Iris Grossmann

Quantifying the hurricane risk to offshore wind turbines

The U.S. Department of Energy has estimated that if the United States is to generate 20% of its electricity from wind, over 50 GW will be required from shallow offshore turbines. Hurricanes are a potential risk to these turbines. Turbine tower buckling has been observed in typhoons, but no offshore wind turbines have yet been built in the United States. We present a probabilistic model to estimate the number of turbines that would be destroyed by hurricanes in an offshore wind farm. We apply this model to estimate the risk to offshore wind farms in four representative locations in the Atlantic and Gulf Coastal waters of the United States. In the most vulnerable areas now being actively considered by developers, nearly half the turbines in a farm are likely to be destroyed in a 20-y period. Reasonable mitigation measures—increasing the design reference wind load, ensuring that the nacelle can be turned into rapidly changing winds, and building most wind plants in the areas with lower risk—can greatly enhance the probability that offshore wind can help to meet the United States’ electricity needs.

Indicators To Determine Winning Renewable Energy Technologies with an Application to Photovoltaics

Several forms of renewable energy compete for supremacy or for an appropriate role in global energy supply. A form of renewable energy can only play an important role in global energy supply if it fulfills several basic requirements. Its capacity must allow supplying a considerable fraction of present and future energy demand, all materials for its production must be readily available, land demand must not be prohibitive, and prices must reach grid parity in the nearer future. Moreover, a renewable energy technology can only be acceptable if it is politically safe. We supply a collection of indicators which allow assessing competing forms of renewable energy and elucidate why surprise is still a major factor in this field, calling for adaptive management. Photovoltaics (PV) are used as an example of a renewable energy source that looks highly promising, possibly supplemented by solar thermal electricity production (ST). We also show why energy use will contribute to land use problems and discuss ways in which the right choice of renewables may be indispensible in solving these problems.

Hurricane Modification and Adaptation in Miami-Dade County, Florida

We investigate tropical cyclone wind and storm surge damage reduction for five areas along the Miami-Dade County coastline either by hardening buildings or by the hypothetical application of wind-wave pumps to modify storms. We calculate surge height and wind speed as functions of return period and sea surface temperature reduction by wind-wave pumps. We then estimate costs and economic losses with the FEMA HAZUS-MH MR3 damage model and census data on property at risk. All areas experience more surge damages for short return periods, and more wind damages for long periods. The return period at which the dominating hazard component switches depends on location. We also calculate the seasonal expected fraction of control damage for different scenarios to reduce damages. Surge damages are best reduced through a surge barrier. Wind damages are best reduced by a portfolio of techniques that, assuming they work and are correctly deployed, include wind-wave pumps.

Impact of Beliefs About Atlantic Tropical Cyclone Detection on Conclusions About Trends in Tropical Cyclone Numbers

Whether the number of tropical cyclones (TCs) has increased in the last 150 years has become a matter of intense debate. We investigate the efiects of beliefs about TC detection capacities in the North Atlantic on trends in TC num- bers since the 1870s. While raw data show an increasing trend of TC counts, the capability to detect TCs and to determine intensities and changes in intensity has also increased dramatically over the same period. We present a model of TC activ- ity that allows investigating the relationship between what one believes about the increase in detection and what one believes about TC trends. Previous work has used assumptions on TC tracks, detection capacities or the relationship between TC activity and various climate parameters to provide estimates of year-by-year missed TCs. These estimates and the associated conclusions about trends cover a wide range of possibilities. We build on previous work to investigate the sensitivity of these conclusions to the assumed priors about detection. Our analysis shows that any inference on TC count trends is strongly sensitive to ones speciflcation of prior beliefs about TC detection. Overall, we regard the evidence on the trend in North Atlantic TC numbers to be ambiguous.

Solar electricity supply isolines of generation capacity and storage

Significance The recent sharp drop in the cost of photovoltaic (PV) electricity generation accompanied by globally rapidly increasing investment in PV plants calls for new planning and management tools for large-scale distributed solar networks. We found that pairs of electricity generation capacity G and storage S, such that S is minimal to provide a given dispatchable electricity capacity for a given G, exhibit a smooth relationship of mutual substitutability between G and S. These G−S isolines support the solution of several tasks. This includes optimizing the size of G and S for dispatchable electricity, optimizing connections between solar parks across time zones for minimizing intermittency, and management of storage in situations of far below average insolation. The recent sharp drop in the cost of photovoltaic (PV) electricity generation accompanied by globally rapidly increasing investment in PV plants calls for new planning and management tools for large-scale distributed solar networks. Of major importance are methods to overcome intermittency of solar electricity, i.e., to provide dispatchable electricity at minimal costs. We find that pairs of electricity generation capacity G and storage S that give dispatchable electricity and are minimal with respect to S for a given G exhibit a smooth relationship of mutual substitutability between G and S. These isolines between G and S support the solving of several tasks, including the optimal sizing of generation capacity and storage, optimal siting of solar parks, optimal connections of solar parks across time zones for minimizing intermittency, and management of storage in situations of far below average insolation to provide dispatchable electricity. G−S isolines allow determining the cost-optimal pair (G,S) as a function of the cost ratio of G and S. G−S isolines provide a method for evaluating the effect of geographic spread and time zone coverage on costs of solar electricity.

Reply to Powell and Cocke: On the probability of catastrophic damage to offshore wind farms from hurricanes in the US Gulf Coast

As a result of Powell and Cocke’s letter (1) regarding our paper on the hurricane risk to offshore wind turbines (2), we have reviewed and updated some of our analysis. However, our conclusion remains that wind turbines in hurricane-prone areas face extreme wind conditions significantly different from those for which offshore wind turbines are currently designed; some of this risk can be mitigated through engineered mechanisms: [↵][1]1To whom correspondence should be addressed. E-mail: paulina{at}cmu.edu. [1]: #xref-corresp-1-1

Atlantic Hurricane Risks: Preparing for the Plausible

A more robust decision making procedure must be established to best prepare for unknown severity and frequency of hurricanes.

Leveraging Pittsburgh's Energy Efficiency Social Network to Predict Next Adopters

By constructing the social networks of large commercial building managers in a two-phase project, we hope to unveil the catalysts that diffuse energy efficient technologies. Completion of both phases will demonstrate 1) which actors in energy efficiency networks are influential and 2) which attributes are highly correlated with owners who pursue energy efficiency, suggesting owners who do not exhibit these attributes might benefit from additional incentives. Results of this study will outline innovative policies for leveraging existing social networks of building owners to enhance the adoption of energy efficient practices.

Oceans and new renewable energy systems

Major relationships between energy systems and oceans are due to marine transportation of energy resources, emissions from use of these resources, and mining and exploration, in particular of natural gas and crude oil. These relationships are poised to change. A multitude of problems have emerged in the fossil fuel energy sector, e.g., “peak oil” and even “peak coal”, wildly fluctuating prices of energy from fossil fuels, and massive emissions causing environmental problems such as ocean acidification. Hence, globally, significant efforts are directed at the creation of new energy systems based on renewable energy. Such systems, if constructed on a large scale, would change many parameters of ocean affairs. Large-scale construction is expected given significant investments in renewable energy systems in different parts of the globe and the prospect that such systems may become competitive in many regions in 2014. We discuss parameters of such renewable energy systems and elaborate effects on transportation of resources and on the wider environment including oceans, and draw conclusions on possible changes for oceans.