Chapter 4. Technical Characteristics of Renewable Energy by Source
4.1 Status of RE Technology by Source
4.1.3 Hydropower
Onshore and offshore wind power have different LCOE compositions because offshore wind power requires additional equipment, such as substructures and submarine power cables, owing to the challenges associated with such installation. In addition, extra insurance premiums and reserve funds are required for offshore installations.
The European Union is pursuing technology development to reduce the current LCOE rate of 11~18 cent (EUR)/kWh to 9 cents (EUR)/kWh by 2020 for offshore wind power. Siemens, who has the largest market share in offshore wind power, aims to reduce the LCOE rate to a maximum of 5 cent (EUR)/kWh, much lower than the EU target. DONG Energy, one of the major developers of wind farms, remains committed to reducing LCOE by 20~30% by 2017.
The Nuclear Energy Agency (NEA) of the Organization for Economic Cooperation and Development (OECD) has recently analyzed the LCOE of 181 power plants in 22 member states that are scheduled to start their commercial service in 2020. The results showed that nuclear power generation is the lowest at 47.4 USD/MWh, followed by onshore wind (74.7 USD/MWh), coal-fired (76.3 USD/MWh), natural gas (98.3 USD/MWh), and solar PV (121.6 USD/MWh). This implies that grid parity, at which the unit cost of onshore wind-power generation becomes cheaper than coal-fired power generation, could be reached by 2020. Distribution difficulties and a relatively high unit cost compared with fossil fuels have previously impeded wind power generation; however, the unit cost has been dropping because of continuing technological advancements.
[Figure 4-8] Schematic diagram of hydropower plant
As shown in [Fig. 4-8], the hydropower system consists of a penstock that channels the water from a dam or barrage built in a river or reservoir to the power plant, a turbine that converts potential and kinetic energy stored in a water body into mechanical rotational energy, a generator, transmission and a substation to distribute the electricity, and a surveillance and control unit for plant operation, such as power output control.
❙ Table 4-2 ❙ Life cycle GHG emissions from different power sources
Technology Description 50th percentile
(CO2/kWh)
Hydropower Reservoir 4
Wind power Onshore 12
Nuclear energy Various generation II reactor types 16
Biomass Various 18
Solar thermal Parabolic trough 22
Geothermal energy Hot dry rock 45
Solar PV Polycrystalline silicon 46
Source: KEA (2016a), Renewable Energy White Paper
According to the Intergovernmental Panel on Climate Change (IPCC) report, hydropower offers a significant contribution to global warming prevention. This is because it is clean energy, with relatively low carbon dioxide (CO2) emissions compared with other RE sources, such as geothermal and wind power, or fossil fuels, including petroleum and coal.
Hydropower can start to generate electricity within a short time, less than five minutes, and is able to respond quickly to changes in the demand of the power grid. This means that hydropower plays a key role in stabilizing the power grid through peak load and frequency control. Compared with other power sources, hydropower has relatively low production costs and a stable cost structure, in which capital cost accounts for the major proportion, with little inflation or fluctuations in fuel prices. Hydropower, by replacing heavy oil generator with high variable costs, can contribute to price stabilization in the electricity market at peak times.
❙ Table 4-3 ❙ Classification of small hydropower
Source: KEA, KNREC, http://www.knrec.or.kr/
Small hydropower uses the potential energy from heads of water retained in rivers or reservoirs to activate the turbine, which exerts a turning force, and finally produces electricity through a generator connected to the turbine. Small hydropower can be classified based on facility capacity, head, and power generation method.
Sorting remarks
Facility capacity
Micro hydropower Mini hydropower Small hydropower
Less than 100 kW 100~1,000 kW 1,000~10,000 kW
Types of small hydropower available in South Korea include low head, tunnel, and storage hydropower Head
Low head Medium head High head
2~20 m 20~150 m More than 150 m
Power generating
method
Run-of-river type Storage type Tunnel type
A site where the river makes an omega-shaped bend (Ω) Middle and upper stream areas with high gradient streams A site with low gradient streams and high flow
❙ Table 4-4 ❙ Types and characteristics of water turbine
water turbine Characteristics
Impulse turbine
Pelton turbine Turgo turbine Ossberger turbine
- turbine is not immersed fully in water - water is fed only in a certain direction of the
turbine, and only kinetic energy is converted
Reaction turbine
Francis turbine - turbine is immersed fully in water
Propeller turbine
Kaplan turbine Tubular turbine Bulb turbine Rim turbine
- water is fed in a radial direction of the turbine - dynamic pressure and static pressure are converted
Source: KEA, KNREC, http://www.knrec.or.kr/
4.1.3.2 Global Trends in Technology Development
After two oil crises in the 1970s, many developed countries began to invest heavily in the development of hydropower technology, and have standardized the water turbines by types, to be suitable for use in the reference range based on the heads and flows in the early 1990s. Mass production has enabled saving on the construction costs of water turbines, making hydropower more cost effective. Currently, strong government support is being provided for the exploitable resources.
❙ Table 4-5 ❙ Status of turbine manufacturers by country
Country Production Company Turb type
USA Allis-Chalmer Co Tube, Francis, Propeller Turbines
Japan Fuji Francis, Tube, Bulb Turbines
China CMEC Francis, Kaplan Turbines
Norway GE Energy Bulb, Francis, Kaplan, Pelton, Propeller, Mini or Small-Scale Turbines
Germany Voith Hydro Pelton, Francis, Kaplan
Sweden TURAB Francis, Kaplan and Axial, Bulb and Axial Turbines Austria GEPPER Pelton, Francis, Diagonal, Kaplan, Compact Turbines France Alstom Francis, Pelton, S Type & Pit Turbines