Energy tradeoffs

There is no one easy solution to meeting the energy needs of the 21^st century and beyond; every technology has its trade-offs:

Petroleum and coal are both non-renewable and produce greenhouse gases; solar and wind energy both require lots of land and the energy collected from them can not yet be efficiently distributed; and hazardous waste from nuclear power plants must be dealt with for thousands of years.

Less obvious are the hidden costs of energy sources; biofuels, regarded as the “greenest” technology, uses hundred of liters of water to grow the fuel.

The other side of the energy equation is reducing use, which is an issue that involves education and public policy. The solution to our future energy needs requires the input from scientists, engineers, educators, policy makers, and you.

Science magazine has a special section on scaling up alternative energies and the trade-offs involved.

[Adrian Cho, Science, v. 329, 13 August 2010,p. 786-787]

Image from here.

Geothermal energy, revisited

Volcanoes and geysers bear witness to the enormous reservoir of energy--in the form of heat--that lies in the earth's interior. This geothermal energy can be used to generate electricity wherever there is a source of heat close to the earth's surface. Unlike the non-renewable fossil fuels, geothermal energy will last until the earth's internal engine runs out of fuel, millions of years from now.

But geothermal energy has its limitations as an alternative energy source. Production of geothermal energy is limited to relatively few areas with the required local geothermal source, and drilling to tap these sources can have unintended consequences. A geothermal project in Switzerland was canceled in 2007 after drilling caused a magnitude 3.4 earth tremor.

Source: E. Kintisch, Science 329:789, 13 Aug. 2010

Photo from here, along with a list of "Top 10 alternative energy sources"

Ethanol and policy issues

Recently, the U.S. government increased the cap on the amount of ethanol that can be used in gasoline from 10% to 15%. Upping this limit should encourage the development of alternative sources of ethanol, but changing this limit affects the car manufacturers.

A proposal to require cars to use an E85 blend (that is, 85% ethanol, 15 % petroleum) could be accommodated by car manufacturers, but it is not known whether this ethanol-rich blend would damage engines designed to operate on the current 10% blend.

Scaling up the use of cellulosic biofuel is not just a scientific or technological issue, but a policy issue as well. One scenario would be to have the ethanol limit gradually increase from to 85%; the current increase to 15% is a down payment on this strategy.

Learn more about E85 and "flex fuel" vehicles here.

Photo: an E85-powered Chevrolet HHR.

Growing Green

A major roadblock to scaling up the use of cellulosic biofuel is the difficulty and expense of extracting the ethanol from these materials.

The ethanol currently used in gasoline mixtures come from fermentation of sugars present in corn kernels, and is a relatively simple and inexpensive process. However, the sugar in cornstalks and other cellulosic biofuel is locked in chemical structures that are harder to break and the ethanol yield is lower, which means that manufacturers of cellulosic ethanol require much more raw material than the ethanol manufacturers.

Scientists are exploring ways to extract cellulosic ethanol more effectively. One possible solution is to engineer new microbes that can break down cellulose into sugars that can more easily be fermented to form ethanol.

The Great Lakes Bioenergy Research Center is a consortium of organizations working to conduct this sort of "transformational biofuels research". Go Green!

Biofuels

Ethanol is a fuel derived from plant material, primarily corn kernels. Although a renewable resource, one of the down-sides of using corn-derived ethanol as fuel is that it diverts grain from food to energy use, driving up food prices. This concern was addressed by research into using biowaste, that is, grasses, cornstalks, and wood chips not used for food.

The problem with using this “cellulosic” ethanol is that the ethanol is much harder to extract. Currently, just 40% of the energy content available in cellulosic plant sources is recoverable, compared to 90% of the energy in kernal ethanol.

But another issue with ethanol from corn is that the process requires a lot of energy, and the end-product ethanol does not represent a big savings in the use of fossil fuels in the process and still contributes to greenhouse gas emissions.

More on the pros and cons of ethanol, here.

Wind energy, revisited

Wind..it’s clean, and does not produce climate-changing greenhouse gasses...

But problems associated with modern wind turbines threaten the growth of wind as an alternative energy source. Birds and bats have been killed by the spinning blades, the motion of the blades can show up on flight controller’s radar, and noise is an issue for people who live near wind turbines.

Twenty years of using modern wind technology has led to some improvements; siting wind turbines now takes into account migratory routes and roosting sites of birds and bats. Engineers are working to make the turbine blades less visible to radar and less noisy.

Ultimately, however, changing negative attitudes toward wind farms must involve more than technological fixes and include public education of the benefits and tradeoffs of wind energy technology.

Source: E. Kintisch, Science 329:788-789

Nuclear power, revisited

Nuclear energy became anathema after nuclear plant accidents released radioactivity into the environment. But in the wake of environmental accidents due to oil spills and growing concerns about the environmental impact of burning coal, nuclear power is making a comeback.

More than 100 new nuclear power plants are planned to come online, worldwide, over the next 10 years. Lessons learned since Three-Mile Island insure that the new reactors will be safer.

Still a challenge to acceptance and wide-spread use of nuclear power is the disposal of high-level nuclear wastes (HLW), especially the spent fuel rods, which may continue to emit dangerous levels of radiation for a million years. Disposal of HLW is not just a scientific issue but a political hot potato.

