The path to a 100% carbon-free energy economy is not straightforward. The challenge lies in meeting the increasing demand for electricity while complying with state and federal mandates for emissions reduction that requires an increasing amount of power from intermittent renewable sources. This gap between current energy production and future goals is the energy gap.
Since October, we’ve been discussing coal alternatives that could help bridge the energy gap. This month, we’re focusing on renewables — specifically wind and solar — paired with batteries.
Reliability
Wind and solar generation are crucial to the energy transition. Both are relatively low-cost and utilize carbon-free fuel, but they have a key limitation: They depend on an intermittent fuel source — Mother Nature. We can reduce their output when demand is low, but we can’t increase it when demand is high.
“We can’t create more wind or move the clouds,” Tri-State Generation and Transmission Vice President of Energy Resources Susan Hunter said.
Batteries, however, can store excess power from wind and solar during low-demand periods and discharge it when demand spikes. These projects are typically referred to as hybrid projects since batteries are paired with a renewable source. Some storage projects use stand-alone batteries that are charged directly from the grid instead of from a renewable source.
“While short duration battery storage projects provide value during normal load patterns and under expected operational conditions, their limited discharge cycle cannot always provide power during unexpected or abnormal conditions.” Hunter continued. Most utility-scale batteries have about four hours of storage. This makes them less useful during prolonged extreme weather events. However, private companies are working on long-duration storage technologies, but those efforts are still in development.
It’s important for utilities to be able to load shift: the process of when electricity use is moved to off-peak times to save money and help keep the power grid stable; batteries can help accomplish this. An example of this is when a utility charges a battery during off-peak hours and then discharges the energy during higher load, on-peak hours. Doing this is important because power plant outages can happen, and having backup and redundant baseload resources helps ensure a stable supply.
Cost
Are wind and solar on their own the most affordable resources? Renewables are not as cheap as they once were. Supply chain pressures, tariffs, and rising labor costs have increased prices. Still, existing wind and solar often remain cost-competitive with coal and natural gas. Often overlooked in considering the cost of utility scale wind and solar resources is the large cost of building transmission lines to bring the energy from remote areas, ideal for building wind and solar, to more populated areas where the demand for electricity is high.
While there is an influx of temporary jobs during the build phase, there are limited local long-term employment opportunities with utility scale wind and solar. The push for more domestic manufacturing may reduce reliance on imports, but trade disputes and higher labor costs could negate the savings.
Safety and the Environment
All power generation has an environmental footprint. While wind and solar produce no carbon emissions during operation, their large land use and the mining of materials and rare earth metals for solar, wind, and batteries pose environmental challenges.
Recycling old chemicals and minerals in panels and fiberglass blades remains a hurdle. Solar panels, wind blades, and nacelles, the cover that houses the generation parts of a wind turbine that sits on top of the tower, have a fairly short usable life of about 20 to 25 years.
Repowering — replacing key components while keeping existing infrastructure — is gaining traction. “It’s a better financial decision to maximize lifespan and efficiency without starting from scratch,” Hunter said. When constructed, significant investments are made to secure land, permits, and to build the foundations and framework. Plants will keep the basic support structures and just replace the panels, or the blades and nacelles.
Safety is also a priority. Wind and solar farms are sited to avoid wildlife habitats and migratory paths, military training activity, and airspace f light paths. However, incorporating batteries introduces risks like thermal runaway — when a battery heats up too rapidly, potentially leading to a fire or explosion as the battery releases stored energy uncontrollably. Hunter says the key to safety and reliability is hiring an experienced maintenance staff to do visual checks, monitor equipment to prevent overheating, or note a marked decline in production.
A Balancing Act
The move from fossil-fuel power generation is complex. “We are seeing growing concerns about where wind and solar projects are being proposed,” Hunter mentioned.
The shift to renewables often pits urban demand against rural land use. Many people don’t like the impacts of huge solar and wind farms because they may limit the visual enjoyment and usability of the land. They typically end up in rural areas where land is more abundant. Agrivoltaics projects that allow the land to still be used for livestock grazing, farming, and creating pollinator habitats are becoming more popular, but they are still rare and solve only part of the problem.
Bridging the energy gap will require a mix of resources, including reliable baseload power, intermittent resources, storage, and peaking plants.
Recent Comments