Potential contribution of hydro power plants to the energy consumption of East Asian islands

POTENTIAL CONTRIBUTION OF HYDRO POWER PLANTS TO T H E ENERGY

CONSUMPTION OF EAST ASIAN ISLANDS

O.A.C. Hoes', L.J.J. MeijerVO.R. Sarfianto^ and R.J. Van der Endt'*

ABSTRACT: Population growth, increasing energy demand and depleting fossil fuel resei-ves put a pressure on conventional methods of electricity generation. Hydropower is an alternative energy source that is known to have a large capacity potential. However, previous estimations of the potential capacity have been inconsistent and incomplete. In this study we identified all locations on East Asian islands (from Japan, Taiwan Phillipines to Indonesia) which are suitable for hydropower. For this we combined USGS's HydroSHEDS elevation data with Global Runoff data from the Global Runoff Data Centre. Such large spatially data gives especially unique information which was not available before. We computed that the total gross hydropower capacity potential is about 2885 TWh per year. Large hydropower accounts for over 27% of this potential, around 39% by small plants, 28% by mini hydropower plants, while micro hydropower only accounts for 6 % of the total potential capacity. Overall this study provides spatially detailed global data that allows both a quick comparison of hydropower potential between regions as well as detailed infomiation on specific hydropower locations, which is especially unique new information for micro hydropower.

Keywords: runoff, hydropower plants, energy, rivers

INTRODUCTION

Today, the worldwide annual energy need is over 22,000 TWh/year (WEC 2013). With depleting fossil fuels, economic growth, and an increasing population it is inevitable that alternative energy resources are going to play a significant role, including the 'renewables'. The future energy supply will have to shift to a different mix of sources and techniques. There are a lot of scenarios of compositions, but the common consensus is that renewables will have to f u l f i l l over 50% of the energy consumption within 40 years from now (Shell 2008).

New renewables such as hydropower, wind, solar, geothermal and bio&els are currently accounted for only 15% of the total energy production (WEC 2013). However they are growing rapidly. From these sources the hydropower plants are contributing the most. Together they produced 2,800 TWh of electricity in 2011 according to the World Energy Council (WEC 2013), and 3,700 TWh in 2012 according to the Renewable Energy Policy Network for the 2T' centuiy (REN21, 2013). Despite this difference, they agree on the installed hydropower capacity, which was about 990 GW in 2012 and growing with about 30GW per year.

The recent growth in installed hydropower capacity has been concentrated in the emerging markets in Asia and South America, where increased access to electricity and improved reliability are major requirements to support the rapid economic development. This trend is most visible in China where over 15 GW was deployed in 2012 (WEC 2013).

Energy potential is typically divided into gross a) theoretical, b) technical, and c) economical feasible potential. The gross theoretical capability expresses the total amount of electricity which could potentially be generated, i f all available water resources were turned to this use. The technically exploitable capability expresses the hydropower capability which is attractive and readily available with existing technology. The economically exploitable capability is that amount of hydropower generating capacity which could be built, after cariying out a feasibility study on each site at cuixent prices, and producing a positive outcome. Different methods and opinions exist on how to determine gross theoretical, technical and economical feasible hydropower potential. They might even differ from country to countiy. The World Energy Council stated that the technical potential hydropower is mainly based on visfted spots in the past and therefore excludes sites that could be developed.

' lALT member, Delft University of Teclinology, Stevinweg 1, 2628 CN, THE NETHERLANDS, o.a.c.hoes@Uidelft.nI ^ Witteveen+Bos, Engineering Consultants B.V., Deventer, THE NETHERLANDS

^ ROE Engineering, Jalan Pasirluyu XII 16, Bandung, INDONESIA

The common consensus is that tliere is a technical potential of about 15,000 PWli/year and a gross theoretical potential of about 40 PWh/year (Bartle 2002) (See Table 1). These numbers from "Hydropower and Dams", World Atlas & Industiy Guide are also presented in reports on renewable energy from the International Renewable Energy Agency (IRENA) and the World Energy Council (WEC). Quantifying the world hydropower capacity however is open to debate and there are significant discrepancies and inconsistencies between data for each countiy (WEC 2010).

