Modelling Wind Energy Development in the Electricity Sector Using a System Dynamics Framework
Figure 6: Cumulative Turbine Installations and Installed Capacity for Denmark – Simulated and Actual
Denmark Cumulative Turbine Installations
-1,000 1,000 3,000 5,000 7,000 9,000 11,000 13,000 15,000
Simulated cumulative installations Actual cumulative installations Denmark Cumulative Installed Capacity
2,000 4,000 6,000 8,000 10,000
0
The simulation in Figure 3 captures some of the early development but not nearly enough to match the actual dynamics that occurred during that period (also shown). For this reason, the early development is under-represented and the later development over-represented. This can be seen even more prominently in Figure 4. This graph shows fractional installations of new turbines on a yearly basis, where thousands of turbines were installed in the early 1980s during the ‘wind rush’. The combined incentives at local, state and federal level caused unprecedented growth in the sector, where some non-working machines were installed to capture investment tax grants in particular.38,39
Spain
Spanish development has been higher in generation and lower in turbine trends (see Figure 5), indicating again that the exogenous trend for marginal rotor diameter increase with size may not be appropriate. There may also be some limitations of the database source information, since individual case data involve a large number
Simulated cumulative installed capacity Simulations
Simulations were run for the different cases in order to compare the main output parameters of number of installed turbines (annual and cumulative) and installed generation capacity (annual and cumulative).
Selected examples are discussed and the data presented in a number of figures.
Colorado
The first case is Colorado in the US, which passed legislation by ballot vote in 2004 to institute a Renewable Portfolio Standard. The standard required compliance at various levels after 2007 and included a tradable certificate market. The expected value of the certificates acts as a price incentive for wind energy development in the state. Data on certificates show their values in compliance markets to be on the order of $0.02–0.05/kWh.32
As can be seen in Figure 2, wind development is slow until 2004, with large increases in 2006 before the first year of required compliance to the Renewable Portfolio Standard. The simulation also captures the strong growth trend after the year 2000.
California
The case of California involved a series of fiscal incentive programmes and negotiated power purchase agreements with utilities in the early 1980s and then the institution of a Renewable Portfolio Standard in 2003. The strong incentives in the early 1980s led to a boom in installations of modest sized turbines, many of which still operate today.
50
of data points from all over the globe. The similarity in the trend of development indicates that some of the relevant dynamics have been captured at the case level, but some of the assumptions render the model to simple to capture all of the important feedbacks for the case of wind energy development in Spain.
Denmark
The same issue holds true and is even more prevalent in the case of Denmark, where several different incentive programmes have been enacted since the late 1970s. From investment subsidies to negotiated power purchase agreements to research and development funding and finally a feed-in tariff programme, Denmark has used an aggressive policy scheme to push domestic wind energy development. The model overestimates the amount of wind energy development in the state after mid-2000, see Figure 6.
After the turn of the century, policy support for wind development in Denmark was reduced. However, the reinforcing feedback dynamics of the model would indicate that growth should continue despite the removal of the support. Thus, there are additional dynamics in the case of Denmark which may also be active such as those regarding system integration or differences between onshore and offshore development of the technology and costs.
Discussion
The collection of simulations shows that the scope of the case model with its focus on land availability, industry development and population allows us to capture some of the dynamics that have
MODERN ENERGY REVIEW – VOLUME 3 ISSUE 1 Actual cumulative installed capacity
Each state or country has a different set of policies that have or have not been applied in order to affect renewable energy development in general or wind energy in particular.
Installed capacity (MW)
1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009
1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009
Turbine number
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