Renewable Energy. David Elliott
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transition, it may not in fact cost consumers too much. The European Commission (EC) says that, under its proposed renewables-led transition, ‘by 2050, households would spend 5.6% of income on energy-related expenses, i.e. nearly 2 percentage points lower than in 2015 and lower than the share in 2005’ (EC 2018). However, that is speculative, and the EC does include more than just renewables in its proposed mix, as do some other studies. Indeed, although most agree that renewables will boom, some see fossil fuel, and possibly nuclear, remaining as a vital part of the energy mix into the far future (BP 2019; WEC 2019).
So the question remains: are they right, or can the renewables meet all our energy needs? That may depend on what sort of future global energy system and economy we are looking to create, how rapidly the changes can be made and how we go about making them, issues explored in subsequent chapters.
The first part of the book focuses on the technological aspects, starting off, in chapter 2, with an overview of the technological options and key related transition issues. Chapter 3 then looks at what energy supply technology choices have been made in some of the existing future-energy scenarios, while chapter 4 looks at system integration and balancing requirements and options.
The second part of the book moves on from essentially technologically defined issues and options to an exploration of the wider strategic issues and choices, including social change options, asking whether we can and should move to a low- or zero-growth sustainable energy future. Chapter 5 looks at the issue of growth, and at the need for a socially equitable transition process, while chapter 6 focuses on the wider geopolitics of the transition. Chapter 7 looks at some examples of what is happening around the world, leading to an overall conclusion in chapter 8.
Energy metrics and climate impacts – a short guide
The emphasis in this book is on energy policy, in particular the technological choices ahead. I have tried to use plain English and avoid technical terms but, inevitably, getting on top of what is a complex field requires some understanding of basic energy systems and technology and related issues. Box 1.3 provides a short guide to the measurement units used in this book. Perhaps surprisingly, not all of the metrics used are uncontroversial.
Box 1.3 Energy and power units
The terms ‘power’ and ‘energy’ are sometimes used interchangeably, which can be confusing. In this book, ‘power’ is used to mean electric power, whereas ‘energy’ covers all sources/end uses (power, heat and transport), not just electricity, although of course some electricity is used for heating and for transport.
In physics, the definition of power is more specific. It is a measure of the ability (or capacity) of a device to do work, rendered in watts and multiples of watts: 1,000 watts is a kilowatt (kW), 1,000 kW is a megawatt (MW), 1,000 MW is a gigawatt (GW), 1,000 GW is a terawatt (TW). Energy also has a more specific meaning in physics. Strictly, it is always conserved and cannot be ‘generated’ or ‘consumed’, only converted from one form to another. But we still commonly talk of energy generation and consumption, and the amount of energy converted (generated or consumed) is measured as power × time, i.e. the power of the device multiplied by how long it is run for, so it is ‘kilowatt hours’ (kWh) and multiples, MWh, GWh and TWh.
There will always be losses in energy conversion from one form to another and so, for a generation system, the finally available end-use energy will be less than the so-called primary energy inputs (for example, the energy in the fuel used in fossil-fuel-fired plants). The actual energy output of a generation plant will also usually be less than the theoretical full output possible for the plant, especially for systems using variable renewable sources, since they cannot deliver their full theoretically possible output all the time. ‘Capacity factors’ (also called ‘load factors’) are cited for the percentage of the theoretical maximum output capacity that is actually available annually to meet demand loads.
There are some issues with the way renewables are handled in energy analysis, since renewables like wind and solar do not use fuel. To produce a figure for primary energy that is compatible with those used for fossil fuel plans, the output from the renewable plant is sometime ‘grossed up’ by a factor of around three, to reflect the amount of primary fossil energy that would have to be used (given the large losses in fossil energy conversion) to produce the same output. The same is sometimes done with nuclear plants and biomass plants. It might be argued that it would better just to compare final energy outputs in each case. But, done that way round, to get the same output as a wind or solar plant a fossil plant could be depicted as having, nominally, to consume around three times more primary fuel (Sauar 2017).
Although, as I will be exploring, there can be disagreements about the likely technical and economic viability of new energy technologies, the wider climate change and environmental aspects and issues are sometimes even more controversial. For example, there are sometimes fierce debates concerning the likely social and environmental impacts of the combustion of fossil fuel and energy use, and also over how they might be avoided or lessened. However, the basic emissions situation is relatively clear. Box 1.4 summarizes the current global pattern of energy use, in very simplified terms, and also, in rough outline, the resultant global carbon emissions. They are both still expanding.
Box 1.4 Energy end uses and emissions
In terms of what the various energy sources are used for, put very simply, although it varies significantly around the world, the total primary energy that is used for (electric) power generation, for heating and for transport is very roughly split in equal amounts amongst these three end uses, but that pattern is changing with, in some cases, transport taking more.
In terms of carbon dioxide gas emissions from fossil fuel use, total emissions from direct energy production/use have stabilized globally in recent years but rose slightly (by 1.7%) in 2018. Although it varies round the world, there are, very roughly, equal proportions of global greenhouse gas emissions from energy generation (heat and power), transport, industry and agriculture (IEA 2019a). The historical record of emissions illustrates how emissions rose as countries industrialized, led initially by the United Kingdom and then the United States but with China now in the lead (GCP 2020).
For details of energy use and some of the resultant impacts, the UK situation is reported in the annual Digest of UK Energy Statistics (DUKES 2019), the Energy Information Administration produces data on the US situation (EIA 2019), while BP publishes annual global energy outlooks (BP 2019), as does the IEA (IEA 2019a). The IEA’s latest data suggest that global emissions have stabilized again, in part due to reductions in coal use in the United States and the EU (IEA 2020).
The precise extent and timing of the likely social and environmental impacts from the combustion of fossil fuel may still be the subject of some debate, but few doubt that they will continue to grow and cause serious and worsening problems unless major changes are made. Indeed, some fear that, otherwise, the outcome could be catastrophic. Whatever we now do to slow emissions, the impacts from past emissions will have to be faced, in some cases as a matter of urgency. We can also try to adapt in advance to climate change to some extent via ameliorative measures, such as enhanced sea-rise protection in flood-prone areas.
However, if nothing is done to halt or reduce emissions, the impacts will get worse, making adaptation progressively harder, more expensive and in the end futile. It is the same for carbon dioxide removal from the atmosphere: at best, it can deal with some old emissions but more likely, as with post-combustion carbon capture and storage of CO2