Navigant Research Blog

Eclipsing Solar Generation: Lessons Learned from the 2015 European Eclipse

— June 8, 2017

The United States will experience a solar eclipse at 10 a.m. PST on August 21, 2017. This will be the first total solar eclipse in 26 years—and the first since the solar PV industry expanded and PV became a meaningful source of electricity in certain US markets (especially in the California Independent System Operator, or CAISO, territory). The eclipse’s route is expected to skirt the states with the most solar installations, influencing generation in states such as California and North Carolina.

Globally, this will be the second time a region faces this challenge. On March 20, 2015, a total solar eclipse passed through Northern Europe (and partially in the southern part of the continent) between 9:40 a.m. and 12:00 p.m. CET. My colleagues at Ecofys did a presentation at the time to explain the effects the eclipse could have on the German grid. Back then, Germany had a total generation capacity of about 190 GW, 39 GW (20.5%) of which were solar.

At the time, the Ecofys team projected that PV power generation could drop by up to 13 GW for more than 1 hour in Germany and by up to 34 GW across Europe for a few minutes. That would represent 2-3 times the magnitude of variation due to other natural events like sudden storms.

Projected Trajectories of the 2017 and 2024 Total Solar Eclipses

(Source: Xavier M. Jubier)

Prior Knowledge Maps the Way

The nature of solar resources means that the effects can vary significantly depending on the local weather. The day of the 2015 event had cloudier weather conditions than originally forecast, which led to a less severe reduction in PV generation. Those areas that did have clear skies were affected significantly, but European energy markets managed to cope. Some of lessons from the eclipse included:

  • The hourly day-ahead market was mostly unaffected by the eclipse. German transmission system operators (TSOs) successfully marketed the PV in a first step at the hourly market and in a second step at the quarter-hour market.
  • In case of high demand or supply, there is a de facto quarter-hour market (over-the-counter and power exchange) in Germany, Austria, and Switzerland that can provide significant contributions for intra-quarter-hourly compensation. This solution is a fine-tune balancing done by the TSO.
  • The quarter-hour market showed big spreads. A European coupling of quarter-hour markets should contribute to increased liquidity of the market and reduce these spreads. At the same time, the quarter-hour trading should be combined with the hourly market.

The main challenge is how to balance the power system against this dynamically changing generation backdrop. This requires flexibility in the power fleet and significant amounts of reserve control over a short period of time. To tackle this challenge, the European Network of Transmission System Operators for Electricity (ENTSO-E) put in place the framework below to reduce the effects of future eclipses that the US regional transmission organizations/independent system operators (RTOs/ISOs) can use as a guideline:

  • Develop a plan to disconnect part of the installed utility-scale PV generation in advance of the eclipse and establish the amount and timeframe for disconnection and reconnection.
  • Detail the steps necessary to reconnect PV systems to the grid.
  • Add backup generation and/or interconnectors to allow transfers to fulfill load in the absence of PV generation.
  • Establish a clear description of the installed PV capacity and its capabilities to improve the accuracy of forecast studies.
  • Enable real-time measurement of distributed PV generation so operational strategy can be adapted in real-time.

The Effect of the 2015 European Solar Eclipse in the German Market

(Source: Energy Charts)

 

Do Water and Electricity Mix?

— July 21, 2016

Plant - WaterThe water-energy nexus is the interaction between energy, water, and all the aspects of generation and distribution that are involved with each. Many times, this nexus is used to describe the amount of energy used to distribute water and wastewater between water treatment facilities and end uses. This energy use is by no means small. In the United States, energy generated for water ranges from around 4% to 19%; California alone consumes 19% of its electricity for water and wastewater. Variations in energy generation are caused by geographic differences; hilly regions need to expend more energy to pump water across variations in altitude, and arid areas pump source water from aquifers deep underground.

Another aspect of the water-energy nexus is the amount of water it takes to produce electricity. Certain generation types (such as hydroelectric) have an obvious liquid component, but others are less apparent. New innovations in renewable energy, while still consuming water, help to preserve the resource by utilizing more region-specific energies.

A Flood of Electricity Generation

In Hawaii, an ocean thermal energy conversion (OTEC) plant recently began operations. This OTEC plant draws in warm surface water from the ocean, vaporizing ammonia and spinning a turbine, which generates electricity. The ammonia is condensed by water extracted from deep in the ocean. Other types of OTEC plants do not use ammonia at all, but utilize vaporized ocean water to power the turbine. This is the first plant of its kind in the world, though it is worth noting that the United States has been researching OTEC technologies since 1974. Makai Ocean Engineering and the Hawaii Natural Energy Institute developed this 100 kW facility as a way to test the OTEC process, and the plant produces enough energy to power 120 Hawaiian homes for a year.

