Renewable energy sources
Due to drier and increasingly warmer summers, reduced water availability is expected for the cultivation of biomass, which entails corresponding challenges in sufficient irrigation of energy crops. In addition, extreme weather events can negatively affect the supply and quality of biomass.
The relevance of climate change for critical infrastructures
Extreme weather conditions can be a challenge for a stable energy supply.
Energy supply is of great importance to society as a whole. It is therefore to be designated as critical infrastructure because the loss or disruption of energy supply can lead to bottlenecks resulting in long-term supply shortages, substantial disruption of public security and further impairments of other critical infrastructures.
The impacts of climate change on the energy sector can range from purely influencing power generation costs and market trading prices to the loss of transmission, supply or generation capacity relevant for grid stability. Financial loss arising from power supply interruption has already been indicated in a number of studies. An all-day power outage across Germany, for example, could result in a financial loss into the double-digit billion Euro range. In addition, brief regional power interruptions can lead to considerable deadweight losses. The highest average expected cost for a one-hour power outage is 15 million Euros in Berlin, 12.5 million Euros in Hamburg and 10.5 million Euros in Munich.
This article provides an overview of the physical effects of the German energy sector within the central phases of the value chain (i. production and availability, ii. generation and transformation as well as iii. distribution and grids). Different energy sources (fossil and renewable) are also discussed in this context.
Conventional energy sources
Regarding oil and gas, a distinction must be made between onshore and offshore production. While currently no notable effects attributed to climate change have been identified for onshore production, possible risk exists due to sea level rise for offshore production. Not only sea level rise itself, but increasing demands due to changing wave heights and increased wave energy in coastal areas are relevant. This is a danger to production facilities in particular. In addition, oil and gas production, especially offshore, could be influenced due to a possible increase in extreme weather events.
Mining of lignite (brown coal) is undertaken using opencast pits. In order to counteract potential disturbances to local residents arising from dust development from lignite mining after prolonged drought, the lignite must be moistened, for which water must be sufficiently available. Possible effects on water provision for lignite mining are, for example, to be expected due to extreme events such as heat waves or long-term hydrological or meteorological droughts. Sufficient water availability is an important condition because lignite-fired power stations are cooled mostly by the water that is drained and usually seeps back into the opencast mine. Another impact could be induced by severe precipitation conditions, which could lead to slippage in the mine due to erosion and ground degradation. The mining of hard coal in Germany takes place underground, where no climate change-related effects in production are currently expected.
Aside from the rather limited effects of raw material production, the adverse effects of climate change on energy source transport to the power stations are most likely expected where the underlying infrastructure reacts sensitively to climatic changes. This applies first and foremost to shipping transportation; the navigability through inland waterways might be inhibited by water levels that are too high or too low. This effect is primarily seen in the supply for hard coal power stations. Another fundamental risk potential in supplying raw material is, in particular, the potential impact for infrastructures such as pipelines through extreme weather events.
Renewable energy sources
The water level in rivers impairs energy generation in hydroelectric power plants both by too much and too little water availability. A distinction must be made here between run-of-the-river power plants and storage power plants, whereby run-of-the-river plants are more sensitive to water levels that are too low or too high. The former leads at best only to reduced capacity utilization and at worst, the plants must be entirely switched off. River floods can lead to a drop in the usable height difference if the water level downstream of the power stream increases. Germany expects a slight increase in gross hydropower potential as a result of climate change.
With regard to solar power energy generation, a distinction must be made between photovoltaic and solar thermal power plants. While photovoltaic plants, for example, also produce energy during cloudy weather, solar thermal power stations only supply energy when exposed to direct sunlight. An increase in output from solar plants is expected during the summer.
Conventional energy sources
Energy generation from conventional sources is currently – as well as in the future – hindered by two factors: on the one hand, through the availability and temperature of the plants’ cooling water, and on the other, through the projected rising temperatures (of both the air and water), especially during the summer months. The combination of lower water levels and higher air temperatures is increasingly leading to higher water temperatures and must be taken into consideration. Both factors do not, however, hinder energy generation stemming from a certain source of energy, but rather the generation at a certain type of power station.
Because lignite-fired power stations primarily use water pumped from the nearby opencast mine, they are less affected by the cooling water problem.
In contrast, other thermal power plants are often located near rivers. The extraction of cooling water could be limited due to sinking river levels during periods of high temperature. In addition, the water reintroduced must not exceed a certain temperature for legal reasons. Adherence to the maximum permitted temperature is made more difficult by the fact the river water temperature is already increased in the summer. In this regard, it is important to take into account that rising water temperatures initially lead to a higher water withdrawal rate in order to meet the legal and ecological temperature threshold values while at the same time avoiding a reduction in efficiency. If the higher quantity of cooling water is still insufficient for cooling, the power plant’s efficiency is further lowered and energy conversion must be reduced. Unusually long periods of hot or dry weather can ultimately lead to a reduction in production of the power stations affected, less efficient operation or to having a cooling water supply failure.
