge potential of introducing energy efficiency measures with new technologies and last but not least even the 700 PWh could well be delivered by renewable sources only.
In this context it is wrong to talk about “energy saving” as many people associate this with meaning less energy for them and therefore a decrease in the comfort and convenience of their desired services, which they do not want. Instead, we must tell people that with new and energy efficient technologies there will be “the same – or with renewables even better – quality of life but using much less energy”. People must be trained to understand that this could imply that the initial investment in such new products may be somewhat higher, but that over a lifetime, the overall (sometimes called levelized) cost (investment plus running cost plus end of life cost) can be considerably lower than for established products.
In the following, we will analyze a few examples of such new technologies which will be able to deliver the same service but with much less energy. As elements responsible for the decrease in losses as indicated by arrow (1) in Figure 3.1 we have among others: individual transport via electric vehicles, lighting through solid state LEDs and OLEDs both in the industrialized world and in developing countries, and replacing pumps with inefficient part load characteristics with phase angle modulated power both for private and industrial use. Another important decrease in end energy as indicated by arrow (2) in Figure 3.1 is of a passive nature, for example through proper insulation of future houses. Obviously such houses no longer need as much energy for heating and cooling and in the future they will even need no or only little secondary energy compared to today’s standard. Other contributions could come from better urban planning which should result in less transportation miles per inhabitant.
Figure 3.1 Energy efficiency measures to decrease the losses from secondary to end energy (1) and also today’s need for end energy (2).
3.2 Decrease in End Energy Needs with a “Better Quality of Life”
3.2.1 Future Lighting: Energy Saving and Better Service
Today, lighting consumes a considerable fraction of global electricity. According to a publication by E. Mills from the Lawrence Berkeley National Laboratory [3-1] about 14% of global electricity or about 2 PWh is consumed through lighting. The break-down into the various consumption sectors was estimated as being 28% for residential, 48% for service, 16% for industrial use and 8% for street lighting and other applications. It should be remembered that this does not include the fuel- and candle-based lighting for the more than 2 billion people in developing countries. When taking into account the global average of electricity production from primary energy, lighting consumes about 6 PWh of primary energy. There is still a huge number of traditional light bulbs in use, which produce the needed lumens from electricity very inefficiently. Only about 10% of the electricity consumed is converted into light and 90% is lost as heat. Fluorescent lights are already better and have an efficiency of about 30 %. The advent of solid state lighting will change this picture considerably. Light Emitting Diodes (LED’s) are already used in many applications as a bright point light source with a high efficiency of about 50%. The brightness has already reached the level needed in order to be used as head lights on upper class cars. The necessary production equipment and the required materials have now reached a mature state and will develop further in the future. Research is underway to explore laser based head lights with even higher efficiencies (the brand-new BMW i8 is expected to be equipped with laser head lights). Light tiles based on Organic Light Emitting Diodes (OLED’s) which emit light homogeneously are now at the beginning of commercialization. These light sources emit light not from a filament or an arc, but homogeneously over an area. This is similar to a solar module, where light is captured over the module area and electricity is generated but works the other way round: electricity is fed into an OLED device and light is emitted all across the area homogeneously. Knowing that one can change the emission spectrum of the OLED device, it is possible to create very different colors, opening up a multitude of additional possibilities for designers, which is very important to create a new lifestyle product which will be attractive to many people.
