But unlocking the potential is proving difficult. Geothermal projects involve drilling wells deep into the earth to tap steam or hot water to power turbines. Not all of the challenges are terrestrial in nature. It's a capital-intensive process made worse by tortuous red tape and other stumbling blocks in places such as Indonesia and the Philippines.
Indonesia's Bedugul project, set among volcanoes on the Hindu enclave of Bali, aims to develop up to 175 MW of power, or roughly half of the resort island's needs. But the project is now on hold because local residents fear it could damage a sacred area and affect water supplies from the nearby lakes.
Most of Bali's power is currently supplied from neighbouring Java island via an undersea cable.
Supporters say the project is essential to meet growing electricity demand on the resort island, which is at the heart of Indonesia's tourism industry.
'We hope that the project will run, not just because of the investors but for Bali's future,' said Ni Made Widiasari of Bali Energy, the firm behind the project. She denied the project would be damaging.
In the Philippines, currently the world's second-biggest geothermal producer behind the US, one of the main obstacles to developing the reserves is the high acidity associated with active volcanoes, which can corrode the pipes.
'There are many fields that are still acidic, meaning the dead volcanoes underlying them are not really dead,' said Paul Aquino, president of PNOC-Energy Development Corp, which operates nine steamfields with a capacity of 1,199 megawatts (MW), or about 60 per cent of the country's geothermal capacity.
That would make it hard for the Philippines to achieve its goal of raising geothermal capacity from an existing 1,931 megawatts to 3,131 MW by 2013, and overtaking the United States as top global geothermal producer, he added.
Geothermal power accounts for around 18 per cent of the Philippines' energy needs.
'We have already exploited those areas with the biggest geothermal resource,' Mr Aquino said, adding that many of the Philippines' most attractive untapped sites are located in natural parks or protected by the Indigenous Peoples Rights Act.
Catherine Maceda, spokeswoman for the Renewable Energy Coalition, a group promoting the use of alternative energy, also warned that the Philippines needed to push through a renewable energy bill to provide greater incentives and clarity.
While President Gloria Macapagal Arroyo has earmarked the bill as urgent, political bickering is holding up its passage.
'Right now there is no predictability,' said Ms Maceda.
Electricity networks in the Philippines and Indonesia, with a combined population of 316 million, are already under strain.
Philippine power demand is estimated to be growing at an average rate of 4.8 per cent a year, while Indonesia has suffered power blackouts with a razor- thin supply cushion when demand peaks.
Indonesia currently supplies just 850 MW of an estimated 27,000 MW potential from geothermal, or about 3 per cent of its current power output.
While the government wants to focus on using more coal-powered stations to meet energy needs, Energy Minister Purnomo Yusgiantoro has said power from geothermal could reach 9,500 MW by 2025.
Despite the setbacks and stalled projects, high energy prices are providing the spur for firms to look at geothermal again, and several are keen to expand their existing operations or bid for fresh projects in Indonesia under a new government framework.
Indonesian energy firms Medco Energi Internasional and Star Energy are looking at making new investments, while Chevron, the world's largest private producer of geothermal energy, plans to double its geothermal business in Indonesia and the Philippines by 2020 despite the heavy capital outlays.
Meanwhile, Indonesia is putting the finishing touches to new regulations for the geothermal sector, after many projects collapsed in the wake of the 1997-98 Asian financial crisis.
'I think we're virtually on the cusp of seeing all of that come together in the next year or so,' said Chevron's Mr Andrews.