The Potential for Offshore Wind Farms in California

In order to take advantage of the many benefits of wind power, it is important to first identify which regions could viably harness the technology. Without a clear picture of the extent of wind resources it would be impossible to know their potential impact on the grid, and therefore, the environment. Dvorak et al. (2009) modeled the average wind speeds off the coast of California to measure the total available offshore wind power for the state. Remarkably, 17–31% of California’s electricity demand could be met using current offshore turbine technology. Factoring in floating turbines (which are still in prototype stages, but could be constructed in deeper waters) offshore wind power could provide 174–224% of the state’s energy needs. Clearly, not all of this energy capacity can be harnessed; however, there is still an enormous renewable energy resource to be developed off the coast of California. — Noah Proser 
Dvorak, M.J., Archer, C.L., Jacobson, M.Z., 2009. California offshore wind energy potential. Renewable Energy 35, 1244–1254.

 In order to measure the total wind power available, Dvorak et al. used data from offshore buoys to create a weather model. Unfortunately, data from the buoys could not be used directly since there are too few to create a useful map of wind speed; however, when the buoy data were compared to the weather model the variance between the two was relatively low. The researchers also examined bathymetry (water depth) data to determine the type of turbine foundation that could be constructed in each area. Typically, monopile foundations can be used in waters up to 20 m in depth; multi-leg foundations are used up to 50 m in depth, and floating turbines would be used in deeper waters.
Though the authors discounted the power available in deeper waters somewhat, floating turbine technology will soon be a reality. Currently, a 2.3 MW floating turbine is operating in the North Sea off the coast of Norway. As more research is conducted on this technology, the wind resources available to California and many other coastal states will greatly increase.
Overall, California has an abundant wind power resource that should not be ignored. The offshore wind capacity in Northern California is particularly impressive, potentially providing 2.2 GW of average output. Furthermore, offshore wind is relatively consistent throughout the day unlike land-based wind power. Though only a fraction of this resource is likely to be utilized, it can still have a substantial impact on California’s energy independence and greenhouse gas emissions.

Urban Wind Power: Another Source of Renewable Energy

Wind power can also be used on a small scale to reduce greenhouse gas emissions and household energy costs. While roof-top wind turbines are not as efficient as those used for large-scale wind farms, they have the advantage of not being subject to energy losses from transmission and distribution. Nalanie Mithraratne (2009) performed a life cycle assessment of 1.5 kW Swift wind turbines in New Zealand to determine their net energy savings and emissions reductions. She found that, for households in New Zealand, a roof-top turbine would take 7–11 years to make returns on energy, and 10–16 years to compensate for the CO2 emitted in its manufacture, transport, and maintenance. — Noah Proser 
Mithraratne, N., 2009. Roof-top wind turbines for microgeneration in urban house in New Zealand. Energy and Buildings 41, 1013–1018.

 First, Mithraratne had to determine what locations and turbines would be viable for micro-scale wind power production. In the urban environments being considered, wind resources are affected by nearby buildings and trees as well as the architecture of the building the turbine is mounted on. These obstacles can significantly reduce wind energy production. Additionally, the turbines cannot exceed community noise standards and must be light enough to be installed on an average household’s roof. The inherent difficulties involved with urban wind power effectively limit turbines to areas with average wind speeds of at least 5.5 m/s. Mithraratne also suggests that turbines should only be installed on buildings that are 50% higher than the surrounding structures.
The life cycle analysis of the turbines revealed that the manufacturing process accounts for nearly 80% of the energy used and roughly 70% of the greenhouse gases emitted in the turbine’s life. The author also evaluated the energy costs of transporting, installing, maintaining, and, finally, decommissioning the turbines. Overall, one turbine can be expected to emit 2312 kg of CO2, while generating 10520–16820 kWh of electricity during its 20-year lifespan. Thus, using urban wind power can create a net reduction of 539–2246 kg of CO2. The wide range of this statistic is due to the different scenarios Mithraratne considered, which involved different maintenance regimes and disposal techniques.
It is important to note that the life cycle analysis presented here was focused on urban wind power in New Zealand. Transportation of the turbines from the UK was a large factor in the energy costs and emissions in this scenario (roughly 18%). Clearly, less remote locations would have lesser transportation costs, and, correspondingly, higher net CO2 reductions with quicker returns on investments. Though urban wind power is unlikely to make up any large portion of worldwide energy production, it could be a useful and practical addition to the grid.

