Weather Variability and its Energy Impacts

James Fallon & Brian Lo –  j.fallon@pgr.reading.ac.ukbrian.lo@pgr.reading.ac.uk 

One in five people still do not have access to modern electricity supplies, and almost half the global population rely on burning wood, charcoal or animal waste for cooking and eating (Energy Progress Report). Having a reliable and affordable source of energy is crucial to human wellbeing: including healthcare, education, cooking, transport and heating. 

Our worldwide transition to renewable energy faces the combined challenge of connecting neglected regions and vulnerable communities to reliable power supplies, and also decarbonising all energy. An assessment on supporting the world’s 7 billion humans to live a high quality of life within planetary boundaries calculated that resource provisioning across sectors including energy must be restructured to enable basic needs to be met at a much lower level of resource use [O’Neill et al. 2018]. 

Adriaan Hilbers recently wrote for the Social Metwork about the renewable energy transition (Why renewables are difficult), and challenges and solutions for modern electricity grids under increased weather exposure. (Make sure to read that first, as it provides an important background for problems associate with meso to synoptic scale variability that we won’t cover here!)  

In this blog post, we highlight the role of climate and weather variability in understanding the risks future electricity networks face. 

Climate & weather variability 

Figure 1 – Stommel diagram of the Earth’s atmosphere 

A Stommel diagram [Stommel, 1963] is used to categorise climate and weather events of different temporal and spatial scales. Logarithmic axes describe time period and size; contours (coloured areas) depict the spectral intensity of variation in sea level. It allows us to identify a variety of dynamical features in the oceans that traverse magnitudes of spatial and temporal scales. Figure 1 is a Stommel diagram adapted to describe the variability of our atmosphere.  

Microscale Smallest scales to describe features generally of the order 2 km or smaller 
Mesoscale Scale for describing atmospheric phenomena having horizontal scales ranging from a few to several hundred kilometres 
Synoptic Largest scale used to describe meteorological phenomena, typically high hundreds or 1000 km or more 

Micro Impacts on Energy 

Microscale weather processes include more predictable phenomena such as heat and moisture flux events, and unpredictable turbulence events. These generally occur at scales much smaller than the grid scale represented in numerical weather prediction models, and instead are represented through parametrisation. The most important microscale weather impacts are for isolated power grids (for example a community reliant on solar power and batteries, off-grid). Microscale weather events can also make reliable supply difficult for grids reliant on a few geographically concentrated renewable energy supplies. 

Extended Range Weather Impacts on Energy 

Across the Stommel diagram, above the synoptic scale are seasonal and intraseasonal cycles, decadal and climate variations. 

Subseasonal-to-Seasonal (S2S) forecasts are an exciting development for decision-makers across a diverse range of sectors – including agriculture, hydrology, the humanitarian sector [White et al. 2017]. In the energy sector, skilful subseasonal energy forecasts are now production ready (S2S4E DST).  Using S2S forecasts can help energy users anticipate electricity demand peaks and troughs, levels of renewable production, and their combined impacts several weeks in advance. Such forecasts will have an increasingly important role as more countries have higher renewable energy penetration (increasing their electricity grid’s weather exposure). 

Decadal Weather Cycle and Climate Impacts on Energy 

Energy system planners and operators are increasingly trying to address risks posed by climate variability, climate change, and climate uncertainty.  

Figure 2 was constructed from the record of Central England temperatures spanning the years of 1659 to 1995 and highlights the modes of variability in our atmosphere on the order of 5 to 50 years. Even without the role of climate change, constraining the boundary conditions of our weather and climate is no small task. The presence of meteorologically impactful climate variability at many different frequencies increases the workload for energy modellers, requiring many decades of climate data in order to understand the true system boundaries. 

Figure 2  – Power spectra of central England from mid 17th century, explaining variability with physical phenomena [Ghil and Lucarini 2020]

When making models of regional, national or continental energy networks, it is now increasingly common for energy modellers to consider several decades of climate data, instead of sampling a small selection of years. Figure 2 shows the different frequencies of climate variability – relying on only a limited few years of data cannot explore the extent of this variability. However significant challenges remain in sampling long-term variability and change in models [Hilbers et al. 2019], and it is the role of weather and climate scientists to communicate the importance of addressing this. 

