By Valerie Volcovici and Simon Jessop

NEW YORK (Reuters) - A coalition of some of the world's biggest companies, finance houses and cities urged governments on Tuesday to adopt policies that they said could unleash up $1 trillion in clean energy investments by 2030.

The group Mission 2025, backed by Britain's Energy Transitions Commission, said policies such as setting new capacity targets and offering tax credits or long-term electricity contracts would boost the industry's case for investment.

Countries are talking this week on the sidelines of the U.N. General Assembly. With global energy demand on the rise, countries will need to use more renewable energy in order to avoid burning more fossil fuels.

Leaders from Kenya, Barbados, the European Union and other nations were set to discuss their countries' efforts to triple renewable energy capacity by 2030 – a key pledge made at last year's COP28 summit in Dubai.

Separately, U.S. President Joe Biden is set to address to the U.N. General Assembly for the final time as president, and a separate event will discuss his administration's push for clean energy under the $360 billion Inflation and Reduction Act passed in 2022.

"What he will show is how the United States has changed the playbook fundamentally -- not focused on the doom and gloom, focused instead on the massive economic opportunity, a chance to build U.S. manufacturing and infrastructure, and a chance to build the American middle class," White House National Climate Adviser Ali Zaidi.

Sounding a somewhat hopeful note, the International Energy Agency said Tuesday that the goal of tripling clean energy capacity was within reach – but will require a big effort to unlock bottlenecks such as permitting and grid connections.

The agency warned that increasing renewables alone would not lower energy prices or fossil fuel use without "a concerted push to build and modernise 25 million kilometres of electricity grids by 2030," along with some 1,500 GW of energy storage capacity.

African leaders are especially anxious to find ways for growing their electricity portolios, both to fuel development and to reach hundreds of millions of people who still have no access to electricity at all.

The African Development Bank and World Bank presidents spoke Monday about their project to expand electricity access to more than 300 million people on the continent, for which the banks were seeking $30 billion in private sector investment.

"You cannot really grow the global economy without energy," said Africa Development Bank president Akinwumi Adesina, during an event hosted Monday by the Global Energy Alliance for People and Planet.

"You cannot industrialize in the dark."

(Reporting by Valerie Volcovici and Simon Jessop in New York; writing by Katy Daigle; editing by David Evans)