(CNN) -- President Barack Obama concluded his trip to Africa Tuesday after making a final pitch for partnership at a Tanzanian power plant.

Some 70% of Africans lack access to reliable electricity, Obama said, and the United States can help bring more power on line.

"The first step that we're going to take is to try to bring electricity to 20 million homes and businesses," he said.

The president spoke at the Symbion Power Plant at Ubungo, was had been idle until the Tanzanian government used U.S. help to revamp it.

"This is just the beginning. We look forward to even more companies joining this effort," he said.

Such partnerships create more jobs and exports in the United States, he said.

Before his remarks, Obama kicked around an energy-generating soccer ball that harnesses kinetic energy to provide power.

"I don't want to get too technical, but I thought it was pretty cool," Obama said.

Also Tuesday, Obama was joined by former President George W. Bush for a wreath-laying ceremony at the U.S. Embassy in Dar es Salaam, the site of a 1998 terror attack that killed 10 Tanzanians and injured more than 85 Americans and Tanzanians.

Survivors of the bombing were present as Obama and Bush stood by the wreath at a memorial that is on a piece of rock under a big tree near the entrance to the embassy.

Obama was in Africa to promote an increased partnership amid criticism the United States has, outside of military interests, focused its attention on other areas of the world.

The three-nation trip began last week and included stops in Senegal, South Africa and Tanzania