Study Finds East Coast Can Handle 30% Renewable Energy


Researchers at the National Renewable Energy Lab (NREL), the country’s preeminent laboratory for the study of renewable energy, recently found that the eastern US’ electrical grid can handle up to 30% renewable energy from wind and solar.

The findings were published in August 2016 in a report commissioned by the US Department of Energy. The study examines if the region’s electrical grid could handle a high amount of solar penetration, how the region’s electrical generation would need to change to accommodate it, and how operational aspects would need to be tweaked as well.

The Current System – Controllable and Predictable

Historically, utilities have had complete control over electricity generation. Basing decisions on historical data of when and how residents use energy, the utilities then decide when to ramp production up or ramp it down, as well as which type of generation needs to be used –coal, hydro, natural gas, etc.

Reliability is of the upmost importance to the utility. With decades of experience in predicting energy use, utilities are very, very good at knowing when they need to increase or decrease generation. This isn’t just a nice thing to have though – it’s a necessity.

Most utilities have no way to store electricity, so knowledge and data on typical energy use is key. If residents begin to use more electricity, the utility must know how and when to immediately and instantaneously ramp up generation to meet that demand.

As a rule, energy use generally increases in the morning, as people wake up and start their day. It continues until late afternoon when it spikes, as everyone gets home and turns on all the lights, cooks dinner, and watches TV. At night, as everyone is asleep, energy use drops significantly, though air conditioning, refrigerators, and pool pumps continue to run, drawing power throughout the night.

Different generation types lend themselves to different hours of the day. Nuclear power, for instance, is  a base load power plant – providing constant energy throughout the day and night, never really shutting off. Coal plants also run pretty much day in and day out, though utilities can ramp up production slightly if needed.

For times when electrical usage spikes and utilities need to provide electricity fast, they have power plants called “peakers” which are constantly on call, ready to provide power when there’s a spike or peak in electricity usage. These plants are fast to turn on, but aren’t as efficient or economical as base power plants, some even use diesel oil as fuel!

If it seems like there’s a lot of different systems going on, you’re right! Keeping the lights on24/7 is a complicated process that involves constant vigilance every hour of every day.

Solar and Wind are Unpredictable

So where does the problem with solar and wind come in?

As you can imagine, photovoltaic (PV) solar and wind are quite unpredictable. Clouds move in and block sunlight. Wind comes and goes throughout the night. Storms roll in for days at a time and bring clouds, rain, and wind. With renewable energy, utilities can’t predict or control the generation, so it’s very difficult to account for these energy sources when planning on a day-to-day basis.

To accommodate these unpredictable energy sources, the utilities have to scale up or scale back other generation sources at certain times of the day to fill in the generation gaps caused by the unpredictable nature of renewables.

In addition, as more and more homeowners install solar panels and create electricity during day light hours, a real issue is created for the utility, who must instantaneously provide quite a bit of electricity the minute the sun goes down and PV systems stop producing electricity. With coal and natural gas generation plants, it’s quite a challenge for utilities to ramp up production as fast as is required, adding more challenges to integrating renewable energy into their generation mix.

Study Looks at Feasibility of Incorporating Large-Scale Renewables

By commissioning the study, the US Department of Energy wanted to see if the eastern United States electrical grid could handle the unpredictability of 30% of its generation coming from renewable energy.

Using weather and energy usage data from 2006, as well as new modeling methods and high performance computing, researchers were able to see how a large amount of renewable energy would affect the eastern electrical grid. They looked at energy generation in 5 minute intervals, seeking to understand how the renewables would affect grid operators’ ability to quickly ramp up electricity generation.

They ran analyzed 4 different scenarios to see how the area could account for different penetrations of renewable energy:

  1. A grid with 3% of its generation from wind energy. In essence, a situation in which no new renewable energy was installed after 2012. In this scenario, nuclear, coal, natural gas, and a handful of other fossil fuel-based mixes covered all generation needs.
  2. A grid with 12% penetration of wind and .25% of solar. Twelve percent is the minimum requirement of renewables set forth in state-mandated RPSs (Renewable Portfolio Standard). In this instance, coal generation drops considerably to make room for wind power.
  3. 30% renewable energy – 20% from wind and 10% from PV – with a focus transmitting electricity only regionally. We now start to see solar producing quite a bit of electricity during the day, with natural gas and coal producing more energy at the beginning and end of the day, when energy use is high but solar installations haven’t ramped up yet.
  4. 30% renewable energy – 25% from wind and 5% from PV – with expansion of large transmission lines between regions to allow for greater movement of electricity between large areas. Without as much PV in the mix, wind provides quite a bit of electricity, rivaling coal and nuclear in production.

Study Found 30% Renewables is Feasible

After studying the four different scenarios, researchers found that the eastern US can, in fact, handle up to 30% of its generation from renewable energy, with spikes of renewable generation accounting for up to 50%! However, many things would need to change or be tweaked for this to happen:

  • The generation mix would look very different than what it is today. Overall coal and natural gas use would decrease. Some generation types, like thermal and hydro, would need to ramp up faster in the morning or afternoon and operate for shorter amounts of time to provide balance when solar and wind are producing at high quantities.
  • This type of generation mix requires constant vigilance and flexibility to change quickly. Huge data sets on generation, energy usage, and weather are necessary for this system to work. To help make sense of all this data, researchers designed new software that cuts data up into easily understandable, detailed graphs. They note that this type of software is necessary when working with such variable generation mixes and even provide their software online so other researchers can build on their foundation.
  • Operational changes are also required. With 100s of gigawatts of wind and solar constantly in flux on the eastern grid, more cooperation between regional operators is crucial, especially during times when electricity use is extremely high, wind and PV are producing high amounts of power, and at times when a lot of electricity is needed fast (in the morning, for instance). The report notes that there might not be enough incentive for transmission and generation operators to change the status quo, so regulators might need to step in and provide incentives to cooperate more.

A Landmark Research Report

Why is the report important for homeowners looking to install solar?

Utilities are often afraid that their current operational, transmission, and generation systems can’t handle the uncertainty of renewables. Many states have capped how much solar can be connected to the grid, not wanting to overload it. This happened in late 2015, when the state of Nevada met it’s solar production cap earlier than expected due to the huge interest in solar by homeowners. Just a few months later NV Energy, the largest utility in the state, slashed its net metering program, effectively ending new residential solar in the state.

This report, published by a respected research organization, looks more deeply into this issue than any study has before, and found that the grid can handle large amounts of solar energy (for context, nationwide in 2015 solar accounted for just 0.6% of all electricity generation).

The report creates a building block for other research organizations as well as utilities to study and base future decision-making on. It also gives regulators a reputable source to cite so they can say with authority that the current electrical grid can handle more solar and wind power.

By encouraging these regulators to rethink the rules on capping the amount of renewable energy that is allowed, policies favorable to renewables will become more commonplace, allowing homeowners and business owners can go solar in the future.

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