The United States is in the middle of a big debate about energy. Some people say fossil fuels like gas and coal are the best path forward. But a major financial firm just ran the numbers — and the results tell a different story.

Lazard, one of the world's largest investment firms, released its 19th annual "Levelized Cost of Energy+" report earlier this year. The report compares how much it costs to build and run different types of power plants. This year, the headline is clear: wind, solar, and battery storage remain the cheapest new energy sources in the country.

That matters because it means whenever someone wants to build a new power plant, renewable energy is usually the most affordable choice. Lazard notes that wind, solar, and storage are expected to make up most of America's new power capacity in the coming years — partly because they can be built much faster than other options.

The report did point out that costs are rising across the board. Higher interest rates, supply chain problems, and new tariffs are pushing up prices for wind and solar equipment. Even so, Lazard found that renewables still cost less than the alternatives.

"Renewables therefore maintain their relative cost advantage despite facing the same cost pressures affecting the rest of the generation stack," the report states.

That includes gas. Lazard found that new gas power plants are at their most expensive point in 15 years. Building them is also taking longer than before, because there's a shortage of gas turbines. Meanwhile, renewable energy can now compete with gas even after adding the cost of battery storage to keep the lights on when the sun isn't shining or the wind isn't blowing.

The report also raises doubts about efforts to revive coal plants. While extending the life of existing coal plants can be cheaper than building new ones, Lazard points to risks tied to commodities markets, aging infrastructure, and railroad capacity — challenges that aren't easy to solve.

So what does this mean going forward? Lazard suggests that wind, solar, and storage will keep their cost edge for years to come. That could make it harder for fossil fuels to compete — not because of politics, but because of simple math.

The numbers are in. The cheapest power, it turns out, comes from the wind and the sun.