renewable energy – Cabot Institute for the Environment blog

Bats are avoiding solar farms and scientists aren’t sure why

Posted on August 10, 2023 by amanda.woodman-hardy

The common pipistrelle. Rudmer Zwerver/Shutterstock

As our planet continues to warm, the need for renewable energy is becoming increasingly urgent. Almost half of the UK’s electricity now comes from renewable sources. And solar accounts for one-fifth of the energy capacity installed since 2019.

Solar farms are now a striking feature of the British landscape. But despite their growth, we’re still largely in the dark about how solar farms impact biodiversity.

This was the focus of a recent study that I co-authored alongside colleagues from the University of Bristol. We found that bat activity is reduced at solar farms compared to neighbouring sites without solar panels.

This discovery is concerning. Bats are top predators of nighttime insects and are sensitive to changes in their habitats, so they are important indicators of ecosystem health. Bats also provide valuable services such as suppressing populations of insect pests.

Nonetheless, our results should not hinder the transition to renewable energy. Instead, they should help to craft strategies that not only encourage bat activity but also support the necessary expansion of clean energy sources.

An aerial shot of a solar farm in south Wales. — Solar farms are now a striking feature of the British landscape. steved_np3/Shutterstock

Reduced activity

We measured bat activity by recording their ultrasonic echolocation calls on bat detectors. Many bat species have distinctive echolocation calls, so we could identify call sequences for each species in many cases. Some species show similar calls, so we lumped them together in species groups.

We placed bat detectors in a solar farm field and a similar neighbouring field without solar panels (called the control site). The fields were matched in size, land use and boundary features (such as having similar hedges) as far as possible. The only major difference was whether they contained solar panels.

We monitored 19 pairs of these sites, each for a week, observing bat activity within the fields’ centre and along their boundaries. Field boundaries are used by bats for navigation and feeding.

Six of the eight bat species or groups studied were less active in the fields with solar panels compared to the fields without them. Common pipistrelles, which made up almost half of all bat activity, showed a decrease of 40% at the edges of solar panel fields and 86% in their centre. Other bat species or groups like soprano pipistrelles, noctules, serotines, myotis bats and long-eared bats also saw their activity drop.

Total bat activity was almost halved at the boundaries of solar panel fields compared to that of control sites. And at the centre of solar panel fields, bat activity dropped by two-thirds.

Why are bats avoiding solar farms?

Conflict between clean energy production and biodiversity isn’t just limited to solar farms; it’s an issue at wind farms too. Large numbers of bats are killed by colliding with the blades of wind turbines. In 2012, for example, one academic estimated that around 888,000 bats may have been killed at wind energy facilities in the United States.

The way solar farms affect bats is probably more indirect than this. Solar panels could, in theory, inadvertently reduce the abundance of insects by lowering the availability of the plants they feed on. We’re currently investigating whether there’s a difference in insect numbers at the solar farm sites compared to the control sites.

Solar panels may also reflect a bats’ echolocation calls, making insect detection more difficult. Reduced feeding success around the panels may result in fewer bats using the surrounding hedgerows for commuting, potentially explaining our findings.

However, bats are also known to collide with smooth vertical flat surfaces because they reflect echolocation calls away from bats and hence appear as empty space. Research has also found that bats sometimes attempt to drink from horizontal smooth surfaces because they interpret the perpendicular echoes as coming from still water. But, given the sloped orientation of solar panels, these potential direct effects may not be of primary concern.

Improving habitats

An important lesson from the development of wind energy is that win-win solutions exist. Ultrasonic acoustic deterrents can keep bats away from wind turbines, while slightly reducing the wind speed that turbines become operational at (known as “cut-in speeds”) has reduced bat fatality rates with minimal losses to energy production. Research suggests that increasing turbine cut-in speeds by 1.5 metres per second can reduce bat fatalities by at least 50%, with an annual loss to power output below 1%.

A slightly different approach could be applied to solar farms. Improving habitats by planting native trees along the boundaries of solar farm fields could potentially increase the availability of insects for bats to feed on.

Research that I have co-authored in recent years supports this theory. We found that the presence of landscape features such as tall hedgerows and even isolated trees on farmland has a positive effect on bat activity.

Carefully selecting solar sites is also important. Prior to construction, conducting environmental impact assessments could indicate the value of proposed sites to bat populations.

More radically, rethinking the siting of these sites so that most are placed on buildings or in areas that are rarely visited by bats, could limit their impact on bat populations.