Climate Change Can Affect Local Wind Power Resources

As wind power becomes a more important part of electricity production around the world there will be increased efforts to locate suitable regions with high wind power density where wind farms can be developed. Normally, wind farm sites are selected based on the proximity of transmission lines, the environmental impact of installing turbines, and the abundance of wind resources in the area. This process fails to take into account possible future changes in wind availability due to variations in surrounding vegetation, or even global climate change. De Lucena et al. (2009) project that wind conditions in Brazil may actually improve as the climate changes, making investment in new wind farms an attractive prospect. — Noah Proser 
De Lucena, A.F.P., Szklo, A.S., Schaeffer, R., Dutra, R.M., 2009. The vulnerability of wind power to climate change in Brazil. Renewable Energy 35, 904–912.

 In this study, researchers examined the A2 (high future CO2 emissions) and B2 (low future CO2 emissions) IPCC scenarios using a downscaled, regional HadCM3 general circulation model (GCM). They focused on Brazil, which has a flourishing market for renewable energies, especially wind power. Though wind power density is affected by both wind speed and wind shear, they were only able to project the average wind speeds for the region due to the limitations of the GCM. Furthermore, there is no way to account for factors like future changes in vegetation, and land use that can also affect wind power density.
Overall, De Lucena et al. demonstrate very little certainty regarding their predictions. Even with advanced climate models, it is impossible to account for all of the factors affecting wind power density in an area. Matters are further complicated by man-made changes in vegetation like deforestation. Such changes can have huge effects on wind patterns; however, they cannot be effectively modeled.

Nonetheless, the study does provide some important insights. Unlike conventional power plants, which have a quantifiable supply of fuel, renewable sources depend on resources that are in constant flux. Just as hydroelectric power plants are dependent on rain to renew their water sources, wind farms are subject to changing wind patterns. Brazil may, in fact, gain better wind resources due to climate change. Though this projection is relatively uncertain, it highlights the dependence of wind power on climate conditions and it is important that energy investors and regulators are aware of this dependence when planning for renewable energies.

Public Demand for Green Energy May Eliminate the Need for Renewable Energy Price-Equivalency

The relatively high cost of renewable energy sources, like wind and solar power, is a major hurdle to reducing greenhouse gas emissions and meeting green energy goals. While wind power has relatively low operating costs, the initial costs of wind projects are quite high. This is especially true when new transmission lines are required in order to connect wind farms to the grid. Though other sources of power may be cheaper, Yoo and Kwak (2009) suggest that consumers are willing to pay more for clean energy. This willingness to pay (WTP) is enough to foster investments in renewable energy that can increase green energy production while reducing future costs. Consequently, the current high cost of wind power may not be a problem for the industry. Noah Proser
Yoo, S.H., Kwak, S.Y, 2009. Willingness to pay for green electricity in Korea: a contingent valuation study. Energy Policy 37, 5408–5416.

The researchers performed a dichotomous choice contingent valuation survey to determine the WTP for green energy of individual households in South Korea. Participants in the survey were first given information about renewable energy sources, as well as governmental policies on green energy. They were then asked whether they would accept a specified surcharge on their monthly energy bill in order to increase South Korea’s renewable energy from 0.2% to 7% of total energy consumption (a goal that has been set by the South Korean Government). Following a ‘yes’ or ‘no’ answer the researchers would offer another bid to arrive at a more specific WTP. They used a total sample of eight hundred households with varying starting bids to insure the amount originally specified did not affect the responses.
On average, households offered a monthly WTP of about 1681 (South Korean Won), or roughly $1.8. Though this amount may seem small, when multiplied by the number of households it translates to about $160 million per month. This amount should provide a large incentive for energy corporations and governments alike to supply renewable power.
It is important to note that this result is an average of the responses offered. In reality, the large majority of participants showed no willingness to pay whatsoever. There are many reasons for this outcome. Contingent valuations are often criticized for depending on easily influenced responses rather than actual behavior, which can be studied through revealed preference valuation. Furthermore, Yoo and Kwak found that only 19.5% of participants had a thorough knowledge of renewable energy. Though the survey included basic information on the subject, it is unlikely that this information alone would be enough to sway a response. With a more educated public there may have been a higher WTP.
Nonetheless, a significant amount of the population was willing to pay extra for renewable energy. Even if a surcharge like the one described in the survey was purely voluntary, it seems a substantial amount of money could be raised for green energy sources. Governments and energy providers should take note of this WTP when creating energy policies and building new power plants. Essentially, the price disparity between renewables and cheaper sources may not matter if the public is willing to pay for cleaner energy.

