Birdlife soars on nature-friendly solar farms
Birds across Eastern England's arable landscapes are thriving on solar farms managed with nature in mind.
Electricity prices across Europe to stabilise if 2030 targets for renewable energy are met, study suggests
Hitting the current national 2030 quotas for solar and wind energy could reduce the volatility of electricity markets by an average of 20% across 29 European countries, according to a new study from the University of Cambridge.
The intensity of spikes in power prices are predicted to fall in every country by the end of the decade if commitments to green energy are met, as natural gas dependency is cut.
The UK and Ireland would be the biggest beneficiaries, with 44% and 43% reductions in the severity of electricity price spikes by 2030, compared with last year.
Germany could experience a 31% decline in electricity price volatility, with the Netherlands and Belgium seeing price spikes ease by 38% and 33% respectively.
The simulations conducted for the new study show that scaling up renewable energy minimises the market impact of fluctuations in natural gas price – increasing stability even when considering the reliance of renewable technologies on weather.
Some EU leaders and energy ministers have called for renewables targets on grounds of energy security as well as decarbonisation, particularly since Putin’s war on Ukraine stemmed the flow of Russian gas.
The study, published in the journal Nature Energy, calculates in detail how such aims would affect the volatility of wholesale electricity prices in energy markets across Europe.
“The volatility of energy prices is a major cause of damage to national economies,” said Laura Diaz Anadon, the University of Cambridge’s Professor of Climate Change Policy.
“Consumers are still reeling from sharp increases in electricity prices brought about by natural gas shortages following Russia’s invasion of Ukraine,” said Anadon. “We show that hitting renewables targets reduce the likelihood of such price spikes in the future.”
Daniel Navia, a researcher with the University’s Centre for Environment, Energy and Natural Resource Governance (CEENRG), said: “Meeting renewable energy targets is not only good for carbon neutrality, but we can see it is a boost to economic resilience”
“We had probably underestimated how costly energy price shocks are to our societies, and the last crisis has been a stark reminder.”
The Cambridge researchers used the University’s high performance computing facilities to model a wide range of factors – from fluctuations in weather patterns and energy demands to fuel capacity – to map the current and future grids of all 27 EU nations plus the UK and Switzerland.
They assessed electricity markets in 2030 based on the commitments to renewables as stated in each nation’s national energy and climate plan.
“The UK in particular is projected to see major benefits to its energy market stability from renewables,” said Anadon.
“The UK has struggled with its exposure to gas prices due to a lack of energy storage and limited connections to the European grid. This has led to more hours where electricity prices are set by natural gas.”
The research also suggests that wholesale prices of electricity could fall by over a quarter on average across all countries in the study by decade’s end if they stick to current national renewables targets.
Again, populations in the UK and Ireland stand to gain significantly, with electricity prices predicted to fall by around 45% by 2030, compared with the current situation.
Several of the Nordic nations could see over 60% reductions in electricity costs by 2030, while in Germany the price is predicted to fall by 34%, with Belgium seeing a similar drop of 31%. The study suggests the Netherlands could see the price of electricity fall by 41%.
While the study’s authors caution that trends in electricity prices depend on factors that are “impossible to predict”, they say their results are in line with recent outputs by institutions such as the International Energy Agency.
In fact, Navia and Anadon say their modelling may even underestimate the potential for electricity price stability across Europe, as the projections were calculated using data from 1990-2021 – before the energy crisis created by Russia’s attack on Ukraine.
“It makes sense to think about renewables as a security investment, and if we lose the momentum towards green energy, we are clearly harming the climate, but we also exposing ourselves to unknowable risks down the line,” said Anadon.
The new study also charts the effects on electricity prices if countries overshoot on renewables. If Europe exceeds its renewable energy goals by 30%, electricity prices could become 50% less sensitive to natural gas, compared to just meeting renewables targets.
However, the study suggests there are tipping points where renewables cause the price of power to fall so far that it stops providing sufficient return on investment, and the green energy industries may stall.
Added Navia: “If we are to fully utilise solar and wind as a security tool, Europe might have to rethink how its energy markets are designed, and what incentives it can offer the private sector to maintain the societal insurance value it gets from renewable energy.”
National targets for solar and wind power will see reliance on natural gas plummet, reducing electricity price volatility across Europe, with major beneficiaries including the UK and Ireland, the Nordics, and the Netherlands.
The UK in particular is projected to see major benefits to its energy market stability from renewablesLaura Diaz AnadonAnton Petrus via Getty images High voltage electricity towers combined with economic charts
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Wrong trees in the wrong place can make cities hotter at night, study reveals
Temperatures in cities are rising across the globe and urban heat stress is already a major problem causing illness, death, a surge in energy use to cool buildings down, heat-related social inequality issues and problems with urban infrastructure.
Some cities have already started implementing mitigation strategies, with tree planting prominent among them. But a University of Cambridge-led study now warns that planting the wrong species or the wrong combination of trees in suboptimal locations or arrangements can limit their benefits.
