In March 2022, the U.S. Energy Information Administration (EIA) released a report that projected renewable energy generation will supply 44% of US electricity by 2050.
At first glance, it would seem that energy independence—a state of self-reliance in regard to energy resources, supply, and generation—is nearly here, at least in the US. However, energy independence is still restricted by large imports of coal for power stations. To mitigate the reliance on imports and achieve true energy independence, distributed generation programs and renewables like solar will be instrumental.
Distributed Generation and Renewables
“Distributed generation” refers to the generation and storage of electricity on-site, rather than electricity generated at distant power plants and transmitted via infrastructure to end-users. It encompasses any energy-generating method that can be performed on-site, including solar photovoltaics, wind turbines, fuel cells, microturbines, reciprocating engines, energy storage systems, and many others. Many of these technologies can be classified as renewables.
The International Energy Agency (IEA) forecasts that by 2026, the global renewable electricity capacity will rise more than 60% from 2020 levels, reaching over 4,800 GW (equivalent to the current capacity of fossil fuels and nuclear combined). Solar energy remains the powerhouse of renewables, and it is set to provide more than half of the IEA’s forecasted 2026 global power capacity. However, as solar technology continues to enter existing energy networks at residential and regional levels, traditional power networks need to adapt to an increasing number of distributed, non-synchronous generators. Unfortunately, this shift has created vulnerabilities within existing power systems that were originally designed for top-down, coal-fueled energy supplies.
The Potential of Solar Power
Solar technologies can be split into two categories: photovoltaics (PV) and concentrating solar-thermal power (CSP). Photovoltaics directly convert sunlight into electricity via semiconductors. In the US, rooftop solar accounts for (at the time of this report) 3% of the nation’s power capacity, while projections show that by 2035, it may supply up to 40% of it. On the other hand, CSP uses mirrors (a.k.a., “heliostats”) to harness solar radiation by heating an inexpensive medium such as sand, rocks, or molten salt for on-demand energy dispatch. An increasing level of next-generation CSP research and development is being funded by the US government in order to contribute to the lowering of energy prices.
Of the two solar technologies, PV is the most popular. However, it’s not without its drawbacks: light-to-electricity conversion efficiency, sunlight exposure, and available generation hours all affect the widespread adoption of PV-based solar power. “Photovoltaic conversion efficiency” refers to the amount of solar radiation that is converted into electricity. On average, 1.73 x 105 terawatts (TW) of solar radiation continuously strike the Earth. In comparison, the global electricity demand averages 2.7 TW.
Harnessing this energy potential is a key goal of solar power technology developers. Yet, current PV conversion efficiencies for commercial PV only hover between 15–20%. Recent research, however, has shown significant improvements, with efficiencies up to 47.1%. There are also other challenges, such as the effect of various environmental conditions that cause PV energy fluctuations. These, too, have remedies, including optimizers, microinverters, lenses, mirrors, and adjustments to panel design parameters (e.g., the size the panel). Intelligent actuators are also used to allow PV panels to follow the sun’s position to optimize energy production throughout the day.
Solar Power, Infrastructure, and the Duck Curve
The most significant issue affecting the adoption of solar PV is its integration into existing power systems with regard to its variable energy output. This phenomenon, known as the “duck curve,” was originally a forecasted model of the effects of the increasing share of solar and wind energy production on the net energy load in California. The duck curve demonstrates the difference in the daily demand for electricity and the available supply of solar energy. When the sun shines in the middle of the day, solar energy floods the market. During this time, demand is low as people travel, share energy-dependent resources in common workspaces, and more. (This dip in demand is the “belly” of the duck.) In the evening, as the sun drops, so too does the solar energy supply. At the same time, electricity demand peaks as people stop “sharing” energy-reliant resources and turn to their own. (This is the “neck” of the duck.)
