Energy Scenario for the UK: NBS M016

A hydro scheme comprises a system for extracting energy from water as it moves, normally dropping from one elevation to another.

Water that is restricted in a sloping pipe will build up a head of pressure at the bottom, which can be used to drive a turbine wheel (or runner).

In flatter areas where there is less pressure build-up or no pipe at all, much larger flows are required to compensate for the reduced head, and so larger turbines are used.

IN ADDITION TO FLOW AND HEAD, A DESTINATION OR LOAD FOR THE POWER IS NEEDED.

THE LOAD IS THE NATIONAL GRID. AS CONNECTION AND THE COST OF LINES ARE SIGNIFICANT PARTS OF MOST SCHEMES, DISTANCE FROM THE GRID MAY BE THE DECIDING FACTOR OF WHETHER A SCHEME IS VIABLE.

FURTHERMORE, THE GRID OPERATOR MUST TAKE INTO ACCOUNT THE CAPACITY OF THE LOCAL GRID BEFORE ALLOWING A SCHEME TO CONNECT.

THE ISSUE OF ACCESS TO DISTRIBUTION AND TRANSMISSION NETWORKS IS FACING SIGNIFICANT CHANGE

It is hoped that a relaxation of the distribution network charges and the Transmission Network Use of System (TNUoS) charges (paid by generators and suppliers making direct use of the grid) in the future will or could....

make the whole process more attractive to would-be investors in hydropower.

Time will tell this tale..

When a hydro scheme is generating electricity, every unit of electricity exported to the grid brings revenue.

In addition, for energy generated the scheme operator will receive Renewable Obligation Certificates (ROCs) which have a market value.

Levy Exemption Certificates (LECs) are also a useful support to the small-scale power producer and currently have a value of around £4/MWh.

OTHER SMALLER REVENUES OR BENEFITS MAY ALSO BE RECEIVED. AS DIFFERENT LAYOUTS AT A SITE CAN COST MORE OR LESS TO CONSTRUCT, BUT MAY ALSO GENERATE MORE OR LESS ELECTRICITY, THE BEST PAYBACK CAN ONLY BE FOUND BY EXAMINING A NUMBER OF ALTERNATIVE SOLUTIONS.

THIS IS ONE REASON WHY HYDRO SITE DESIGN IS COMPLEX. . .

In 2008, hydro power approximately generated :

1.55% of all electricity sold annually in the UK

Total electricity generation from renewables in 2008 amounted to 21,597 GWh, an increase of 1,952 GWh (+10 per cent) on 2007...

24 % was from Hydro sources....

  2010 2015 2020 2025 2030         Energy delivered from hydro (PJ) 1 18.2 16.0 15.0 16.0 18.2

Pumped storage capacity (PJ) 2 0.11 0.14 0.17 0.21 0.33

Pumped storage energy delivered (PJ) 2 13.8 17.9 22.1 26.22 44.62         

Sources:1.BERR (2009), ‘Electricity supply, electricity supplied (net), electricity available, electricity consumption and electricity sales’, Digest of UK Energy Statistics (DUKES), [Online], Available at http://stats.berr.gov.uk/energystats/dukes5_5.xls2.Mackay, D. (2008), Sustainable Energy: Without hot air, p. 191, [Online], Available at www.inference.phy.cam.ac.uk/sustainable/book/tex/ps/113.252.pdf