Let us now draw two important lessons with respect to energy efficiency and cost from the example of lighting. The easy part is to understand that to create the same illumination in lumen (= light intensity), LED/OLED require a five times less energy than today’s light bulbs. Hence, the secondary energy needed for the same quality of illumination is five times less than what it is today. Now, the more difficult part is understanding the “total cost of ownership”. Let us take a simple example: a 60 W light bulb costs about one Euro and makes about 800 lumen over a lifetime of 1,000 hours. At an electricity price of 20 €ct/kWh the total cost when using the light bulb is 1€ + 60W x 1,000 hr x 0.2 €/kWh = 13 € (plus the cost for replacing the lamp every 1000 hours). An LED lamp costs much more for the same 800 lumen, e.g. 40 € but has a lifetime of 25,000 hours. In addition, it consumes less electricity. So the total cost of ownership here is 40 € + 12 W x 25,000 hr x 0.2 €/kWh = 100 €. For the same 25,000 hours, the total cost of ownership for the light bulb would be 25 times the above mentioned 13 €, which is 325 €,; more than three times more expensive. Hence, the new LED lamp is – although more expensive at first sight – less expensive for the same service. It becomes more and more important – and this is also true for many other new technologies – to take an integrated look at the whole lifetime of alternatives before making a decision. This is especially important for renewable technologies producing electricity when compared to traditional fossil and nuclear ones: while the initial investment for renewables is considerably more expensive, over their whole lifetime the cost of fuel is zero in the form of wind and solar. Hence the so called “levelized cost of service (LCOS)” which includes all cost components over a lifetime becomes the important number to look at when comparing. In our case, the service is lumen multiplied by time. For the traditional light bulb, we obtain a cost of 1.6 €ct/(1,000 lm hr) and for the LED lamp the cost is only 0.5 €ct/(1,000 lm hr). It is also important to clearly specify whether the stated levelized cost is “real LCOS” or “nominal LCOS” In the example above, we have neglected inflation over time which gives us the “real LCOS” (by definition). If we had included inflation (e.g. 2.5%), the resulting “nominal LCOS” would have increased by 10% to 20%, depending on the (lm hr) per year. Whenever numbers for LCOS are compared, it is important to state clearly which of the two possibilities has been chosen in the calculation.
Taking a global look at what can be saved in electricity whilst maintaining the same quality of illumination, it can easily be seen that replacing today’s portfolio of light bulbs and other light sources with solid state LED’s and OLED’s could decrease the 2 PWh electricity need to only 500 TWh.
3.2.2 Electro-Mobility: Powerful and Halving Consumption (But Only If Electricity Comes From Renewables)
It is interesting to note that when the automobile was first developed in the late 19th century, the first thing to be considered was an electric drive. Due to the fact that with oil it was more convenient, everyone has concentrated on the Otto and diesel engine until now. The advantages of electric drive compared to traditional engines are: a much easier and smoother acceleration due to the torque dependency on the number of revolutions, which is much better than in a traditional engine. We all know this from by the experience of riding a tram. In addition, one does not need all the mechanical devices like clutches, gear boxes and ultimately the motor is part of the wheel, which will give even more freedom to the designers of future cars. A very important feature of electric vehicles is the much higher efficiency when comparing the secondary energy input. Electric motors have an efficiency of more than 90%, the battery efficiency is also in the range of about 90% (or better in the future) and all other processes to enable the movement of the car have another +/−70%. All together we have an efficiency of 0.9 × 0.9 × 0.7 = 0.57 or about 60%. This can be compared to a diesel engine which delivers only up to 30% of the secondary energy diesel fuel to the motion of the car. It is important to note at this point that there has to be an important prerequisite to really make the electric car superior to the traditional diesel car: namely, we have to compare the primary energy inputs in our traditional world. For the electric car this means that on a global level for every unit of electricity, two units are lost. This would make the electric car only 20% efficient, which is less efficient than a state of the art diesel engine. Only if the electricity is produced by renewables do we have the true benefit of electric cars which are more than twice as efficient as traditional cars.
It should also be noted that today most transportation for private cars, trucks, buses, ships and planes is powered by petrol – with the exception of railways which run on electricity in many countries. This will change in the future and as in the case of long range trucks, ships and planes electricity will not be the fuel of choice. Instead, these vehicles will be powered in the future either through biofuel or “power to gas”. The latter is obtained through hydrogen produced by water electrolysis (with renewable electricity) which reacts with CO2 to get CH4. In the case of trucks and ships I could imagine the use of hydrogen (or gas with a reformer, which splits hydrogen from the used gas), if an infrastructure can be envisaged. For planes, although it has already been demonstrated in the past that jet engines could use hydrogen, this may not be a good solution as the exhaust fumes will emit water vapor. This is more dangerous in the stratosphere as the small H2O water vapor molecule acts like CO2 but stays in the atmosphere much longer.