Important contributions to uncertainty in energy system planning don’t just come from weather and climate. Variability in future energy systems will depend on technological, socioeconomic and political outcomes. Predictions of which future technologies and approaches will be most sustainable and economical are not always clear cut and easy to anticipate. A virtual workshop hosted by Reading’s energy-met group last summer [Bloomfield et al. 2020] facilitated discussions between energy and climate researchers. The workshop identified the need to better understand how contributions of all these different uncertainties propagate through complex modelling chains. 

An Energy-Meteorologist’s Journey through Time and Space 

Research is underway into tackling the uncertainties and understanding of energy risks and impacts across the spectra of spatial and temporal scales. But understanding of energy systems, and successful future planning requires decision-making involving a broad (and perhaps not fully identified) group of important technological and other factors, as well as the weather and climate impacts. It is not enough to consider any one of these alone! It is vital experts across different fields collaborate on working towards what will be best for our future energy grids. 

Tracking SDG7 – The Energy Progress Report https://trackingsdg7.esmap.org 

Why renewables are difficult – Adriaan Hilbers Social Metwork 2021 https://socialmetwork.blog/2021/01/15/why-renewables-are-difficult

O’Neill, D.W., Fanning, A.L., Lamb, W.F. et al. A good life for all within planetary boundaries https://doi.org/10.1038/s41893-018-0021-4 

Stommel, H., 1963. Varieties of oceanographic experience. Science, 139(3555), pp.572-576. https://www.jstor.org/stable/1709894

White et al (2017) Potential applications of subseasonal‐to‐seasonal (S2S) predictions https://doi.org/10.1002/met.1654 

M Ghil, V Lucarini (2020) The physics of climate variability and climate change https://doi.org/10.1103/RevModPhys.92.035002

AP Hilbers, DJ Brayshaw, A Gandy (2019) Importance subsampling: improving power system planning under climate-based uncertainty https://doi.org/10.1016/j.apenergy.2019.04.110 

Bloomfield, H. et al. (2020) The importance of weather and climate to energy systems: a workshop on next generation challenges in energy-climate modelling https://doi.org/10.1175/BAMS-D-20-0256.1 

Why renewables are difficult

Adriaan Hilbers – PhD researcher at Imperial and Reading a.hilbers17@imperial.ac.uk

Adapted from a 2018 blog post: see the original here

Renewable energy represents one of the most promising solutions to climate change since it emits no greenhouse gases. However, it poses some difficulties for power systems. Source: U. Leone

The public have been aware of the importance of reducing carbon emissions since around the 1980’s. Furthermore, renewable technologies such as solar and wind have been around for decades. Under these conditions, it’s surprising that most countries still generate the majority of their electricity from carbon-emitting fossil fuels. Why, after decades of both the problem and a possible solution being known, haven’t renewables taken off yet? This article describes why renewables are “difficult”, and how the world can keep the lights on into the future in a cheap, secure, and sustainable way. 

Until recently, the primary reason was economics. It was impossible to build wind turbines and solar panels cheaply enough to compete with fossil fuel technologies, which have become highly cost effective after more than 100 years of use. Governments were not willing to spend billions to subsidise renewables when electricity could be generated cheaply by other means. Recently, however, improved manufacturing methods, economies of scale and increased competition sent prices plummeting. The price of solar panels has decreased by a factor of 200 in the last 45 years, and wind farms (even offshore) are now cost-effective without subsidy.  

So, is it just a matter of time before fossil fuel electricity disappears? Why are societies still so hesitant to go 100% renewable? To understand why, one needs a quick introduction to power systems: the industries, infrastructures and markets based around electricity. 

At their core, power systems are supply & demand problems. Industries and consumers use electricity provided by generators. One key feature distinguishes power systems from other economic markets: there is very limited means of storing it at large scale (with the notable exception of hydropower, discussed below). For this reason, supply must match demand on a second-by-second basis. 

