If there is a lab to test the "all of the above" approach to energy, it's Africa. And the results of that experiment could have profound implications for climate change.

Businesses, lawmakers, heads of state and policy experts have different solutions to Africa's energy needs, but they all boil down to the idea that Africa needs a little bit of everything.

But as African nations continue to grow, that approach will make it harder to reduce carbon emissions that contribute to climate change.

"We have to invest in energy. Cheap energy," Liberia Finance Minister Amara Mohamed Konneh said Tuesday in a video played at the United States-Africa Business Forum in Washington, part of a landmark summit that brought African leaders to the nation's capital.

The economic development prospects for Africa alone, which has taken center stage at the event, are a sign of the increasing energy use by businesses and residents on the continent.

Some of the electricity needed to support a growing, more prosperous Africa would come from fossil fuels such as natural gas, which Africa has a lot of. Some of it could be through renewable energy — hydropower, biomass and solar — in the form of mini-grids that can exist apart from the main electric grid. Improving energy efficiency will also play a key role.

Those policies are being encouraged by both the government and the private sector in the U.S.

The range of initiatives the Obama administration has launched to bolster energy and electricity in Africa incorporate renewable and natural gas generation. Legislation in the House and the Senate would set guidelines for improving electricity access and development in Africa. Investors across the world are bullish on the continent's renewable energy potential.

But as African nations continue to grow and demand more electricity, nations that currently provide a bulk of greenhouse gas emissions will have to cut even further to reduce the risk of climate change. A full 57 percent of the continent lacks access to electricity, according to the Paris-based International Energy Agency. The problem is most acute in Sub-Saharan Africa, where the rate is 68 percent, or about 600 million people.

The IEA spells it out like this — it predicts Africa will invest $176 billion in fossil fuel-fired power through 2035, $114 billion of which will be coal-based. That compares with $28 billion of investment between 2000 and 2013, all of which was natural gas-fired. Renewable energy investment, however, would be a major source of growth — IEA said it would hit $264 billion over the same period under that scenario, compared with the $28 billion invested since 2000.

The U.S. is helping drive some of that activity. President Obama announced a $7 billion effort called Power Africa last June that has leveraged $26 billion in private sector commitments to support investments in six sub-Saharan Africa countries: Ethiopia, Ghana, Kenya, Liberia, Nigeria and Tanzania. The program has been so successful that Obama announced Tuesday the program would triple its original goals — it now hopes to add 30,000 megawatts of electricity to provide power for 60 million homes and businesses.

So far, a large chunk of Power Africa's private sector cash is headed toward developing natural gas-fired power plants. The White House supports that, noting that several African nations have sizable gas, along with oil, deposits, making burning the fuel a win for providing electricity and sustaining investment in resource development.

But even coal will play a role, noted Jeffrey Immelt, president of General Electric.

"There's going to have to be some coal in the mix," Immelt said Tuesday in a panel moderated by former President Bill Clinton. "We need to be practical about where that goes."

That's not to say there's no role for renewable energy in Africa. In fact, there are potentially significant opportunities.

About 85 percent of people rural Sub-Saharan Africa don't have electricity. Building out energy infrastructure to serve those far-flung communities presents high costs — as such, part of the Power Africa effort aims to build out distributed generation, such as blocs of solar panels, to serve such areas. Many of the $12 billion in new commitments for the program announced Tuesday will go toward developing such off-grid projects, the White House said.

Doug McMillion, president of Walmart, said that African nations could be where new technologies leap frog older ones. That means that rather than starting nascent infrastructure projects with the same varieties industrial and post-industrial nations began with, the continent could start from a different point.

"In Africa, it just seems that there's a place ... for investments to accelerate this process, to do some generation skipping," McMillon said Tuesday.

Still, some experts suggest that United Nations and IEA projections for African energy demand are too low. The Breakthrough Institute, a centrist think tank, said that would present problems for tackling climate change, but that asking African nations to adopt renewable energy technology that isn't yet cost effective enough to serve large population centers isn't an answer to the issue.

"In practical terms, such approaches seek to minimize, or even forbid, the use of the very energy technologies that enabled the prosperity of developed countries, and that are now spurring the rapid growth of many economies in the developing world," the think tank said in an April report.