CAPÍTULO II.2: REVISIÓN DE PROGRAMAS DE DEPORTE ESCOLAR
Yecla 45 es una de las que oferta esta campaña.
16. Deporte escolar en la Comunidad Valenciana
CNPC
= the net present cost ($)Cann.tot
= total annualised costs of the system ($/yr)Rproj
= project lifetime (yrs) i = real interest rate (%)CRF
= the capital recovery factor Source: Lilienthal et al. (2003).The cost recovery factor is calculated as follows:
Equation 9.2 The cost recovery factor calculations used in HOMER.
CRFU,
N) = i(
1 + if
(
1 + if
- 1 Where :N = the project lifetime (yrs)
i'-f i =
--
1 + fi' = nominal interest rate f = inflation rate
Source: Lilienthal et al. (2003).
Another output of HOMER used in the decision analysis process is the levelised cost of energy (COE), expressed as $/kWh. This is defined as the average cost per kWh of useful electrical energy produced by the system (Equation 9.3).
Equation 9.3 The levelised cost of energy (CO E) calculations used in HOMER
COE =
Cann.tot
Eprim
+Egrid.
Where :Cann.tot =
the total annualised cost of the system ($/yr)Eprim =
the amount of the primary load served (kWh)Egrid
= the amount of energy exported to the grid (kWh)Source: Lilienthal et al. (2003).
The total annualised cost of the system is the sum of the annualised capital costs, replacement costs, and the annual operation and maintenance costs (Lilienthal, et aI, 2003).
9. 1 . 2 Full- Term Duration - Settings and Inputs
The load profiles used in HOMER (Figure 6.7 and Figure 6.8) were based on the monitored data and have had all the data gaps modelled using Equation 6. 1 . The wind data used in the HOMER modelling was profiled (Figure 7.7), and the period of January to December 2000 has been re-scaled to match the modelled mean wind-speed of Site 3, 6.27 m/so The
solar data used in HOMER modelling was profiled (Figure 7.39), and the period of January to December 2000 was used. The hydro data used in HOMER (Figure 9.2) was based on the findings of the hydro monitoring (section 7.2.5). A residual flow of 30 fls will be allowed for in the modelling of the hydro systems.
250 200 en � 1 50 Q) �
�
1 00 I CL 50 oJan Feb Mar Apr May Jun Jul Aug Sep Qct Nov Oec
Figure 9.2 The annual stream flow of Totara Stream used in the HOMER modelling based on measured data.
Sensitivity Values
HOMER simulations can involve any number of sensitivity variables as required. The inputs that have sensitivity variables in this study are annual mean daily electricity load (kWh/d), mean annual solar insolation (kWh/m2/d), and mean annual wind-speed (m/s) inputs. The values entered were used by HOMER to re-scale the original data to match the sensitivity value. The sensitivity values in HOMER each comprise one part of a parametric analysis and therefore, each has an equal probability of occurrence. There was no way of indicating that one sensitivity value had more chance of occurring than any other value.
The mean electricity used per day (kWh/d) summary load data used in the HOMER model is listed in Table 9 . 1 . The 'monitored load' figure is a mean kWh/d value derived from the load data used (Chapter 6). The 'reduced load -1 0%' and the 'increased load +25%' figures were intended to assess the affect of decreasing the mean daily load by 1 0% due to energy efficiency uptake or increasing the mean daily load by 25% due to the potential for future growth.
Table 9.1 The electricity load inputs to be used in a sensitivity analysis in HOMER.
Site Load type profile (kWh/d) Gap-filled load Reduced load - 1 0% (kWh/d) I ncreased load +25% (kWh/d)
Domestic & Farm 1 22 1 09.8 1 52.5
1 - 9
Water heating 75 67.5 93.8
A figure of 1 0% was used as the lower limit partially because as a nation this is representative of the amount we could collectively reduce our electricity use during the recent electricity shortages (MED, 2002). The value of 25% has been used to account for load increases in the future.
Distributed Generation System Modelling
The wind energy resource at Totara Valley was monitored and recorded at five locations (Figure 5.3). The monthly wind-speed profile used in the HOMER modelling was compiled from the time-series profile of Wind Site 1 , and was re-scaled to the modelled mean wind-speed of Wind Site 3, 6.29 m/s (Figure 8.6). The wind-speed profile from Wind Site 1 was used because of the close proximity to Wind Site 3, and it was assumed that the profile would not differ much.
A figure of ± 1 5% was used as the uncertainty level for the sensitivity analysis values, and was based on reported long-term annual average wind-speed variation of between 5% to 1 0% (Reid, 1 991), 1 0%, (Van Lieshout, 1 997), and 6% (Raftery et al. , 1 999), and an analysis of the long-term wind-speed data from Grasslands, Palmerston North (Figure 9.3). A figure of 1 5% has been used as the upper and lower uncertainty value, thus the sensitivity figures of 7.21 mls and 5.33 mls were used.
The Weibull 'k' used was derived from the modelling (Figure 8.6), but the autocorrelation factor, diurnal pattern strength, and the hour of peak wind-speed were set at the Site 1 levels because the monitoring period at Wind Site 3 was too short to assess them, a nd the sites were close enough for these modelling values to be relatively similar.
4.0 �3 5 E :; 3.0 Cl> Cl> a. '? 2.5 "0 c: � 2.0 ' 1 . 5 1 988 1 989 1 990 1 991 1 992 1 993 1 994 1 995 1 996 1 997 1 998 1 999 2000 2001 2002 2003 2004 Year
Figure 9.3 The annual mean wind-speeds for Grasslands Research Centre, Palmerston North over a 1 7 -year period.
The solar resource at Totara Valley was monitored and the mean annual value of 2.99 kWh/m2/d for the period January to December 2000 was calculated from this time series. Given the location of the solar monitoring site at a higher-altitude relative to the houses in the valley floor (Figure 5.3) there will be shading at these sites (Figure 7.42). The estimated losses from this shading and the fluctuation of the solar resource from year to year were used to estimate a lower sensitivity analysis value. This has been estimated as being approximately 5% for actual shading loss (Table 7.3), and 1 5% for annual year-to-year differences (Table 7.5). The solar sensitivity value for the community has therefore been estimated at up to 1 5% less (15% being the greater of the two figures) than the monitored value for Sites 1 - 9. Therefore, 2.54 kWh/m2/d will be used as a sensitivity variable in the HOMER simulations. A higher level of sensitivity value was not used because it was considered unlikely that the resource at the valley floor would be much higher than that monitored at the higher altitude.
The parametric effects of all the sensitivity variables on the simulation results will be used in an analysis of renewable energy generation system performance under both load and
resource uncertainty. The use of these sensitivity values in this way will produce results based on the assumption of equal probability of occurrence, that is, a drop in load is as likely as a rise in consumption etc.
Fixed Values
Fixed value inputs into HOMER are values not used in sensitivity analyses. These were the economic inputs, grid-connected values, constraints, and the system technologies (wind turbines, solar photovoltaic arrays, micro-hydro systems and all other equipment). All renewable energy technology costs have been derived from surveying the retail costs of several suppliers and averaging these back to a unit cost ($/kW) for each of the technologies.
The Economic Settings were set as follows:
• The annual real interest rate of 3.8% was used, and was based on Equation 9.4 (Lilienthal et al., 2003), with the 2001 nominal loan interest rate of 6.8%27 and a rate of inflation of 3%. Equation 9.4 The formula used to calculate the real interest rate used in the HOMER economic model.
.
-(
I real
-
- 1 + ( Where :i real = the real interest rate