A still from Drax Electric Insights, where electricity demand and generation levels can be browsed through, both in real time and historically. Source: Drax Electric Insights

(As an aside, in the UK, there is a fantastic website, called Drax Electric Insights, in which the total UK electricity demand, and exactly from which sources it is being generated, can be browsed through in real time as well as historically. Looking through it for a few minutes will give a better feel for how power systems work than any blog post can). 

Before renewables, most electricity came from fossil fuel plants. Fuel (mostly coal or gas) was burnt at different rates and level of electricity supply was directly adjusted to meet demand. This isn’t always easy; for example, the UK’s system operator had to deal with a massive demand spike just after the royal wedding, as millions turned on their kettles at the same time.  

A famous graph showing total UK electricity demand during the 1990 World Cup semi-final against Germany, with spikes at times that viewers turned on their kettles en masse. System operators had to rapidly adjust supply to ensure the lights stayed on. Source: National Grid

With renewables, the single biggest difficulty is that their production levels can’t be controlled. It’s not always windy or sunny, and times of high renewable output do not always align with times of high demand. How does one ensure the lights stay on on a cloudy day or when the wind tails off? 

In most countries, this is not yet a problem since renewable capacity is still small and there’s ample conventional backup capacity. Renewables produce whatever electricity they can, and the rest is picked up by the conventional plants.  

A problem occurs when countries start generating most of their electricity from renewables as this drastically changes the economic outlook of power markets. In a nutshell, building renewable capacity displaces fossil fuel generation, but not generation capacity; all power plants must be kept open for the rare days when there isn’t any wind or sun. Keeping these plants open but using them infrequently is very expensive, and closing them is impossible, unless you want to accept significant risks of blackouts on calm, cloudy days. It’s a perilous choice: higher electricity prices or reduced security of supply, and this problem defines the difficulties of renewable electricity systems. 

Thankfully, there are a few ways that society can generate most of their electricity from renewables while keeping prices low and supply secure. They fall broadly into two categories. 

The first is electricity storage. With grid-scale storage, excess electricity production on windy or sunny days can be stored and used in times when renewable output is low. Besides adding to supply security, this would enhance the economic picture since storage owners buy up electricity when price is low and sell it when price is high, evening out price jumps and allowing a smaller number of conventional plants to run more often. Almost all grid-scale storage currently in existence is hydropower, which countries like Norway use to generate almost all their electricity but requires a mountainous terrain and access to water. The reason other grid-scale storage is rare is economics. Most storage technology (e.g. battery) prices still have to drop significantly before they can be used at large scale. 

Hydropower provides an economical option to store electricity, but requires mountainous terrain. Source: skeeze

A second solution is interconnecting different countries and allowing them to share electricity. When it is wind-free in London, it usually is in Scotland as well, bit it may be windy in Germany or Spain. Transporting electricity around could help alleviate supply insecurity. Many countries are doing just this; the UK, for example, currently has interconnections with France, the Netherlands, Belgium and Ireland, and more are in the pipeline. They may eventually from part of the European Supergrid, where electricity can be transported across Europe to balance out regional renewable supply peaks and troughs. 

The prospect of combining hydropower and interconnections between countries is tempting, since it means countries with lots of wind but little storage capacity, like Germany or Denmark, could “use Norway as a battery” by exporting their excess wind power to Norway in windy periods, which allows dams to accumulate water. In calm spells, hydropower generation levels are increased and excess electricity exported back the other way. Making this work will require significant increases in Norwegian hydropower infrastructure, interconnection lines and international cooperation. 

The batteries in electric cars can be used for grid management provided that owners agree to this. Source: Marilyn Murphy

Another creative solution to the storage problem is to use the batteries in electric cars. Electric car uptake will lead to demand spikes when people return from work and plug them in. An electric car owner can get the option of cheaper electricity if it means her car’s battery is not charged (smart charging), or even emptied (known as vehicle-to-grid), during demand spikes and recharged when demand is lower. Such approaches are currently being trialled in the UK

Current power systems are not yet ready to use renewables for the majority of their electricity supply. However, the immediacy of the climate change danger means business-as-usual is not an option, and a total energy revolution is required. Presently, the most realistic solution is the use of renewables (see a separate blog post on nuclear power here). Nobody knows exactly how the power system of the future will look. But everyone agrees it will be very different. 

