15 Green Energy Trends for 2023

Image Source: Adobe Stock/robu_s

By Adam Kimmel for Mouser Electronics

Published February 21, 2023

Introduction

In December 2015, 196 parties assembled in Paris at the COP 21 meetings and agreed to actively address climate change. The output, the Paris Agreement, legally binds participating countries to commit to limiting global temperature rise to well below 2°C (targeting 1.5°C) between the pre-industrial era and the end of the 21^st century. Participants will achieve this by targeting a climate-neutral world by 2050. Climate-neutral translates to substantially and immediately reducing greenhouse gas emissions.

Greenhouse gas emissions derive from carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), water vapor, sulfur hexafluoride (SF₆), and chlorofluorocarbons (CFC) and hydrofluorocarbons (HFC). Scientists represent the severity of greenhouse gases by their global warming potential (GWP), a parameter representing the warming potential of a material as a magnitude of the CO₂ baseline over a specific period (usually stated as the 100-year value). The following are 100-year GWPs of some of these greenhouse gases:

• CH₄: 27–30
• N₂O: 273
• SF₆, CFC, HFC: >1000–10000

While carbon dioxide has a GWP of 1 (the baseline), it remains in the atmosphere for thousands of years and increases water vapor concentration, presenting a significant opportunity. Carbon dioxide and water vapor are primary combustion products. While water vapor is highly sensitive to pressure and temperature, its presence in the atmosphere increases with higher concentrations of carbon dioxide, raising the atmospheric temperature. Methane and nitrous oxide enter the atmosphere through agriculture, biomass, fossil fuel extraction, and industrial processes.

Sulfur hexafluoride comes from high-voltage power and chemical processing, while CFCs and HFCs derive from atmospheric leakage of fluorochemicals. The Montreal Protocol—adopted in 1987—mandated a global phase-out of CFCs, while the Kigali Amendment to the protocol created a scheduled phase-down of HFCs beginning in 2019. In December 2022, the U.S. Environmental Protection Agency proposed a rule to restrict HFCs for applications in which a lower-GWP alternative exists.

As evidenced by participation in the Paris Agreement, most countries accept that the world must transition away from using fossil fuels to using renewable (green) energy, a market opportunity expected to reach $2 trillion by 2030. This article will outline the current state and recent technical developments for green energy sectors.

Renewable sources already comprise a significant proportion of global energy generation. Hydropower is the majority by a wide margin, but wind and solar are quickly catching up. Figure 1 shows the global energy generation in 2021, illustrating how wind and solar are gaining traction.

Figure 1:

 Modern renewable energy generation by source, World 2021. (Source Hannah Ritchie, Max Roser and Pablo Rosado (2022) - "Energy". Published online at OurWorldInData.org. Retrieved from: 'https://ourworldindata.org/energy')

Solar and Photovoltaic Cells

Scientists and engineers have made substantial gains in solar and photovoltaic (PV) energy. Historically, some of the barriers to implementing solar have included the following:

• Land usage footprint necessary for the required power
• Capital and initial costs of solar panels
• Inverter
• Grid integration technology
• Aesthetic of installing a large area of solar panels on consumers' rooftops or agricultural land

Given the importance of increasing the proportion of solar energy and the timing to meet Paris commitments, governments are beginning to mandate solar panel installation to remove the choice from consumers. For example, Tokyo is mandating solar panels on new houses built after 2025.

Integrated PVs

Two primary drawbacks of renewable energy are inefficiency and unreliability. Power sourced from nature is less efficient and reliable than more processed energy. For example, commercial solar panels are only between 15–20% with a theoretical maximum of ~30% for a single material, driven mainly by energy conversion losses and solar dispersion.

Engineers are integrating PVs wherever practical to increase the overall power output of an inefficient process. Much of the opportunity comes from installing PVs on legacy fossil fuel plants and the toxic ground that municipalities had written off. With the highest solar efficiencies coming from southern-facing, unshaded surfaces, system designers can optimize PV integration for value. In addition, the large footprint of solar panel arrays can create secondary benefits like diffusing the ambient heat of parking lots with solar panel-covered parking structures. Finally, sunlight travels to an exposed roof even on cloudy days, so it makes sense to install solar panels to collect as much energy as possible.