The study, published today in Communications Earth & Environment found that urban trees can lower pedestrian-level air temperature by up to 12°C. Its authors found that the introduction of trees reduced peak monthly temperatures to below 26°C in 83% of the cities studied, meeting the ‘thermal comfort threshold’. However, they also found that this cooling ability varies significantly around the world and is influenced by tree species traits, urban layout and climate conditions.
“Our study busts the myth that trees are the ultimate panacea for overheating cities across the globe,” said Dr Ronita Bardhan, Associate Professor of Sustainable Built Environment at Cambridge's Dept. of Architecture.
“Trees have a crucial role to play in cooling cities down but we need to plant them much more strategically to maximise the benefits which they can provide.”
Previous research on the cooling effects of urban trees has focused on specific climates or regions, and considered case studies in a fragmented way, leaving major gaps in our knowledge about unique tree cooling mechanisms and how these interact with diverse urban features.
To overcome this, the authors of this study analysed the findings of 182 studies – concerning 17 climates in 110 global cities or regions – published between 2010 and 2023, offering the first comprehensive global assessment of urban tree cooling.
During the day, trees cool cities in three ways: by blocking solar radiation; through evaporation of water via pores in their leaves; and by foliage aerodynamically changing airflow. At night, however, tree canopies can trap longwave radiation from the ground surface, due to aerodynamic resistance and ‘stomatal closure’ – the closing of microscopic pores on the surface of leaves partly in response to heat and drought stress.
Variation by climate typeThe study found that urban trees generally cool cities more in hot and dry climates, and less in hot humid climates.
In the ‘tropical wet and dry or savanna’ climate, trees can cool cities by as much as 12 °C, as recorded in Nigeria. However, it was in this same climate that trees also warmed cities most at night, by up to 0.8°C.
Trees performed well in arid climates, cooling cities by just over 9°C and warming them at night by 0.4 °C.
In tropical rainforest climates, where humidity is higher, the daytime cooling effect dropped to approximately 2°C while the nighttime heating effect was 0.8 °C.
In temperate climates, trees can cool cities by up to 6°C and warm them by 1.5°C.
Using trees more strategicallyThe study points out that cities which have more open urban layouts are more likely to feature a mix of evergreen and deciduous trees of varying sizes. This, the researchers found, tends to result in greater cooling in temperate, continental and tropical climates.
The combined use of trees in these climates generally results in 0.5 °C more cooling than in cities where only deciduous or evergreen trees feature. This is because mixed trees can balance seasonal shading and sunlight, providing three-dimensional cooling at various heights.
In arid climates, however, the researchers found that evergreen species dominate and cool more effectively in the specific context of compact urban layouts such as Cairo in Egypt, or Dubai in UAE.
In general, trees cooled more effectively in open and low-rise cities in dry climates. In open urban layouts, cooling can be improved by about 0.4 °C because their larger green spaces allow for more and larger tree canopies and a greater mix of tree species.
“Our study provides context-specific greening guidelines for urban planners to more effectively harness tree cooling in the face of global warming,” Dr Ronita Bardhan said.
“Our results emphasize that urban planners not only need to give cities more green spaces, they need to plant the right mix of trees in optimal positions to maximize cooling benefits.”
“Urban planners should plan for future warmer climates by choosing resilient species which will continue to thrive and maintain cooling benefits,” said Dr Bardhan, a Fellow of Selwyn College, Cambridge.
Matching trees to urban formsThe study goes further, arguing that species selection and placement needs to be compatible with urban forms. The orientation of the ‘street canyon’, local climate zones, aspect ratio, visible sky ratio and other urban features that influence the effects of trees all need to be carefully considered.
Although a higher degree of tree canopy cover in street canyons generally results in more cooling effects, excessively high cover may trap heat at the pedestrian level, especially in compact urban zones in high temperature climates. In such locations, narrow species and sparse planting strategies are recommended.
The researchers emphasise that we cannot rely entirely on trees to cool cities, and that solutions such as solar shading and reflective materials will continue to play an important role.
The researchers have developed an interactive database and map to enable users to estimate the cooling efficacy of strategies based on data from cities with similar climates and urban structures.
ReferenceH. Li et al., ‘Cooling efficacy of trees across cities is determined by background climate, urban morphology, and tree trait’, Communications Earth & Environment (2024). DOI: 10.1038/s43247-024-01908-4
While trees can cool some cities significantly during the day, new research shows that tree canopies can also trap heat and raise temperatures at night. The study aims to help urban planners choose the best combinations of trees and planting locations to combat urban heat stress.
Trees have a crucial role to play in cooling cities down but we need to plant them much more strategically to maximise the benefits which they can provideRonita Bardhanhannahisabelnic via Flikr (Public domain)Trees in an Indian city street. Photo: hannahisabelnic via Flikr (Public domain)
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