The African Union, an alliance of 54 countries, announced a plan to mobilize $20 billion to develop at least 10 gigawatts of renewable energy on the continent by the end of the decade. The African Renewable Energy Initiative was announced Tuesday at the United Nations climate summit in Paris. It will be hosted by the Abidjan, Ivory Coast-based African Development Bank, which will also act as a trustee, according to Alex Rugamba, director of energy,…