Floatovoltaics

Another trend in solar energy is the installation of solar panels in bodies of water, sometimes known as floatovoltaic power. The large amount of open water on earth provides natural benefits for offshore solar, such as liquid-cooled integration with the seawater and added source energy through the water reflecting solar rays onto the panels. Liquid cooling carries a much higher heat transfer efficiency than air-cooled systems, reducing the component size for a comparable amount of energy. Furthermore, energy reflected by the water onto the panels increases the source energy converted to electrical without additional infrastructure, increasing system efficiency.

Agrovoltaics

Like floatovoltaics, agrovoltaic (or agrophotovoltaic) energy takes advantage of a large area to place PVs—in this case, installing solar panels on farmland to integrate with crop-growing operations. This practice also provides remote, resilient energy in locations that may not have ready access to the electrical grid or that can augment grid power allocated to agriculture. Adding power generation to land that is already profitable for farming increases its value, and the panels can reduce soil temperatures and evaporation, increasing the yield of the farmland.

Concentrated Solar Power

Another way to mitigate the natural inefficiency of solar energy is to collect the renewable power onto a small area using concentrated solar power (CSP) mirrors or lenses and then convert it to thermal energy for on-demand use. This thermal-to-electrical conversion is similar to how Stirling engines and steam turbines operate. Additionally, enabling factors for CSP include access to high-voltage transmission lines, sufficient land acreage, and high-quality sunlight (like in the U.S. Southwest).

PV Materials Advancements

Commercial, single-material PV only operates at an efficiency of around 20%. However, there are significant material advancements that are raising that ceiling. For example, a sustainable materials approach is to simply reduce the PV cells' material thickness. This approach increases material elasticity for expanded applications, reduces costs, and raises the sustainability profile with reduced material. In addition, thinner PVs reduce planar conduction losses across the material thickness (heating up of thicker material), increasing energy conversion efficiency.

Additional materials advancements are in bismuth (Bi)-based materials and coatings to push past the ~30% theoretical limit. The leading coating material is perovskite, which raises the theoretical efficiency limit to 43% through expanded wavelength absorption on the solar spectrum, which then increases the quantity of available source energy. Perovskite durability remains an open question, however, which could limit the duration of the increased efficiency over the solar cells' lifetimes. Other films and coatings have demonstrated 5–10% efficiency gains by capturing and redirecting light beams, similar to CSP.

Wind Energy and Hydropower

Renewable power has become more affordable due to technology advancements and increased market adoption. But while construction of new wind and solar plants is currently more economical than that of coal or gas plants, fossil fuels still dominate global consumption compared to renewables.

However, as the demand for green energy skyrockets due to global sustainability commitments, the costs per unit (kWh) of wind and solar power generation capacity are also falling—occasionally lower than cost per kWh of fossil fuels. As a result, renewable energy's lower capital and per-unit cost when compared to fossil-derived power create a compelling business case when met with unconstrained global demand.

Hydropower, which comprises the highest proportion of renewable energy production, takes advantage of water's prevalence. This method harnesses the kinetic energy of flowing water, which spins a turbine to drive a coupled generator, producing electricity. In addition, many of the wind innovations leverage integration with ocean sources.

Offshore Wind

One such innovation, the use of offshore wind, takes advantage of the space available for turbine construction and combines it with wind energy from sea wave movement. As a result, offshore wind turbines and towers are larger, reducing the relative cost per kWh vs. on-shore wind. In addition, the use of floating supports for the towers further reduces the deployment cost and increases the location flexibility for offshore wind turbines. Though still an intermittent renewable energy source, offshore wind is stronger and more consistent than on-shore due to fewer obstructions and a more significant temperature gradient between land and the ocean. While a higher-efficiency solution, offshore wind carries technical challenges through the corrosive sea environment and difficulty reaching the remote plant sites to perform maintenance.

