x Abu Dhabi, UAEMonday 24 July 2017

Drilling deep for green energy

Engineers are to drill for heat 4km below Abu Dhabi in the Gulf's first geothermal energy project.

Abu Dhabi will begin drilling for heat instead of oil in a bid to develop a cheap new source of clean energy to meet up to half of the needs of Masdar City, the zero-carbon development at the edge of the capital. In the first geothermal energy project in the Gulf, engineers this year will drill 4km beneath the city in search of boiling temperatures to generate electricity and fuel the cooling system.

"We have found that Abu Dhabi has a very good chance to generate energy from geothermal sources," said Sanad Ahmed, a senior project manager at Masdar, which is owned by the Government. "It's one of the cheapest sources for renewable energy available." Until now, solar energy projects have taken centre stage in the race to meet a goal of generating 7 per cent of electricity from renewables by 2020.

But the heat beneath the emirate is already well known to engineers at the Abu Dhabi National Oil Company (ADNOC). At Masdar City, engineers will circulate water through two deep wells that will be heated into steam and used to turn electricity generators and directly power air conditioning systems. Masdar awarded a US$1.6 million (Dh5.8m) contract to Reykjavik Geothermal, an Icelandic firm, to help drill the wells, and plans to hire five or six contracting companies to work on the project by the end of the year, Mr Ahmed said. Iceland is the world's leader in geothermal technology and generates a quarter of its electricity from it.

The consortium has set a target date of November 1 to begin drilling, said Thorleifur Finnsson, the project manager for the Icelandic company. Mr Ahmed was more cautious, saying work would start by the first quarter of next year. If all goes according to plan, temperatures at the bottom of the well will range from 140°C to 150°C and the heat will be used to boil water to generate up to 5 megawatts of electricity.

A second well, used to power cooling systems, will be drilled to a depth of 3km, with engineers expecting a temperature range of 80°C to 120°C, Mr Thorleifur said. "If everything goes in the best way" the wells could generate up to half of the total energy used at the city, said Gudmundur Thoroddsson, the chief executive of Reykjavik Geothermal. But engineers are also mindful that they may find nothing, he said.

"We are in the exploration phase," Mr Gudmundur said. "They're just looking for what's down there." Masdar's estimates for subterranean heat are based in part on data compiled by ADNOC, which drilled an oil well to a depth of 6km about 15km from the Masdar City site, Mr Ahmed said. A key challenge will be providing enough water for the wells, which could each absorb up to 3,000 litres per minute in a high-consumption scenario, Mr Ahmed said.

One option is to extract water from aquifers under Masdar City, which has a low enough salinity to be used in the geothermal project, he said. Engineers will also face the challenge of limiting heat loss as the water is pumped back up the 4km hole. Masdar plans to insert a special lining into the hole to limit the heat losses to less than 4°C, Mr Ahmed said. cstanton@thenational.ae