The market
The global pumped-storage market reached just over 127 GW in 2010. Hydropower, including pumped storage, is the most widely used renewable energy generation technology today. Pumped storage is the combined generation of hydropower, much like steam power is for coal-fired power plants. Pumped storage uses low-cost, off-peak electricity to pump water from a lower reservoir to a higher elevation. During periods of high demand, the water is circulated through turbines to generate electricity. Although pumping involves some energy loss, revenue increases by selling electricity at higher prices during peak periods. The European Union had a net capacity of just under 40 GW, representing more than a third of global capacity, or 5% of the EU's baseload power generation capacity. Europe is the most active in increasing storage capacity. Japan has invested over the years and has 26 GW, representing a quarter of global capacity. The United States has 22 GW, or about a fifth of global storage, and 2.5% of the US baseload power generation capacity of 1,088 GW. The pumped storage market is expected to grow by 60% over the next four years, reaching 203 GW by 2014. Additional investments amount to just under $60 billion in capital expenditure. The World Bank and the European Investment Bank are proactively providing funding for the expansion of pumped storage from Portugal, Switzerland, Spain, and the United Kingdom to Russia, Indonesia, China, and Vietnam. The cooperation between RWE, one of Europe's leading electricity providers, and RAG, the German coal mining company, to jointly develop an integrated pumped-storage and wind power project in coal slag heaps represents an exciting new development. The concept integrates intermittent wind power with hydroelectric power that could be delivered in less than a minute. The system will use wind power during periods of strong winds and low demand to pump water 50 meters higher to the top of the waste mountain. It is expected to be operational by 2016. Voith Hydro (Germany) is a market leader in the supply of generators and turbines, with more than 40,000 units installed. Last year, the company faced stiff competition from Toshiba, Mitsubishi, and Sumitomo (Japan) and Alstom (France).
Innovation
Since renewable energy is produced intermittently, it must be backed up through energy storage. The traditional storage technology has been batteries, but this chemical solution is only viable for small installations. Sodium-sulfur batteries only reach a capacity of 200 MW. Compressed air energy storage (CAES) as an alternative is struggling to gain traction in the market, with only two commercial-scale applications worldwide. A flywheel with extremely low friction, placed in a vacuum chamber, stores the energy produced by composite materials to provide centripetal forces. Hydrogen, compressed or liquefied, is stored for later conversion into energy and/or heat. Thus, although pumped hydro storage is the most widely used system today, one of its main obstacles is its environmental impact and the permitting process, which takes an average of a decade. James Fiske, a specialist in magnetic levitation (maglev), graduated with a degree in electrical and computer engineering from the Massachusetts Institute of Technology in 1978. He worked for Hughes Aircraft on signal processing systems, is the lead architect of a mini-supercomputer, and has designed cutting-edge computer-aided engineering software. He holds six patents. While envisioning a new class of maglev freight transport, he became interested in using gravity as a grid-scale electricity storage system. He studied pumped-storage hydroelectricity and decided to take this proven technology in a new direction: downwards. He realized that the two large reservoirs and the environmental disruption could be overcome by installing a gravity-fed power module (GPM) underground. This modular system has a small environmental footprint and can be installed almost anywhere energy storage is needed. James then created Gravity Power as a spin-off from LaunchPoint Technologies, where he holds the position of Vice President of Advanced Systems.
The first cash flow
James realized that we shouldn't just focus on how to capture energy from the sun, wind, and waves, but that we should also have the ability to store it for many hours after sunset and the wind dies down. He assessed the total investment cost per kilowatt and found that batteries range from $1,750 to $3,640 per kW, while pumped hydro storage could reach the lower end of $1,500—comparable to the cheapest batteries, but for more than double the storage hours (10 hours). With extensive access to design and computer-aided simulations, James concluded that a 2 GW storage facility requires less than 2 hectares. Because the technology relies on a deep, water-filled, and concrete-reinforced well, it will withstand earthquakes. The pumped hydro storage system is a vertical column bored several hundred meters into the ground and filled with water. A massive piston, composed of thick pancakes of concrete and iron ore for high density and low cost, rests on the water column with sliding joints to prevent leaks. It stores energy and is lowered to release it through a return pipe. When energy is abundant, water is pumped downward, displacing the weight and the water column upward. Releasing the weight drives the water through a turbine, generating power as needed. A single well could store over 50 MW of energy for four hours, totaling 200 MW of storage time. Gravity Power is collaborating with Robbins Co., the inventor of the mechanical mole, to adapt its technology for vertical tunneling capable of excavating 100 meters deep in 24 hours. Speed, low cost, and construction using readily available, inexpensive materials should reduce investment costs by at least half and the time between decision and implementation to a few years instead of a decade. The first unit was installed in Texas in 2011.
The opportunity
The introduction of renewable energy requires energy storage for commercial purposes, which is a massive undertaking. One possibility is to work with existing wells, thousands of which have been drilled over the past few centuries by mining companies worldwide. The MineWater project in Heerlen, the Netherlands, already uses the temperature difference in deep mines for cooling and heating residential areas. Now, the focus is not just on temperature, a proven technology in the Netherlands, but on the presence of water itself. Ideal wells are located, seals are installed, and the readily available water in disused and abandoned mines—water that often has to be pumped—is harnessed at the heart of the GPM (Global Power Mill). In a country like South Africa, where the mining industry pumps millions of liters of water, accounting for up to 25% of all energy consumption by mines around Johannesburg, the breakthrough offered by James and his team would ensure a continuous power supply. With shafts reaching depths of up to 4000 meters, mining companies are only just beginning to grasp the enormous potential they hold.
