Artificial photosynthesis is a chemical process that biomimics the natural process of photosynthesis to convert sunlight, water, and carbon dioxide into carbohydrates and oxygen. The term artificial photosynthesis is commonly used to refer to any scheme for capturing and storing the energy from sunlight in the chemical bonds of a fuel (a solar fuel). Photocatalytic water splitting converts water into hydrogen and oxygen and is a major research topic of artificial photosynthesis. Light-driven carbon dioxide reduction is another process studied that replicates natural carbon fixation.
Research of this topic includes the design and assembly of devices for the direct production of solar fuels, photoelectrochemistry and its application in fuel cells, and the engineering of enzymes and photoautotrophic microorganisms for microbial biofuel and biohydrogen production from sunlight.
- "Artificial Photosynthesis" | 2018-08-26 | 30 Upvotes 10 Comments
Standard battery nomenclature describes portable dry cell batteries that have physical dimensions and electrical characteristics interchangeable between manufacturers. The long history of disposable dry cells means that many different manufacturer-specific and national standards were used to designate sizes, long before international standards were reached. Technical standards for battery sizes and types are set by standards organizations such as International Electrotechnical Commission (IEC) and American National Standards Institute (ANSI). Popular sizes are still referred to by old standard or manufacturer designations, and some non-systematic designations have been included in current international standards due to wide use.
The complete nomenclature for the battery will fully specify the size, chemistry, terminal arrangements and special characteristics of a battery. The same physically interchangeable cell size may have widely different characteristics; physical interchangeability is not the sole factor in substitution of batteries.
National standards for dry cell batteries have been developed by ANSI, JIS, British national standards, and others. Civilian, commercial, government and military standards all exist. Two of the most prevalent standards currently in use are the IEC 60086 series and the ANSI C18.1 series. Both standards give dimensions, standard performance characteristics, and safety information.
Modern standards contain both systematic names for cell types that give information on the composition and approximate size of the cells, as well as arbitrary numeric codes for cell size.
- "Battery Nomenclature" | 2019-07-14 | 16 Upvotes 3 Comments
A black start is the process of restoring an electric power station or a part of an electric grid to operation without relying on the external electric power transmission network to recover from a total or partial shutdown.
Normally, the electric power used within the plant is provided from the station's own generators. If all of the plant's main generators are shut down, station service power is provided by drawing power from the grid through the plant's transmission line. However, during a wide-area outage, off-site power from the grid is not available. In the absence of grid power, a so-called black start needs to be performed to bootstrap the power grid into operation.
To provide a black start, some power stations have small diesel generators, normally called the black start diesel generator (BSDG), which can be used to start larger generators (of several megawatts capacity), which in turn can be used to start the main power station generators. Generating plants using steam turbines require station service power of up to 10% of their capacity for boiler feedwater pumps, boiler forced-draft combustion air blowers, and for fuel preparation. It is uneconomical to provide such a large standby capacity at each station, so black-start power must be provided over designated tie lines from another station. Often hydroelectric power plants are designated as the black-start sources to restore network interconnections. A hydroelectric station needs very little initial power for starting purposes (just enough to open the intake gates and provide excitation current to the generator field coils), and can put a large block of power on line very quickly to allow start-up of fossil-fuel or nuclear stations. Certain types of combustion turbine can be configured for black start, providing another option in places without suitable hydroelectric plants. In 2017, a utility in Southern California successfully demonstrated the use of a battery-based energy-storage system to provide a black start, firing up a combined-cycle gas turbine from an idle state.
- "Black Start" | 2013-04-29 | 289 Upvotes 105 Comments
The Centralia mine fire is a coal-seam fire that has been burning underneath the borough of Centralia, Pennsylvania, United States, since at least May 27, 1962. Its original cause is still a matter of debate. It is burning in underground coal mines at depths of up to 300 feet (90 m) over an 8-mile (13 km) stretch of 3,700 acres (15 km2). At its current rate, it could continue to burn for over 250 years. It has caused most of the town to be abandoned: the population dwindled from around 1,500 at the time the fire started to 7 in 2013, and most of the buildings have been levelled.
