There isn't a company you can call up because projects of this magnitude aren't quoted over the phone to internet forums users.
50 GWh is stored in ~30,000 barrels of synthetic fuel. GWh is an incomplete way to specify storage, there are different technologies for the different ways storage may be needed, depending on what resources are on the grid: short term to handle the peaks of everyone microwaving their breakfast and coffee at 7am or long term storage to handle a once every few decades event like a Texas snow storm.
No one is presently making these because the policy of the grid was developed around power plants that dig stuff out of the ground and burn it - the markets are based on bidding with the assumption every power plant will have a marginal cost of generation relative to the cost of its fuel. This policy doesn't reflect the nature of renewables which besides their capital cost have very low to 0 marginal cost of production. This has disrupted the energy markets in many ways and policy is still being developed to incentivize storage capacity.
The point is that saying "No one is presently making these" on one hand, and claiming that they're within existing industrial capacity is contradictory. Energy markets like Hawaii and California are already hitting situations where energy cost is near zero due to overproduction from intermittent sources. But the promise that entrepreneurs will store this energy and put it back on the grid later has yet to pan out - contrary to the insistence of storage evangelists, hydrogen storage, synthetic methane, thermal batteries, and whatnot are a lot harder to build than one might think.
It's not contradictory. The storage is not being done now not because it's impossible, but because the market conditions that would cause it (specifically, high carbon taxes) aren't there yet. Something like pumped thermal storage requires no new technology. It's just putting together things we can already build.
No one is presently making these because the policy of the grid was developed around power plants that dig stuff out of the ground and burn it - the markets are based on bidding with the assumption every power plant will have a marginal cost of generation relative to the cost of its fuel. This policy doesn't reflect the nature of renewables which besides their capital cost have very low to 0 marginal cost of production. This has disrupted the energy markets in many ways and policy is still being developed to incentivize storage capacity.