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Trimming the Duck Curve with Energy Efficiency

Solar energy is potentially the largest energy source on Earth. The amount of solar energy that hits 1 square mile in a year is estimated to be the energy equivalent of 4 million barrels of oil[1]Harnessing the power of the sun will be essential if we are to stave off the estimated 2-degree Celsius rise in global temperatures. While solar energy holds an enormous potential to decarbonize our electricity grid, solar integration also presents a host of problems. First, solar energy is intermittent and variable. From a utility standpoint, distributed solar generation is not ‘dispatchable’ – which means that it is less reliable than traditional fuel sources. Paring solar generation with battery storage is one solution to increase reliability, but also adds additional layers of complexity and cost.  Another downside to solar integration is that it changes a utility’s net load profile.  Net load is the difference between the load the grid operator must supply and the amount of generation being powered by renewables. Changes to net load matter, because base and peaking generation are still needed to reliably meet customer demand.  The National Renewable Energy Lab, or NREL, discovered this phenomena 10 years ago. Since then, we have come to call this observation the “duck curve”.


Addressing the duck curve matters because our world is electrifying. According to DNV GL’s recent Energy Transition Outlook, global electricity consumption will increase 140% by 2050 and electricity’s share in total energy supply will rise from 18% to 40%. By 2050, DNV GL estimates that 85% of global electric demand will be supplied by renewables, including solar. Knowing that increased penetration of solar generation changes net load, utilities should be looking towards multi-faceted strategies that limit the negative consequences of renewable generation.

One major negative consequence to changes in net load is the increased slope of the evening ramping period. It is the steepness of this ramp which gives the duck curve its “neck”.  The California Independent Systems Operators (CAISO) estimates that ramping needs will be 13,000 MW in a three-hour period by 2020. Targeting energy efficiency measures to the periods that overlap with the increased ramping needs is one potential strategy that utilities can employ.  In their “Teaching the Duck to Fly” publication, the Regulatory Access Project (RAP) noted that targeted energy efficiency is the most impactful strategy that a utility can employ to mitigate the duck curve, and estimates an 11% impact on system load, with a 4:1 ratio of on-peak to off-peak savings[3].

Instituting a Smart Lighting program is one easy first step that a utility can pursue to begin to change peak loads. Smart Lighting, which is a system of networked fixtures and sensors that run off software, can easily be programmed to reduce load to help a utility shave peak. Some systems, which have native Automated Demand Response (ADR) capability can even be programmed to automatically shed load at the discretion of the utility. If you are interested in learning more about how Smart Lighting can impact peak, please register for my upcoming webinar on June 27 at 2 PM ET.   I will review a case study of an office that dropped its consumption between 3-5pm from 41kW to 3kW, a 93% reduction! I will also provide a detailed overview of the trends that are driving the duck curve.  If you would like more information on how DNV GL can help your utility minimize the disruption caused by solar integration, please review our Solar Response flyer. For more information on Smart Lighting Solutions, please visit our Knowledge Hub or reach out to me directly.

Post Script: DNV GL and Smart Lighting Systems

DNV GL has successfully designed and implemented Smart Lighting Systems projects on behalf of our utility clients for four years. Our team has significant project experience in both retrofitting and new construction of lighting projects. We work through the project life-cycle to identify, justify and evaluate energy saving measures and provide post-installation engineering review to verify savings.

Our team is available to work directly with large institutions to assist them with Smart Lighting Systems projects. For more information, please contact Wesley Whited. Wesley Whited is a Senior Consultant for Smart Lighting Systems at DNV GL. Mr. Whited has seven years’ experience in the commercial lighting market ranging from project management to sales. Mr. Whited is a graduate of West Virginia University (WVU) and holds a MBA from Capital University in Columbus, OH.

[1] http://energyinformative.org/potential-of-solar-energy/

[2] https://www.greentechmedia.com/articles/read/eia-charts-californias-real-and-growing-duck-curve#gs.e1XVDSA

[3] http://www.raponline.org/wp-content/uploads/2016/05/rap-lazar-teachingtheduck2-2016-feb-2.pdf

3 Comments Add your comment
Wes Whited Wes Whited says:

Hey Nathan – DOE estimates that lighting is 17% of total US electric consumption. 45% of the total lighting load comes from buildings in the C+I space. Smart Appliances and DR for residential HVAC loads should also be targeted as part of a larger strategy to impact peak – I’m calling this “silver buckshot” I think that we need a variety of tools in our DSM toolkit to better integrate renewables onto the grid. Advanced Lighting is 1 BB in a “silver buckshot” approach. The fact that we can achieve this type of load reduction in a way that is more comfortable to building occupants should make it appealing to utilities.

Avatar Nathan Kautzer says:

What percentage of a typical grid does lighting account for? I would think appliances and air conditioners would account for a greater share of the spike.

Avatar Nathan Kautzer says:

What percentage of a typical grid does lighting account for? I would think appliances and air conditioners would account for a greater share of the spike when people come home from work.

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