Mt Rainier

Mt Rainier
Mt Rainier

Tuesday, April 26, 2011

Chernobyl 25th Anniversary



An aerial view of Chernobyl Nuclear Power Plant in April, 1986, with the red glow towards the center showing the heat from Unit #4. Source: epa.gov

The Chernobyl Disaster was a nuclear accident which occurred on April 26, 1986. It occurred in the Ukraine Republic (formerly part of the former USSR (Soviet Union)). Now the Chernobyl site is part of the country Ukraine. Today marks the 25th anniversary of the Chernobyl disaster.

It is particularly compelling to consider the impacts of Chernobyl today, twenty-fives years later, as we witness the unfolding of another nuclear disaster at Fukushima, Japan, following the 9.0 earthquake and tsunami on March 11, 2011. The two disasters arose from different circumstances and unfolded differently, however they share in common the impact of a low probability-high risk event.

They are set apart in both time and space, one occurring in vastness of the then-Soviet Union; the other set on the more densely populated island of Japan. The Chernobyl Disaster and the Fukushima disasters were both were graded as a 7 on the International Nuclear Event Scale. (Fukushima was raised from a 5 to a 7 on April 12, 2011, one month and a day following the earthquake and tsunami on March 11th).

How do we fathom such events as we seek to understand the risks of pursuing nuclear energy? How do we internalize these low probability-high risk events so that we carefully assess risks yet do not fall prey to unwarranted fears and suspicions? Do we hide our heads in the sands of improbability and ignore the potential of a very small yet very dangerous risk? Do we pour millions and billions of dollars to hedge against a risk that may never, in our lifetime occur? Do we even care about the impact of our decisions on those ancestors who may follow us many generations down the turnpike?

It is critical how we answer these questions, because our fate and the fate of our planet may hang in the balance. With the burgeoning population on this planet, the growing scarcity of resources, and the challenges presented by rising carbon dioxide levels, and other indications of planetary strain, we must find a way to make informed decisions that appropriately incorporate the low probability/high risk event in our search for and use of energy resources.

In my last blog posting, Emperor Penguin Energy-Risk Model - Part 2 , I discussed mathematical modeling, random variables and evolved a stochastic model of emperor penguin energy-risk behavior. I discussed some of the variables that may be considered in the emerging emperor penguin population, including mortality, morbidity and accident. I introduced the concept of a low probability event into the model (an eruption of an Antarctic volcano), and discussed the values of the stochastic process in informing results. The post was intended to discuss energy seeking behavior in a different (emperor penguin) population as an energy seeking risk example using stochastic modeling.

In my last post I stated “The objective of the stochastic processes is to help us inform our decision making process, to help us understand the impact of variables under a wide range of assumptions, conditions, and scenarios. Thus a stochastic process should inform us about the expectations of the model under a wide variety of conditions, including the impacts of low probability / high risk events.”

However, a stochastic process cannot inform without reasonable assumptions. Assumptions must be developed to allow the stochastic process to produce a credible range of results that will indeed be informative for the intended usages. There are many variables to consider, and assumptions to be made in analyzing risk. For a variety of reasons it may be difficult to obtain a robust set of assumptions that everyone agrees with for all potential uses.

Thursday, April 21, 2011

Emperor Penguin Energy-Risk Model - Part 2



Emperor Penguin Diving onto Ice Shelf from Sea, Stancomb Wells Ice Edge, Weddell Sea, Antarctica (Image on Alamy.com)

In my last blog post “An Emperor Penguin Energy-Risk Model” on April 14, 2011, l discussed the predator-prey relationship between the leopard seal and emperor penguin in Antarctica. The leopard seal waits at the edge of the ice shelf and opportunistically picks off emperor penguins entering or leaving the sea. For the emperor penguin, feeding at sea is a decision between the need to feed to live and the risk of dying in the mouth of a leopard seal..