Image of the atom from here.

National Fossil Day

The record of life on Earth is written in stone--

National Fossil Day is a celebration organized by the National Park Service to promote public awareness and stewardship of fossils, as well as to foster a greater appreciation of their scientific and educational values.

Learn more...

Solar power has matured as an alternative energy source over the last 20 years, but there are still obstacles to overcome before the energy from the sun can significantly supplement other sources of energy.

Collecting solar energy is only part of the process, storing it for later use is still “technically and economically challenging.”* Concentrating solar power plants, or CSPs, like the one shown here, use mirrors to focus solar radiation and generate heat that can be converted to energy, but CSPs are located where the solar radiation is most abundant year-round, which is not where most people and most of the energy demand is.

There are environmental issues, as well. Recently the California Energy Commission recommend against building a new installation in the Mohave desert because of its potential impact on turtles.

*Source: Science, 329:773, August 13, 2010, Roeb, M, and H. Muller-Steinhagen

Photo of concentrated solar power plant, and other information on solar power is available here. This structure's resemblance to Isengard is interesting...

It's Earth Science Week

If you are under the age of 30, you may not be aware that the term “energy crisis” was NOT coined during your lifetime. Your parents might remember the lines at gas stations in the late 1970s.

We find ourselves in the 21^st century apparently not having learned the lessons from our earlier crises that stemmed from dependence on a non-renewable energy source—petroleum—the production and transportation of which can have profound environmental effects (two examples: Exxon Valdez and the Deep Horizon oil rig) and the combustion of which contributes to global climate change.

We have learned that our energy choices have profound geopolitical, social, and environmental consequences. The American Geological Institute designates a week in October as Earth Science Week, and this year's theme is energy.

AGI's webpage for Earth Science week is here.

Flower Power

What would a world without flowers be like?

The dinosaurs knew the answer to that question, as they lived in an age before the evolution of angiosperms, the flowering plants.

Angiosperms are the most diverse group of land plants on Earth today, and include not only all the plants whose blooms we appreciate, like roses, but all our deciduous trees and grasses, and grains--corn, rice, and wheat.

Paleontologists have modeled the flower-less Earth scenario, and found that an Earth without flowers would not only be less colorful, but it would be hotter and drier, as the leaves from angiosperms add a significant amount of water vapor to the atmosphere through the process of transpiration.

Moisture impacts biodiversity as well, and a flower-less Earth would have fewer species of plants and animals. Angiosperms add more than just color to our lives

More information on a world without angiosperms, and a link to the original research here.

Melville's Whale

Modern sperm whales, the largest predators alive today, have teeth only on the lower jaw and use suction to catch their cephalopod prey.

The discovery of a new fossil species of sperm whale from rocks 15 million years old helps to fill in our understanding of the evolution of sperm whales. The newly discovered whale has jaws that have both upper and lower teeth, teeth that are 36 cm long, giving this fossil predator the biggest bite known. Based on the size of the skull, paleontologists estimate a body length of 13 to 17 meters.

Named Leviathan melvillei, for the novelist Herman Melville, author of Moby Dick, this sperm whale's appearance in the fossil record coincides with diversification of baleen whales. Leviathan melvillei probably fed on baleen whales and as a top predator, helped shape Miocene marine communities.

See summary of the Nature article and more illustrations here.

Warm-blooded reptiles?

Modern reptiles are cold blooded, but what about extinct reptiles?
Based on their teeth, large extinct swimming reptiles, like ichthyosaurs, plesiosaurs, and mosasaurs are thought to have been predators in the Mesozoic oceans. Their streamlined body profile also suggests an active lifestyle. An active lifestyle requires high metabolic rates, which are usually correlated with at least some ability to regulate body temperature.
Scientists analyzed oxygen isotopes from the teeth of these extinct marine reptiles and compared the values with those from cold-blooded fossil fish. The results showed ichthyosaurs and plesiosaurs differed significantly from fish, and suggest that these two reptiles, both of whom were active, "pursuit predators", probably controlled their body temperature. The data for mosasaurs were equivocal and suggest that mosasaurs led a different lifestyle perhaps as an opportunistic ambush predator.
Illustration of an ichthyosaur is from here.

The fauna that keeps on giving

The Burgess Shale of British Columbia, Canada, is famous for its exceptional preservation of bizarre, soft-bodied invertebrate lifeforms, a window into the Middle Cambrian World of 510 million years ago.

Burgess Shale-like faunas are now known from localities world-wide, but recently paleontologists discovered in Morocco a Burgess fauna from rocks 30 million years younger than the Cambrian faunas.

Burgess shale faunas were thought to have gone extinct after the Middle Cambrian. This new discovery suggests that the disappearance of the older fauna was a due to the absence of suitable conditions for fossilization rather than extinction, and it underlines the importance of understanding the conditions and processes leading to fossilization, and it opens the possibility of finding other Burgess faunas.

From P. Van Roy, P. J. Orr, J. P. Botting, L. A. Muir, Jacob Vinther, B. Lefebvre, K. el Hariri, and D. E. G. Briggs. 2010. Ordovician faunas of Burgess Shale type. Nature 465:215-218. A longer summary of their research is here. Photo of Marella, a Burgess arthropod, from the original article.