Case study: Centrosolar panels in Kenya
Approaches to managing energy in developing countries must be sustainable. Centrosolar is a company that has managed to reduce energy insecurity in one Kenyan village through the use of photovoltaic (PV) panels.
Kenya is a developing country located in east Africa. The country has high rates of poverty and over a million children have been orphaned due to HIV/AIDS. SOS Children is a charity that works with children in Kenya. SOS Children's Villages provide homes for orphaned children. Five Children's Villages have been set up in Kenya, one of which is the Mombasa home in the south of the country.
What are Centrosolar panels?
Centrosolar is a German company. They make photovoltaic solar panels, over 60% of which are used outside of Germany. Centrosolar fitted 312 solar modules at the Mombasa SOS Children's Village in March 2011. The system has an energy output of 60 kilowatt peak (kWp), which provides enough electricity for the 130 children living at the site.
Solar panels are an effective energy source in rural areas throughout the developing world
The Centrosolar project has had many successes:
- The Centrosolar project is the largest of its kind in east Africa. The panels provide enough electricity for the 130 students living in the village, plus an additional 500 local school students who visit the site.
- Any surplus energy generated is sold to a national grid, which helps to reduce costs at the site.
- The Centrosolar project is an example of appropriate technology. The solar panels require very little maintenance and they are relatively cheap. Kenya is a very sunny country and so the solar panels will continue to generate clean electricity.
The Centrosolar project has been very successful, but it is only a small-scale solution. A larger national grid of solar panels could be the solution to energy insecurity in Kenya.
Happisburgh, on Norfolk's North Sea coast, is a village with a population of 1400 people in about 600 houses. The village contains a notable stone church dating from the 14th century, an impressive manor house, listed buildings and a famous red and white striped lighthouse (Figure 1).
Although now a coastal village, Happisburgh was once some distance from the sea, parted from the coast by the parish of Whimpwell, long since eroded away. Historic records indicate that over 250 m of land were lost between 1600 and 1850.
More recently the village was affected by the tragic floods of 1953 that claimed the lives of 76 Norfolk residents. Figure 2 gives an example of the rapid coastal erosion at Happisburgh.
Coastal defences built at Happisburgh have slowed down the rate of retreat. However, large sections are now in disrepair. Sea-level rise and climate change, including increased storminess, may also increase the rate of erosion. Agriculture and tourism contribute significantly to the economy of the village and surrounding hinterland although this is threatened by the receding cliff line that, prior to the construction of a rock embankment at the northern end of the survey site, had claimed at least one property per year plus significant quantities of agricultural land.
The cliffs at Happisburgh range in height from 6 to 10 m and are composed of a layer-cake sequence of several glacial tills (Figure 3), separated by beds of stratified silt, clay and sand (Hart, 1987; Lunkka, 1988; Hart, 1999; Lee, 2003). The basal unit within the stratigraphic succession at Happisburgh is the How Hill Member of the Wroxham Crag Formation. These deposits are typically buried beneath modern beach material but are periodically exposed following storms (Figure 3). They consist of stratified brown sands and clays with occasional quartzose-rich gravel seams that are interpreted as inter-tidal/shallow marine in origin.
Unconformably overlying these marine deposits are a series of glacial lithologies deposited during several advances of glacier ice into the region during the Middle Pleistocene (c.780 to 430 ka BP) (Lee et al., 2002; Lee et al., 2004). The survey site has a tripartite geological succession.
The Happisburgh Till Member, crops-out at the base of the cliffs and its base is frequently obscured by modern beach material: it has a maximum thickness of 3 m. The Happisburgh Till Member is a dark grey, highly consolidated till with a matrix composed of a largely massive clayey sand with rare (<1%) pebbles of local and far-travelled material.
The upper surface of the till undulates and comprises a series of ridges and troughs upon which the overlying Ostend Clay member outcrops. This unit is between 2.3 and 3.4 m thick and consists of thinly-laminated light grey silts and dark grey clays.
