EPES, Alabama —When Enviva began construction here on the world’s largest wood-pellet plant, it had contracts worth more than $20 billion to supply overseas power plants with an alternative to coal. The company’s shares were near an all-time high. That was two years ago. The Epes facility is still under construction, but Enviva is in bankruptcy court. Demand hasn’t been an issue. …Enviva’s problem is that it promised buyers more pellets than it could make, and for cheaper than it ended up costing to produce them. …Power producers from Germany to Japan are counting on shipments from Enviva to keep their customers’ lights on, as well as to meet renewable-energy mandates. Enviva has continued to operate while it sheds debt and reworks long-term deals with customers. …The plant in Epes is scheduled to open next year. Another plant, planned for Bond, Miss., is on hold. [to access the full story a WSJ subscription is required]