The race is on for a huge piece of the Massachusetts electricity market.

A number of electricity generators and power-line developers submitted bids by the deadline Thursday to supply up to 1,200 megawatts, enough for roughly 1 million homes, from hydroelectric and other clean-energy sources.

State officials, working with the state’s big utilities, will pick a winner early next year. A 2016 state energy law set this marathon — and a similar offshore wind competition — in motion.

So who is in the mix? Hydro-Quebec dominates the field, as expected. The Canadian powerhouse has separately teamed up with three power-line developers: Eversource (Northern Pass), Avangrid’s Central Maine Power utility, and Blackstone-backed TDI. HQ submitted two bids for each line: one that would rely completely on hydro, the other on a mix of wind and hydro.

TDI said it has all its permits and its line would be completely underground or underwater. Eversource says Northern Pass can get online sooner. And Central Maine says its proposal is less expensive.

At least two other big transmission projects are jockeying for position. National Grid’s Granite State Power Link would connect to wind turbines in Quebec, and Emera wants to build a power line under the ocean, from New Brunswick to Plymouth.

Only one of these projects, which range in cost from $1 billion to $2 billion, can win the long-term contracts. (National Grid and Central Maine Power also submitted plans for smaller power lines.)

The goals include curbing greenhouse gases, ensuring more reliability for the grid, and possibly saving consumers money.

Jon Chesto can be reached at jon.chesto@globe.com. Follow him on Twitter @jonchesto.