Energy

Can Our Global Energy Industry Weather Extreme Weather?


Last week, the International Atomic Energy Agency published their new report, Adapting the Energy Sector to Climate Change, that explores a range of climate impacts on the energy sector resulting from gradual climate change together with extreme weather events. The report also considers possible ways to counter them.

The report considers the effect of extreme weather events on fossil fuel power, renewable energy technologies, nuclear power and electricity grids. The competing problems to these effects is the push to transform the energy sector to low-carbon sources, provide energy to adapt to climate change, and to provide enough energy to eradicate global poverty and raise every human up into a good life.

This is not an academic exercise. The figure below shows the reported occurrence of droughts and floods globally since 1977, which exhibit a significant increase.

The biggest impacts of gradual climate change on thermal power plants such as natural gas, nuclear, oil and coal are the reduction of thermal efficiency due to warmer average temperatures, and the lesser volume and higher temperature of water in nearby rivers and lakes, which affects cooling efficiency and water availability.

Various alternative cooling options are available, ranging from simple and conservative options like using non-traditional water sources, reusing process water from flue gases, coal drying and using condensers, to more radical and expensive technologies such as dry cooling.

The implications of extreme weather events for fossil fuel thermal power plants are diverse and can lead to severe structural damage and financial losses. Protecting fossil fuel stockpiles (coal, oil, gas) from overheating, flooding, extreme winds and lightning is of major importance to ensuring the uninterrupted operation of the plants even under severe weather conditions.

While extreme weather events have rarely affected nuclear plants, they have often affected fossil fuel generation. Polar vortexes, hurricanes and flooding make flood protection and reinforcement of buildings, cooling towers and other structures key for safe and reliable operation in the future.

Because fossil fuel is all about the fuel, delivery of fuel during extreme events is a key failure point, especially for coal and gas, as we’ve seen during previous events. Coal stacks are frozen or diesel generators simply can’t function in extremely low temperatures. Gas chokes up – its pipelines can’t keep up with demand – and prices skyrocket. Flooding prevents fossil fuel from being loaded, unloaded or transported (see figure below).

Renewable energy technologies are important actors in decarbonizing our global energy system as a way to mitigate anthropogenic climate change. Hydropower has the largest share globally (16%), followed by wind energy (4%) and solar photovoltaic (1%). All other renewable sources contributed about 3%.

Under most ambitious mitigation scenarios, renewable sources will provide over 60% of global electricity by mid-century. This immense growth will require large increases in generation capacities, back-up power and grid-coordination as never before, as well as huge investments in site exploration, design and construction, keeping in mind changing climate and weather patterns.

Hydro’s vulnerability is river flows and their changes in volume and temperature from changing precipitation and warming. Run-of-river plants, like most in the Pacific Northwest, do not have expensive storage dams, hence their capital costs are lower and the capital return period is shorter. But their sensitivity to changing weather is larger, especially if they have to factor in fish and wildlife protection.

The resource base of wind power will also be affected by gradual changes in temperature, leading to changes in pressure differences, which determines windiness. Lower air density resulting from higher mean air temperatures will reduce power.

Even though total wind resources are projected to remain close to current values in North America and Europe, changes in inter-annual, seasonal and diurnal variability will vary locally, providing substantial uncertainty in estimating resources during pre-construction siting.

Improving wind resource assessments is about the only improvement that can positively affect wind. Extreme weather episodes will not affect the resource base but can severely impact the operation of wind energy facilities.

Similarly for solar production. Gradual climate change will change cloudiness and insolation which will affect power output. According to the report, concentrated solar power is the most affected.

Applying a rougher surface on photovoltaic panels to use diffuse light better, optimizing the fixed mounting angle and applying a tracking system to adjust the angle for diffuse light conditions, and increasing the storage capacity for concentrated solar power are possible ways to adapt to these gradual changes.

