In debates about renewable energy hydropower is the elephant in the room, the work beast unjustly starved of attention. This week we’ll rectify that oversight with a global snapshot of the industry along with geothermal power, another often overlooked renewable energy source.

Like last week’s report on trends in solar PV and wind power, this analysis is based on two recently released energy annuals, The BP Statistical Review of World Energy 2013 and REN21’s 2013 Renewables Global Status Report (GSR). (Disclosure: I have been a reviewer for the GSR for the past three years).

Hydropower

Hydropower accounts for more electricity production than solar PV, wind, and geothermal combined. It gets far less press because it is a more mature technology with a much lower growth rate than most renewables. While solar PV increased capacity by an average of 60 percent per year over the past 5 years, new hydropower capacity increased at a much more modest annual rate of 3.3 percent.

However the installed base for hydropower and the capacity factors for hydropower are much higher than those for wind and solar power. As a result, the amount of electricity produced from hydropower dwarfs that of other renewable options. (The capacity factor is simply the amount of power produced divided by the power that would be produced if the power source was producing at full capacity at all times.)

Between 2002 and 2012, the amount of hydropower consumed globally increased by more than 1,000 terawatt hours (TWh). Over that same period of time, the amount of wind and solar power consumed increased by 560 TWh.

The capacity of hydropower plants also dwarfs that of other renewables such as wind and solar. In fact, the four largest power plants in the world are all hydropower plants. The only non-hydropower plant in the Top 5 is the Kashiwazaki-Kariwa Nuclear Power Plant in Japan.

Despite hydropower’s current dominant position among renewables, growth in consumption of hydroelectricity will likely continue to be modest, because many of the best sites for hydroelectric dams have already been developed. The exception to this is in the Asia Pacific region, where hydroelectric consumption more than doubled over the past decade. The region currently accounts for 35 percent of global hydroelectric consumption, and that percentage is likely to increase as countries continue to develop hydroelectric power plants.

The top countries for hydropower — accounting for 52 percent of global capacity — are China, Brazil, the US, Canada, and Russia. Global hydropower capacity at the end of 2012 was estimated to be 990 GW, which is about 2.5 times the combined global capacity of wind and solar power. (Capacity refers to peak generating capacity at a point in time, while the terawatt hour consumption statistics multiply that instantaneous capacity by the number of hours it was deployed.)

Source: REN21’s 2013 Renewables Global Status Report

Investors seeking to diversify into hydropower don’t have a lot of options in the US. Idaho Power (NYSE: IDA) and Portland General Electric (NYSE: POR) are two US-based public utilities with a substantial base of hydropower generating resources. However, neither is a pure hydropower play. Investors looking for purer hydropower plays will have to look abroad at companies like Brazil’s Cia Energetica De Minas Gerais (NYSE: CIG), Austria’s Verbund AG (OTC: OEZVF), or China Yangtze Power, which operates the Three Gorges Dam and trades on the Shanghai stock exchange.

Geothermal

Geothermal energy is energy obtained from the earth’s internal heat. It is one of the most environmentally benign sources of energy, producing little to no emissions during normal  operation. Geothermal also has the advantage of being a firm renewable power source, which simply means that is designed to be available as needed, as opposed to intermittent power which may only be available when the sun shines or the wind blows. Like hydropower, producing electricity from geothermal resources is a relatively mature renewable technology, which is reflected by its modest 4 percent annual growth rate over the past five years.

Geothermal electricity is produced when the heat from the earth is used to produce steam, which is then passed through a turbine. Electricity produced in this way generally requires fairly shallow geothermal reservoirs (less than 2 miles deep). Geothermal electricity has a high capacity factor, and the cost of generation is comparable to that of coal-fired generation. Its usage, however, is geographically limited.

In addition to electricity production, geothermal energy can be also be used for heating or cooling. Hot springs or water circulating in hot zones can be used to heat buildings. Geothermal heat pumps take advantage of the earth’s temperature a few feet below the ground—consistently 50° to 60°F—to heat buildings in the winter and cool them in the summer.

In 2012, at least 78 countries used geothermal energy. Over two-thirds of the geothermal energy used globally was through geothermal heat pumps. In addition, 24 countries operated geothermal plants for electricity production.

Total geothermal electricity capacity was 11.7 GW at the end of 2012. Capacity was led by the US with 3.4 GW, followed by the Philippines at 1.9 GW, Indonesia (1.3 GW) Mexico (1.0) and Italy (0.9). On a per capita basis, Iceland leads the world with 0.7 GW of capacity, and used geothermal energy to produce 30 percent of its electricity in 2012. Last year new geothermal electricity capacity came online in the United States (147 megawatts), Indonesia (110 MW), Nicaragua (36), and Kenya (7.5).

The largest producer of geothermal power in North America is Calpine (NYSE: CPN), which operates The Geysers complex of 15 geothermal power plants in the mountains north of San Francisco. The 725 megawatts of geothermal power produced there represents some 40 percent of the North American total. The largest producer of geothermal power in the world, however, isn’t a company that many people might guess. It is Chevron (NYSE: CVX), which pioneered the development of The Geysers, and today operates geothermal plants in Indonesia and the Philippines.

Ormat Technologies (NYSE: ORA) offers a purer play as a builder and operator of geothermal plants and supplier of related equipment, but its earnings have fallen steadily in recent years. While the company did beat expectations during the most recent quarter, it will need to string together several quarters of outstanding performance to earn back investors’ trust.

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