Recent studies already made accurate potential estimations based on a systematically, mostly GIS-based, approach for specific areas. For example the hydropower potential assessment of the La Plata basin (Palomino Cuya et al. 2013), and the Kopili River basin in Assam (Kusre et al. 2009). Different hydrological data and approaches are used vaiying fi-om poorly gauged basins in Turkey using remote sensing and hydrologie modelling (Gonca Coskun et al. 2010) to a new GIS based model applied in Korea (Yi et al. 2010). Other studies use more specific locally recorded data to calibrate their hydrologie models. On the other hand more systematically and larger applicable methods have been generated (Larentis et al. 2010). These studies pointed out that GIS-based tools combined with hydrological models or data are useful to assess hydropower for a specific area, but not yet applied for vast areas. The International Renewable Energy Agency states that further work on mapping global hydropower potential is required and should be encouraged (IRENA 2012).

Next to a categorization in theoretical-technical-economical, hydro power can also be divided into micro, mini, small and large hydropower plants. Large hydropower plants are plants with an installed capacity above 10 MW. Many locations with a potentially large capacity are either developed or at least the feasibility is surveyed. Small (1-10 MW), mini (0.1-1 MW) and

Table 1 Theoretical, technical and economical feasible hydropower capacity (H&D World Atlas & Industry Guide 2011)

theoretical technical economical (TWh/yr) (TWh/yr) (TWh/yr)

Africa 4,380 1,484 830 Asia 19,717 8,000 4,684 Oceania 658 185 90 Europe 3,129 1,199 843 N America 7,601 1,842 1,058 S America 7,893 2,807 1,677 World 43,378 15,515 9,180

micro (<0.1 MW) hydropower spots however are many, and their locations are mostly unknown, therefore the accumulated potential for especially micro hydropower is unclear. East Asian islands were selected to survey as these reflects well global differences between developed and less developed countries with and without a hydropower histoiy.

As such, this research aims to give insight in a) the theoretical gross capacity of hydropower potential of East Asian Islands, b) its distribution between micro, mini, small and large hydropower and c) to which amount hydropower plants can fulfill the present energy consumption.

The outline of this paper is as follows. Section 2 explains hydropower plants, how the potential theoretical hydropower capacity is calculated. Section 3 explains the data sources used and the limitations for large scale modeling. Section 4 presents the resuhs of this study and gives insight in the availability and distribution of hydropower. In section 5 the resuhs are discussed and compared with available data. Finally section 6 contains conclusions and suggestions for improvement and further research.

HYDROPOWER

Hydropower exists because of gravity bringing back collected precipitation in rivers and streams to the oceans. The potential or kinetic energy of the river water can be transferred by a turbine and a generator into electricity. The major advantage of water compared to other energy sources is that hydropower plants do not consume the water that drives the turbines. Which makes that after power generation, the water is still available for other puiposes. E.g. irrigation, water supply, or mitigate droughts.

Hydropower plants come in different typologies: a) run-of-the-river hydropower, b) storage hydropower c) pumped storage. Run-of-the-river hydropower plants are plants without or a limited storage reservoir. The power produced is subject to seasonal river flow fluctuations, and therefore provide a source of energy that is not continuously available. Storage hydropower are the more conventional plants with a reseivoir. They can store water to provide energy for peak demand or provide a continuous base supply. When well designed, they can operate independently of the hydrological regime, and be started up en shut down at short notice. Pumped storage hydropower plants provides peak load supply. This type of plants consist of a lower and upper reseivoir, between which water is cycled by using the surplus energy at times of low demand to pump the water to the upper

resei-voir. During peak hours the water from the upper resei-voir is converted back in to energy while flowing back to the lower reservoir. Pumped storage is also attractive in combination with wind and solar power.