Solar power is the fastest-growing source of renewable energy worldwide. Its capacity is projected to overtake natural gas by 2026 and coal by 2027. Ensuring that its ecological footprint remains minimal is now particularly important.

——————————

This blog is written by Gareth Jones, Professor of Biological Sciences, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Limiting global warming to 2℃ is not enough – why the world must keep temperature rise below 1℃

Posted on June 29, 2023 by amanda.woodman-hardy

Warming of more than 1℃ risks unsafe and harmful outcomes for humanity.
Ink Drop/Shutterstock

The Paris Climate agreement represented a historic step towards a safer future for humanity on Earth when it was adopted in 2015. The agreement strove to keep global heating below 2℃ above pre-industrial levels with the aim of limiting the increase to 1.5℃ if possible. It was signed by 196 parties around the world, representing the overwhelming majority of humanity.

But in the intervening eight years, the Arctic region has experienced record-breaking temperatures, heatwaves have gripped many parts of Asia and Australia has faced unprecedented floods and wildfires. These events remind us of the dangers associated with climate breakdown. Our newly published research argues instead that humanity is only safe at 1℃ of global warming or below.

While one extreme event cannot be solely attributed to global heating, scientific studies have shown that such events are much more likely in a warmer world. Since the Paris agreement, our understanding of the impacts of global heating have also improved.

A fishing boat surrounded by icebergs that have come off a glacier. — Fishing boat dwarfed by icebergs that came off Greenland’s largest glacier, Jakobshavn Isbrae.
Jonathan Bamber, Author provided

Rising sea levels are an inevitable consequence of global warming. This is due to the combination of increased land ice melting and warmer oceans, which cause the volume of ocean water to increase. Recent research shows that in order to eliminate the human-induced component of sea-level rise, we need to return to temperatures last seen in the pre-industrial era (usually taken to be around 1850).

Perhaps more worrying are tipping points in the climate system that are effectively irreversible on human timescales if passed. Two of these tipping points relate to the melting of the Greenland and West Antarctic ice sheets. Together, these sheets contain enough ice to raise the global sea level by more than ten metres.

The temperature threshold for these ice sheets is uncertain, but we know that it lies close to 1.5℃ of global heating above pre-industrial era levels. There’s even evidence that suggests the threshold may already have been passed in one part of west Antarctica.

Critical boundaries

A temperature change of 1.5℃ might sound quite small. But it’s worth noting that the rise of modern civilisation and the agricultural revolution some 12,000 years ago took place during a period of exceptionally stable temperatures.

Our food production, global infrastructure and ecosystem services (the goods and services provided by ecosystems to humans) are all intimately tied to that stable climate. For example, historical evidence shows that a period called the little ice age (1400-1850), when glaciers grew extensively in the northern hemisphere and frost fairs were held annually on the River Thames, was caused by a much smaller temperature change of only about 0.3℃.

A sign marking the retreat of a glacier since 1908. — Jasper National Park, Canada. Glaciers used to grow extensively in the Northern Hemisphere.
Matty Symons/Shutterstock

A recent review of the current research in this area introduces a concept called “Earth system boundaries”, which defines various thresholds beyond which life on our planet would suffer substantial harm. To avoid passing multiple critical boundaries, the authors stress the need to limit temperature rise to 1℃ or less.

In our new research, we also argue that warming of more than 1℃ risks unsafe and harmful outcomes. This potentially includes sea level rise of multiple metres, more intense hurricanes and more frequent weather extremes.

More affordable renewable energy

Although we are already at 1.2℃ above pre-industrial temperatures, reducing global temperatures is not an impossible task. Our research presents a roadmap based on current technologies that can help us work towards achieving the 1℃ warming goal. We do not need to pull a technological “rabbit out of the hat”, but instead we need to invest and implement existing approaches, such as renewable energy, at scale.

Renewable energy sources have become increasingly affordable over time. Between 2010 and 2021, the cost of producing electricity from solar energy reduced by 88%, while wind power saw a reduction of 67% over the same period. The cost of power storage in batteries (for when the availability of wind and sunlight is low) has also decreased, by 70% between 2014 and 2020.

An aerial photograph of a photovoltaic power plant on a lush hillside. — A photovoltaic power plant in Yunnan, China.
Captain Wang/Shutterstock

The cost disparity between renewable energy and alternative sources like nuclear and fossil fuels is now huge – there is a three to four-fold difference.

In addition to being affordable, renewable energy sources are abundantly available and could swiftly meet society’s energy demands. Massive capacity expansions are also currently underway across the globe, which will only further bolster the renewable energy sector. Global solar energy manufacturing capacity, for example, is expected to double in 2023 and 2024.