- "Pennsylvania town coal mine has been on fire since 1962" | 2021-02-07 | 60 Upvotes 35 Comments
- "The fire that has been burning for 56 years" | 2018-12-13 | 12 Upvotes 5 Comments
The cubic mile of oil (CMO) is a unit of energy, aiming to give the general public an understanding of large quantities of energy. It is approximately equal to 1.6×1020 joule. It was created by Hew Crane of SRI International to aid in public understanding of global-scale energy consumption and resources.
Large scale sources of energy include wind, solar photovoltaic, solar thermal, nuclear, hydroelectric, oil, coal, natural gas, geothermal, and biomass (primarily the burning of wood). Traditionally, many different units are commonly used to measure these sources (e.g., joules, BTUs, kilowatt hours, therms) but only some of them are familiar to a global general public, and some argue that fewer are needed and a standard should be chosen. Still, these common energy units are mainly sized for everyday activities, for example a joule is the energy required to lift a small apple one metre vertically. For regional, national, and global scales, larger energy units, such as exajoule, terawatt-hour, billion barrels of oil equivalent (BBOE) and quad are used. Derived by multiplying the small common units by large powers of ten these larger units pose additional conceptual difficulties for many citizens.
Crane intended the cubic mile of oil to provide a visualizable scale for comparing the contributions of these diverse energy components as a percentage of total worldwide, energy use.
In 2005, the global economy was consuming approximately 30 billion barrels (4.8 billion cubic metres; 1.3 trillion US gallons) of oil each year. Numbers of this magnitude are difficult to conceive by most people. The volume occupied by 1 trillion US gallons (3.8 billion cubic metres) is about 1 cubic mile (4.2 billion cubic metres). Crane felt that a cubic mile would be an easier concept for the general public than a trillion gallons.
DESERTEC was a large-scale project supported by a foundation of the same name and the consortium Dii (Desertec industrial initiative) created in Germany as a limited liability company (GmbH). The project aimed at creating a global renewable energy plan based on the concept of harnessing sustainable power from sites where renewable sources of energy are more abundant and transferring it through high-voltage direct current transmission to consumption centers. All kinds of renewable energy sources are envisioned, but the sun-rich deserts of the world play a special role.
There are some parallels between Desertec and the Atlantropa project plan in the 1920s. Atlantropa aimed to integrate Europe and Northern Africa and its electricity grid based on a giant hydro power station at Gibraltar. The industry platform Dii is continuing to pave the way for renewables and grid integration on a very pragmatic basis. As of 2019 the project is described as largely "stalled" and "failed".
- "Desertec" | 2015-03-23 | 70 Upvotes 27 Comments
In utility-scale electricity generation, the duck curve is a graph of power production over the course of a day that shows the timing imbalance between peak demand and renewable energy production. The term was coined in 2012 by the California Independent System Operator.
- "Duck Curve" | 2019-10-27 | 154 Upvotes 128 Comments
The gravitation water vortex power plant is a type of micro hydro vortex turbine system which is capable of converting energy in a moving fluid to rotational energy using a low hydraulic head of 0.7–3 metres (2 ft 4 in–9 ft 10 in). The technology is based on a round basin with a central drain. Above the drain the water forms a stable line vortex which drives a water turbine.
It was first patented by Greek-Australian Lawyer & Inventor Paul Kouris in 1996, who was searching for a way to harness the power inherent in a vortex.
Later, Austrian Inventor Franz Zotlöterer created a similar turbine while attempting to find a way to aerate water without an external power source.
- "Gravitation water vortex power plant" | 2018-04-21 | 227 Upvotes 80 Comments
Ixtoc I was an exploratory oil well being drilled by the semi-submersible drilling rig Sedco 135 in the Bay of Campeche of the Gulf of Mexico, about 100 km (62 mi) northwest of Ciudad del Carmen, Campeche in waters 50 m (160 ft) deep. On 3 June 1979, the well suffered a blowout resulting in one of the largest oil spills in history.
- "In 1979, a Gulf of Mexico oil spill went on for 10 months at about the BP rate." | 2010-05-28 | 88 Upvotes 41 Comments