optimization

Efficiency Of Offshore Wind | Earth Wise

December 10, 2021 By EarthWise Leave a Comment

After many years of debates, delays, and controversies, offshore wind is about to expand in a big way in the United States. The White House has announced the goal to deploy 30 gigawatts of offshore wind – enough to power 90 million homes – along the East Coast seaboard by 2030.

In New York State, there are now five offshore wind projects in active development. The state goal is to have nearly a gigawatt of offshore wind by 2035, enough to power over 4 million homes.

These projects involve the use of thousands of physically large, high-capacity wind turbines deployed over large areas at an unprecedented scale. Such mammoth installations bring with them unique problems.

Low-turbulence conditions over water lead to the fact that individual wind farms will experience each other’s wake (the disturbance of their airflow) even when turbine arrays are 15 to 50 miles apart. As a result, turbines may fatigue earlier, and groups of turbines may experience up to 30% lower power production due to wake effects.

Industry trends are causing an increased probability of large wake-induced energy losses within individual wind farms and an increasing probability of wake interactions.

These issues have been studied in new research published by researchers at Cornell University. The research presents simulations that may be helpful to optimize turbine spacing in the ongoing deployments and assist plans for future ones. Improved understanding of wind turbine and wind-farm wake is essential in ensuring that the financial investments in offshore wind result in electricity-generation goals met at the lowest possible cost.

According to Department of Energy studies, offshore wind resources around the United States could potentially generate more electricity than the entire country currently uses.

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Scientists bring efficiency to expanding offshore wind energy

Photo, posted August 9, 2016, courtesy of Lars Plougmann via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Solar-Powered Desalination | Earth Wise

March 20, 2020 By EarthWise Leave a Comment

About 1% of the world’s population is dependent on desalinated water to meet daily needs, but water scarcity is a growing problem that experts believe will affect 14% of the world’s population within the next five years.

Desalination takes much more energy than, for example, transporting fresh water over large distances. In general, desalination costs are much higher than those associated with fresh water, but beyond costs, freshwater is simply not always available.

Researchers at MIT and Shanghai Jiao Tong University in China have developed a completely passive solar-powered desalination system that could provide more than 1.5 gallons of fresh drinking water per hour for every square meter of solar collecting area. Such a system could provide an efficient, low-cost water source for coastal areas that are off the grid.

The system uses multiple layers of flat solar evaporators and condensers topped with transparent aerogel insulation. The key to its efficiency is the way it uses each of its multiple stages to desalinate water. At each stage, heat released by the previous stage is harnessed instead of wasted. The proof-of-concept device, which was tested on an MIT building rooftop, produced more than twice as much water as the record amount produced by any previous passive solar-powered desalination system.

The researchers plan further experiments aimed at optimizing the choice of materials and configurations and to test the system under realistic conditions. The hope is to have a technology that can play a role in alleviating water scarcity in parts of the world where electricity is scarce, but seawater and sunlight are abundant.

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Simple, solar-powered water desalination

Photo courtesy of MIT/researchers.

Earth Wise is a production of WAMC Northeast Public Radio.

Weather-Responsive Traffic Signals

April 17, 2019 By EarthWise Leave a Comment

We all spend time sitting at red lights – sometimes it seems like a whole lot of time. There is a fair amount of science applied in the design of traffic signals that at least has the aim of easing congestion and improving traffic safety.

Signals in modern cities are timed using optimization models that analyze multiple factors including traffic volume and speed with the goal of safely getting as many vehicles as possible through intersections. It sure doesn’t seem that way in many places, but that is the intent in any case.

But a real problem with these models is that they assume normal conditions including weather conditions. In places that experience real winter conditions, the assumptions of traffic models fail. If the road surface is covered with snow and ice and visibility is poor, variables like speed and stopping distances become very different.

Researchers at the University of Waterloo in Canada collected data from real-world intersections and ran computer simulations to determine the effects of adjusting traffic signal behavior in bad weather (as well as in the presence of other conditions such as accidents or construction.) They found that such adjustments could reduce traffic delays by as much as 20%.

Cities with computerized signal systems are already equipped to remotely and inexpensively adjust the timing of traffic lights. To gain the benefits of smarter signals, there would need to be video cameras and a certain amount of artificial intelligence software that would be able to automatically tweak the timing of lights in response to traffic changes caused by weather, accidents or construction.

It sounds like a great idea.

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Weather-responsive intersections could ease traffic congestion

Photo, posted September 22, 2009, courtesy of Tristan Bowersox via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.