the use of larger sources. The optimal balance between these elements is debated and will vary by location. However, the emphasis is likely to change from that at present. In its visionary UK projections, the UK Institute for Public Policy Research looked to a new smart energy system which ‘empowers citizens and communities to be more self-sufficient while being part of a connected, inter-dependent system that offers security of supply and resilience in the face of changing demand and climate’ (IPPR 2018).
In addition to wider strategic debates on issues like this concerning the mix and scale of renewables, there are some general issues in relation to other possible pathways ahead, for example the role of carbon capture and storage and its potential use with biomass. Biomass use has its supporters but, as already noted, also its opponents, who are concerned about the likely environmental impacts and land-use implications of growing energy crops on a large scale. The stakes have been raised since some supporters want to go for biomass combustion combined with carbon capture and storage (BECCS), so as to achieve a net negative carbon outcome, assuming the biomass used is replaced with new plantations and the CO2 is stored.
Not everyone is convinced that biomass use can be fully carbon neutral, much less carbon negative, given that it takes time for new biomass to grow to re-absorb CO2 and replace the lost carbon sinks, a key issue in terms of the use of forestry products, as I explore in chapter 3. It is also not clear if all the carbon emissions can be captured and stored effectively by carbon capture and storage systems on a permanent and wide-scale basis. Nevertheless, some still see carbon-negative options as vital. I will be looking at the carbon sequestration issues further in chapter 4.
Finally, there is the overreaching issue of whether we should be seeking to develop new energy supply and carbon reducing/storing technologies, of whatever sort, as opposed to technologies for avoiding the need for more energy supply. The more efficient use of energy can, arguably, avoid emissions/kW of finally used energy at lower cost than adding more supply. Certainly, energy saving and demand reduction ought to have been given much higher priority than they have so far. In most industrial countries, energy has in the past been relatively cheap and the social and environmental impacts of using it have been externalized (i.e. left to society to deal with). That situation has now changed, so there should be more of an incentive to avoid energy waste.
There are clearly significant potentials for energy (and carbon) saving. For example, a UK study claimed that ‘one quarter of the energy currently used in UK households could be cost effectively saved by 2035; and this could increase to one half if allowance is made for falling technology costs and the wider benefits of energy efficiency improvements’ (Rosenow et al. 2018).
Similar gains are also possible in all the other sectors, including industry and transport. Overall, a recent report from the Centre for Research into Energy Demand Solutions at Oxford University sees improved energy use efficiency as being the key to the decoupling of energy demand from economic activity, thereby cutting emissions, much more so than clean energy supply. ‘In recent decades, more than 90% of the progress in breaking the relationship between carbon emissions and economic growth globally has come from reducing the energy intensity of the economy. By comparison, reducing the carbon emissions per unit of energy has, to date, been a relatively minor effect’ (Eyre and Killip 2019).
However, that may overstate the role of efficiency. Some of the reductions in energy use have been due to structural changes in the economy and to the rising cost of energy, not to improved energy efficiency per se, issues I will be returning to in later chapters. There may also be conflicts between energy saving and energy supply. The increasingly low cost of renewables may undermine the economic attraction of energy saving. In some situations, it may be cheaper (per tonne of carbon avoided) to invest in green power supply than to invest in energy efficiency, especially once all the easy, low-cost energy savings have been achieved. That is debated: some say there will be economies of market scale as energy-saving techniques develop and are widely adopted (Lovins 2018).
Also much debated is the potential impact of the so-called ‘rebound effect’: the money saved by investing in energy efficiency may be re-spent on other uses of energy, so wiping out some of the energy and carbon savings (Wei and Liu 2017). Unless, that is, the money is spent on renewable power. Then the carbon savings from efficiency will be fully captured, a point I made a while ago (Elliott 2004).
Nevertheless, issues like that aside, it still makes overwhelming sense to avoid energy waste, and there are also valuable synergies between renewable supply and energy saving: if combined, they can limit the rebound effect. In addition, if demand can be reduced and also managed flexibly, it is easier to meet it from renewables. Moreover, since there are some impacts from using renewables and the renewable supply technologies also have material requirements, it is foolish, in resource and impact terms, to waste the energy that they can supply and then have to generate more.
The bottom line is that we need to pay attention to both the supply side and the demand side. It will be hard for renewables to meet demand unless that is reduced but, equally, even if demand is reduced dramatically (Germany is aiming for a 50% cut by 2050), we will still need carbon-free supply. Some say that the balance should tip towards demand-side initiatives, and certainly in the past energy suppliers have not seen it as commercially sensible to support energy saving. In the new environmentally constrained context, the balance definitely needs to be changed. However, that should not be too difficult. In the new context, in most cases, with possible exceptions as noted above, the supply and demand sides are not in conflict: both are needed for a sustainable energy future.
Choices ahead
In the next chapter, I will look at how these various strategic issues have been dealt with in some of the long-term scenarios and plans that have emerged. Some analysts stress the demand side and, as noted above, that is clearly very important. For example, the Oxford Environmental Change Institute’s director, Professor Nick Eyre, has said that ‘The goals of a secure, affordable, low-carbon energy system are only achievable if energy demand is reduced, decarbonized and made more flexible’ (ECI 2018). But even in that formulation, decarbonization is presented as a key element, and that means new low- or zero-carbon supply technologies.
Nuclear power is one such option, but not one that I have covered here in much detail since, as I have argued at length elsewhere (Elliott 2010, 2017b), it has many drawbacks, including economic, safety and security issues and the problem of long-lived radioactive waste. There is also the already mentioned more practical problem that nuclear plants are inflexible and will not be much use for balancing variable renewables. They just get in the way of the more flexible supply and demand system that will be needed for a renewables based system. There have been proposals for smaller, more flexible nuclear plants, but that is some way off, their economics, as well as their safety and security risks, still being uncertain (Thomas et al. 2019).
While some still look to nuclear as an interim option, possibly using new technology, in the longer term there is the fundamental issue that nuclear fission relies on fuels that, like fossil fuels, are a fixed planetary resource. They are not being renewed and cannot be relied on indefinitely. Indeed, although estimates vary, current reserves seem likely to be sufficient to supply the global reactor fleet for only a few decades, optimistically maybe up to a hundred years or so, although less if, as some would like, the use of nuclear is expanded. New uranium finds may be made as costs rise, and new technologies, like breeder reactors and the use of thorium, can extend the use of the fissile resource, but nuclear fission is not a renewable option.
The fuel sources for nuclear fusion, if it is ever successfully developed at commercial scale, are more extensive, with one key hydrogen isotope fuel, deuterium, being available from seawater, although for the other, tritium, there may be limits to its availability on this planet. There are other uses for lithium, the main current source