The trending data shows that morning and evening demand peaks are relatively consistent. However, as solar technology adoption continues to grow, so too does the challenge: an increasing oversupply of solar energy at a time of the day when it’s least needed (as predicted by the California Independent System Operator). Oversupply is a concern because it can lead to overgeneration, which requires manual intervention by utilities to maintain grid reliability. This leads system operators to curtail PV generation at low demand/high supply hours, and then increase other electricity generation methods during peak demand hours when the supply of solar energy is low. This problem extends beyond California, and even beyond solar technology: in 2018, China’s national curtail average for wind was 7%. In Ontario, Canada, approximately one-quarter of renewable energy was curtailed in 2017. All this reduces the economic and environmental benefits of renewable energy.
Yet, there are solutions. One proposed answer is the installation of batteries to store surplus solar energy. During peak hours, grid operators can utilize this stored energy to balance demand. For example, the Hornsdale Power Reserve (supported by Tesla) in South Australia supports that state’s 40% share of renewable energy. However, such battery systems are still expensive. Establishing interconnections with neighboring grids (e.g., between the northeastern US and California) may allow one network to supply, or “share,” enough surplus energy to meet demand during peak hours. In addition, surveys have found that lighting usage is a key load. Encouraging residents and businesses to use more efficient lighting (and appliances) may also contribute to reducing the duck curve.
Distributed Generation Programs
Distributed generation (DG) programs implement various renewables on-site, close to energy loads (and users). This can include generators that power houses, businesses, or even microgrids (e.g., for an industrial facility or campus). Distributed generators are often still connected to the power grid, allowing DG operators to sell the electricity back to the grid during times of surplus energy (e.g., excess solar PV output). However, the increase in the use of renewables via DG programs and subsequent decommissioning of coal-fueled synchronous generators has created problems for the stability and security of the grid.
“Active power” refers to what users consume, while “reactive power” controls the supply (maintaining the voltage to deliver active power). Wind and solar energies do not provide rotational inertia and reactive power in the same way as traditional synchronous generators. Inertia and reactive power are vital for the smooth and reliable functioning of the power system. In addition, reactive power is essential to move active power through the transmission and distribution system to the end-user.
So how does solar overcome these challenges?
As distributed generation and solar programs gain more confidence with consumers, there is a movement to design new power systems to facilitate energy independence and fully utilize cleaner energy sources while maintaining a secure and reliable grid. Solar technologies rely on converter-based technology to supply the grid, losing the slow-responding mechanical components of synchronous generators. However, these have been replaced by electronic sensors that can measure frequency and respond quickly. Such fast frequency-response control systems are quickly exceeding the frequency response abilities of inertia. In cases where inertia is required, synchronous condensers (i.e., a DC-excited synchronous motor not connected to anything) can be utilized to help maintain frequency stability. When it comes to compensating for the lack of reactive power, static VAR compensators (SVCs) (“VAR” refers to volt-ampere reactive—the unit for reactive power) have already begun to be integrated into grid infrastructures. SVCs are based on power electronics devices known as thyristors and can either generate or absorb reactive power. SVCs help to maintain the voltage level on the local grid, thereby improving the stability and reliability.
Static synchronous compensators (STATCOM) are also used to continuously provide variable reactive power in response to voltage variations and support the stability of the grid. To further balance upstream effects of reactive power injection, transformers can be fitted with an On-Load Tap Change (OLTC), which regulates the output voltage of a transformer. These technologies, known as flexible AC transmission system (FACTS) devices, are key to supporting the integration of renewable sources of energy within existing power systems.
The Road to Energy Independence
The solutions to these problems are many, and they are not insurmountable. As more attention is given to distributed generation programs and solar energy, technologies that facilitate their use grow. At the same time, the grid is expected to become more flexible and over-generation risks mitigated. New technologies will allow PV to provide on-demand capacity and, ideally, reach the EIA’s forecast: renewable energy generation supplying 44% of U.S. electricity by 2050.
For more than a decade, High Touch Group has partnered with climate technology and renewable companies, including extensive work in the offshore wind and solar industries. Our marketing and communication strategies have helped secure venture capital, foundation, and government funding to move emerging technologies out of the lab and into the commercial sector. We have coordinated effective public and media relations campaigns, developed community outreach programs, and supported multi-million-dollar governmental funding proposals for climate technology R&D programs. Our team is passionate about supporting energy independence and works hard to drive our clients’ climate technologies forward.
Contact us to discover how High Touch Group supports your climate technology marketing plan.
