* Thermoelectric had been blocked on environmental grounds * Green groups say mining lobby behind approval * World No.1 copper producer Chile facing energy woes SANTIAGO, Dec 3 (Reuters) - A Chilean ministerial group has lifted a suspension on energy firm Endesa's 740-megawatt Punta Alcalde coal-fired thermoelectric project, the company said on Monday, in a boon for miners in the mineral-rich north of the world's No.1 copper-producing nation. An environmental commission in June blocked Endesa's $1.4 billion complex, citing the project's potential to cause water and air pollution. Government sources were not available to comment on Endesa's statement or explain why the suspension had been lifted. Environmental groups are increasingly opposing power projects ranging from coal-fired thermoelectric plants in Chile's northern Atacama, the world's driest desert, to hydropower dams in the pristine Patagonia region. "With the aim of canceling emissions of material particles, Endesa Chile will be the first electrical company in Latin America to use domes to cover the two fields that will be used for the stockpiling of coal in Punta Alcalde," Endesa said in a statement. Once in operation, the project will have the capacity to supply around 12 percent of energy demanded in Chile's central energy grid. Chile's power grid has a capacity of 17,000 megawatts. The government aims to add another 8,000 megawatts by 2020. The ministerial committee, made up of six ministries, meets to review appeals against environment-related decisions. Chile's energy, environmental and economy ministries were not available for comment. Marine conservation group Oceana has decried Punta Alcalde, saying the project will saturate the coastal area of Huasco, already home to thermoelectric plant Guacolda and a factory belonging to steelmaker CAP. "This is a completely arbitrary decision, tainted by pressure from the mining sector," said Oceana's executive director Alex Munoz. "We're waiting for further details to figure out how to follow up in court or via other paths." The two 370-megawatt units are planned in Chile's Atacama region, close to Antofagasta Minerals' Los Pelambres mine, Barrick Gold's Pascua Lama and Lumina Copper's Caserones mine, among others. Several energy and mining projects in the Atacama region are reeling from legal setbacks. Chile's energy and mining sector is putting pressure on conservative businessman and president Sebastian Pinera's administration to clarify regulatory rules surrounding mega projects. During the annual mining council dinner late last month, Pinera said "we need ... to face the topic of increasing lawsuits against approvals given to projects that this country needs ... We need to urgently advance in materializing energy investment." The Andean country is banking on attracting $100 billion in mining investment and boosting annual copper output by more than 30 percent to over 7 million tonnes by 2020, but many analysts and even miners themselves have called into question the investment aim. Shares in Endesa rose 0.90 percent on Monday, outpacing a 0.45 percent increase on Santiago's blue-chip IPSA stock index.