For cities farther from the water, solar power might seem like the way to go. However, to get the most out of solar, many plant operators are turning to auxiliary steam components. For example, the Ivanpah Solar Power Facility in the Mojave Desert of California utilizes heliostat mirrors to focus sunlight on solar power towers. These towers are heated by the solar energy, and steam is created to drive a steam turbine. The combination of steam power and photovoltaics makes this plant one of the largest solar installations at 377 MW capacity. In addition, its air cooling system means that other than the water used to generate energy, the plant uses 90% less water than other solar thermal technologies with wet cooling systems. However, there are drawbacks to solar power at this concentration. On May 19, 2016, one of the solar generating towers at Ivanpah caught fire due to improperly tracking mirrors that focused sunlight on the wrong part of the tower. There have also been reports of effects on wildlife, such as birds and tortoises. The issues in the development of high intensity renewable energy must be ironed out before these types of plants become widespread.

Renewable energy is important, and not just for the conservation of fossil fuels. Well-integrated renewable energy will utilize the natural resources of the region to produce sufficient electricity without wasting scarce ones. Traditional electricity production uses large quantities of water, but renewables (even those designed specifically to utilize water) can help conserve this. Producing energy may be a very water-intensive process, but many innovations in electricity production hold the promise that this market is becoming less thirsty.

 

The Overlooked Renewable

— May 19, 2015

Hydropower may account for just 7% of U.S. electricity generating capacity, but this sometimes overlooked renewable energy source could play a more significant role. That’s one of the conclusions from a first of its kind study on hydropower that quantifies the size, scope, and variability of hydropower in the United States.

The new U.S. Department of Energy (DOE) study (2014 Hydropower Market Report) describes a diverse fleet of hydropower plants that collectively produce enough electricity to power more than 20 million homes. The report also notes that the size of the hydropower fleet has grown in the last decade, mainly as owners have upgraded existing hydro assets, with a net increase of nearly 1.5 GW from 2005 to 2013. Total investment in hydropower amounted to more than $6 billion for refurbishments, replacements, and upgrades during that timeframe.

 One Major Hurdle

On the plus side, the report indicates that the United States has more than 77 GW of potential hydropower capacity, and that the current development pipeline encompasses a mix of proposed projects at non-powered dams, conduits, and undeveloped rivers or streams. These projects, as well as large-scale pumped storage hydropower (PSH) projects, account for the bulk of current development plans. However, there is a major hurdle that clouds this picture. The widely available bond, grant, and tax-credit programs that helped drive development of hydropower projects in recent years have gone away, and new projects are likely to depend on alternative funding sources, which more than likely means a slower pace for upcoming projects.

Without a doubt, hydropower has it limits and cannot be thought of as a viable alternative in certain regions – drought areas of the Southwest come to mind. But given its potential for adding tens of gigawatts of untapped power, it should be part of the overall energy conversation because of its proven track record as a source of clean, reliable power, despite the potential funding hurdles.

 

Major Shifts Ahead for European Power Generation

— May 4, 2015

Across Europe, major changes in the power generation sector are driving the development, expansion, and deployment of new and reconfigured electric transmission and distribution systems. The forces driving these changes include the retirement of much of the existing coal and nuclear generation fleet, the European Union’s energy policy goals, concerns over security of supply, climate change mitigation efforts, and the ongoing integration of distributed energy resources (DER) across the region. Power peak load is expected to grow between 8% and 28% by 2030, according to the Ten-Year Network Development Plan produced by the European Network of Transmission System Operators for Electricity, or ENTSO-E.

The net generation capacity of the European power sector must grow from about 1,000 GW today to between 1,200 GW and 1,700 GW by 2030 in order to keep up with demand, according to the Plan. To accomplish this massive increase, the generation fleet must not only add new capacity, but also replace present units that will be retired in the next 15 years. This represents a 3%4.6%  expansion per year across all potential resources.

Age of Wind

Looking to 2030, the generation fleet in Europe will morph in a number of significant ways, including:

  • Major nuclear generation plant retirements will happen across the region, including those in Germany, Belgium, and Switzerland. All present nuclear units in the United Kingdom are scheduled to be shut down, and France plans to reduce the share of nuclear to 50% of the country’s power supply by 2025. This adds up to a net 30 GW and 45 GW of nuclear capacity being shut down. At the same time, 20–30 GW of new nuclear capacity is expected to be added. New plants may be added in the United Kingdom, Finland, and Central Europe.
  • New generation additions will occur in new locations. Wind farm development will be located where wind speeds are optimal; a significant share of the new generation fleet in Western Europe is being built on new sites, mostly in harbors.
  • The shutdown of nuclear and fossil-fired units across Germany will require additional grid investment necessary to transport remote power to population centers.
  • New generation capacity will primarily be made up of distributed wind and solar systems. The generation capacity of wind, solar, and biomass is expected to reach at least 405 GW and could triple, reaching more than 870 GW by 2030.
  • DER will be located in Germany and in countries with favorable wind conditions, such as the Iberian and Italian peninsulas and Nordic countries bordering the North Sea.
  • New hydropower capacity is expected to increase from 198 GW to between 220 GW and 240 GW, with most new development in the Alps, the Iberian Peninsula, and Norway.

These major generation shifts will be the primary drivers for investments in high-voltage transmission systems across the region. Navigant Research’s forthcoming report, Submarine Cable and High Voltage DC, will detail many of these changes and additions, which promise to transform Europe’s power sector.

 

 

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