ONE look at the landscape will give you a good idea why locals refer to Erta Ale as the gateway to hell – the black volcano’s lava lake smoulders between two cracked plates of desert. Out here in the Afar region of Ethiopia you can literally watch the world tearing itself apart.
The buckles and fissures that contort this ground only hint at the violence below the surface. Here in East Africa, Earth’s tectonic forces are doing battle, forging new plates by tearing up the old ones. Tap into the roiling depths and the reward would be enormous. Hot magma from deep inside the planet wells up through the cracks, heating the rocks close to the surface. Where these meet groundwater, the intense steam can be harnessed to achieve the three ideals of perfect energy: pollution-free, sustainable and extremely reliable.
See an interactive 3D map: “Ethiopian rift volcanoes“
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There are few sites in the world where such a mix is so easily accessible. But thanks to a combination of factors we have not been able to access this natural powerhouse. However, recent research raises new hope of exploiting this resource – and the possibility of lifting an entire region out of poverty.
The East African rift begins in Syria and blazes a 6400-kilometre trail through Sudan, Ethiopia, Kenya, Djibouti and Tanzania to Mozambique. “The continent of Africa is splitting apart by about 1 to 2 centimetres a year,” says Michael Kendall, who heads the School of Earth Sciences at the University of Bristol, UK. As the crust splits, magma wells up and forms volcanoes; 30 of them have already formed along the rift. Eventually, the crack will let in the sea, it will widen, just like the Red Sea before it, and the eastern horn of Africa will become an island.
Almost by definition, rifts usually only exist under the ocean, where the crust is thinnest. One exception is Iceland: so much hot magma has welled up out of Earth’s depths here that it has risen above sea level to form land. This geological heritage has made Iceland a veritable powerhouse of geothermal energy, a unique source of clean electricity that unlike many other sustainable energy sources, is available regardless of wind or weather. In Iceland geothermal provides not only electricity but also heat to most of the country’s homes.
The East African rift region has greater potential than Iceland (see diagram). The United Nations Environment Programme (UNEP) estimates its potential at 15 gigawatts, the equivalent of 15 moderate-sized nuclear power plants. That’s .
Though this potential has been apparent since the mid-1950s, it has gone largely untapped. Indeed, only two countries on the East African ridge – Kenya and Ethiopia – use any geothermal power at all. The geothermal capacity there today is 212 megawatts and 7 megawatts, respectively, according to the World Bank. But even for Kenya, that barely makes a dent. “Kenya is the furthest along in terms of geothermal development,” says Pierre Audinet, who is in charge of energy development at the World Bank, but only 17 per cent of the country is electrified – a paltry percentage that nonetheless puts it first among all rift countries.
Risky endeavour
Indeed, according to the UN, although 13 per cent of the world’s population lives in East Africa, they use less than 3 per cent of its electricity. “The East African rift system is one of the most highly endowed regions on Earth, yet the least connected with electricity,” says Achmin Steiner, who directs UNEP. So why has it not been possible to simply drill into the ground and get that energy?
To harvest vast stores of geothermal energy, you first need to be able to find it and reach it. That’s the tricky bit. Even in geologically rich locations, you can’t drill just anywhere. Because the precise combination of hot, permeable rocks and water doesn’t exist everywhere, the risk is that a local utility drills a hole – an endeavour that can easily cost between $3 and $7 million – and finds only a dry well that produces no steam. Take Aluto Langno, Ethiopia’s sole, small geothermal power plant. Of the 12 boreholes drilled there for exploration, only three emit steam. The others are fallow. “This leaves the question why is it good in some places, but not in others,” says Kendall.
Recently developed “enhanced” geothermal systems have more leeway (see “Geothermal, hold the water“), but they require expensive cheats like injected water, which is not plentiful in regions prone to drought. To access “easy”, naturally occurring geothermal energy, “you have to know where to drill very precisely”, says Audinet.
Countries with successful geothermal programmes have generally had plenty of funding to insure against such risks. In Iceland, for example, exploration was subsidised by the government. However, in East Africa, local governments have other, more pressing financial priorities.