For the majority of private cars, it is well known that most of the cars drive less than 100 km per day, which is a distance easily covered even by today’s electric cars. I can see an easy adoption in areas where many families have a second car which is often hardly used for distances above this range. Even when the first car travels less than the mentioned 100 km per day on most days, it is desirable to have the possibility of driving longer distances on some days. This could be done in a variety of ways: either one could have a car-sharing program for such rides, or one could use cars which are already available today from Opel (the Ampera) which have a small 1.41 / 54 kW engine only used to charge the batteries and making all the positive advantages of the electric drive possible. Since November 2013 BMW also offers such a range extender with its all-electric i3 car. Alternatively, one could also use hydrogen either in a combustion machine or in combination with a small fuel cell producing electricity to recharge the battery. Other possibilities could combine the use of long distance trains and renting electric cars at the point of destination.
In summary, one could envisage the following situation with future transportation:
- Private cars:
most with electrical engines, many with an additional range extender (turbine with fuel/power gas or fuel cell with hydrogen) - Public transport by buses:
local range buses in the urban sector could efficiently use electric engines; for long range buses one could also use a range extender as with private cars - Trucks:
in many cases one would use biofuel to be most flexible; electric drive with range extenders is also a possibility - Ships
could be run either by fuel cells with hydrogen or on biofuel - Planes
most probably running on biofuel
Summarizing the potential for the transportation sector impressively shows how we could decrease the energy needs but keep the same level of comfort for all transportation activities. It should also be highlighted that when we speak about hydrogen it only makes sense when the electricity for water electrolysis comes from renewable sources. The following picture could emerge for the secondary energy used:
- Private cars
Assuming the majority (~3/4) of driving distance is covered with electricity and the remaining distance is covered with petrol/power gas or gas/H2, approximately one third of today’s secondary energy could be saved. - Buses
Assuming half of the cumulated distance traveled is in or near towns and the rest of travel is powered by petrol or gas/H2, about one quarter could be saved. - Trucks will see little and ships and planes will see no change.
With the split of energy used in the various transportation sectors described in the preceding chapter and the specific energy needs for the different applications, we can estimate the potential savings today if we assumed that future technology will be implemented. For the same quality of transport, this saving could be 40% or, in energy numbers today’s 24 PWh could be reduced to 14.4 PWh.
3.2.3 Comfortable Houses: Properly Insulated, Facing South (In The Northern Hemisphere) and Producing More Energy than Needed
In many countries, a major part of primary energy is used to provide the heating and cooling of buildings. For the example of Germany, this amounts to approximately 40%. Hence, a relatively large amount of money is spent by individuals to buy gas and oil for heating and cooling purposes. Obviously, this is an area where we could drastically decrease the amount of energy used today.
Technologically, this topic is one of the easiest, but in reality it is one of the biggest challenges to overcome. It all starts with the proper orientation of the buildings – at least the future ones as quickly as possible – with the roof and the respective rooms facing south and north. If we go back to ancient times, people already knew how to make the best use of orientation in order to have cool houses in the southern regions and not to need too much heat for houses during winter in northern parts of the globe. Unfortunately, most of this knowledge is no longer used by most architects and urban district planners, but it could provide the basis for integrating the local situation of solar radiation to ensure the comfort of a house. The easiest way to make the best use of a roof for solar capturing is the orientation of houses with one roof facing south. All that needs to be done is a proper orientation of the roads and guidance on how to orient one roof towards the south. This was already done years ago in North Rhine-Westphalia in Germany, when the Green party pushed for integrating more renewables and implemented such a regulation for new district buildings. It would be a major achievement if we could all agree on such simple measures which do not cost additional money – they just have to be planned properly!
While new houses now have all the possibilities to include proper insulation at a reasonable price, the installation of the different electrical wiring and piping for cold and hot water is necessary, too. It remains to be seen when it makes sense to have a dual wiring for DC and AC in a house, knowing that many of the appliances of a house today use DC electrical power provided by transforming AC. This includes most of the audio and IT systems, solid state lighting and many more. Taking into consideration that a future house will have a DC PV system with a several kWh battery system, one could save energy which otherwise gets lost by transforming AC into DC, especially for the many small appliances. It also greatly enhances the self-consumption of electricity produced within the same house, at least within the low voltage region where the house is located. These considerations are very different for existing houses, which only undergo major renovations at a rate of about 1% to 2% per year, during which new state of the art features can be implemented at a reasonable price.