In turn, these beds are overlain by 2 to 4 m, of weak, stratified sand (Happisburgh Sand Member) with occasional silty-clay horizons.
It is likely that the Norfolk cliffs have been eroding at the present rate for about the last 5000 years when sea level rose to within a metre or two of its present position (Clayton, 1989). Therefore, the future predictions of sea level rise and storm frequency due to climate change are likely to have a profound impact on coastal erosion and serious consequences for the effectiveness of coastal protection and sea defence schemes in East Anglia in the near future (Thomalla and Vincent, 2003).
Rapid erosion of the cliffs at Happisburgh means that we can observe processes that for other sites may normally take thousands of years. This means that we can look for patterns in the erosion at Happisburgh, which may help our understanding of sites elsewhere that are eroding more slowly.
As part of a programme of work monitoring coastal erosion and landsliding at several sites around the coast of Great Britain, we are surveying the cliffs adjacent to the village of Happisburgh in Norfolk — see Terrestrial LiDAR Survey Techniques
The resulting computer model (Figure 4 ) enables volume calculations and observations to be made as to the way in which the coast is eroding. The results from the survey provide data for models of coastal recession.
From this survey, the following conceptual model has been proposed (Figure 5).
- In winter, erosion caused by groundwater as seen in the gullying of the cliff face, coupled with increased seasonal storminess, causes small-scale, frequent, shallow landsliding in the Happisburgh Sand Member. The Happisburgh Sand Member is easily eroded and undercutting of the cliff toe reduces slope stability and cliff failure occurs. The beach surface is low and scouring of the upper surface of the till extends the till platform.
- In summer, the beach surface is higher and covers the 'winter platform'. Wave attack is the dominant form of erosion accompanied by landsliding in the Happisburgh Sands.
The cliff surface profiles show that the erosion process is non-uniform, involving the cyclic formation of a series of embayments that continually enlarge (Figure 6). This could infer landsliding processes involving block falls, mudflows and running sand.
For more information on the results from this survey see:
Hobbs, P.R.N., Pennington, C.V.L, Pearson, S. G., Jones, L.D., Foster, C., Lee, J. R. & Gibson, A. (in press), Slope Dynamics Project Report: Norfolk Coast (2000-2006), British Geological Survey Open Report OR/08/018.
Poulton, C.V.L. 2004. Disappearing Coasts, Planet Earth, Volume Summer 2004, 26-27.
Poulton, C.V.L., Lee, J.R., Jones, L.D., Hobbs, P.R.N., and Hall, M. 2006. Preliminary investigation into monitoring coastal erosion using terrestrial laser scanning: case study at Happisburgh, Norfolk, UK: Bulletin of the Geological Society of Norfolk, 56, 45-65.
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COSGROVE, A.R.P., BENNETT, M.R. & DOYLE, P. 1998. The rate and distribution of coastal cliff erosion in England: a cause for concern? In: BENNETT, M.R. & DOYLE, P. (Eds), Issues in Environmental Geology: A British Perspective. The Geological Society, London.
GRAY, J.M. 1988. Coastal cliff retreat at the Naze, Essex since 1874: patterns, rates and processes. Proceedings of the Geologists Association, 99, 335-338.
HART, J.K. 1987. The genesis of the north east Norfolk Drift. Unpublished PhD thesis, University of East Anglia.
HART, J.K. 1999. Glacial sedimentology: a case study from Happisburgh, Norfolk. In: Jones, A, Tucker, M and Hart, JK (Eds), The Description and Analysis of Quaternary Stratigraphic Field Sections. Technical Guide 7, Quaternary Research Association, London, 209-234.
HIATT, M.E. 2002. Sensor Integration Aids Mapping at Ground Zero. Photogrammetric Engineering and Remote Sensing, 68, 877-879.
HOBBS, P.R.N. 2008. Coastal cliff monitoring, GeoConnexion, June/July 2008.