This paper deals with the f u st two type of plants. The choice between a run-of-the-river or storage hydropower plant depends on different factors like e.g. the unevenness of the inter annual runoff distribution, the flexibility of the existing grid to already alleviate peak hours, and the extent to which wildlife, fish, and people get affected by the construction. The capacity for both types of plants remains the same, and can be calculated with:

P=p-g-H-Q'ïi [Watt] (1) Where P is the hydropower capacity (W), p is the

water density (kg/m3), g is the gravitational acceleration (m/s^), H is the head (m), Q is the discharge (mVs), and T] is the turbine efficiency (%).

METHODS

Regardless a run-of-the-river or storage hydropower plant, the maximum annual energy production is reached when 100% of the aimual runoff is diverted trough a hydropower plant. This makes that gross theoretical potential is estimated a potential annual generation (Wh/year), and not an installed capacity (W) by dividing the annual generation by 8760 hours.

To calculate the annual generation one needs the annual runoff and the head. The annual runoff data is taken from the UHN-GRDC Composite Runoff Fields VI.0 dataset. (See Fig. 1) This dataset is produced by combining river discharge measurements with a climate-driven water balance model, resuhing in a monthly average, 30-minute spatial data set. These composite runoff fields can be regarded as best global estimate of terrestrial runoff (Fekete et al. 2004).

The digital elevation model p E M ) used in this study are taken from 'Hydrological data and maps based on Shuttle Elevation Derivatives at multiple Scales' or

-.^^i-ww::^—-y --- -r-.

^1»»-,

M?3l^r,

Fig. 1 Composite annual runoff data (Balazs et.al. 2000, download: http://www.compositerunoffsr.unh.edu/)

HydroSHEDS (www.hydrosheds .org). A lot o f effort has been taken by the USGS to improve the DEM for hydrological purposes. Modifications in the DEM and several improvements such as 'sinl<; removal' have been carried out to obtain a Conditioned DEM with optimal river flow characteristics (Lehner 2008).

Locally, more detailed data, models and information might exist on both hydrology and geography but on a global scale the UHN-GRDC (0.50) and HydroSHEDS (3") data provide us with consistent and high resolution near-global information, suitable for a modeling approach.

To systematically suivey all rivers, the DEM data were used to delineate a river network for all islands with for each location or raster cell the average annual discharge by two standard GIS operations (flow direction and flow accumulation) with the composite runoff data as weight factor. Only rivers with an average discharge Q > 0.1 mVs second were selected.

The river network with same elevation data were combined to calculate the drop between two adjacent river raster cells. Only locations with a drop H > 4 meter between two adjacent cells were selected as suitable hydropower. For our analyses the efficiency was set to 100% and can be further modified for specific locations or regions. The actual efficiency i] for a hydropower plant may differ fi'om 50% up to 95%. Depending on the size and quality of the turbine.

A combination of Q=0.1 m^/s and H=4 m delivers the smallest potential hydropower plant locations on our map with a capacity of 4kW or 35,000 kWh per year. In our analyses we combined the capacity of adjacent potential locations mountainous regions to prevent cascades of numerous micro turbines. As a requirement to combine locations we used the presence of an uninterrupted chain of drops of at least 4 m between river raster cells.

RESULTS

The runoff weighted fiow accumulation as explained under 'methods' resulted in a river raster database. Table Table 2 Obsei-ved and calculated mean annual discharge

River, station, countiy Qobs- Q c a l c A Q / Q

(mVs) (m'/s) Kitakami, Tome, Japan 252 250 - 1 % Tokati, Moiwa, Japan 206 173 -16% Gaoping, Donggang, Taiwan 241 269 -f-12% Ciliwung, Jakarta, Ind. 16 16 0% Bengawan, Bojonegoro, Ind. 381 349 -8% Kapuas, Kalimantan, Ind 6000 5400 -10%

2 presents the obsei-ved and calculated mean annual discharge of a selection of rivers from different islands.