A still from an online tutorial on power system models, showing generation from different sources.

Want to know more? For a similar discussion on the merits of nuclear power, see this blog post. To get a feel for how a power system works, see this page. It allows users, inside a cloud (no downloads or installs necessary), to create their own power system for the United Kingdom, and see how electricity is generated from renewable and conventional sources. 

Note: this article was adapted from a 2018 blog post: see the original here

How does plasma from the solar wind enter Earth’s magnetosphere?

Earth’s radiation belts are a hazardous environment for the satellites underpinning our everyday life. The behaviour of these high-energy particles, trapped by Earth’s magnetic field, is partly determined by the existence of plasma waves. These waves provide the mechanisms by which energy and momentum are transferred and particle populations physically moved around, and it’s some of these waves that I study in my PhD.

However, I’ve noticed that whenever I talk about my work, I rarely talk about where this plasma comes from. In schools it’s often taught that space is a vacuum, and while it is closer to a vacuum than anything we can make on Earth, there are enough particles to make it a dangerous environment. A significant amount of particles do escape from Earth’s ionosphere into the magnetosphere but in this post I’ll focus on material entering from the solar wind. This constant outflow of hot particles from the Sun is a plasma, a fluid where enough of the particles are ionised that the behaviour of the fluid is then dominated by electric and magnetic fields. Since the charged particles in a plasma interact with each other, with external electric and magnetic fields, and also generate more fields by moving and interacting, this makes for some weird and wonderful behaviour.

magnetosphere_diagram
Figure 1: The area of space dominated by Earth’s magnetic field (the magnetosphere) is shaped by the constant flow of the solar wind (a plasma predominantly composed of protons, electrons and alpha particles). Plasma inside the magnetosphere collects in specific areas; the radiation belts are particularly of interest as particles there pose a danger to satellites. Credit: NASA/Goddard/Aaron Kaas

When explaining my work to family or friends, I often describe Earth’s magnetic field as a shield to the solar wind. Because the solar wind is well ionised, it is highly conductive, and this means that approximately, the magnetic field is “frozen in” to the plasma. If the magnetic field changes, the plasma follows this change. Similarly, if the plasma flows somewhere, the magnetic field is dragged along with it. (This is known as Alfvén’s frozen in theorem – the amount of plasma in a volume parallel to the magnetic field line remains constant). And this is why the magnetosphere acts as shield to all this energy streaming out of the Sun – while the magnetic field embedded in the solar wind is topologically distinct from the magnetic field of the Earth, there is no plasma transfer across magnetic field lines, and it streams past our planet (although this dynamic pressure still compresses the plasma of the magnetosphere, giving it that typical asymmetric shape in Figure 1).

Of course, the question still remains of how the solar wind plasma enters the Earth’s magnetic field if such a shielding effect exists. You may have noticed in Figure 1 that there are gaps in the shield that the Earth’s dipole magnetic field presents to the solar wind; these are called the cusps, and at these locations the magnetic field connects to the solar wind. Here, plasma can travel along magnetic field lines and impact us on Earth.

But there’s also a more interesting phenomenon occurring – on a small enough scale (i.e. the very thin boundaries between two magnetic domains) the assumptions behind the frozen-in theorem break down, and then we start to see one of the processes that make the magnetosphere such a complex, fascinating and dynamic system to study. Say we have two regions of plasma with opposing orientation of the magnetic field. Then in a middle area these opposing field lines will suddenly snap to a new configuration, allowing them to peel off and away from this tightly packed central region. Figure 2 illustrates this process – you can see that after pushing red and blue field lines together, they suddenly jump to a new configuration. As well as changing the topology of the magnetic field, the plasma at the centre is energised and accelerated, shooting off along the magnetic field lines. Of course even this is a simplification; the whole process is somewhat more messy in reality and I for one don’t really understand how the field can suddenly “snap” to a new configuration.

reconnection
Figure 2: Magnetic reconnection. Two magnetic domains of opposing orientation can undergo a process where the field line configuration suddenly resets. Instead of two distinct magnetic domains, some field lines are suddenly connected to both, and shoot outwards and away, as does the energised plasma.