Using Wave Power with Wind Power Alleviates Intermittency Problems

Wind power, like many forms of renewable energy, suffers from intermittence that weakens its potential as a baseload power source. Pumped hydroelectric energy storage can mitigate the variability associated with wind power; however, it is not always available. When energy storage is not an option and wind conditions are sub-optimal, conventional power plants are used to supply the grid. These conventional power plants run less efficiently when they are forced to change output on the basis of wind intermittency, creating decreasing marginal reductions of CO2 emissions (ESB 2004). In order to avoid the problems associated with intermittency, Fusco et al. (2009) propose using wind power in combination with wave energy. Since these two resources have an inverse correspondence in some areas, together they could reduce the need for energy storage and CO2 emitting, backup power plants. Noah Proser
ESB National Grid. Impact of wind power generation in Ireland on the operation of conventional plant and economic implications. February 2004.
Fusco, F., Nolan, G., Ringwood, J.V., 2009. Variability reduction through optimal combination of wind/wave resources – An Irish case study. Energy 35, 314–325.

The researchers focused on the ability to combine wind and wave power in Ireland in order to meet the country’s new goal of 33% renewable energy. They used data on wind speeds, wave periods, and wave heights collected from weather buoys by the Irish Marine Institute. Energy potentials were calculated based on 3.5 MW offshore wind turbines and the 750 kW Pelamis wave energy converter. The researchers considered the West, Southwest, South, and East coasts of Ireland separately since wind/wave correlations differ geographically.
Fusco et al. found that the West and South coasts of Ireland experienced winds and waves that were not highly correlated, while there was a high correlation on the East coast. Since the East coast is harbored from the Atlantic, wave energy is largely dependent on local winds, thus creating a high correspondence. On the other hand, the West and Southern coastlines can utilize wave energy created in the open ocean. These higher energy swells provide power when local wind power is insufficient.
In combination, wave and wind power can significantly reduce renewable power variability. Though more dependable power sources will still be necessary without significant energy storage options, this reduced variability will allow these plants to run more efficiently. Fusco et al. also emphasize that wave power is relatively predictable, making grid management easier. Though more research is needed in order to identify the best arrangements of wind and wave power systems, it is clear that grouping these technologies will make Ireland’s energy goals more feasible and efficient.

New High-Capacity Wind Turbines Significantly Reduce Collision-Related Avian Mortality

While wind power has received great support as a carbon-neutral, renewable energy source, it is not without ecological problems. Smallwood and Karas (2009) found that wind turbines in the Altamont Pass Wind Resource Area in Central California were responsible for the deaths of thousands of birds from 1998 to 2003. Many of the birds that were killed were endangered or otherwise protected species.
Fortunately, as outdated wind turbines are replaced with newer, more efficient ones avian mortality decreases by 66%. Nonetheless, it is important to consider migratory pathways and avian habitats when constructing new wind farms in order to best mitigate the environmental impacts of such projects. Noah Proser

Drewitt, A.L., Langston, R.H.W., 2008. Collision effects of wind-power generators and other obstacles on birds. N.Y. Acad. Sci. 1134, 233–266.
Smallwood, K.S., Karas, B., 2009. Avian and bat fatality rates at old-generation and repowered wind turbines in California. Journal of Wildlife Management 73, 1062—1071.

Smallwood and Karas counted the number of birds killed by wind turbines in the Altamont Pass from 1998 to 2003. In 2005, the Diablo Winds Energy Project replaced 126 inefficient turbines with 31 higher capacity turbines. With a higher surface area and lower rotor speed these turbines were expected to be less dangerous for birds flying through the pass. Subsequently, the researchers conducted another survey from 2005 to 2007 to determine whether the new turbines significantly reduced avian mortality. In order to avoid complications from differing bird populations over time, both old and new turbines were included and compared in the later survey.
The authors found that the new turbines killed 66% fewer birds than the old generation of turbines. Furthermore, since the new turbines have a much higher capacity, modern wind farms can be more sparsely populated or smaller while still producing the same amount of power. This reduction in size or density can further reduce the risk for birds. Despite the advantages of the new generation of turbines, these levels of avian mortality may still be unacceptable. For this reason, future wind power proposals should be carefully evaluated to avoid the migratory patterns of endangered birds.
Unfortunately, some level of bird kills may be inevitable when it comes to wind power regardless of the precautions taken. With that said, wind power should not be abandoned. After all, turbines are not the only anthropogenic causes of avian mortality. Untold numbers of birds are killed each year from collisions with windows, television and radio broadcasting towers, and power lines (Drewett and Langston 2008). In all likelihood, wind turbines are responsible for a minute amount of overall avian mortality. Moreover, wind farms can replace power plants, which pollute the habitats these birds depend on. We should make efforts to minimize bird kills from wind turbines; however, avian mortality is not likely to be a vital issue in the future of wind power.

Marine Habitat Creation from Offshore Wind Power

Offshore wind farms are a relatively new source of power that have gained tremendous popularity in Europe. Offshore turbines are often preferable to onshore projects since winds are typically steadier at sea; however, environmentalists have raised concerns about the impact they could have on marine life. In particular, the construction of monopiles to support turbines could destroy important seabed habitats. Surprisingly, Wilson and Elliott (2009) discovered that offshore wind farms can actually create thriving new habitats that far outweigh the amount of seabed disturbed by their construction. Noah Proser
Wilson, J.C., Elliott, M., 2009. The habitat-creation potential of offshore wind farms. Wind Energy 12, 203–212.

