For one, "isn't it common knowledge" does not strike me as a particularly well-informed position.
"The energy storage problem" really never was an energy storage problem. It is a political problem of paying for it, because everyone calculates the costs of building storage systems and pretends that the future costs of continuing the burning of fossil fuels are zero, and then decides to go the "cheaper route" that simply has future generations pay for everything, and potentially orders of magnitude more than building storage systems now would cost.
As for technological solutions that do exist, the most important thing is that there is not the solution. If your topology allows for it, pumped hydroelectric is great. If you are the Netherlands, maybe not. Or rather, it's still useful for peak loads, but not for any kind of long-term storage. Batteries have become cheaper and are great for really fast reaction times to be able to deal with fast fluctuations in production, plus they are very efficient, so they are great for daily cycling. Also, just controlling demand better ("smart grid") can solve part of the actual problem (imbalance between demand and production), so you don't actually need as much storage. Or rather, you can even use the demand side for storage: You can, for example, cool down warehouses a degree or two more when you have excess energy in the grid, thus reducing demand later. For long-term storage, Power to gas seems promising: It's pretty inefficient, but it can achieve a high energy density, and efficiency doesn't matter that much for the exceptional case of extremely low renewable production over a large area. Plus, chances are the efficiency can be increased.
Ths point is: There is no silver bullet, but lots of solutions that can be combined to achieve a stable electricity supply from renewable energy sources.
"The energy storage problem" really never was an energy storage problem. It is a political problem of paying for it, because everyone calculates the costs of building storage systems and pretends that the future costs of continuing the burning of fossil fuels are zero, and then decides to go the "cheaper route" that simply has future generations pay for everything, and potentially orders of magnitude more than building storage systems now would cost.
As for technological solutions that do exist, the most important thing is that there is not the solution. If your topology allows for it, pumped hydroelectric is great. If you are the Netherlands, maybe not. Or rather, it's still useful for peak loads, but not for any kind of long-term storage. Batteries have become cheaper and are great for really fast reaction times to be able to deal with fast fluctuations in production, plus they are very efficient, so they are great for daily cycling. Also, just controlling demand better ("smart grid") can solve part of the actual problem (imbalance between demand and production), so you don't actually need as much storage. Or rather, you can even use the demand side for storage: You can, for example, cool down warehouses a degree or two more when you have excess energy in the grid, thus reducing demand later. For long-term storage, Power to gas seems promising: It's pretty inefficient, but it can achieve a high energy density, and efficiency doesn't matter that much for the exceptional case of extremely low renewable production over a large area. Plus, chances are the efficiency can be increased.
Ths point is: There is no silver bullet, but lots of solutions that can be combined to achieve a stable electricity supply from renewable energy sources.