In the Earth’s magnetosphere there are two main regions where this process is important (Figure 3). Firstly, at the nose of the magnetosphere. The dynamic pressure of the solar wind is compressing the solar wind plasma against the magnetospheric plasma, and when the interplanetary magnetic field is orientated downwards (i.e. opposite to the Earth’s dipole – about half the time) this reconnection can happen. At this point field lines that were solely connected to the Earth or in the solar wind are now connected to both, and plasma can flow along them.

magnetosphere_reconnection_sites
Figure 3: There are two main areas where reconnection happens in Earth’s magnetosphere. Opposing field lines can reconnect, allowing a continual dynamic cycle (the Dungey cycle) of field lines around the magnetosphere. Plasma can travel along these magnetic field lines freely. Credits: NASA/MMS (image) and NASA/Goddard Space Flight Center- Conceptual Image Lab (video)

Then, as the solar wind continues to rush outwards from the Sun, it drags these field lines along with it, past the Earth and into the tail of the magnetosphere. Eventually the build-up of these field lines reaches a critical point in the tail, and boom! Reconnection happens once more. You get a blast of energised plasma shooting along the magnetic field (this gives us the aurora) and the topology has rearranged to separate the magnetic fields of the Earth and solar wind; once more, they are distinct. These dipole field lines move around to the front of the Earth again, to begin this dramatic cycle once more.

Working out when and how these kind of processes take place is still an active area of research, let alone understanding exactly what we expect this new plasma to do when it arrives. If it doesn’t give us a beautiful show of the aurora, will it bounce around the radiation belts, trapped in the stronger magnetic fields near the Earth? Or if it’s not so high energy as that, will it settle in the cooler plasmasphere, to rotate with the Earth and be shaped as the magnetic field is distorted by solar wind variations? Right now I look out my window at a peaceful sunny day and find it incredible that such complicated and dynamic processes are continually happening so (relatively) nearby. It certainly makes space physics an interesting area of research.

Industrial Sponsored Doctorates

Email: a.halford@pgr.reading.ac.uk

When it comes to doctoral funding, the current method means project funds can come from a variety of sources, such as research councils, charities, industry partners or a mixture of these. In this blog post I will talk about my experience of being jointly funded by a research council and industrial partner.

To start with, I am not actually a PhD student like most people in the Meteorology department here at the University of Reading, but an EngD student. An EngD is a more industrial focused PhD, based on collaboration between industry and academia. There is a taught element to an EngD in the first year, during which a range of modules are covered, on everything from business analysis to sustainability. Additionally, a portion of time is dedicated to work for the industrial sponsor during the course of the project. An EngD still has the same end goal of a PhD, of an intellectual contribution to knowledge.

EngDs were started by the Engineering and Physical Sciences Research Council (EPSRC) back in 1992 and after initial success, the program was expanded in 2009. Out of this expansion came the Technologies for Sustainable Built Environments (TSBE) Centre at the University of Reading. The TSBE Centre has produced 40 EngDs over 8 years, covering a wide variety of disciplines, from modelling energy usage in the home to the effect of different roofing materials on bats. Each student is based within multiple academic departments and the industrial partner organisation with the aim of answering real world research questions.

My project is in collaboration with the BT Group and looks at weather impacts on the UK telecommunications network. I have found that being in an industrial sponsored project is of great benefit. It has been useful to get experience of how industry works, as it can be very different to the academic life in which most doctoral students find themselves. There have also been a lot of opportunities for training in specialist subjects including industrial project management and help to get chartership from professional bodies for those who want it. Being linked with an industrial partner can also offer strong networking and knowledge transfer opportunities, as was the case when I attended a recent interdisciplinary conference of the newly formed Tommy Flowers Institute. This institute has been formed by BT, along with other partner organisations, to further support collaboration between industry and academia.

It can be a challenge at times to balance the approaches of academia and industry. They do not always pull you in the same direction but this is often the same with any lengthy piece of work produced under the guidance of different advisors from different disciplines. The strength with the EngD partnership comes from the different perspectives offered from those different fields to ultimately solve the problem in question.