In the blog post I state: “From studying the emperor penguin and the leopard seal we know the emperor penguins will continue to feed, but so will the leopard seal. Some emperor penguins, despite their various risk protection strategies, will get eaten. It is important to note that in a probabalistic sense, we know that some penguins will be eaten by the leopard seal, but we don’t know which specific penguins will “bite the dust”.” This is true casually looking at a row of emperor penguins lined up to go into the sea in search of food.

However, upon closer analysis and study, over a period of time, it might be possible to determine which emperor penguins have a bit of catch in their step, have been injured in a narrow escape from a leopard seal, or have slowed down. These emperor penguins might come a belly-flop short of landing on the ice, and end up as prey in the mouth of a leopard seal. However, it is also possible, that a healthy, fit, member of the emperor penguin colony might suffer a particularly ill-fated episode of bad luck. This penguin might be in the wrong place at the wrong time when the leopard seal is rising out of the water with its mouth wide open ready for business. In fact, you could have the emperor penguin equivalent of the 4.0-40 yard dash champion, and end up as leopard seal “dinner”, with some bad luck and timing.

Looking at emperor penguin energy-seeking behavior and risk, it becomes apparent that probabilities have a great deal to do with the outcome but are not deterministic. You may attach a relatively higher probability of being eaten to the more fragile members of the emperor penguin population and a relatively lower probability of being eaten to those fitter members. The larger the colony size, and the more emperor penguins entering the sea at the same time, the lower the risk, the probability of being eaten, for any particular emperor penguin as there are more penguins entering the sea. (“there’s safety in numbers”).

You can run scenarios with differing proportions of fragile and fit emperor penguins, with higher and lower probabilities of being eaten (mortality rates), varying degrees of illness (morbidity rates) or accident, including leopard seal attack. In such scenarios, the leopard seal would most likely pick off different emperor penguins each time the scenario is run, however there would be objective tendencies to pick off more members of the more fragile group versus those of the fitter group.

In performing mathematical modeling of the fate of the emperor penguins by running scenarios with objective data and assumptions, we may set up a stochastic process which helps us to understand the behavior of the system as it evolves under a variety of scenarios.

Mathematical models involve expressing real world problems in mathematical language. This entails defining variables and establishing a formulaic process which will express the model as evolves. Variables are elements in the model which may change during the model. Because they may change, the model needs to calculate how they change over the course of the model and how they interact with other model variables, and are affected by the constants assumed by the model. Constants may arise from established data or may be assumptions plugged in to the model.

Stochastic processes incorporate non-deterministic, random elements into a mathematical model. The result may vary with time and with each model run. In comparison, a deterministic model will always produce the same result given the same assumptions and initial state. Thus, a stochastic process is run using random processes, employing a variety of assumptions and probability distributions informing objective tendencies for various model events to occur..

The random process in stochastic modeling will randomly choose which penguins are attacked, survive, suffer morbidity or injury from accident, and die over a period of time. Each run will be unique, as specific, members of the colony are differently impacted by the random process each time. By running many such models, one can get a picture of the survival data for the colony as a whole under a wide range of assumptions. Depending on the characteristics of the data, model and variables, results may be similar on an overall group basis, while differing by individual members impacted over time.

Under a normal range of assumptions and outcomes, this model may well predict overall group behavior over a period time. However modeling becomes much challenging when very low probability events enter into the model or rear their head in actual life.

For example, a eruption of an Antarctic volcano may be infrequent, however it could certainly impact emperor penguins. If the model assumed a volcanic eruption with a low probability, a robust number of stochastic model runs may randomly select such an event resulting in a BBQ penguin supper for the leopard seals.

The objective of the stochastic processes is to help us inform our decision making process, to help us understand the impact of variables under a wide range of assumptions, conditions, and scenarios. Thus a stochastic process should inform us about the expectations of the model under a wide variety of conditions, including the impacts of low probability / high risk events.

