Month: October 2012

Optimizing Energy Savings from Direct-DC in U.S. Residential Buildings

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An increasing number of energy efficient appliances operate on direct current (DC) internally, offering the potential to use DC from renewable energy systems directly and avoiding the losses inherent in converting power to alternating current (AC) and back. This paper investigates that potential for net-metered residences with on-site photovoltaics (PV) by modeling the net power draw of the ‘direct-DC house’ with respect to today’s typical configuration, assuming identical DC-internal loads. Power draws were modeled for houses in 14 U.S. cities, using hourly, simulated PV-system output and residential loads. The latter were adjusted to reflect a 33% load reduction, representative of the most efficient DC-internal technology, based on an analysis of 32 electricity end-uses. The model tested the effect of climate, electric vehicle (EV) loads, electricity storage, and load shifting on electricity savings; a sensitivity analysis was conducted to determine how future changes in the efficiencies of power system components might affect savings potential. Based on this work, we estimate that net-metered PV residences could save 5% of their total electricity load for houses without storage and 14% for houses with storage. Based on residential PV penetration projections for year 2035 obtained from the National Energy Modeling System (2.7% for the reference case and 11.2% for the extended policy case), direct-DC could save the nation 10 trillion Btu (without storage) or 40 trillion Btu (with storage). Shifting the cooling load by two hours earlier in the day (pre-cooling) has negligible benefits for energy savings. Direct-DC provides no energy savings benefits for EV charging, to the extent that charging occurs at night. However, if charging occurred during the day, for example with employees charging while at work, the benefits would be large. Direct-DC energy savings are sensitive to power system and appliance conversion efficiencies but are not significantly influenced by climate. While direct-DC for residential applications will most likely arise as a spin-off of developments in the commercial sector—because of lower barriers to market entry and larger energy benefits resulting from the higher coincidence between load and insolation—this paper demonstrates that there are substantial benefits in the residential sector as well. Among residential applications, space cooling derives the largest energy savings from being delivered by a direct-DC system. It is the largest load for the average residence on a national basis and is particularly so in high-load regions. It is also the load with highest solar coincidence.

THE HUNDRED BILLION DOLLAR BONUS: Global Energy Efficiency Lessons from India

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At a time when India and other nations are grappling with myriad energy-related challenges, including unstable, costly power sources and growing greenhouse gas emissions, energy efficiency offers an alternative at a fraction of the cost of other new sources of energy. A consortium of leading Indian regulators, nongovernmental organizations, and international experts has recognized this opportunity and is working to develop effective policies that will bring significant domestic benefits to India while accelerating the global transition to energy efficiency.

Carbon dioxide from water pollution — as well as air pollution — may adversely impact oceans

Read the full story from the American Chemical Society.

“Eutrophication Induced CO2 Acidification of Subsurface Coastal Waters: Interactive Effects of Temperature, Salinity, and Atmospheric PCO2
Environmental Science & Technology

For the abstract, contact

Carbon dioxide (CO2) released into the oceans as a result of water pollution by nutrients — a major source of this greenhouse gas that gets little public attention — is enhancing the unwanted changes in ocean acidity due to atmospheric increases in CO2. The changes may already be impacting commercial fish and shellfish populations, according to new data and model predictions published in ACS’s journal, Environmental Science & Technology.

“Sweet” chemicals from a “green” raw material

Read the full story from the American Chemical Society.

Biobased Summer
Chemical & Engineering News

The biobased world’s traditional focus on producing fuels for cars, trucks and aircraft is quietly undergoing a major transition this summer toward production of chemicals needed for manufacture of hundreds of different consumer products, according to an article in the current edition of Chemical & Engineering News (C&EN). The cover story appears in the weekly newsmagazine of the American Chemical Society, the world’s largest scientific society.

Green chemistry: Cancer research yields nylon?

Read the full story in the Los Angeles Times.

Cancer researchers at Duke University Medical Center in Durham, N.C., have been studying the DNA in tumors called glioblastomas — hoping, ultimately, to help find a cure for the disease.

They haven’t found that yet, but they may have come across something else scientists are seeking: an enzyme that could help companies make nylon without depending on fossil fuels.

Date palm juice: A potential new “green” anti-corrosion agent for aerospace industry

Read the full story from the American Chemical Society.

Anti-Corrosive Properties of Date Palm (Phoenix dactylifera L.) Fruit Juice on 7075 Type Aluminium Alloy in 3.5% NaCl Solution
Industrial & Engineering Chemistry Research

The search for a “greener” way to prevent corrosion on the kind of aluminum used in jetliners, cars and other products has led scientists to an unlikely source, according to a report in ACS’ journal Industrial & Engineering Chemistry Research. It’s the juice of the date palm — those tall, majestic trees that, until now, were noted mainly as sources of food and traditional medicines.

Pets share our environment and our diseases; doctors and vets investigating risks

Read the full story at Environmental Health News.

Pet owners share their homes, their exercise habits and sometimes even their food with their four-legged companions. And increasingly, they are sharing the same diseases: Dogs and cats suffer from obesity, diabetes, heart disease, cancer, thyroid disorders and asthma, just like humans. Now researchers are examining the role that pollutants and other environmental factors may play in these dual diseases. Doctors and veterinarians have begun to work together to investigate common risk factors, such as pesticides, air pollutants, cigarette smoke and household chemicals.

The Fantasy of the “Sad Green Story”

Read the full post at the HBR Blog Network.

Recently, New York Times columnist David Brooks wrote an op-ed entitled “A Sad Green Story” about the (supposed) travails of the green movement over the last 10 years. The idea that the clean technology sector is failing, or that it’s a bad investment, is common enough in the business world and pundit class. But it’s patently false. So what is Brooks talking about?

Webinar: Materials Cycling: A Focus on Plastics

Friday, November 16, 2012 from 12:00 PM to 1:00 PM (CST)
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Less than 30% of plastics used in bottles and less than 9% of all plastic waste is recycled in the United States. While municipal recycling programs have traditionally focused on bottle recycling, other plastics – including film and rigid plastics – compose the majority of available plastic waste. As communities seek to reduce waste sent to landfills and meet higher diversion targets, there is increased interest in including these additional plastics in recycling programs. Through the presentations and discussion in this webinar, we hope to explore plastics recycling and its future potential from a variety of perspectives.

Ready, Fire, Aim!

Read the full post from the University of Minnesota Institute on the Environment.

Virajita Singh, senior research fellow for the College of Design, introduced the concepts of design thinking in her Frontiers in the Environment talk on October 10 titled Design+Community+Sustainability: Accelerating the Transformation. Read the blog post and watch the recording now.

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