Technology

Hybrid power plants

 By Nicholas Newman

Hybrid cars and buses are growing in importance in the transportation sector. Still in the pioneering stage are hybrid power plants, which utilize several different power generation technologies, such as diesel, biogas, gas, solar and wind, often integrated or combined with some form of energy storage…

A hybrid power plant can occupy a single site or comprise a microgrid with several different types of generation working as an integrated unit. While some plants are grid-connected and used primarily to supplement power supplies, others are located in remote areas, far from the grid, and are the main source of power.
For operators, energy security, lower cost and functionality are the main attractions. For example, where batteries are included, surplus renewable power can be stored for later use, sold to the grid or converted into steam to supply district heating. For energy intensive industrial processes such as smelters or remote mining operations, hybrid power plants offer a competitive power supply independent of the grid.

What is hybrid power?

Hybrid power plants offer a range of capacities and combinations of feedstock. Typically, hybrid power plants use a fossil fuel such as diesel or gas, supplemented with a renewable energy source such as solar. Some, combine renewable sources with battery storage in order to minimize consumption of expensive diesel or oil. A case in point is the planned construction of several combined diesel-solar hybrid plants in Russia’s Far East as part of concerted efforts to reduce diesel usage.
A ground breaking renewable-only hybrid is Nevada’s Stillwater power plant, the first triple-hybrid facility in the world, combining geothermal, photovoltaic and solar thermal power generation. However, there is a worldwide trend for natural gas to replace diesel and, with the substantial decline in the cost of batteries, to employ batteries to store surplus power for later use. The main customers of hybrid power plants include telecommunications companies, mine operators and remote rural communities.

Grid-integrated hybrid technology (belectric.com)

Hybrid power plant market

The concept of integrating different types of power generation is still in its infancy. Therefore, it is not surprising that the size of the global market is small. The global hybrid grid- connected market valued at just $1.05 billion in 2014 is set to nearly double and reach $1.92 billion by 2019, facilitated by improvements in renewable technology and falling costs. Current, forecasts suggest that by 2020, at least half the world’s hybrid plants will be combined solar and diesel plants. Around the world, new hybrid power plants are under construction in the USA, Europe and Africa.

Benefits

In developing countries, hybrid power plants offer a source of power and energy security to communities and businesses operating in remote areas or difficult terrain.
Zambian mining companies are building hybrid diesel-solar plants to secure energy independence from the local power grid, which is unreliable and subject to regular power cuts caused by the ongoing severe drought in the region. Equally important is the lower cost of such power. The power produced by the hybrid plants, at 6.02 cents/kWh, is significantly cheaper than the grid-supplied power costing 10.35 cents/kWh.
In the case of hybrid renewable and battery power plants, the battery can even out the plant’s electricity output during times of variable wind and cloudy weather as well as provide uninterrupted electricity supply to the plant owner during network power cuts. In addition, grid-connected plants can sell their surplus energy (stored in batteries) to the grid and earn additional income.

Hybrid power plants in action

Above all, hybrid power plants provide energy security using diverse energy sources and an ability to respond to load fluctuations. They ensure a reliable and cleaner electricity supply for both private and public customers.
The Danish city of Aarhus is integrating all its renewable and heat generation units with existing conventional power systems. Aarhus is doing this to improve energy self-sufficiency and selling its surplus power to the grid.
In South Africa, the remotely situated Crominet’s chromium ore mine, which customarily relied on 1.6 megawatts of power produced by diesel generators, has added solar PV (photovoltaic) to provide up to 60 percent of its power needs. The PV plant is expected to replace between 3 million and 3.4 million liters of diesel fuel per year for 20 or more years. A similar project, soon to be completed for the IAMGOLD gold mine, is expected to save 6 million liters of fuel a year as well as 18,500 tons of CO2 emissions.
    
CRONIMET Mining Power Solutions specializes in integrating renewable energy with off-grid power systems (crm-ps.com)

In Germany, in the midst of the Swabian-Franconian Forest, the first hybrid project to include a wind farm with an integrated hydropower plant is under construction. This prospective four-turbine and hydro-pump storage power plant will produce a combined 29.6 MW, with 16 MW from hydro and 13.6 MW from wind, by the end of 2018.

Prospects

In terms of future prospects, William Ross Williams, CEO of Altresco Companies says, “Technological advances in equipment, computing and growing experience are steadily improving the costs of hybrid power plants over more conventional one-mode systems such as diesel alone. Even so, installing the right control systems and optimizing the equipment to produce competitively priced energy remains a challenge.”

about the author
Nicholas Newman
Freelance energy journalist and copywriter who regularly writes for AFRELEC, Economist, Energy World, EER, Petroleum Review, PGJ, E&P, Oil Review Africa, Oil Review Middle East. Shale Gas Guide. https://nicholasnewman.contently.com/