In the past, the scarcity of the energy sources used by mankind led to the search for new ones to replace them. Those new forms of energy, coupled with technological developments, in turn allowed for new applications that had not been possible until then due to the characteristics of the previous sources.
That is why, in the 17th century, the machine invented by Newcomen, which had initially been designed to extract the water that flooded the coal mines, was rapidly developed into Watt’s steam engine and rolled out for use on looms, trains, boats, etc.
The industrial revolution had begun: since then, energy and technology have been engaged in a continuous cycle that has allowed mankind to achieve an impressive level of development.
Nowadays, we are facing a new challenge. This time, it is not that our resources are dwindling; it’s that we need to reduce emissions. Having said that, we also have new technologies that have progressed even faster than the rate of transformation of the energy sector, such as the digitisation of networks and homes (the Internet in particular), sustainable mobility, the drastic drop in the costs of renewable energies and the collaborative economy.
The only possibility for continuing to use fossil fuels on a mass-scale in future is through carbon capture and storage (CCS) systems. Of course, not all fuels are equal and natural gas combustion produces three times less emissions than coal. That is why natural gas is considered to be a transitional energy source that will help mitigate the issue of climate change.
The first step in a CCS process is to separate nitrogen and CO2 (capture). This process consumes a significant amount of energy, which reduces the efficiency of the process and therefore raises the costs. Current research in this field is geared towards making the process as efficient as possible.
In the second instance, the now concentrated CO2 has to be taken (transferred) to a permanent repository (storage). These geological storage facilities need to be capable of storing millions of tonnes of CO2 on a permanent basis. As well as the difficulty in finding suitable deposits, it is necessary to prove on a reliable basis that the CO2 “in storage” will not end up “escaping”. There is also the issue of building the transport infrastructure.
The state of the art today does not offer convincing solutions to these problems and carbon capture and storage processes have not yet moved beyond the pilot project stage. Their use so far has only been considered possible for “centralised” energy processes. There is no possibility of capturing and storing emissions from what are known as the diffuse sectors, such as transport.
Renewable energies seem the most obvious solution to the environmental problem facing the energy system today. The three main sources – sun, wind and water – are distributed throughout the planet, which ensures their availability and that they can be used by all.
Hydro power is the renewable source that has been in use for the longest time in generating electricity and it has demonstrated its efficacy with a current installed capacity of 1,300 GW. A further 2,600 GW are considered to be as yet unharnessed, which would make an aggregate total capacity of 5,000 GW.
As for wind and sun, there are two problems yet to be solved in order that all their potential may be effectively harnessed: the cost involved and the issues derived from their intermittent nature. Nowadays, it seems self-evident that wind power and solar power are the renewable sources that have sufficient resources and reasonable estimated costs. As regards the other renewable energy sources; either the resources available are not so plentiful (such as the case of geothermal energy) or they are hindered by obvious problems with cost reduction (wave or tidal energies).
As for renewable energy from plant sources, apart from biomass obtained from forestry sources, energy crops have faced strong opposition because they “compete” with food crops for the land and water they use. However, attention should be paid in the medium term to the advances that may be made in the area of genetic engineering. It is possible that in future, genetically modified organisms that are capable of transforming sunlight in a very efficient manner may come to offer a feasible alternative for the production of liquid fuels. There are companies that are currently working in this area with positive results, although costs remain high.
Wind power is a renewable energy source that may now be considered to be mature. Ever since the technology based on wind turbines with three blades was consolidated as the most suitable alternative from the 1980s onwards, cost-cutting efforts have brought wind power down to €60/kWh. This was possible thanks to the development of an industry that has achieved economies of scale by increasing volume, supported by technology that has enabled more efficient machines on account of the increase in power and in the size of the rotors. The fact that the most advantageous sites were already in use in some countries drove the industry to prospect for new projects at sea. However, the complexity attached to offshore wind farms means that the cost has not come down far enough for this alternative to be competitive without premiums.
Solar power is another alternative source available to mankind for its future energy supply. There have been two main areas of development to date. The first has focused on concentrating the sun’s radiation to achieve high temperatures and be able to move thermodynamic cycles. It is known as solar thermoelectric power. The second uses the capacity that some semiconductors have to capture energy from photons and create a difference in potential in an electric circuit.