For me working on a heavily applied problem in the setting of a real organisation has been of greater benefit to me than working on a purely theoretical problem would have been. I have enjoyed seeing my preliminary output being tested within the organisation and look forward to being able to test a more advanced version in the final stages of my project.

Alan Halford is funded by the EPSRC and BT and supported by the TSBE centre.

 

Innovating for Sustainable Development

Email: Rachael.Byrom@pgr.reading.ac.uk

In 2016 the United Nations (UN) Sustainable Development Goals (SDGs) officially came into force to tackle key global challenges under a sustainable framework.

The SDGs comprise 17 global goals and 169 targets to be achieved across the next 15 years. As part of the ‘2030 Agenda’ for sustainable development, these goals aim to address a range of important global environmental, social and economic issues such as climate change, poverty, hunger and inequality. Adopted by leaders across the world, these goals are a ‘call for action’ to ensure that no one is left behind. However, the SDGs are not legally binding. The success of goals will rely solely on the efforts of individual countries to establish and implement a national framework for achieving sustainable development.

UN SDGs
The United Nation’s 17 Sustainable Development Goals

As part of the NERC funded ‘Innovating for Sustainable Development’ programme, students here in the Department of Meteorology were given the opportunity to explore and find solutions to key environmental challenges as outlined in the UN’s SDGs.

Run by the SCENARIO and SSCP doctoral training partnerships, the programme challenged students from a variety of disciplines and institutions to re-frame the SDGs from a multi-disciplinary perspective and to develop tangible, innovative solutions for sustainable development.

The programme began with an ‘Interdisciplinary Challenges Workshop’ where students participated in activities and exercises to review the importance of the SDGs and to consider their multi-disciplinary nature. Students were encouraged to think creatively and discuss issues related to each of the goals, such as: ‘Is this SDG achievable?’, ‘Are the goals contradictory?’ and ‘How could I apply my research to help achieve the SDGs?’

SDGs
Visual representations of SDG 5 and SDG 7

Following this, three ‘Case Study’ days explored a handful of the SDGs in greater detail, with representatives from industry, start-ups and NGOs explaining how they are working to achieve a particular SDG, their current challenges and possible opportunities for further innovation.

The first Case Study day focused on both SDG 7 – Affordable and Clean Energy and SDG 12 – Responsible Consumption and Production. For SDG 7, insightful talks were given by the Moving Energy Initiative on the issue of delivering energy solutions to millions of displaced people, and BBOXX, on their work to produce and distribute off-grid solar power systems to rural communities in places such as Kenya and Rwanda. In the afternoon, presentations given by Climate-KIC start up NER and Waitrose showcased the efforts currently being taken to reduce wasteful food production and packaging, while Forum for the Future emphasised the importance of addressing sustainable nutrition.

The second Case Study day focused on SDG 6 – Clean Water and Sanitation. Experts from WaterAid, De-Solenator, Bear Valley Ventures, UKWIR and the International Institute for Environmental Development outlined the importance of confronting global sanitation and water challenges in both developing and developed nations. Alarmingly, it was highlighted that an estimated 40% of the global population are affected by water scarcity and 2.4 billion people still lack access to basic sanitation services, with more than 80% of human activity wastewater discharged into rivers without going through any stage of pollution removal (UN, 2016).

Case study
Participants discussing ideas during the second Case Study day

The last Case Study day explored SDG 9 – Industry, Innovation and Infrastructure and SDG 11 – Sustainable Cities and Communities. A range of talks on building technologies, carbon neutral buildings and sustainable solar technologies were given, along with a presentation by OPDC on the UK’s largest regeneration project. The day finished off with an overview from the Greater London Authority about the London Infrastructure Map and their new approach to sustainable planning and development across the city.

The programme finished off with a second workshop. Here students teamed up to develop innovative business ideas aimed at solving the SDG challenges presented throughout the Case Study events. Business coaches and experts were on hand to offer advice to help the teams develop ideas that could become commercially viable.

On the 16th March the teams presented their business ideas at the ‘Meet the Cleantech Pioneers’ networking event at Imperial’s new Translation and Innovation Hub (I-HUB). An overview of the projects can be found here. This event, partnered with the Climate-KIC accelerator programme, provided an excellent platform for participants to showcase and discuss their ideas with a mix of investors, entrepreneurs, NGOs and academics all interested in achieving sustainable development.

