UN Secretary-General Ban Ki-moon (C) and his wife Ban Soon-taek receive Brazil’s football team jerseys as gifts from residents during a visit to the Babilonia shantytown in Rio de Janeiro, Brazil, May 27, 2010.

In rural villages in East Africa, nearly 150 women entrepreneurs are selling solar lamps and cell phone chargers that provide clean and reliable lighting and connectivity to remote and energy-poor communities. These women, empowered by the social enterprise Solar Sister, are the ground troops of social and economic development.

On June 20, world leaders will gather in Brazil for Rio+20, the UN Conference on Sustainable Development. Their mission is to set a development agenda for the next 20 years. As shown by groups like Solar Sister, the starting point for such an agenda should be clear: Energy is essential for development, and sustainable energy is essential for sustainable development.

Even in today’s modern world, one in five people do not have access to electricity. Their daily reality is life without light or refrigeration, without energy for water pumping or computers. Twice as many people, nearly three billion, still rely on wood, charcoal or animal waste for cooking and heating, breathing in smoke that harms their lungs, killing nearly 2 million people a year. This energy poverty is an enormous impediment to economic progress.

In industrialized countries, the energy challenge is different – a problem of waste and pollution, not shortage. Inefficient energy use harms economic productivity. Emissions from fossil fuels, especially coal and oil, foul the air and are causing the planet’s climate to change. But rapidly falling costs for renewable energy technologies are now making them the cheapest choice in many parts of the world, and more than $260 billion was invested globally in clean energy last year.

UN Secretary-General Ban Ki-moon has set out three intertwined energy objectives for the world to achieve by 2030: ensuring universal access to modern energy services, doubling the global rate of improvement in energy efficiency, and doubling the share of renewable energy in the global energy mix.

These are ambitious objectives, but they are also achievable.

Development is central to the United Nations’ mandate, and now this global institution is advancing energy as critical to achieving development goals, whether in health care, education or poverty reduction, or to produce more food or clean water.

To deliver sustainable energy for all, government action is necessary but not sufficient. Development assistance from governments will never be enough to deliver the new investment that is needed. And businesses won’t invest where there is not an opportunity for profit.

Energy is the golden thread that connects economic growth, social equity, and environmental sustainability.” – Secretary-General Ban Ki-moon

The UN is bringing both parties to the table to agree on sound policies that can unleash the flow of capital: Governments can enact policies and regulations that expand energy access and encourage private investment. Companies can invest in research and create new energy products, services and markets that will deliver solutions on the needed scale. They can also improve efficiency and adopt renewable energy in their global business operations and supply chains. Investors can provide funding for clean technologies and help scale up successful models.

At the Rio summit, governments, businesses, and non-profit groups will announce their commitments to action on Sustainable Energy for All, demonstrating early progress – a “down payment” toward transforming the world’s energy systems over the next 20 years.

To read more about the UN’s efforts toward achieving sustainable energy for all, click here, and to read about the initiative in Ban Ki-moon’s own words, click here.

This is a unique moment. National leaders, corporate executives, and now the UN have put energy at the top of the global agenda. In the Secretary-General’s words, “Energy is the golden thread that connects economic growth, social equity, and environmental sustainability.”

Achieving sustainable energy for all will require a significant investment in our collective future – but one that will pay off by improving lives, growing businesses, creating new markets, and generating jobs. And by using energy more efficiently and investing in renewable energy sources, we can build the clean energy economy of the future we want.

Timothy E. Wirth is President of the Better World Fund and the United Nations Foundation. He previously served in the U.S. House and Senate and as the Undersecretary of State for Global Affairs.