Few other sources of funding exist. The steep costs of initial surface studies and exploratory drilling makes investors shy away. For geothermal power, there is no guarantee of a return on their substantial investment: even if exploration wells produce steam, the value of that steam is comparatively low. Unlike oil or gas, it can’t be shipped away and sold. It can only be used in one place to generate electricity, with fixed prices.
“It’s a technically important potential,” says Audinet, “but to turn it into economic reality takes technical and financial efforts.”
It also takes more fundamental ingredients: finding out where to drill is far from straightforward in countries that sometimes lack infrastructure as basic as roads, for example. “Some of these places are only accessible by camel,” says Juliet Biggs, a geophysicist at the University of Bristol. Add to that the frequent political dangers and it’s hard to know where to begin. As a result, says Biggs, “this is the least well documented of any plate boundary on the planet”.
A few years ago, though, a possible new way to find geothermal sites revealed itself. Dabbahu, one of the volcanoes at the rift’s northern end in Ethiopia, erupted unexpectedly in 2005. It turned out no one knew the last time any of the rift’s volcanoes had been active or whether any were likely to erupt soon. “Usually the way this is done is by looking at the historical record of eruptions, and using that to predict the future,” Biggs says. “The trouble is, in these places there is no historical record.” In Kenya, for example, the most recent deposit could be from , or from 4000 years ago, Biggs says – “nobody knows”. That’s bad news for the 10 million Ethiopians living within 100 kilometres of unmonitored volcanoes.
Biggs was looking for a better way to predict these eruptions. She realised that any predictions would have to come from looking for signs of activity in the here and now, and the best way to do that over large areas is with the Envisat Earth-monitoring satellite.
The satellite’s data revealed something unexpected. Of the 30 volcanoes along the rift, Biggs and her colleagues found 18 were currently deforming (see “image“). These deformations – ground displacement that shows signs of unrest below – suggested that there was magma just a few kilometres below ground. “I wouldn’t call it a treasure map,” Biggs says, but it is something like that. Because the magma is welling up close to the surface – within about 1 kilometre – places that have a higher than average volcanic hazard are ideal for harvesting geothermal power (). That’s certainly true for Iceland. “There are actually similar patterns of deformations in volcanoes there,” says Biggs.
Envisat had spotted these shallow magma bodies all along the rift. Combined with other techniques, it may help East African countries find the best locations for geothermal power. “If we could understand the fault structures and hydrothermal systems better,” says Kendall, “then we could better guide where you put boreholes.” Indeed, drilling near the deformations should help avoid fallow holes because in addition to finding magma, they also indicate the faults and broken-up rock that let deep underground water flow.
These maps could accelerate a shift that has slowly taken place over the past few years. KenGen, Kenya’s state-owned company and the largest power producer in the country, is now constructing a geothermal plant that will double the country’s geothermal energy production from 2014, and it plans to build a much larger plant by 2019. And recently, the multinational geothermal company Ormat became the first to privately fund and develop a power plant in Kenya.
A new hope
Though Ormat still will not be able to bottle the steam and export it, there is another option for making a profit from geothermal energy: export the electricity. Once the massive expense of exploratory drilling is out of the way – especially if it has been eased by maps that point to low-hanging fruit – geothermal energy is remarkably cheap to produce. And if you have the right electricity infrastructure, says Audinet, it would be possible to make money selling it to other countries. Some of it already exists. “Ethiopia already exports hydropower to Djibouti,” he says. Kenya and Ethiopia engage in limited energy trade, and, he says, there have even been talks of a possible .
Electrification alone won’t change the region – road access and clean water are also crucial – “but once you have those, everything else follows,” says Biggs. Several studies of Africa and China found that when electrification came, development followed, for example increasing the average wage beyond $2 per day (). The best case is Iceland: once that country began to develop its geothermal capacity, Audinet says, it attracted energy-intensive industries like aluminium smelting, which in turn poured money into the area.
So could East African countries rise to Iceland’s geothermal heights? Audinet thinks the Bristol satellite data could make a useful contribution. “The bottom line is you need to drill to know,” he says. So far, Ormat and other exploration companies are not using the maps to guide their exploration. “From about 2008, 2009, we started sending them copies,” Biggs says. Considering what stores of energy they could reveal, she says, “we’re suggesting maybe they should”.