The researchers examined the effects of existing wind farms in the United Kingdom on colonization and fish-use. In particular, they focused on the habitat creating potentials of different types of scour protection. Monopile scour occurs when the sediment around the base of a monopile is washed away, compromising the integrity of its foundation. In order to prevent scouring, monopiles are surrounded with gravel, boulders, or synthetic fronds.
Though such protection disturbs the original seabed habitat, it also increases the surface area and complexity of the area around the monopile. Wilson and Elliott found that both boulder and gravel protection create more than double the habitat lost to their construction. While synthetic frond protection does not perform as well as the other methods, it still almost entirely makes up for the habitat lost.
It is important to note that the habitat created by the scour protection is different from what is lost; however, Wilson and Elliott contend that, since turbines are likely to be placed in areas with relatively sparse seabed, the added complexity from the scour protection will actually raise the carrying capacity of the surrounding environment. Further improvements can be made by using a blend of different scour protection methods on different turbines to promote diversity. ‘Reef balls’ (boulders with holes bored into them to maximize surface area used to create artificial reefs) can also be used in place of other scour protection materials. Furthermore, they suggest that wind farms could act as de facto marine sanctuaries because bottom trawling would not be allowed near them to prevent damages to the turbines.
Despite the concerns over the environmental impact of offshore wind projects, Wilson and Elliott assert that wind farms have a largely beneficial impact on marine life. They expect that the new habitats created by the turbines will boost fish populations and thus benefit fishermen as well. It seems as though productive, complex marine habitats may just be yet another benefit of wind power.

High-Altitude Wind Power May Solve Future Energy Needs

As fossil fuel energy sources fall into disfavor due to climate-warming greenhouse gas emissions and other pollution associated with their use, renewable sources of energy are expected to make up an increasing role in the world’s energy portfolio. Wind energy is one of the cheapest and fastest growing renewable energy sources available; however, conventional wind farms are often criticized for their intermittence and lack of overall power. Harnessing wind power from higher altitudes (500–12,000 m) could mitigate both of these problems by making use of the jet streams’ abundant and relatively persistent wind energy (Archer and Caldeira 2009). Unfortunately, even the jet streams suffer from variations, and high-altitude wind power systems will still require large energy storage capabilities if they are to become reliable sources of electricity. —Noah Proser
 Archer, C., Caldeira, K., 2009. Global assessment of high-altitude wind power. Energies 2, 307–319.

Archer and Caldeira assessed the availability of high-altitude wind power using data collected from the National Centers for Environmental Prediction and the Department of Energy from 1979 to 2006. They focused on wind speed and density in order to determine the optimal elevations and geographic regions for high-altitude wind power. Wind power densities were then divided into percentiles representing the density that was exceeded 50, 68, and 95% of the time as a measure of dependability. For the purposes of this assessment, they considered two means of high-altitude wind power. The first system, KiteGen, uses kites connected to generators on the ground that create electricity when the kites are pulled by the wind. KiteGen is designed for altitudes of 1,000 m and can produce 620 kW per unit. Alternatively, Flying Electric Generators produced by Sky Windpower use rotors to generate electricity, which is transmitted back to the ground. These generators are designed to fly at 10,000 m and produce 40 MW each.
Archer and Caldeira found that cities like Tokyo, Seoul, and New York, which are affected by polar jet streams, could harvest more than 10 kW/m2 at high altitudes (8,000 m) at least 50% of the time. Furthermore, since wind speed increases with altitude, most regions considering wind power would be greatly benefitted by using high-altitude generators rather than conventional turbines. Ideally, these high-altitude generators would be able to adjust their altitudes as winds shift with weather conditions.
Even with all of the advantages of high-altitude wind power, intermittency can still be a problem. To deal with this problem, wind farms can store energy in batteries, pumped hydroelectric, and other forms during non-peak hours. This stored energy can then be supplied to the grid when the wind farm is not at optimal production. Another way to deal with the intermittency of wind power is to have several farms in different locations. When the wind isn’t blowing in one area, farms in other areas can still provide electricity to the grid.

It is still unclear whether wind can provide reliable baseload power for our growing energy demands; however, high-altitude wind power seems like a serious contender among renewable energies. At high altitudes reliability and overall power production are greatly increased. Furthermore, high-altitude wind power is available where ground-level wind power may not be feasible. Nonetheless, before widespread wind power can become a reality, improvements must be made in energy storage technologies, as well as large-scale transmission grids. —Noah Proser