Thursday, April 14, 2011

An Emperor Penguin Energy-Risk Model




Emperor Penguin Preparing to Dive off Riiser-Larsen Ice Shelf (Image on Alamy)

The emperor penguin (aptenodytes fosteri) is the largest of the penguin species and lives in Antarctica in large colonies. Emperor penguins live in the harshest of climates in Antarctica, where the temperatures can get down to 40 degrees Fahrenheit and with strong winds up to 89 mph, developing a sizable wind chill factor. The penguin breeding colony stays together during the harsh winter, constantly churning the boundaries of the colony, sustaining the group.

The female emperor penguin lays one egg, which is nurtured by the male while the female returns to sea to fish. The male will then nurture the young chick in his brood pouch. Later, both parents take turns hiking to the ice shore, diving into the Antarctic waters, in search of food. Fish and crustaceans such as krill provide sustenance for the penguin, energy to keep it going.

This source of penguin energy is available from “the deep”. Lots of krill. Lots of fish. Lots of energy to power penguins. One catch. A predator. The leopard seal (Hydrurga leptonyx). The leopard seal is a large mammal (between 400 and 1300 pounds) that attacks the emperor penguin, often at the edge of the ice where it can make opportunistic kills. This video by BBC Earth shows the interaction between a leopard seal and emperor penguins.






Emperor Penguins Lining up to Dive into water at Halley Bay Ice Edge (Image on Alamy)

A decision by an emperor penguin to dive into the water at ice’s edge is a decision to face a risk of being killed by the leopard seal or starve. Emperor penguins will accumulate in a line at the edge of the ice, waiting to take off, en-masse, into the water to feed. A tipping point is reached at some point where the shared risk of the group warrants all exiting off the ice edge into the cold deep, in quick succession. Feeding takes place in the open water and the emperor penguins quickly launch themselves through the air as they exit the water to land on the ice edge. They are playing the odds.

The emperor penguin’s appearance manages its risk to a certain extent. The emperor penguin’s black and white exterior helps to mitigate risk. The penguin’s black back appears lost looking downward against the black background of the marine deep. Looking upward from below, the emperor penguin’s white belly may be lost in the white glare of the water surface. This provides some degree of camouflage.

The penguins’ group decision, so neatly balanced in their emperor penguin-risk-matrix minds conceptually captures the “weighing of risks” issue as regards satisfying their energy needs. The penguin needs to take risks in order to eat, to supply energy, in order to live.

Food, after all, supplies energy that keeps us in business just as the various types of fossil fuels, nuclear energy and alternative energy sources provide energy for us to meet our various needs.

Our planet seems to shrink around us with population growth, economic development, energy demand and climate change challenges. As we seek to manage our lifestyles in this challenging environment, we are not unlike the emperor penguin. We face risk in pursuing our energy wants and needs.

We can analyze the risk patterns associated with the various energy choices that we have. These risk patterns vary considerably depending on which mix of energy resources are employed.

From studying the emperor penguin and the leopard seal we know the emperor penguins will continue to feed, but so will the leopard seal. Some emperor penguins, despite their various risk protection strategies, will get eaten. It is important to note that in probabalistic sense, that we know that some penguins will be eaten by the leopard seal, but we don’t know which specific penguins will “bite the dust”.

Similarly, as we explore various energy choices, we need to study the associated risks. We need to anticipate risks that may happen and proactively build defenses against them. However, we are kidding ourselves if we think that we can forever eliminate all such risks. It is the nature of evolving life to defeat such a worthy goal, as accidents can happen. It may be possible to predict the fact that accidents may happen while at the same time not being able to pinpoint exactly where or when they may occur. This consideration lends itself to a more global view of risk management, rather than focusing on any one particular potentiality.

In considering the risks associated with expanding energy sources to meet demand, its also appropriate to bring up ways to reduce energy demand, to become more efficient, to do more with what we have. This option becomes more attractive as the costs of the alternative options increases.