LONDON, Dec 20 (Reuters) - Qatar on Monday joined Britain"s Roll-Royce in developing small nuclear power plants capable of delivering low carbon energy to around 1 million homes each. The Qatar Investment Authority (QIA) said it would invest 85 million pounds ($112.2 million) for a 10% stake in the project, joining existing shareholders Rolls-Royce, BNF Resources UK and Exelon Generation in the British government-backed project. QIA Chief Executive Mansoor bin Ebrahim Al-Mahmoud said Qatar, which is the world"s largest producer of LNG (liquefied natural gas), was investing in the energy transition and funding the technologies that enabled low carbon electricity generation. Rolls-Royce Chief Executive Warren East said the company had now raised the capital needed to establish its SMR (small modular reactors) unit. Britain last month agreed to invest 210 million pounds in the project, alongside 195 million pounds from Rolls-Royce and its partners, in a drive to reach net zero carbon emissions and promote new technology with export potential. The SMRs will not be available until the early 2030s and all new nuclear power projects need approval from Britain"s Office for Nuclear Regulation (ONR) and its Generic Design Assessment, which can take around four years to complete for large plants. Rolls-Royce said it would ultimately own about 70% of the unit. ($1 = 0.7574 pounds)