The Crow Tribe on Thursday agreed to host a massive new $7 billion coal-to-liquids plant on its reservation land in Montana. The plant would produce about 50,000 barrels a day of diesel fuel when it opens, and eventually up to 125,000 barrels a day. Coal for the plant would come from a yet-to-be-developed mine on nearby Crow land with an estimated 9 billion tons of recoverable, largely untapped coal reserves. The project is still many years from even the construction phase, but the deal could eventually become a major economic engine for the tribe’s 12,000 members since, like most reservations in the United States, unemployment and poverty there are among the highest in the country. The project could eventually pay the tribe nearly $1 billion a year; their current annual budget is roughly $26 million. Tribe officials said the plant will be built to capture about 95 percent of its carbon emissions that could then, at least theoretically, be sequestered underground. When up and running, it will take roughly one ton of coal to produce one barrel of diesel fuel at the plant.