In a televised roundtable discussion, Mrs. Arroyo said her nine-day trip had unlocked opportunities for Filipinos and enhanced other countries interest in the Philippines.
She said the country, with its stronger economy, had also managed to get back the confidence of the international community.
Lotilla declined to specify the projects and the investments involved, saying the investors themselves wanted to make the announcement in the coming days.
"At this time we cannot announce for the private sector but I assure you there are substantial investments that moved forward," Lotilla told reporters.
"You see my smile? I find it difficult to contain my exuberance," he said.
Lotilla said Denmark, Finland, Belgium and England have expressed interests in investing in renewable energy sources in the Philippines.
Lotilla said the Danish ambassador based in Kuala Lumpur, Malaysia would be sent to Manila to help assist in the development of wind power.
The Finnish government, on the other hand, will send a mission to the Philippines to explore different areas of cooperation in the energy sector, Lotilla said.
He said Finland is good in alternative sources of power particularly biomass. Lotilla added a Finnish company has been supplying oil-based power plants in smaller islands like Iloilo.
"They (Finnish) are the ones who provided the 72-megawatt power plant there, so they want to be able to go into a renewable power including biomass. So this is something that can be explored further," Lotilla said.