Removing carbon dioxide from the atmosphere

Low-cost renewable energy will enable our energy systems to transition away from fossil fuels. But it also provides the means of directly removing CO₂ from the atmosphere at a large scale.

CO₂ removal is crucial for keeping warming to 1℃ or less, even though it requires a significant amount of energy. According to research, achieving a safe climate would require dedicating between 5% and 10% of total power generation demand to effective CO₂ removal. This represents a realistic and attainable policy option.

Various measures are used to remove CO₂ from the atmosphere. These include nature-based solutions like reforestation, as well as direct air carbon capture and storage. Trees absorb CO₂ from the atmosphere through photosynthesis and then lock it up for centuries.

A group of people planting a mangrove forest next to the sea. — A mangrove forest being planted in Klong Khone Samut Songkhram Province, Thailand.
vinai chunkhajorn/Shutterstock

Direct air capture technology was originally developed in the 1960s for air purification on submarines and spacecrafts. But it has since been further adapted for use on land. When combined with underground storage methods, such as the process of converting CO₂ into stone, this technology provides a safe and permanent method of removing CO₂ from the atmosphere.

Our paper demonstrates that the tools and technology exist to achieve a safer, healthier and more prosperous future – and that it’s economically viable to do so. What appears to be lacking is the societal will and, as a consequence, the political conviction and commitment to achieve it.

————————-

This blog is written Cabot Institute for the Environment member Jonathan Bamber, Professor of Glaciology and Earth Observation, University of Bristol and Christian Breyer, Professor of Solar Economy, Lappeenranta University of Technology. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Geothermal workshop: accelerating the impact of research and development in East Africa

Posted on August 19, 2013April 21, 2023 by janet.crompton

Geothermal power is a carbon free, sustainable and renewable energy source.

Throughout the East African Rift, the prospect of harnessing geothermal energy is huge, with the potential to provide 15,000 megawatts of power – larger than the present-day global geothermal production.

Olkaria Geothermal Power Plant, Kenya. Image by Elspeth Robertson

This week, the University of Bristol, NERC and the Cabot Institute are hosting a two-day workshop that aims to strengthen the links between researchers and the geothermal industry.UK universities have a long history of research into the volcanic and tectonic processes occurring in the East African Rift. The data being collected could help industry improve geothermal production and reduce the uncertainty and risk associated with geothermal development by understanding the interactions between magmatic and geothermal processes.

Setting up a GPS site at Corbetti volcano, Ethiopia in November 2012. Corbetti is a potential site for future geothermal power production. Image by Elspeth Robertson

Through talks and discussion groups, the workshop will address themes of ‘Improving Productivity’ and ‘Reducing Risk’ in geothermal research and development. The workshop will wrap up with a detailed analysis of best practice and future actions in order to accelerate the relationship between academia and industry.Travelling to attend this workshop are participants from the Universities of Addis Ababa, Nairobi, Edinburgh, Oxford and Bristol. Industry representatives come from the rich geothermal regions of Iceland, Ethiopia, Kenya and Cornwall with colleagues from Schlumberger and the British Geological Survey also in attendance.Geothermal activity may be subsurface phenomena, but the impact of deep heat sources can be felt on the Earth’s surface, particularly where faults and fissures draw up geothermally heated water to form hot springs. To explore natural geothermal processes in action, workshop participants will visit England’s most famous springs in the Bristol-Bath area with a tour of the historical Roman Baths on Tuesday. The workshop rounds off on Wednesday with a day trip to Kilve in Somerset to investigate fractured reservoir rocks that are now exposed on land.

Keep an eye out for posts in the following weeks exploring the key themes discussed during the workshop. You can follow tweets during workshop using #CabotGeothermal

This blog has been written by Elspeth Robertson, Earth Sciences, University of Bristol

Elspeth Robertson

Electricity Market Reform simplified

Posted on July 29, 2013April 20, 2023 by janet.crompton

Energy policy circles have been abuzz for months over proposed changes to the way renewable energy is to be supported, and the government’s overall plan to balance the supply and demand for energy in the years to come. The Department of Energy and Climate Change have recently released details of the draft ‘strike prices’ for the Contracts for Difference(CfD) scheme, marking an important step towards a radical change in the way renewable energy producers are aided by the government.

As a mathematician working in the field of energy policy, I’m keenly aware of the sheer number of complicated schemes, financial instruments and legislative hurdles electricity producers have to face. At the same time, the health of the UK’s energy generation and distribution system is vital to every member of the population, not just the select few who understand the intricacies of these new energy policy schemes.