Geothermal, hold the water
Around 40 countries have the potential to technically satisfy their entire electricity demand using just geothermal power, but it will require a bit of engineering. The United States, for example, now gets 3.3 gigawatts from geothermal power, roughly equivalent to the output of three nuclear power plants, but an assessment found that the potential from tapping the heat deep within the ground is closer to 3000 gigawatts – nearly enough to meet the entire country’s energy demand.
But tapping geothermal energy always requires water. In some places, nature provides. These areas are the low-hanging fruit of geothermal energy, producing steam from the combination of hot, permeable underground rocks and deep geothermal fluids. But those geological conditions are unusual. How to obtain the energy from the heat beneath our feet without water? You can do it by drilling into hot, dry rocks, forcing cold water through, and letting it come back up through a second well at the other end of the system as steam.
This wouldn’t be possible in drought-ridden East Africa, but luckily it is beginning to seem that the region’s deep geothermal fluids are plentiful enough to allow its gargantuan geothermal reserves to be accessed (see main story).
Hotspots
How much energy could we extract from geothermal sources around the world? Current estimates range from 35 to 2000 gigawatts – 1 gigawatt being the output of a medium-sized nuclear power plant. Around 40 countries have the geothermal resources to satisfy their entire electricity demand using geothermal power alone, but only 24 use it at all. Here’s what the world’s biggest players , in terms of the rate at which they generated electricity geothermally.
US: 3093 megawatts
The US leads the world in generating electricity from geothermal sources, but it still produces a mere tenth of the potential estimated by the US Geological Survey. Most of that is in the Southwest, where the country sits on the Pacific “Ring of Fire”, a volcanic region where three tectonic plates are colliding.
Philippines: 1904 megawatts
At the Philippines’ location on the western Pacific rim, deep fractures in Earth’s crust have given rise to many volcanoes that can be easily accessed for geothermal power.
Indonesia: 1197 megawatts
A prime location on the western Pacific rim gives Indonesia 40 per cent of the world’s potential geothermal resources – estimated at 28,000 megawatts.
Mexico: 958 megawatts
The world’s largest geothermal power station in the world is the 720-megawatt Cerro Prieto plant in Sonora, Mexico. The country sells much of the power from the plant to its northern neighbour, the US.
Italy: 843 megawatts
The world first geothermal plant was built in 1904 in Lardarello near Italy’s Mount Amiata, right above the point where Earth’s crust was fractured by the collision of the Eurasian and African continental plates. More than 100 years later, all of the country’s geothermal plants are in this area.
New Zealand: 628 megawatts
New Zealand sits over the Indo-Australian and Pacific plates, both of which are active. Most of New Zealand’s high-temperature geothermal resources had been mapped by the 1980s, and it obtains 10 per cent of its energy from this resource.
Iceland: 575 megawatts
Geothermal sources account for 66 per cent of Iceland’s energy use, the largest proportion of any country. This is largely down to its location atop the boundary between the Eurasian and North American tectonic plates, one of the major fault lines in Earth’s crust. Here, deep mantle material wells up to create unusual amount of volcanic activity.
Japan: 536 megawatts
Pressure has been on in Japan to develop its geothermal resources since the disaster at Fukushima-Daiichi caused the country to shut down most of its nuclear power plants. There is certainly massive potential: Japan is third in the world in geothermal energy potential, sitting on an estimated 20 gigawatts. So far, however, this has gone largely untapped; its 17 geothermal plants produce less than 1 gigawatt.
El Salvador: 204 megawatts
Known as the land of volcanoes because of its location on the Ring of Fire, El Salvador has a geothermal potential estimated at about 13,000 megawatts, and is the largest producer of geothermal electricity in the region. Even so, it derives only around 24 per cent of its electricity from geothermal resources.
Kenya: 167 megawatts
East Africa has a vast, 15,000-megawatt reserve of geothermal energy potential, and Kenya is the first country to tap it – see main article above. Sally Adee
This article appeared in print under the headline “Hidden under a volcano”