A good way to push for implementing state of the art technologies in new buildings is the new European directive which gradually gives a mandatory goal for proper insulation in the first place and goes further into a future house, which produces more energy than it consumes over the course of a year. This will consequently start with passive measures like insulation but will increasingly include the production of electricity and heat at the point of its use, which is perfectly well provided by decentralized PV systems and thermal collectors on the individual houses. It should also be highlighted that the insulation of houses alone is not enough for the well-being for the residents: in order to prohibit the growth of mold fungus if the house is not carefully ventilated (…and most people are just too lazy), a well-functioning forced ventilation must also be installed. It will still require a lot of work for a standard package at a reasonable price to be available for existing houses.
An interesting question arises in the longer term as to the provision of heat in a well-insulated house in the future. The residual heat for achieving the right temperature becomes very little and one could wonder whether the hot water that is needed could be provided more cheaply by individual electrical heating at the point of use, thereby eliminating the additional future piping for hot water. This discussion brings me to a more fundamental point. While it makes most sense today to use solar thermal systems and more and more district heating – as it has been nicely and successfully done in Denmark – integrating seasonal heat storage from summer to winter in large quantities will also determine the appropriate infrastructure of the whole district NOW, including the provision of hot water piping in all of the houses. Over the lifetime of such systems (…and beyond) this will determine the way heating will be done in such an area. I would argue that anything we can do today for the coming years by using renewables like solar thermal is OK, even if in future years there may be a more cost efficient solution available for new houses in new districts.
3.3 Today’s Energy Needs with Known Energy Efficiency Measures
The potential split of sectors and electricity for today’s world would look fundamentally different to Figure 2.3 and is shown in Figure 3.2. For the various sectors, I assumed a decrease in energy needs of ~-40% for mobility, ~-80% for low temperature heat, ~-20% for the rest of the industry and ~-40% for electricity in industry as well as for the rest of the electricity consumption. The original secondary fossil fuel for transportation is assumed to shift completely to electricity or hydrogen/fuel derived from renewable electricity (in the latter case we have to provide an additional fraction of electricity corresponding to the associated losses). The total secondary energy would shrink from 90 PWh to approximately half of that (47 PWh) – in other words we would have an increase of the energy efficiency by a factor of 2. Total electricity would account for 54% of secondary energy, low temperature heat would decrease to 11% and process heat for industry and SMEs would be at 35%.
Figure 3.2 Today’s secondary energy sectors with known conservative efficiency and passive measures, which would only be ~47 PWh compared to the actual 90 PWh.
Before we take a closer look to the potential and today’s situation with the most important renewable energies, two different approaches for pushing energy efficient products as well as passive measures should be analyzed.
3.4 Support Mechanisms to Facilitate New Products: Ban The Old or Facilitate The New Ones
Let us assume that after a thorough analysis society and politics came to the conclusion that a better product compared to an existing one should be used in the future, for example energy efficient light devices. As always in the beginning of the lifecycle of new products, the cost will be high which should result in a high price. There are two fundamentally different ways to facilitate the introduction of such new products: politics could ban the old product by law – which happened in Europe with the traditional light bulbs – and force the industry to produce new products which were not working as they should at the time the law was put in place. Solid state lighting devices where not yet being mass produced and in the case of the energy efficient bulbs, it was realized that they only work if poisonous mercury is used, causing major difficulties when disposing of them after use. So obviously the demon “high energy consumption” was replaced with the demon “highly poisonous substances”. The big mistake in this approach was that there was no intensive discussion between industry and politics.
There is obviously a much better way, as demonstrated in Japan with the so called “Top Runner” project. In short it works as follows, using the hypothetical case of energy efficient light bulbs: on an annual basis the industry is asked to create the best efficient bulb for the existing technology status. With the help of a well thought out evaluation procedure with relevant figures of merit the best e.g. 3 products from companies A, B and C are recognized as the best ones and receive a big push for free advertising and other promotional activities. The following year, only the three chosen products are allowed to be sold, all others are then banned and the same procedure would take place again and so on. Most probably we would have avoided the energy efficiency bulbs containing mercury and instead would have created an interim solution with bulbs containing halogen before an even more efficient solution in form of solid state LEDs and OLEDs in the future would have also penetrated the market.
As a general observation, I see major drawbacks to bureaucrats simply banning something without properly consulting with industry. It is much more advisable to reward the best product but to leave the details up to the respective industry. This definitely works for consumer products; strategic products which will be defined and discussed in Chapter 5.1.1 may need a different procedure.