Local Turbine Assembly and Construction

The massive size of wind turbines makes transportation of complete units problematic for logistics leaders. As a result, engineers are designing turbines for modular transportation and construction on-site. In addition to alleviating transportation headaches, modular construction reduces the number of unique parts while increasing production quantities, thereby improving turbine economics.

Blade Aerodynamics and Numerical Modeling

To improve the efficiency of wind power production, engineers are focusing on blade design. For example, 3D numerical modeling or computer-aided engineering (CAE) can assess the airflow over a turbine blade to rapidly optimize performance. This analysis, called computational fluid dynamics (CFD), can look at transient and static conditions to select an optimal design. For example, through CFD analysis, a design engineer may modify a blade's shape and tip curve geometry to increase wind energy efficiency.

Digital Twins

An increasingly popular numerical design tool is digital twinning, which replicates a physical part with a digital match. The digital twin incorporates performance data from the physical part for model calibration. Then, design updates can happen rapidly in the digital realm before manufacturers begin a new physical prototype, saving massive amounts of time and cost.

Energy Harvesting

Any differential in properties creates the opportunity for power generation. For example, many residential water storage tanks are elevated to provide consistent delivery pressure. Similarly, naturally occurring differentials in thermal energy, salinity, and tidal pressures in the ocean can be harnessed for hydropower.

Ocean Thermal Energy Conversion and Gradient Energy Capture

Water temperatures can vary significantly from the surface to hundreds of meters deep. Ocean thermal energy conversion (OETC) converters use hot and cold seawater to vaporize and condense a working fluid in a vapor-compression refrigeration cycle. The larger the temperature difference, the higher the energy efficiency and output. Similarly, osmotic and tidal pressure differentials can produce energy as the initial state seeks equilibrium with the lower-energy state.

Energy Storage and Grid Integration

A significant source of green energy innovation is occurring in energy storage. Renewable energy is inconsistent, so storing the power allows the user or utility to dictate how to smooth out the intermittency.

Battery Chemistry

With the rise of electrification, battery chemistry is constantly evolving. Technologies like lithium iron phosphate (LFP), sodium ion, and solid-state are poised to improve the power density, charge/discharge speed, and safety profile.

Distributed Energy Storage and Microgrids

As the trends and innovation in wind and solar evolve, integrating that energy with the electrical grid will be the next critical hurdle to driving the energy transition. Like gallium nitride and silicon carbide semiconductors, grid electronics allow various energy forms to communicate through power integration. In addition, this technology provides distributed energy storage in alternative power forms.

Grid electronics also enable microgrids—local collections of power sources that can operate independently, like a generator, or integrate with the grid. These arrangements provide an additive effect of all renewable energy sources to augment primary grid power or strengthen resiliency during outages, improving power utilization efficiency.

Microcontrollers

Microcontrollers play a part in renewable energy integration by providing operators control over how they distribute renewable energy. Integrating these controllers with AI-driven smart systems can automate the power balance for optimal efficiency, adapting to changes in demand or during peak periods. The controllers can also adapt to fluctuations in voltage through power intermittency and correct them in-application.

Vehicle to Grid (V2G)

A significant challenge to the widespread adoption of green energy is lack of access. Engineers have increasingly started considering energy like a fluid, able to travel back and forth where needed. With this in mind, the proliferation of electric vehicles may solve the access problem, as they can act as mobile batteries or create a bi-directional path between the vehicle and the grid. This is especially beneficial for remote areas that are not connected to the grid, enabling these areas to create power resiliency should they have excess stored energy. This application can also improve the business case for electric Class VIII trucks while reducing power demand and intermittency of the existing grid. As a result, V2G will be a significant green energy enabler.

Conclusion

Many green energy innovations target the principal challenges of naturally sourced power: intermittency and inefficiency. The primary themes in this article concern decentralization, shifting power deployment to a deliberate final delivery scheme, and leveraging the existing features of natural, renewable energy to increase their effectiveness for societal use.

How these inventions integrate with the existing grid will determine the speed and effectiveness at which green energy becomes widespread.