Hydraulics and hydropower

Research topics:

  • Hydraulic analysis of sediment loaded rivers and optimum design of intakes in sediment carrying rivers
  • Dam safety and emergency action planning
  • Rehabilitation of dams
  • CFD
  • Small hydro

Hydropower:

Hydroelectric power is the technology of generating electric power from the movement of water through rivers, streams, and tides thanks to the potential energy of the elevation of waters. Water is fed via a channel to a turbine where it strikes the turbine blades and causes the shaft to rotate. To generate electricity the rotating shaft is connected to a generator which converts the motion of the shaft into electrical energy.

Hydroelectric power now supplies about 715,000 MW or 19% of world electricity and large dams are still being designed. Apart from a few countries with an abundance of it, hydro power is normally applied to peak-load demand, because it is so readily stopped and started. Nevertheless, hydroelectric power is probably not a major option for the future of energy production in the developed nations because most major sites within these nations with the potential for harnessing gravity in this way are either already being exploited or are unavailable for other reasons such as environmental considerations.

Hydroelectric power can be far less expensive than electricity generated from fossil fuel or nuclear energy. Areas with abundant hydroelectric power attract industry with low cost electricity. Recently, increased environmental concerns surrounding hydroelectric power, have begun to outweigh cheap electricity in some countries.

The chief advantage of hydroelectric dams is their ability to handle seasonal (as well as daily) high peak loads. When the electricity demands drop, the dam simply stores more water. Some electricity generators use water dams to store excess energy (often during the night), by using the electricity to pump water up into a basin. The electricity can be re-generated when demand increases. In practice the utilization of stored water in river dams is sometimes complicated by demands for irrigation which may occur out of phase with peak electrical demands.

Small hydro:

Small hydro is the application of hydroelectric power on a commercial scale serving a small community or medium sized industry. A generating capacity of up to 10 MW is becoming generally accepted as the upper limit of what can be termed small hydro. Small hydro can be further subdivided into mini hydro, usually defined as less than 1,000 kW, and micro hydro which is less than 100 kW. Micro hydro is usually the application of hydroelectric power sized for small communities, single families or small enterprise.

Small scale hydro or micro-hydro power has been increasingly used as an alternative energy source, especially in remote areas other power sources are not viable. Small scale hydro power systems can be installed in small rivers or streams with little environmental effect on things such as fish migration.

There are some major factors to consider when installing a micro-hydro system. First, the amount of water flow available on a consistant basis. Periods of little or no rain can greatly affect power output. Second is what is known as head, this is the amount of drop the water has between the intake and the exit of the system. The more head, the larger amount of power can be generated. Third, there can be legal and regulatory issues that must be researched. Most counties, cities, and states have their own regulations about water rights and easements.

Norwegian small hydropower potential

Norway has a very large hydropower potential and has developed it to great extend so that today hydropower covers over 99% of the electricity consumption of the country. Since most of the main sites have already been developed, the focus is now on the development of small hydropower plants. NVE (Norwegian Water Resources and Energy Directorate) has assessed the small hydropower potential and found that 18 TWh could be developed for less than 3 NOK/kWh. NVE estimates that 5 TWh out of 18 TWh could be developed within the next 10 years, which would be an increase of 4.5 % from today’s hydropower production. 5 TWh represent 1000 small hydropower plants with an installed capacity of 1 MW and an investment of 10 to 15 billions NOK.

For further information on Norwegian small hydropower potential, please check NVE’s web page (in Norwegian): NVE - hydropower potential

Hydraulics research group

Computational Fluid Dynamics in Hydraulic Engineering

Illustrasjonsbilde/FOTO

Our department has been using and developing CFD models for hydraulic and sedimentation engineering since 1990. Initial work was focused on sediment problems with regards to hydropower intakes, primarily due to the difficulties of modelling fine sediment in physical models. Since then the scope of our CFD research has expanded to other hydraulic and environmental topics.

The hydraulic engineering group

The hydraulic engineering group covers areas within hydropower engineering, hydrology and hydraulics. The research profile of the group includes both basic research particularly in the field of computational fluid dynamics, and applied research and development. In many areas the applied part is of great importance and a close relationship between the research group and consultants and authorities using the results for practical applications exists.