* To boost capacity to over 2,000 MW in next 3-4 years
* Signed 700 MW wind power deal in Vietnam
* Southeast Asia at early stages of renewable boom
* Superblock expects revenue to more than double this year
BANGKOK, Aug 23 (Reuters) - Thailand's Superblock PCL , one of Southeast Asia's biggest renewable energy producers, plans to spend up to 20 billion baht ($602 million) per year on expansion at home and abroad to tap rising demand for green energy, its chairman said.
As part of plans to more than double power generation capacity by 2021 from 845 megawatts (MW) currently, Jormsup Lochaya told Reuters in an interview his company signed a deal to develop new wind power projects in Vietnam last week with combined capacity of 700 MW.
"Over the next three-four years, we want to have more than 2,000 MW, which will come from investment in Thailand and overseas," the executive said, speaking in an interview late on Tuesday.
Jormsup said Superblock also plans massive expansion in China - raising its solar capacity there from just 30 MW to 1,000 MW over the next three years.
Superblock, which previously made building materials, is among Thai firms shifting to renewables like solar and wind to benefit from a government drive to promote renewable energy.
Thailand is leading a nascent boom in Southeast Asian renewable power generation, which has already taken off in countries from China to India and Japan.
Combined global wind and solar power capacity has soared from just 18,600 MW in 2000 to 763,000 MW in 2016, according to the International Renewable Energy Agency (Irena), outpacing expansion in other fuels.
Superblock plans to invest 15 billion to 20 billion baht per year, largely in renewables.
"We are looking at several power deals but expect to finalize one later this year," he said. Sources of finance will include a 10 billion baht infrastructure fund the firm plans to launch late this year, he added.
The firm aims to grow quickly, targeting revenue of 9 billion baht to 10 billion baht this year, more than double the 3.8 billion baht it booked last year, he said.
As part of its expansion, Jormsup said that Superblock plans to list a subsidiary, Super Solar Energy, on the Thai bourse next year.
Jormsup said demand for renewables was strong in Vietnam, where the deal signed last week covers the development of six wind power projects.
"Foreign direct investment is flowing into Vietnam... so demand for electricity will increase," he said. "Nuclear is banned there and people don't like coal, so they will turn to renewable energy more."
The company also plans to invest in solar power in Vietnam, he said.
Vietnam is struggling to meet its soaring electricity demand growth of around 11 percent a year and wants to boost its renewable energy output amid rising resources scarcity and environmental concerns.
As well as Vietnam and China, Superblock also plans to invest in Japan, Cambodia, Laos and Myanmar, the executive said. ($1 = 33.23 baht)
(Writing by Orathai Sriring; Editing by Henning Gloystein and Kenneth Maxwell)