Coal, Gas, Renewables

CO2 + 1,000

Issue 2 and Volume 115.

New research indicates the impact of rising CO2 levels in the Earth’s atmosphere will cause unstoppable effects for at least the next 1,000 years, leading researchers to estimate a collapse of the West Antarctic ice sheet by the year 3000 and a rise in global sea levels of at least four meters.

The study, published in the Jan. 9 Advanced Online Publication of the journal Nature Geoscience, makes predictions 1,000 years from now. It is based on best-case, “zero-emissions” scenarios built by researchers from the Canadian Centre for Climate Modelling and Analysis and the University of Calgary.

“We created ‘what if’ scenarios,” said one researcher. “What if we completely stopped using fossil fuels and put no more CO2 in the atmosphere? How long would it then take to reverse current climate change trends and will things first become worse?” The research team explored zero-emissions scenarios beginning in 2010 and in 2100.

Seems the Northern Hemisphere fares better than the south in the simulations, with climate change patterns reversing within the 1,000-year timeframe in places like Canada. At the same time, parts of North Africa see desertification as land dries out by up to 30 percent. Ocean warming of up to 5 C off of Antarctica is modeled to trigger widespread collapse of the West Antarctic ice sheet, a region the size of the Canadian prairies.

Modeling Power Systems

Power outages can result in billions of dollars in costs. Research from North Carolina State University has led to development of an approach by which high-resolution power-system measurements, known as Synchrophasors, can help develop models of large power systems.

Synchrophasors are real-time measurements of voltages and currents that provide a high-resolution view of complex events in a power system. They are measured by digital recording devices called phasor measurement units (PMUs). PMUs are comparable to surveillance cameras that monitor the dynamics of groups of people in busy places and indicate how people respond and interact with each other.

The North American power grid is divided into operating zones, each of which has several such generation pockets, across which a disturbance can disseminate.

During the 2003 Northeast Blackout, generating units in Ohio and New England appeared to be functioning smoothly. However, there was disparity between the two regions when it came to reactive power. That created a cascading series of voltage collapses. This cut off power to some 50 million people, was linked to multiple fatalities and cost an estimated $4 to $10 billion. The event highlighted the need to monitor the system more broadly, rather than focus on individual nodes in isolation.

Researchers have developed an approach to create cluster models, which uses Synchrophasors from PMUs at specific points within a cluster of nodes. The approach also allows operators to identify how the clusters are connected by comparing PMU measurements at different points in the system. “Once you have modeled the clusters and determined their connections,” a researcher said, “our algorithm enables you to model the interactive behavior of the clusters within the larger system in the face of large disturbances.” The models could help system operators track and predict the global health of any distributed power system in real time. The hope is that catastrophes such as the 2003 blackout can be prevented.

Tidal Energy Impacts

Engineers at the University of Washington developed numerical models, solved by computers, to study how changing water pressure and speed around tidal turbines affects sediment accumulation and fish health.

The models look at windmill-style turbines that operate in fast-moving tidal channels. The turbine blade design creates a low-pressure region on one side of the blade. A small fish swimming past the turbine will be pulled along with the current and so will avoid hitting the blade, but might experience a change in pressure.

If the pressure change happens too quickly the fish might be unable to control its buoyancy and, like an inexperienced scuba diver, would either sink to the bottom or float to the surface. In a worst-case scenario, pressure changes could cause internal hemorrhaging and death.

Another set of numerical modeling looked at whether changes in water flow speed could affect the settling of suspended particles. Slower water speeds behind the turbine would allow more particles to sink to the bottom rather than being carried along by the current.

Modeling suggests this is the case, especially for particles about a half-centimeter in diameter. This could mean that a rocky bottom near a tidal turbine might become sandier, which might affect marine life.

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