Sustainable Energy & the Duck Curve

Going Green with Brown

The southwest region of the United States is one of the largest producers of solar energy. This generation of electricity has proven to be a viable source of renewable energy used to offset electricity produced from fossil fuels. As states like California mandate solar on all new residential construction, this will aid in creating a duck curve in the energy grid. 

What is The Duck Curve?

The duck curve is a power production scale showing low demand during solar energy production during the day and then a scaling increase in demand at night. 

With employees working from home during the COVID-19 pandemic, solar energy usage decreased in 2020, reflected in a more exaggerated duck curve. A report generated by California Independent System Operators (Ca ISO) showed a current overproduction of daytime solar energy in California. A vital part of the report details the need for 13,000 MW of electricity when solar production when the sun sets.

(source: California ISO)

The use of solar power for electricity has its merits and provides a good source of sustainable electricity to the grid. Absent the creation of a duck curve and with the need to move electricity around the grid, solar has locked its place in the California grid. 

Finding the Energy Balance

The next part of the equation is creating a flexible and manageable grid network that continues to be sustainable. The ability to have baseload energy systems to supplement the demand for 13,000 MW of electricity is now a realistic path. The combination of waste to value energy and the use of renewable natural gas (RNG) can generate baseload electricity to bring balance to the duck curve. A benefit to using RNG as a baseload power provider is that the energy system is using sequestered methane to generate electricity. This would normally be methane that is released into the atmosphere. Southern California Edison has recognized the benefits of using RNG in its energy mix and has committed to replacing 20% of its natural gas use with RNG. 

The use of batteries for daytime storage is becoming an accepted addition to solving the surge created by the duck curve. Battery storage systems are continuing to become more cost-effective. There are environmental concerns with the mining of lithium and the overall life cycle of batteries, however, battery storage is now part of an active design with storing renewable solar electricity.

The prevailing argument for creating a sustainable grid is cost. New baseload energy plants are expensive to construct and can take time to recover the investment. This barrier does need to be addressed. California has attempted to use programs like the BioMat program to allow for more sustainable energy systems to enter the grid. However, these are small-scale 5 MW systems that are often cost-prohibitive and often have feedstock challenges. Additionally, the program has only generated 20% of the allocated 250 MW allotted for the program. The merits of the BioMat have allowed for the program to be extended until 2025. The takeaway here is that a pathway has been created to design more sustainable grids. Collaboration between policymakers and energy engineering can eventually move the program forward. 

Sustainable energy grids can happen with proper evaluation and design. A whole systems approach is becoming the practice in energy design. As more states adopt renewable energy portfolios, there will be a need to meet quick baseload demands. Therefore, a sustainable energy system will be the key to green energy success. 

Bernard Brown
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