Archive for August, 2008

Green Futures

Tuesday, August 26th, 2008

Another UC, Berkeley Forefront magazine article discusses Green Future: Engineers Forge Novel Technologies For A Sustainable World.

Environmental Footprints: Sustainability by the Numbers

When given a choice—paper or plastic, cloth diapers or disposables, garbage can or recycling bin—most of us do what we think is greenest. The problem is, we’re often wrong.

“We make emotional decisions, but often there’s no scientific proof to back things up,” says Arpad Horvath, professor of civil and environmental engineering. For several years Horvath has focused on developing systematic methods to assess the environmental impact of our industrial processes, consumer goods and services and beyond…

In a 2004 study, for example, Horvath’s assessment revealed that reading the New York Times wirelessly on a PDA instead of having the paper delivered to your door requires consumption of about 140 times less carbon dioxide and 26 to 67 times less water. Now he is bringing his research to bear on the building industry, examining a building’s sustainability in the context of the entire supply chain behind its construction, operation, maintenance and end of life.

“Besides transportation and electricity generation, buildings are the single greatest consumers of energy and other resources,” he says. “And nearly every sector of our economy—mining, manufacturing and services—supplies to the building industry.”

Tiny Generators: Recapturing Waste Heat

Almost all the world’s power, roughly 10 trillion watts, is produced by burning fossil fuels and running engines based on heat. For every watt of power generated, one and a half watts are dumped as waste heat. It’s a law of thermodynamics.

“Can we extract some of the juice from that waste heat?” asks mechanical engineering professor Arun Majumdar. He and his colleagues are working at the nanoscale to build super-efficient devices that directly convert heat into electricity. Their research could some day lead to hybrid automobiles that generate electricity from the radiator to charge their batteries, or homes powered by extracting energy from their walls or the ground they stand on.

“When you generate 10 trillion watts of power, you’re wasting a staggering 15 trillion watts,” Majumdar says. “Extracting even a fraction of that would amount to huge fuel savings and reductions in carbon dioxide emissions.”

See the article for more on thermoelectricity.

Thermoelectric generator
Thermoelectric generator

Curb Your Car: Transforming Public Transit

The next time you’re stuck in rush-hour gridlock, try to imagine traffic in China, where automobile ownership is growing at the astounding rate of 80 percent annually. In just three years, China will have more cars on its roads than the United States. To help keep that growth sustainable, researchers at UC Berkeley’s Institute of Transportation Studies (ITS) are designing an urban transportation system that could curb the need for cars in Chengdu, China, and similar developing cities without sophisticated mass transit systems.

“The Chinese government is concerned with two issues: air quality as impacted by vehicle emissions and energy consumption,” says Samer Madanat, Xenel Professor of Civil and Environmental Engineering and ITS director. “China wants to depend as little as possible on foreign energy sources.”

Lee Schipper of EMBARQ also works on transit, first and third world.

Nuclear Renaissance: Reviving Greenhouse-Gas-Neutral Power

A coal-fired power plant capable of producing 1,000 megawatts of electricity burns at least 7.3 million kilograms of coal and releases upwards of 24 million kilograms of carbon dioxide into the atmosphere per day. The equivalent nuclear fission plant consumes just 3.2 kilograms of uranium per day and emits no carbon dioxide….

The newest designs [worked on by Vujic and colleagues], called “nuclear batteries” or small-footprint nuclear reactors, are self-contained power plants that can be installed in remote locations and crank out 100 to 300 megawatts for 15 to 20 years without refueling. Some serve as their own shipping crates for return to the factory, where the fuel is reprocessed for another battery.

“These would be especially useful in developing regions without a central electricity grid or advanced infrastructure, where we could provide cheap nuclear energy but also limit access to the fissile fuel,” Vujic says.

Nuclear battery

Nuclear battery See text for more information.

Get Smart: New Thermostat For Comfort And Savings

“Wouldn’t it be great if your meter could receive information about when the price is lowest to run your appliances and air conditioning?” asks mechanical engineering professor Paul Wright, acting director of the Center for Information Technology Research in the Interest of Society (CITRIS). To increase home energy efficiency and cut the cost of keeping cool,Wright and colleagues are bringing electronic brains into our home’s electrical systems, the next generation of “smart” meters and thermostats.