As reported by WNA, the world’s nuclear reactors made a growing contribution to supplying clean and reliable electricity in 2018. Global nuclear generation was 2563 TWh, up 61 TWh over the previous year. The number of reactors under construction at the end of 2018 was 55, with construction starts on five reactors, compared to the nine that have been connected to the grid following completion of construction. 

In Asia, nuclear generation rose by more than 10%, to reach 533 TWh, now more than one-fifth of global nuclear generation.

Fortunately, nuclear plants are not very susceptible to extreme weather events, even as these events at nuclear plants are on the rise again after declining, as shown in the figure below.

The report concludes that the most significant impacts of climate change on nuclear power plants are the slight loss of thermal efficiency, and the volume and temperature of water in adjacent water bodies affecting cooling water availability.

Alternative cooling options are available or increasingly considered to deal with water deficiency. At Arizona’s Palo Verde Nuclear Plant, the largest electricity generator in America, 100% of cooling water is recycled municipal wastewater.

The report states that nuclear power plants are built to withstand extreme weather events better than any other generating source on the basis of past experience, especially for the worst expected event over a 50 or 100 year period or much longer, such as 500-year floods. However, as climate changes, past events are becoming less reliable as a predictor of the severity of future events.

Many acute safety threats from extreme weather events can be minimized by shutting down nuclear reactors until an event has passed, but this strategy leads to increasing outages if climate changes dramatically or if extreme weather events become increasingly extreme and frequent.

The electrical grid is not immune to the effects of massive cold snaps and other extreme weather events (IEEE). The grid provides the link between power generators and users and its reliability is key to withstanding climate and weather changes.

History shows that the grid is the weak point with respect to extreme weather events, while power plants weather extreme weather better than any other part of the system.

Half of the loss of supply, and two thirds of the largest blackout events (with over a million customers affected) in North America between 1984 and 2006 were caused by weather events. Extreme weather events were found to be the major cause of interruptions in distribution networks in the United States as well as for other countries.

So hardening the grid against climate change is the most effective way to minimize these effects on the energy sector.

A robust connection to the grid system with multiple redundancies is essential. Precautionary and defense measures range from hard engineering options, like civil engineering or technological changes, to soft measures such as modifying legislative or regulatory directives and changing operating regulations.

Warmer temperatures cause increased transmission line losses resulting from greater electrical resistance. At the same time, the sag on overhead lines increases with increasing mean temperature, as does the growth rate of underlying vegetation and trees, which affects the lines’ rating.

The increase in electricity lost owing to rising temperature is estimated at about 0.4%/°C.

These losses should be able to be compensated for in the design calculations for new lines. The sag effect can be handled by extending towers or continuous vegetation clearing.

Other vulnerabilities of extreme weather include icing (see figure at top of column) and heavy rain, which increase the probability of flashover faults and short circuits. Improving insulator design, siting ground installations outside hazard zones and reinforcing supporting elements can help reduce these impacts.

Landslides or avalanches caused by heavy rain or snow can damage overhead lines, underground cables and substations. Reinforcing structures and siting ground installations out of the hazard zones is the solution here as well.

On the other hand, prolonged periods of drought causes the land surface and subsurface to dehydrate, affecting underground lines and equipment. Both the thermal and electrical conductivity of dry ground is lower than that of wet ground, and this reduces the rating of subsurface cables, making the impact of the warmer temperatures worse.

If vegetation close to overhead lines dries out, flashover can ignite the undergrowth, as seems to have occurred in California recently. Ionized air in the resulting smoke and combustion particles may turn into an electricity conductor that would cause arcing on the overhead line.

Forest or bush fires caused by drought can also damage overhead lines directly by damaging conductors and insulators and by burning wood poles.

Again, simple care and maintenance can reduce many of these negative effects.

From other case studies discussed in the report, the IAEA shows that the amount of additional energy to address these climate-induced issues is only a few percent, easily achieved relative to the more daunting tasks of making the sources green, which will take overhauling 80% of our electricity generation.

So mitigation and adaptation are both necessary to prepare for the future.



READ NEWS SOURCE

This website uses cookies. By continuing to use this site, you accept our use of cookies.