Energy
Coal Tar in Pavement Sealants | Risks and Bans
The high cost of low grade coal
Thirty-two years ago, my interest in the oil price shocks of the 1970s took me to the University of California at Berkeley to study energy. That same year the Liquid Fuels Trust Board was established in New Zealand. The Board clearly saw lignite as the country’s future source of transport fuel. However, because lignite is poor quality coal, extracting energy from it creates particularly high emissions of carbon dioxide. My concern about this is not new. Twenty years ago I co-authored a report called Transport fuels in New Zealand after Maui – lignite on the back burner.
It now looks as if lignite is making its way to the front burner. Two companies, state owned enterprise Solid Energy and the L&M Group, are proposing to mine lignite in Otago and Southland and convert it to diesel. In addition, Solid Energy is proposing to make two more products from lignite: the nitrogen fertiliser urea, and briquettes (made by drying out lignite into a better form of coal) primarily for export. Using lignite for generating electricity is another possibility.
The foundation of this report is a set of carbon footprint calculations for these four uses of lignite – diesel, urea, briquettes, and electricity. These calculations are presented in as open and transparent a manner as possible. I ask those who may question these calculations to be equally transparent.
Nature Conservancy maps places where wind turbines pose minimal danger to wildlife οΏ½ Yale Climate Connections
The First Summer
60 Hz Alternating Current Power Kind of Sucks.
The truth is …. 60 Hz Alternating Current Kind of Sucks
In North America, 60 Hz is the standard of alternating current. It was a rather nasty compromise between frequencies, chosen as a “sweet spot” between:
- Line losses due to high-frequency currents – The higher the frequency of AC the greater loses due to impedance caused by the voltage and current becoming out of sync due to the induction created by the line (time it takes for the magnetic field to appear and collapse on the wire). It’s not practical to send 400 Hz over any length of wire due to losses.
- Size of the transformer needed to step and step down voltage – The higher the frequency of AC, the smaller the transformer needs to be. The magnetic energy in alternating current “exists” in the alternating voltage, so if the voltage is alternating faster, a small transformer can move more power. Smaller transformers use less copper, they’re cheaper to build, and they’re generally more efficient.
- The ability to power light bulbs with minimal smoothing. Incandescent bulbs can be powered directly from 60 Hz alternating current, as it takes more then 1/60th of a second for an incandescent bulb to cool down enough to notice the crossing of zero point. Additionally, with 60 Hz power, a relatively small capacitor can be used to smooth out rectified power to drive an LED light, for fixtures that use a large number of LEDs in series.
- The ability to power low-power AC motors. 60 Hz alternating current can and does drive many AC motors, but it does require relatively large motors compared to motors operating at 400 Hz. Not only do 60 Hz alternating current motors require much larger coils then 400 Hz motors, they are less efficient.
Airplanes traditionally use to 400 Hz power, as it saves quite a bit on weight for their electrical motors and transformers. Likewise, traditional automotive alternators generate power in the 400 Hz range, before going through a bridge rectifier to convert 3-phase AC output to direct current. But transferring 400 Hz power, or for that matter boosting and bucking high-current DC can be difficult and prone to electronic failure compared to traditional mains frequency transformers.
But increasingly, we are seeing more uses of high frequency alternating current and direct current, especially in consumer devices. Most modern electronics are powered by switch-mode power supplies, which use high-frequency transformers (as high as 1,000,000 Hz) to safely step down voltage in an isolated fashion. More motors today are driven using inverters, which similarly create a higher-frequency current to provide more power with loss copper and less losses. Controlling the frequency of the current, allows motors to be precisely controlled in their speed, it’s more efficient and accurate then simply chopping off part of the sine wave using thyristor as was done in the olden days to control motor speed.
Great Lakes offshore wind approval a ‘poison pill’ – The Allegheny Front
When Ohio recently approved construction of a wind farm in Lake Erie, the first ever freshwater offshore wind project in North America, the developers were shocked.
The approval by the Ohio Power Siting Board included conditions that the developer, Lake Erie Energy Development Corporation (LEEDCo), says will essentially kill the project. The turbines must be shut down at night for eight months of the year, from March to October, to protect birds and bats.
The Black Swamp Bird Observatory, in northern Ohio, and the Washington, D.C.-based American Bird Conservancy (ABC), filed a federal lawsuit in December against the Department of Energy and other agencies. They want a more thorough environmental assessment, and are challenging the government funding for Icebreaker Wind, which has been more than $50 million.
ABC is pleased that Ohio regulators put nighttime limitations on the turbines in their decision. “We thought that was appropriate,” said Steve Holmer, the group’s vice president of policy. “There still has not been adequate monitoring or proven mitigation and so it makes sense to take a cautionary approach here.”
“This has been already identified as a globally significant bird area,” he continued. “The issue is whether we’re going to fully, adequately consider wildlife when we make these decisions and in our view, they simply haven’t. We think that this is just not an appropriate location for wind development.”