At this stage, it seems evident that electricity from solar thermal sources is not capable of achieving the same rate of price drop as solar photovoltaic energy, which means that the second is the option that is preferred when developing solar projects.
The advances made in the electronics industry and the increase in knowledge of how semiconductor materials behave have enabled the development of increasingly cost-effective photovoltaic cells. As costs have dropped, the applications in which energy from photovoltaic sources is employed have broadened, ranging from use in the space industry to include the generation of electricity in standalone systems and more recently, to be considered a competitive option for generating electricity on a large scale.
In the past, nuclear energy has demonstrated its ability to generate competitive, emissions-free energy on a continuous and reliable basis. Commercial reactors use the energy that is released in the process of fission of certain isotopes of uranium or plutonium. Research has also been ongoing for years on the construction of a reactor capable of obtaining energy from the fusion of two hydrogen atoms, while producing a helium atom in a reaction that is similar to what happens in the sun.
However, despite the huge efforts undertaken by the nuclear industry to implement the best possible safety measures, the accidents that have occurred at Three Mile Island (USA), Chernobyl (USSR) and Fukushima (Japan) have shrouded this energy source in doubts. The increasingly demanding safety requirements for new projects have seen a steep rise in the associated costs and this has in turn led to a certain degree of stagnation in the development of this energy source.
The energy products that are currently ready for use by consumers (which are referred to as ‘energy vectors’) are mostly oil by-products, natural gas and electricity.
Electricity is the energy vector that stands out the most for its versatility, in the sense that it can be produced by very diverse energy sources and that it can be used in almost any application.
Electricity can be transformed into any type of energy needed by mankind without producing any pollution at local level and once the infrastructure is in place, it can be transmitted on an immediate basis from the production facilities to the consumer.
However, its main problem lies in the difficulty it presents for storage. This issue is the reason why electricity has failed to achieve a significant level of penetration in the transport sector (which accounts for over 25% of total energy consumption). However, this situation could be poised for change in the very near future.
Once again, technological advances in the area of materials, combined with the demand for longer-lasting, safer batteries for mobile devices, have enabled significant progress in this field. It is just a matter of time until the new battery chemistries – mostly based on lithium-ion technology – make the leap to the transport sector.
Electric bicycles and motorcycles, plug-in hybrid and pure electric cars are entering a stage of development that will increase the economies of scale, reducing prices as they move along the experience curve. The factory that Tesla is building in Nevada alone will double the world battery output.
As well as transport, the electrification of the economy will be further boosted by the increased use of electricity in heating and cooling systems for buildings in particular and in general in all processes that require heat (in total, over 40% of the final demand for energy). The use of heat pumps with efficiency ratings of over 400%, which are capable of extracting (“pumping”) heat from sources with lower temperatures, will be crucial in ensuring that electricity achieves a higher penetration rate in this area.
Finally, the way that we use energy in future will have to enable us to avail of more services with lower energy consumption. Energy intensity is a measure of the energy consumed per unit of GDP produced. In the developed countries, economic growth may be said to have been decoupled from energy consumption.
Once again, technology should have a leading role to play in this change. In sectors such as lighting, the appearance of LED technology provides the same level of brightness but with an energy expenditure that is 10 times lower than that of incandescent lights.
In the residential sector, adequate insulation in homes can provide savings of up to 50% on the energy expenditure on heating and cooling. The gradual introduction of efficiency measures in electric engines and electronic equipment is enabling the development and roll-out of an entire generation of class A electrical appliances that offer savings of 50% on energy consumption compared to the technology that was previously available.
In the transport sector, there are two parallel trends in energy efficiency. On the one hand, the ongoing improvement in combustion engines is enabling a continuous reduction in consumption per kilometre travelled, with the gradual roll-out of technologies such as “start-stop” systems (savings of 8%) or continuously variable transmissions (savings of 6%).
The introduction of electric engines in the automotive sector in the form of plug-in hybrid vehicles is opening up a new world of possibilities such as braking energy recovery systems or the optimisation of combustion cycles.
Ultimately, when batteries reach a higher level of development, pure electric vehicles will reduce consumption to less than 20 kWh/ 100 km, compared to approximately 60 kWh/100 km that can be consumed by an internal combustion vehicle.