The approach, known as demand–response technology, uses the smart dust sensors…to monitor temperatures in various rooms of your home or apartment and relay data to a networked thermostat. Sensors coupled to electrical circuits in breaker boxes monitor power consumed by other appliances and indicate the cost of running, say, the washing machine at 2 p.m. on a sweltering day, when energy is most expensive. As energy prices shift, they are transmitted wirelessly from the utility company to the home’s smart meter.

The resident will simply program temperature preferences on a user-friendly thermostat. Employing control algorithms, the system then sets the air conditioner to match the desired profile as temperatures shift throughout the day…

The [California Energy Commission’s] goal is to equip every California home with new meters within 10 years, and the researchers hope their technology will be inside those devices. According to an Electric Power Research Institute report, the technology could eliminate the state’s need for five to ten new power plants over the next decade.


Sunday, August 24th, 2008

Updated September 7, 2008

Amid widespread concerns about how rapidly and radically greenhouse gas emissions can be reduced, discussions of geoengineering have become more common.

David Keith, eg, Engineering the Planet, describes geoengineering as

intentional, large-scale manipulation of the environment. Both scale and intent are important.

So most changes to land and the atmosphere, such as landscaping and pollution, are excluded.

Carbon dioxide and other greenhouse gases we add to the atmosphere are warming the Earth. The increased levels of atmospheric carbon dioxide shift plant balance, for example, favoring C3 over C4 plants; C4 plants have more efficient uptake of carbon dioxide, but this becomes less important as carbon dioxide levels increase. Even worse, the ocean becomes more acidic as it absorbs much of the excess carbon dioxide added each year, with especially serious consequences for shelled organisms.

Geoengineering schemes that cool the Earth do nothing to protect ocean and land ecosystems from increased carbon dioxide.


One method would imitate volcanoes, and inject aerosols into the stratosphere.

Injecting sulfates
Injecting sulfates

Temperature change from sulfate injection
Temperature change from sulfate injection

Unfortunately, this plan has problems: it would extend the repair of the ozone hole over Antarctica for decades, and create an ozone hole over the Arctic during particularly cold winters.

Additionally, instead of ridding the Earth of more infrared energy, sulfate aerosols block visible light, with small effects on everything from photosynthesis to solar energy. More dramatically, evaporation depends more on visible light than IR, and evaporation would decrease even if the temperature stayed constant. Decreases in rainfall are expected to be substantial in the northern tropics, particularly the Sahel and the monsoonal belts.

Policy people like David Keith see geoengineering not as a substitute for reducing greenhouse gas emissions rapidly, but an additional tool if, for example, the temperature increase for a given atmospheric level of greenhouse gas is not in the middle of the expected increase, but in the far extreme:

Projected temperature increase
Projected surface temperature changes for the early and late 21st century relative to the period 1980 to 1999. Notice that uncertainty (on the left) is much greater for larger increases.

Update See also the Nature blog Climate Feedback, Geoengineering: Preparing for the Worst.

It links to a special issue of the Royal Society, Geoscale engineering to avert dangerous climate change, and a review by Stephen Schneider in that issue. He ends the review this way:

In short, my personal prescription for climate policies can be summarized in five sequenced steps.

i. Adaptation is essential now to assist those who will likely be harmed by ‘ in the pipeline’ climate change. Actions that simultaneously enhance ‘ sustainable development’ would seem the most attractive options.
ii. Performance standards required of buildings, appliances, machines and vehicles to wring the maximum potential for cost-effective engineering energy efficiency need to be mandatory and widespread.
iii. A ‘ learning-by-doing feeding frenzy’ needs to emerge, where we set up public– private partnerships to fashion incentives to help us ‘ invent our way out’ of the problem of high-emitting technological and social systems.
iv. A shadow price on carbon has to be established to ensure that the full costs of any energy production or end use system is part of the price of doing business. Cap and trade and carbon taxes are the prime examples of such schemes to internalize external risks from business-as-usual emissions, but these schemes must recognize the special problems they may pose for certain groups: poor people and coal miners or SUV workers. So, in addition to internalizing these externalities to protect the environmental commons, we need to consider side payments or other compensation schemes to be fair to the losers of the mitigation policies and to provide a transition for them to a softer economic landing, so to speak.
v. Finally, my last policy category in the sequence is to consider deploying geoengineering schemes. However, as has been said by all in this issue, and as I fully agree, R&D is needed and should be an early part of the climate policy investment sequencing, even if deployment is the last resort.

US Climate Change Hot Spots

Saturday, August 23rd, 2008

More powerful computers are describing what will happen in our various neighborhoods this century. Earlier reports divided the continental US into west, central, and east. The 15 August Science, Climate Change Hot Spots Mapped Across the United States (subscription needed) discusses the newest results.

