BANGKOK, Oct 21 (Reuters) - Thai chemical firm, PTT Global Chemical Pcl on Thursday said it plans to invest over $22 billion in the next three decades to achieve net zero carbon emissions by 2050.

"We will invest $5 billion to directly reduce greenhouse gases and $17 billion in restructuring the business," chief executive Kongkrapan Intarajang said at a news conference.

This will include efficiency improvements, energy storage, and carbon capture technology, he said.

New businesses in our portfolio will be low-carbon, like performance and speciality chemicals, he said, adding the company will grow around 4% over the next five to six years.

In July, it bought German https://www.reuters.com/article/us-allnex-m-a-pttgc-idUSKBN2EI0L0 coating resins maker Allnex for $4.75 billion, but the rate of carbon emission to growth came down because it was a low-carbon business.

This year PTTGC, a unit of the state-owned PTT Pcl, released about 8 million tonnes of greenhouse gas (GHG) and CO2 equivalents and will reach a peak of 9.1 million tonnes in 2025.

"There will be a 20% reduction of emissions in 2030 and net zero by 2050," said Kongkrapan.

(Reporting by Chayut Setboonsarng; Editing by Martin Petty)