I-HUB
The final showcase event at Imperial’s I-HUB

Overall the programme provided a great opportunity to examine the importance of the SDGs and to work closely with PhD students from a range of backgrounds. Fundamentally the process emphasised the point that, in order for the world to meet the 2030 Agenda, many sustainable development challenges still need to be better understood and many solutions still need to be provided – and here scientific research can play a key role. Furthermore, it was made clear that a high level of interdisciplinary thinking, research and innovation is needed to achieve sustainable development.

Institutes

References:

UN, 2016: Clean Water and Sanitation – Why it matters, United Nations, Accessed 05 March 2017. [Available online at http://www.un.org/sustainabledevelopment/wp-content/uploads/2016/08/6_Why-it-Matters_Sanitation_2p.pdf]

The impact of Climate Variability on the GB power system.

Email: h.bloomfield@pgr.reading.ac.uk

Bloomfield et al., 2016. Quantifying the increasing sensitivity of power systems to climate variability. View published paper.

Within the power system of Great Britain (GB), there is a rapidly increasing amount of generation from renewables, such as wind and solar power which are weather-dependent. An increased proportion of weather-dependent generation will require increased understanding of the impact of climate variability on the power system.

blog1

Figure 1: Predicted installed capacity from the National Grid Gone Green Scenario. Source: National Grid Future Energy Scenarios (2015).

Current research on the impact of climate variability on the GB power system is ongoing by climate scientists and power system modellers. The focus of the climate research is on the weather-driven components of the power system, such as the impact of climate variability on wind power generation. These studies tend to include limited knowledge of the whole system impacts of climate variability. The research by power system modellers focuses on the accurate representation of the GB power system. A limited amount of weather data may be used in this type of study (usually 1-10 years) due to the complexity of the power system models.

The aim of this project is to bridge the gap between these two groups of research, by understanding the impact of climate variability on the whole GB power system.In this project, multi-decadal records from the MERRA reanalysis* are combined with a simple representation of the GB power system, of which the weather-dependent components are electricity demand and wind power production. Multiple scenarios are analysed for GB power systems, including 0GW, 15GW, 30GW, and 45GW of installed wind power capacity in the system.

This study characterises the impact of inter-annual climate variability on multiple aspects of the GB power system (including coal, gas and nuclear generation) using a load duration curve framework. A load duration curve can be thought of as a cumulative frequency distribution of power system load. Load can be either power system demand (i.e. the NO-WIND scenario) or demand minus wind power (ie. the LOW, MED and HIGH scenarios).

The introduction of additional wind-power capacity greatly increases the year-year variability in operating opportunity for conventional generators, this is particularly evident for baseload plant (i.e. nuclear power plants). The impact of inter-annual climate variations across the power system due to present-day level of wind-farm installation has approximately doubled the exposure of the GB power sector to inter-annual climate variability. This is shown in Figure 2 as the spread between the red and blue curves (from the LOW scenario) is double that of the black curves (the NO-WIND scenario).

blog2

Figure 2: Load duration curves for the NO-WIND and LOW scenario in black and grey respectively. The two most extreme years from the LOW scenario are 1990 and 2010, plotted in red and blue respectively. Vertical dashed lines show the percentage of time that baseload-plant (91%) and peaking plant (7%) are required to operate

This work has shown that as the amount of installed wind power capacity on the power system is increased, the total amount of energy required from other generators (coal, gas, nuclear) is reduced. Wind therefore contributes to decarbonising the power system, however the reduction is particularly pronounced for plants which are operating as baseload rather than peaking plant (i.e. oil fired generation) where an increase in required production is seen.

This study adds to the literature which suggests that the power system modelling community should begin to take a more robust approach to its treatment of weather and climate data by incorporating a wider range of climate variability.

For more information contact the author for a copy of the paper with details of this work: Quantifying the increasing sensitivity of power system to climate variability (submitted to ERL).

* A reanalysis data set is a scientific method for developing a record of how weather and climate are changing over time. In it, observations are combined with a numerical model to generate a synthesised estimate of the state of the climate system.