What the study actually modeled
If you pay a Los Angeles Department of Water and Power bill, you already feel the two forces pulling on it: the heat that drives the afternoon air-conditioning peak, and a city promise to run on clean power within about a decade. The bill does not explain how those two things get reconciled. A study from 2021 does, and anyone can open it for free.
That study is LA100, run by the National Renewable Energy Laboratory (NREL, a US Department of Energy research lab) and paid for by LADWP. It modeled the whole Los Angeles grid, meaning generation, transmission, and hour-by-hour demand, to ask a plain question: can the city reach 100 percent renewable electricity, and by when? This desk keeps returning to it because so much of what shows up elsewhere on this board, the desert solar lines, the battery yards, the rooftop programs, traces back to its findings.
The easy ninety and the hard ten
The readable answer is not a single date. It is a shape. Getting roughly the first 90 percent of the way to a clean grid is well understood and reasonably priced: wind, solar, and batteries, built out at scale, carry most of the load. That part the engineers are confident about.
The last stretch, call it the final tenth or so, is the costly and uncertain part. Covering a hot, windless September evening after the sun drops takes more than the roughly four hours a typical lithium battery delivers. LA100 leans that last piece on long-duration storage (systems that hold energy for many hours or days) and clean fuels such as green hydrogen, which are real but still expensive and not yet proven at city scale. Honest version: the closer LA gets to 100, the less certain the cost and the timing become.
How it shapes the targets on your bill
A model is a planning tool, not a promise. LA100 ran many scenarios out to 2045 and tested a faster path to around 2035, and the city used that work to adopt an accelerated clean-energy goal rather than a slower one. The scenarios are where those targets came from, which is why the study matters to a ratepayer and not just to planners.
Where it turns into money is LADWP's long-term resource planning, the process that decides what actually gets built and bought. A 2023 follow-on, the LA100 Equity Strategies report done with researchers at UCLA, pushed on who pays and who benefits as the buildout lands in specific neighborhoods. Expect the schedule to move. Dockets stall, projects slip, and the final-tenth technologies may arrive later or cost more than any 2021 model assumed.
Worth watching this month
1. LADWP's Board of Commissioners meetings post agendas publicly before each session, and storage, transmission, and rate items surface there regularly, so most of it is routine but the procurement items are the ones that move real money.
2. NREL's LA100 page still hosts the full report and the 2023 Equity Strategies follow-on, worth reading directly before trusting any secondhand summary of what the study did or did not say.
3. Any update to LADWP's long-term resource plan is where the study's scenarios become actual purchases, and that is the document to watch if you want to know what will physically get built.
4. The California Energy Commission's SB 100 progress reporting tracks statewide clean-energy pace and gives context for LA's own timeline, roughly annual and mostly routine.
5. The afternoon-into-evening peak on the hottest September days is the grid's hardest stretch in LA, and it is exactly the gap the uncertain, expensive final tenth is meant to fill.