By Gram Slattery (Reuters) – Shell and Brazil’s Porto do Açu have agreed to jointly build a green hydrogen plant, executives told Reuters, a deal that could result in the debut of the up-and-coming technology in South America’s largest nation. Under the terms of a memorandum of understanding signed on Thursday and first disclosed to the news agency, the firms will build a 10-megawatt green hydrogen plant on the premises of Açu in Brazil’s Rio de Janeiro state. The plant is due to be completed by 2025. Green hydrogen is a zero-carbon fuel made by using renewable power to split water into oxygen…