The comparison between the obsei-ved and calculated discharge is used as a validation indication. In general it is found that the annual average discharge is simulated quite accurate for most rivers. The location of the rivers derived from a DEM is accurate as well, this can be, and has been validated by a graphical overlay of the simulated river network over satellite image data. See Fig. 2 for an example for Taiwan.

Diverging bifurcations are the main source of simulation errors, as the GIS flow direction operation is not capable of diverging flows. In almost any delta these bifurcations occur in lower areas (with veiy little head), which are not suitable for hydropower development and therefore the effect on the gross hydropower potential is damped out.

The gross theoretical annual hydropower potential capacity of East Asian Islands and its spatial distribution between micro, mini, small and large hydropower is presented in Table 3. As an example the spatial distribution over Holdcaido in Fig. 3.

Fig. 2 River network derived from elevation data

The total gross theoretical hydropower potential is 2,885 TWh/year. New Guinea is the largest contributor to this potential with 48%, followed by Borneo (16%)

Table 3 Potential gross hydropower capacity and its distribution over mini, micro, small and large hydropower plants in TWh/yr.

Island micro mini small large total

SUM 182 800 1,129 772 2,885 New Guinea 35 236 589 515 1,37 Borneo 40 146 142 122 450 Sumatra 18 101 125 40 285 Sulawesi 11 55 68 42 176 Honshu 20 59 35 12 126 Taiwan 1.7 20 45 12 79 Java 9.1 25 10 77 Mindanao 7.7 35 26 7.2 75 N . Britain 4.1 25 32 6.1 67 Luzon 6.9 26 15 2.9 51 Kyushu 3.4 8.1 3.7 0.5 16 Ceram 1.7 6.5 4.6 1.4 14 Holdtaido 5.0 4.6 1.6 11 Shikoku 1.8 5.9 2.4 0.2 10 Bum 0.7 3.5 4.3 0.3 8.8 Flores 1.1 4.5 2.3 7.8 N . Ireland 0.4 3.2 1.8 5.4 Timor 1.5 3.0 0.7 5.2 Mindaro 0.5 3.1 1.0 0.1 4.7 Panay 0.6 2.8 0.9 4.4 Negros 1.2 2.4 0.5 4.1 Halniahera 1.3 2.3 0.5 4.0 Samar 0.8 1.9 1.0 3.7 S achat in 2.2 1.0 0.1 3.2 Bah 0.8 1.8 0.3 2.9 Leyte 0.7 1.3 0.1 2.0 Sumbawa 0.8 0.9 0.3 2.0 Hainin 0.3 0.3 0.2 0.9 Sumba 0.3 0.4 0.1 0.9 Cebu 0.3 0.4 0.1 0.8 Lombok 0.2 0.3 0,1 0.6 Palawan 0.3 0.3 0.6 Bohol 0.1 0.2 0.1 0.4 Ambon 0.1 0.1 0.1 Rest 3.0 5.3 0.9 9.2

Table 4 Annual generated and calculated production

<5GWh/vear y-.,;'. IJ}:,

S-lOGWh/year L . ' i ' r l . ' : Resei-voir

>10 GWh/year

•'irj

Sum Hokkaido 11,700 GWH/year

Fig. 3 Spatial hydropower capacity distribution at Hokkaido. The gross potential is 11.7 TWh/year.

and Sumatra (10%).

The large hydropower plants account for about 27% of the gross theoretical annual hydropower potential capacity, small hydropower accounts for 39%, mini hydropower plants for 28% and micro hydropower accounts for 6%. However, for most islands the mini hydropower plants with a capacity between 100 kW and 1 M W are the main contributors to the islands gross theoretical annual hydropower potential.

DISCUSSION

The Phillipines energy need today consist of 68 TWh/yr, from which around 8 TWh/yr is produced with hydropower plants at the moment. The gross theoretical annual hydropower potential reaches according to our analyses around 146 TWli/yr. Half of this potential can be produced on Mindanao, which has already a frequent power outages, due to a supply deficit of 170 MW. The estimated value of 146 TWh/yr is about 3 times more than the gross potential of 47 TWh/yr estimated in the "Hydropower and Dams", World Atlas & Industry Guide.