Renewable energy sources
A distinction must be made between onshore and offshore wind power generation. Both onshore and offshore installations are substantially affected in two regards by a possible increase in strong winds – on the one hand, the demands increase on the stability and the mechanical load-bearing capacity of the components. On the other hand, forced shutdowns could become necessary on a more frequent basis. Additional demands are placed on the stability of offshore installations due to rising wave heights.
Solar energy generation facilities are generally considered robust in regards to climatic changes. Neither photovoltaic nor solar thermal facilities are fundamentally impaired in their operability due to higher temperatures. One minor vulnerability arises during weather extremes such as strong winds, hail and lightning, as a result of which safety requirements are increased, for example, on affixing roofs panels. The efficiency of photovoltaic plants can, however, be slightly reduced in high temperatures, particularly during longer heat waves.
Power stations for biomass energy generation are to be assessed similarly to lignite-fired power plants in terms of operations. Higher ambient temperatures only slightly affect efficiency levels.
Producing energy from geothermal sources can be positively influenced by continued warming because the increased temperature in the atmosphere also directly affects underground temperatures. This increased warming can be particularly exploited by geothermal heat probes.
The energy transfer and distribution value creation levels are to be ascribed the greatest physical vulnerability. Certain individual events can be equally critical for both power plants as well as energy transfer infrastructures, but the impact on the energy transfer infrastructures is potentially more substantial as they are more difficult to compensate. On the one hand, physical conductivity is affected at high temperatures in summer and low temperatures in winter. On the other hand, the energy transfer infrastructure itself (pylons, cables, transformers) can be impaired or damaged in extreme events.
There are clear differences in the degree of impact on different types of grids. While the distribution grids currently already extend to a considerable extent underground and are thus only exposed to climate to a limited extent, the transmission grids are largely above ground and are directly exposed to weather and climate influences. It must be assumed, however, that the pylon failures observed thus far were not solely attributable to ice and snow load, but to the interaction of various influencing factors — what are known as cumulative extreme events.
Flood events are a further risk potential. Floods could submerge pylon foundations, which could result in changing stability requirements. Transformer installations as well as power distributors could increasingly be affected by high water levels resulting from floods.
Although overland cables are highly exposed to climatic influences, isolated potential hazards also exist for underground cables. Thus, it is conceivable that cable lines could be washed out during floods or ground cables could be damaged during long periods of heat. There are, however, still no conceptual models that can explain altered failure behaviour in connection with a change of climate or weather parameters (soil temperature and humidity).
A large number of societal sectors are affected by the possible impact of climate change, whereby the energy sector as one of the critical infrastructures attains special significance. Based on analysing the current state of knowledge concerning climate change effects on the energy sector, it is evident that most value chain sectors will be adversely affected. Water availability as well as extreme weather events can be identified as substantial influencing factors. The rising average temperatures can negatively influence the cooling of power stations by enhancing the temperature increase of the cooling water supply. In contrast, positive effects of rising temperatures are to be expected for geothermal energy use. It has also become clear that the grid infrastructure is the most vulnerable component of the energy system. Although individual aspects have shown different estimations, it can nevertheless be stated that the overall impact on energy supply is judged as fundamentally manageable through technical means.
Furthermore, the effects of climate change on energy production and supply can be seasonally differentiated. Damage from extreme weather conditions is mostly to be expected during the winter months. Supply bottlenecks could arise during the summer as a result of an increased demand for cooling energy, while at the same time, electricity generation in water and thermal power plants could be impaired.
This article is based on the following publications, which also contain comprehensive references on the aspects mentioned here:
Cortekar, J. und Groth, M. (2013): Der deutsche Energiesektor und seine mögliche Betroffenheit durch den Klimawandel – Synthese der bisherigen Aktivitäten und Erkenntnisse. Report Nr. 14. Climate Service Center Germany (GERICS). Hamburg.
Groth, M. und Cortekar, J. (2015): Die Relevanz von Klimawandelfolgen für Kritische Infrastrukturen am Beispiel des deutschen Energiesektors, University of Lüneburg Working Paper Series in Economics, Working Paper Nr. 335, Januar 2015. Lüneburg.
Cortekar, J. und Groth, M. (2015): Adapting energy infrastructure to climate change – Is there a need for government interventions and legal obligations within the German “Energiewende”?, in Energy Procedia 73: 12-17.