The US Southwest and northern Mexico are currently and will continue to be the most responsive to climate change. The big difference is not warmer weather, or changes in precipitation (either up or down), but in variability.

The coastal portion of the southeast is predicted to be least responsive, less variable weather, but this doesn’t make it “‘safe’ or ‘immune'” from climate change–more severe weather is a major risk.

Lake Mead
The southwest is drying. There is a 50% chance that Lake Mead will go dry by 2021, and a 50% chance that by 2017, there will be too little water for hydroelectric power.

Pollutants on the fly

Tuesday, August 19th, 2008

UC, Berkeley’s Forefront magazine has an article on Pollutants on the fly: Connecting the dots between pollutant sources and us.

William Nazaroff studies air pollution, including characterization and control of pollutants.

Intake fraction refers to the fraction of pollutant that is actually inhaled.

“Only a fraction of emissions from each source is inhaled,” says Nazaroff, who has studied the physical and chemical processes that control human exposure to air pollutants for more than two decades. “We’re trying to understand what controls that fraction, then explore how knowing it changes the way we think about the importance of different pollution sources.”

Both the amount of pollutant produced, and where people are relative to that pollution, will determine how dangerous it is.

Nazaroff’s focus has been

on three issues: transportation emissions and their effect on human health, electricity and newly emerging distributed generators, and modeling spatial relationships between people and pollutant sources to help inform public policy.

So what does concentrating people along an efficient transportation corridor do to public health? No answer provided.

A second focus was distributed generators (DGs), which are cheap and efficient and give greater control for the user. In California, about 7% of power generation is lost through the transmission and distribution. In some locations, this will be more, and DGs may make more sense there. But how does pollution compare?

A relatively novel power source, DGs are making their way into our lives. While they can be designed to run on diesel fuel, natural gas, even solar and wind power, it’s those that run on natural gas that are proliferating most quickly. While natural gas is cleaner than most other fuels, some researchers are concerned that even natural gas DGs may harm our health more than large power plants because they pollute air right where we are — at home or at work.

“They are being placed in neighborhoods all over the country in close proximity to people, unlike more traditional, large power plants, which were routinely located far from urban centers,” says Garvin Heath, who is pursuing dual master’s degrees in civil and environmental engineering (CEE) and ERG.

Power generation has been a hot button issue since the summer of 2001, when rolling blackouts threatened Californians and the price of electricity skyrocketed from $30 per megawatt to $330. Traditional power plants — nuclear, coal, or natural gas-burning plants — are tremendously expensive and time consuming to build. Deregulated in 1996, the power industry has not built a new major power plant in 15 years, despite growing demand.

To help alleviate that demand, industry turned to small, quick-to-build distributed generators. The California Air Research Board estimates that there are 11,000 distributed generators in California. There are 40 on the Berkeley campus alone.

In contrast to more traditional ambient air quality monitoring, intake fraction stresses the proximity of pollution sources to people. Garvin Heath (left) and Abby Hoats are using intake fraction to investigate human exposures to pollution.

“Distributed generators are largely unregulated,” says Heath, “and there is no clear understanding of their impact on public health. With the intake fraction approach, we hope to clarify key issues and gain a better understanding of the health risks.”

Using the Los Angeles air basin, Heath compared a small DG power source to a central station plant and found a dramatic difference in the proportion of emitted pollution that is inhaled.

“Per unit of electricity delivered, the DG unit increased the amount of pollutants inhaled by nearby residents by an order of magnitude,” says Heath. These small generators let out their exhaust just five meters from the ground. In contrast, large centralized power station stacks spew their exhaust sky high.

Heath and Hoats
Heath and Hoats

An order of magnitude. This means that DGs lead to about 10 times as much pollution inhaled.

A third focus is on public policy: where you live compared to large fixed sources of pollution. Studying the flow of pollutants, and quantifying the intake fraction, will hopefully lead to better public policy so that some groups don’t suffer disproportionately.

Mandatory mpg meters?

Thursday, August 14th, 2008

Does it make sense to install a mpg gauge in all new cars?

MPG Meter
MPG Meter

(Or a gallons per 100 miles meter?)

Would people drive more efficiently with instant feedback? Have early warning of maintenance problems? Always drive the car that uses less gas when there is a passenger? Disable it as soon as possible?

What reason do you have to use/reject a mandatory mpg meter?