Ask any power system engineer about renewable energy and you are likely to be told that it doesn’t deliver “base-load” power. In other words, renewable energy can’t be relied upon to provide power 24 hours a day, seven days a week: wind doesn’t always spin the turbines on the hill, the sun cannot shine on solar power stations at night, and even hydroelectricity can run short if the rains don’t come.
The inherently erratic behavior of the major renewable energy technologies presents serious problems for power system planners. It limits how much of these types of renewable power can usefully be fed into the world’s electricity grids. After all, consumers expect power always to be available.
The engineering solution is to keep a large amount of reliable base-load power as a major component of the generating mix and supplement this with “peaking plants” that can be brought on-line when needs arise. This peaking capacity is built around hydroelectric systems in some countries, but usually it is based on burning fossil fuels such as gas, diesel, or fuel oils.
The base-load power, too, is predominantly based on fossil fuels, with around 39 percent of global electricity generation sourced from burning coal. In some countries, nuclear power has been seen as an answer, but deposits of high-grade nuclear fuel worldwide appear to be limited, and the long-term costs of waste storage and plant decommissioning are high.
The challenge, then, is to reduce our current reliance on fossil and nuclear fuels for base-load power. The answer may be under our feet.
Earth is an extraordinarily hot planet. Six thousand kilometers below the surface, the planet’s core is as hot as the surface of the sun. Yet, even at shallow depths, useful temperatures for power generation are often available. This “conventional” geothermal energy has been used to generate reliable base-load electricity for more than 100 years, and is now used in many countries including Italy, Iceland, Japan, New Zealand and the western US.
The technology is well established, and the track record of reliable power generation includes more than 9,000 megawatts of generating capacity. But conventional geothermal power requires a natural source of large quantities of steam or hot water, and such sources are usually found only in volcanic regions, which rules out its use in large parts of the world.
More tantalizing, however, for humanity’s need for widely available, clean base-load power is the non-conventional geothermal energy called “hot dry rocks” or HDR.
With HDR, useful heat is present in rocks only a few kilometers below the Earth’s surface. But, with no natural steam or hot water to bring the energy to the surface, an engineered solution is needed, and, during the past 35 years, more than US$600 million has been spent worldwide devising one.
The concept is beguilingly simple: drill at least two boreholes 5km deep, inject cold water into one, pass it through the hot rocks, and then bring it back to the surface, where the energy is removed in a power station. Then re-inject the now cooled water for another pass through the subsurface. Only the heat is extracted at the surface, and everything else that is brought up to the surface is re-injected again, eliminating waste.
But it is the economics of HDR geothermal that will eventually determine its long-term role, because deep boreholes are expensive to drill, and their costs must be met before power stations can begin to generate electricity.
The shallower the heat resources and the cheaper the capital, the more competitive an HDR project will be. The rising costs of fossil and fissile fuels will also make HDR more compelling, since the long-term economics of geothermal power is effectively quarantined from fuel price movements.
Deposits of hot dry rocks are common, and large amounts of heat are within reach in many places. But the science and engineering of HDR has been challenging, and it is only now that the first power stations are emerging. A small power station is operating in Landau, Germany, and others are under construction in France and Australia.
These first power stations will develop the operational and financial performance histories that will be necessary before HDR geothermal energy can begin making an impact on world energy supplies. Re-engineering humanity’s power systems is going to be an expensive undertaking, regardless of what mix of technologies are used, and the chosen systems will have to be reliable and widely available.
The road to HDR geothermal energy has been long and expensive, but, like all developing technologies, the basic research and development had to be done before commercial development could follow. With power stations now being built, the signs are bright for widespread use of geothermal energy to generate clean, emissions-free base-load power.
Prame Chopra was until recently, a reader in geophysics at the Australian National University. He is a founding director of Geodynamics Ltd, the world’s first publicly listed hot rock energy company.
Copyright: Project Syndicate
Taiwan’s semiconductor industry gives it a strategic advantage, but that advantage would be threatened as the US seeks to end Taiwan’s monopoly in the industry and as China grows more assertive, analysts said at a security dialogue last week. While the semiconductor industry is Taiwan’s “silicon shield,” its dominance has been seen by some in the US as “a monopoly,” South Korea’s Sungkyunkwan University academic Kwon Seok-joon said at an event held by the Center for Strategic and International Studies. In addition, Taiwan lacks sufficient energy sources and is vulnerable to natural disasters and geopolitical threats from China, he said.
After reading the article by Hideki Nagayama [English version on same page] published in the Liberty Times (sister newspaper of the Taipei Times) on Wednesday, I decided to write this article in hopes of ever so slightly easing my depression. In August, I visited the National Museum of Ethnology in Osaka, Japan, to attend a seminar. While there, I had the chance to look at the museum’s collections. I felt extreme annoyance at seeing that the museum had classified Taiwanese indigenous peoples as part of China’s ethnic minorities. I kept thinking about how I could make this known, but after returning
What value does the Chinese Nationalist Party (KMT) hold in Taiwan? One might say that it is to defend — or at the very least, maintain — truly “blue” qualities. To be truly “blue” — without impurities, rejecting any “red” influence — is to uphold the ideology consistent with that on which the Republic of China (ROC) was established. The KMT would likely not object to this notion. However, if the current generation of KMT political elites do not understand what it means to be “blue” — or even light blue — their knowledge and bravery are far too lacking
Taipei’s population is estimated to drop below 2.5 million by the end of this month — the only city among the nation’s six special municipalities that has more people moving out than moving in this year. A city that is classified as a special municipality can have three deputy mayors if it has a population of more than 2.5 million people, Article 55 of the Local Government Act (地方制度法) states. To counter the capital’s shrinking population, Taipei Mayor Chiang Wan-an (蔣萬安) held a cross-departmental population policy committee meeting on Wednesday last week to discuss possible solutions. According to Taipei City Government data, Taipei’s