The Japanese energy need today consist of 858 TWh/yr, fi-om which around 92 TWh/yr is produced with hydropower plants at the moment. The gross theoretical annual hydropower potential reaches according to our analyses around 164 TWh/yr. Which equals the net capacity of the nuclear power plants in Japan of 163 TWh/year (WEC, 2013). A high proportion of Japan's potential for hydro generation has already been harnessed. Most of the sites suitable for the installation of large-scale conventional hydropower plants have now been developed. The great majority of the larger hydro projects presently under construction or planned in Japan are pumped-storage schemes. The estimated value of 164 TWh/yr is about 4.4 times less than the gross potential of

Waduk Saguling, Jawa, Ind Waduk Mi-ica, Jawa, Ind Waduk Jatiluhur, Jawa, Ind Waduk Wlingi, Jawa, Ind Waduk Mi-ica, Jawa, Ind Waduk Sutami, Jawa, Ind

Generated Calculated (GWh/yr) (GWh/yr) 1694 910 2440 1731 171 101 130 70 446 442 416 225

718 TWH/yr estimated in the "Hydropower and Dams", World Atlas & Industry Guide.

Average annual hydro output in Indonesia is only about 12.5 TWh/yr which is approximately 8% of Indonesia's electricity supply. The gross theoretical annual hydropower potential reaches according to our analyses around 2410 TWh/yr, indicating the evident scope for further development within the feasible potential. For simplicity the Malaysian part of Borneo and Papua New Guinea are included in this estimate. The value of 2410 TWh/yr is close to the gross potential of 2147 TWh/yr estimated in the "Hydropower and Dams", World Adas & Industry Guide.

Average annual hydro output in Taiwan is only about 4.3 TWh/yr which is approximately 2.1% o f Taiwan's electricity supply. The gross theoretical annual hydropower potential reaches according to our analyses around 79 TWh/yr, which is somewhat behind the 103 TWh/yr estimated in the "Hydropower and Dams", World Afias & Industi-y Guide.

Overall the gross theoretical annual hydropower potential in Taiwan and Indonesia match estimates fi-om earlier studies. There is however a large difference in the estimations For Japan and the Philippines. The difference in estimates is expected to be due to inconsistencies between countries and approaches. In the most recent report from the World Energy Council (WEC, 2010) the Philippines for example isn't mentioned at all. For Japan on the other hand it is not clear whether pumped storage capacity is included in the previous estimates.

Besides numerous potential locations, our database also contains gross potential hydropower capacity at existing reservoirs (See Table 4). A validation between calculated and generated production for several large hydropower plants showed that for all plants the calculated capacity is less than the produced energy. Next to inaccuracies in the elevation data, this might also be caused by uneven, intra, and inter annual runoff distribution.

CONCLUSION AND RECCOMMENDATION

The aim of this research was to give insight in the theoretical gross capacity o f hydropower potential of East Asian Islands, its distribution between micro, mini, small and large hydropower and to which amount hydropower plants can f u l f i l l the present energy consumption. We attempted to do this by creating a model and simulate consistent input data.

The gross theoretical hydropower capacity potential is about 2,900 TWh/yr and this estimations is in the order of magnitude made by previous studies. Large, small, mini and micro hydropower account for respectively 27%, 39%, 28% and 6% of this potential.

Depending on the country, the total amount of gross theoretical hydropower capacity can fulfill the electricity demand. The Philippines and Indonesia have a huge untapped potential. While Japan has used nearly all potential sites for constructing hydropower plants.

Much of the gross potential is neither be technically nor economically feasible yet, but with depleting oil and gas resources and rising prices might be in the future.

This research clearly indicates areas with a lot of hydropower potential, and has successfully provided insight in the spatial distribution.

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