I strongly believe that an intuitive understanding of how energy subsidy really works must be spread beyond the corridors of Westminster and Whitehall. A wider debate will result in more informed decisions from policymakers, who currently lack a strong mandate for helpful policies and accountability for poor ones.

In this blog post, I’m going to try to explain one half of the Electricity Market Reform bill, namely the Feed-in Tariff with Contracts for Difference (FiT with CfD) scheme. I’ll do this through diagrams and a maths-free description of the way the scheme works, and the consequences for customers like you and me.

Unfortunately, I can’t avoid making enormous oversimplifications, but it should provide a basic sketch, accessible to sustainability enthusiasts from all backgrounds.

Breaking even

Before we look at how the Feed-in Tariff with Contracts for Difference (FiT with CfD) scheme works, let’s think about what would happen without it (or some other equivalent subsidy scheme).

Renewable energy producers are for the most part private-sector, for-profit organisations. They need a financial incentive in order to invest in our energy sector; at the very least, they need to avoid making a loss in order to remain operating. I’ve drawn a very simple figure to represent the profits and losses they can expect to make over the next couple of decades.

The horizontal axis in the figure represents time; we begin on the left-hand side of the diagram, and time continues as you travel to the right, with the right hand side being around 20 years from now. At the moment, the cost of producing most types of renewable energy (the blue line) exceeds the price electricity producers would get for selling it on the open market (red line). The red shaded area represents a financial loss for the producer of the electricity, whereas the green shaded area is the profit they can expect.

As time goes on, current projections are for the cost of production to fall, and electricity prices to rise. At some point, the cost of producing renewable energy and the money producers get for selling it will be equal. This is the so-called break-even point, and is where the red and blue lines meet.

The point of break-even is extremely important to policy makers. So long as electricity producers think they are going to make a loss, they have no financial incentive to expand the UK’s renewable energy generation capacity. Once the break-even point is passed the industry should grow, as potential investors see that the industry is profitable. In order to meet the steep legislative carbon-reduction targets of the UK, the government will want to reach this break-even point as quickly as possible, as it promises a growing renewable energy sector for the years to come.

So how do we get to the break-even point more quickly? Well, that’s a question of how much money we’re willing to spend, and the mechanism through which we support renewable electricity producers.

Contracts for difference

A contract for difference, or CfD, is a financial instrument that’s been around for many years. Until recently, CfDs were predominantly used in commodities and stock trading. However, the last few years have seen CfDs adopted as an instrument of energy policy, used by major renewable energy producing nations like the Netherlands and Denmark http://www.publications.parliament.uk/pa/cm201012/cmselect/cmenergy/742/74208.htm. The UK will soon be adopting a form of CfD scheme too, known officially as the Feed-in Tariff with Contracts for Difference (FiT with CfD) scheme. Let’s take a look at how it works.

In the FiT with CfD scheme, the government enters into contracts with electricity producers in an individual, case-by-case basis. They agree a ‘strike price’, at which electricity generated by the producer is to be valued for the duration of the contract. When revenues from selling electricity at market prices (red line) are below the strike price (brown line), the producer can ask the government to make up the difference (orange shaded area). This effectively takes the place of subsidy in more orthodox schemes, and brings forward the break-even point to where the blue line meets the brown line, making the industry profitable sooner and attracting new investors.

When the market price of electricity exceeds the strike price, the deal is reversed. Electricity producers must pay the government the difference, shown on the diagram as the dark green shaded area. This allows the government to recoup some of the money it spent on keeping the industry afloat earlier. Producing renewable electricity still remains profitable though, as shown by the light green shaded area.

What does this actually mean to you and me, the consumers of electricity? Well, whatever the government spends on supporting renewable energy will be added on to our tax bills, regardless of how much electricity we might individually use. On the other hand, we will reach our carbon-reduction targets quicker. It’s possible to balance the pros and cons of the scheme by changing the strike price, but it’s not an easy problem given the politics surrounding renewable energy.

As I’ve hinted before, things are much more complicated than the explanation I’ve given here, and while I’ve tried to describe the scheme as it is intended to work, we can’t be sure that it will behave as expected; we haven’t reached the break-even point yet, so there’s little evidence to go on!

What’s next for the Electricity Market Reform (EMR) bill? Well, it’s currently under review by the House of Lords and is expected to be given Royal Assent before 2014. EMR, for good or for ill, is coming soon.

This blog is written by Neeraj Oak, from the department of Complexity Sciences at the University of Bristol.

Neeraj Oak