HOBBS, P.R.N., HUMPHREYS, B., REES, J., TRAGHEIM, D., JONES, L., GIBSON, A., ROWLANDS, K., HUNTER, G. & AIREY, R. 2002. Monitoring the role of landslides in 'soft cliff' coastal recession. In: Instability Planning and Management. (Eds, McINNES, R.G. and JAKEWAYS, J.) Thomas Telford, Isle of Wight, 589-600.
HOBBS, P.R.N., PENNINGTON, C.V.L, PEARSON, S. G., JONES, L.D., FOSTER, C., LEE, J. R. & GIBSON, A. (in press), Slope Dynamics Project Report: Norfolk Coast (2000-2006), British Geological Survey Open Report OR/08/018.
HOOKE, J.M. & KAIN, R.J.P. 1982. Historical change in the physical environment: a guide to sources and techniques. Butterworth, London.
HR WALLINGFORD. 2001. Ostend to Cart Gap Coastal Strategy Study. EX 4342. November.
HR WALLINGFORD, 2002. Southern North Sea Sediment Transport Study Phase 2: Sediment Transport Report, Report produced for Great Yarmouth Borough Council by HR Wallingford, CEFAS/UEA, Posford Haskoning and Dr Brian D'Olier, Report EX 4526.
HULME, M., JENKINS, G.J., LU, X., TURNPENNY, J.R., MITCHELL, T.D., JONES, R.G., LOWE, J., MURPHY, J.M., HASSELL, D., BOORMAN, P., McDONALD, R. & HILL, S. 2002. Climate Change Scenarios for the United Kingdom: The UKCIP02 Scientific Report, Tyndall Centre for Climate Change Research. School of Environmental Sciences, University of East Anglia, Norwich, UK, 120pp.
LEE, J.R. 2003. Early and Middle Pleistocene lithostratigraphy and palaeoenvironments in northern East Anglia, UK. (Unpublished). Ph.D., University of London.
LEE, J.R., ROSE, J., HAMBLIN, R.J.O. & MOORLOCK, B.S.P. 2004. Dating the earliest lowland glaciation of eastern England: a pre-M1512 early Middle Pleistocene Happisburgh Glaciation. Quaternary Science Reviews.
LEE, J.R., ROSE, J., RIDING, J.B., HAMBLIN, R.J.O.& MOORLOCK, B.S.P. 2002. Testing the case for a Middle Pleistocene Scandinavian glaciation in Eastern England: evidence for a Scottish ice source for tills within the Corton Formation of East Anglia, UK. Boreas, 31, 345-355.
LEE, M. & CLARK, A. 2002. Investigation and management of soft rock cliffs. Thomas Telford.
LUNKKA, J.P. 1988. Sedimentation and deformation of the North Sea Drift Formation in the Happisburgh area, North Norfolk. In: CROOT, D. (Eds), Glaciotectonics: Forms and Processes. Balkema, Rotterdam, 109-122.
McCAVE, I.N. 1978. Grain-size trends and transport along beaches: examples from Eastern England. Marine Geology, 28, M43-M51.
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OHL, C., FREW, P., SAYERS, P., WATSON, G., LAWTON, P., FARROW, B., WALKDEN, M.& HALL, J. 2003. North Norfolk - a regional approach to coastal erosion management and sustainability practice. In: International Conference on Coastal Management 2003. (Ed, McInnes, RG) Thomas Telford, Brighton, 226-240.
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PENNINGTON, C.V.L. & HOBBS, P.R.N. 2008. Coastal surveying techniques: a case study at Happisburgh, Norfolk, UK, GeoInformatics: magazine for surveying, mapping and GIS professionals, 6.
POULTON, C.V.L. 2004. Disappearing Coasts, Planet Earth, Volume Summer 2004, 26-27.
POULTON, C.V.L., Lee, J.R., Jones, L.D., Hobbs, P.R.N., and Hall, M. 2006. Preliminary investigation into monitoring coastal erosion using terrestrial laser scanning: case study at Happisburgh, Norfolk, UK: Bulletin of the Geological Society of Norfolk, 56, 45-65.
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Contact the Landslide Response Team
British Geological Survey
Telephone: 0115 936 3143
Fax: 0115 936 3276