Advanced Energy Perspectives

Solar Thermal Electric (STE), often called concentrating solar power (CSP), uses mirrors or lenses to concentrate sunlight, generating temperatures high enough to produce steam and drive steam turbines. There are three configurations of STE systems in commercial use: power towers focus sunlight at a point, while parabolic troughs and Fresnel reflectors focus sunlight onto linear receiver tubes. Parabolic troughs and power towers are the most commonly used STE technologies today, and along with linear Fresnel configurations are deployed in large-scale projects that generally range in capacity from tens to hundreds of MW. STE plants can incorporate thermal energy storage, typically using molten salt, allowing them to generate electricity when it is needed even if the sun is not shining. A number of commercial and demonstration projects have also been built to integrate STE technology into natural gas and coal power plants, reducing the fuel inputs needed for the same energy output.

This post is one in a series featuring the complete slate of advanced energy technologies outlined in the report This Is Advanced Energy. 

Image courtesy of Stem, Inc.

Without energy storage, electricity must be produced and consumed instantaneously, requiring generating capacity to be built and available to meet peak demand no matter how rarely peaks occur. To relieve this requirement, several energy storage technologies are currently mature and commercially available, including pumped hydro, compressed air energy storage (CAES), flywheel systems, electrochemical batteries such as sodium-sulfur batteries and lithium- ion batteries, flow batteries, and thermal storage. These technologies take in electrical energy when it is produced and store it as kinetic, chemical, thermal, or potential energy for conversion back to electricity when needed.

Waste-to-energy (WTE) is the process of generating electricity and/ or heat by combusting municipal solid waste (MSW). The most common form of WTE is mass-burn combustion, in which MSW is burned “as is” to produce steam that spins a turbine attached to an electric generator.

Drinking water treatment systems and wastewater treatment plants account for approximately 3% of electricity use in the United States, or 100 billion kWh annually — enough to power over 9 million homes. These facilities have several options to reduce their electricity use, with potential savings estimated at 15% to 30% nationally. In water treatment systems, approximately 80% of electricity is used for pumping, so savings come mostly from pumps, motors, and variable-frequency drives. By allowing motors to adjust to fluctuating pumping needs, variable-frequency drives can reduce electricity use by up to 50% while also extending motor life.

Image courtesy of AEE member General Electric.

In recent years, the transmission system in many places has been upgraded with new sensors and automated control equipment, allowing for more data collection and efficient control. The distribution system, however, is further behind in deploying similar technologies, which could improve system operations. Distribution automation technologies include a combination of line sensors, control equipment, and software tools that constantly optimize distribution equipment, such as transformers, capacitor banks, and reclosers. Together, these tools and technologies improve reliability and efficiency.