Misplaced Pages

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49-542: The power station, which consists of an area of 150 ha (370 acres), was constructed in six sequent phases (completed in 2008), in each phase they built a new power plant, so the generation capacity increased to 150 MWth for the district heating and the nameplate capacity to 75 MW for electricity power. Svartsengi power station provides hot water for the district heating system of the entire Reykjanes Peninsula , including Keflavík , Njarðvík , Vogar , Garður , Sandgerði and Grindavík – more than 21,000 households. It

98-558: A light bulb with a power rating of 100 W is turned on for one hour, the energy used is 100 watt hours (W·h), 0.1 kilowatt hour, or 360  kJ . This same amount of energy would light a 40-watt bulb for 2.5 hours, or a 50-watt bulb for 2 hours. Power stations are rated using units of power, typically megawatts or gigawatts (for example, the Three Gorges Dam in China is rated at approximately 22 gigawatts). This reflects

147-513: A motor is the product of the torque that the motor generates and the angular velocity of its output shaft. Likewise, the power dissipated in an electrical element of a circuit is the product of the current flowing through the element and of the voltage across the element. Power is the rate with respect to time at which work is done; it is the time derivative of work : P = d W d t , {\displaystyle P={\frac {dW}{dt}},} where P

196-492: A constant opposing force of one newton , the rate at which work is done is one watt. 1   W = 1   J / s = 1   N ⋅ m / s = 1   k g ⋅ m 2 ⋅ s − 3 . {\displaystyle \mathrm {1~W=1~J{/}s=1~N{\cdot }m{/}s=1~kg{\cdot }m^{2}{\cdot }s^{-3}} .} In terms of electromagnetism , one watt

245-399: A force F A acting on a point that moves with velocity v A and the output power be a force F B acts on a point that moves with velocity v B . If there are no losses in the system, then P = F B v B = F A v A , {\displaystyle P=F_{\text{B}}v_{\text{B}}=F_{\text{A}}v_{\text{A}},} and

294-485: A logarithmic measure relative to a reference of 1 milliwatt, calories per hour, BTU per hour (BTU/h), and tons of refrigeration . As a simple example, burning one kilogram of coal releases more energy than detonating a kilogram of TNT , but because the TNT reaction releases energy more quickly, it delivers more power than the coal. If Δ W is the amount of work performed during a period of time of duration Δ t ,

343-537: A new pipeline was connected. In response to the threat of lava flows, the Icelandic parliament authorised the construction of protective earth barriers around the power station and the Blue Lagoon, which were largely in place by the time of the 8 February eruption. In June 2024, a small flow of a'a lava overflowed the berms, required additional berm construction and the first use of water to slow lava flows since

392-452: A period of one year: equivalent to approximately 114 megawatts of constant power output. The watt-second is a unit of energy, equal to the joule . One kilowatt hour is 3,600,000 watt seconds. While a watt per hour is a unit of rate of change of power with time, it is not correct to refer to a watt (or watt-hour) as a watt per hour. Power (physics) Power is the amount of energy transferred or converted per unit time. In

441-420: A periodic function of period T {\displaystyle T} . The peak power is simply defined by: P 0 = max [ p ( t ) ] . {\displaystyle P_{0}=\max[p(t)].} The peak power is not always readily measurable, however, and the measurement of the average power P a v g {\displaystyle P_{\mathrm {avg} }}

490-541: A turbine, which generates 648 MW e (i.e. electricity). Other SI prefixes are sometimes used, for example gigawatt electrical (GW e ). The International Bureau of Weights and Measures , which maintains the SI-standard, states that further information about a quantity should not be attached to the unit symbol but instead to the quantity symbol (e.g., P th = 270 W rather than P = 270 W th ) and so these unit symbols are non-SI. In compliance with SI,

539-495: A unit of time, namely 1 J/s. In this new definition, 1 absolute watt = 1.00019 international watts. Texts written before 1948 are likely to be using the international watt, which implies caution when comparing numerical values from this period with the post-1948 watt. In 1960, the 11th General Conference on Weights and Measures adopted the absolute watt into the International System of Units (SI) as

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588-458: Is a condenser plant with unique high pressure steam turbines and a total capacity of 30 MW. It produces only electricity, which depends on the using of the district heating and the electrical use. The 2023–2024 Sundhnúkur eruptions caused major disruption to the power station, which was threatened by swarms of earthquakes and repeated lava flows in its near vicinity. The power station was switched to remote operation but suffered minimal damage from

637-412: Is constant, the amount of work performed in time period t can be calculated as W = P t . {\displaystyle W=Pt.} In the context of energy conversion, it is more customary to use the symbol E rather than W . Power in mechanical systems is the combination of forces and movement. In particular, power is the product of a force on an object and the object's velocity, or

686-452: Is given by P ( t ) = p Q , {\displaystyle P(t)=pQ,} where p is pressure in pascals or N/m , and Q is volumetric flow rate in m /s in SI units. If a mechanical system has no losses, then the input power must equal the output power. This provides a simple formula for the mechanical advantage of the system. Let the input power to a device be

735-675: Is more commonly performed by an instrument. If one defines the energy per pulse as ε p u l s e = ∫ 0 T p ( t ) d t {\displaystyle \varepsilon _{\mathrm {pulse} }=\int _{0}^{T}p(t)\,dt} then the average power is P a v g = 1 T ∫ 0 T p ( t ) d t = ε p u l s e T . {\displaystyle P_{\mathrm {avg} }={\frac {1}{T}}\int _{0}^{T}p(t)\,dt={\frac {\varepsilon _{\mathrm {pulse} }}{T}}.} One may define

784-733: Is named after the Scottish inventor James Watt . The unit name was proposed by C. William Siemens in August 1882 in his President's Address to the Fifty-Second Congress of the British Association for the Advancement of Science . Noting that units in the practical system of units were named after leading physicists, Siemens proposed that watt might be an appropriate name for a unit of power. Siemens defined

833-414: Is power, W is work, and t is time. We will now show that the mechanical power generated by a force F on a body moving at the velocity v can be expressed as the product: P = d W d t = F ⋅ v {\displaystyle P={\frac {dW}{dt}}=\mathbf {F} \cdot \mathbf {v} } If a constant force F is applied throughout a distance x ,

882-401: Is the electrical resistance , measured in ohms . In the case of a periodic signal s ( t ) {\displaystyle s(t)} of period T {\displaystyle T} , like a train of identical pulses, the instantaneous power p ( t ) = | s ( t ) | 2 {\textstyle p(t)=|s(t)|^{2}} is also

931-499: Is the limiting value of the average power as the time interval Δ t approaches zero. P = lim Δ t → 0 P a v g = lim Δ t → 0 Δ W Δ t = d W d t . {\displaystyle P=\lim _{\Delta t\to 0}P_{\mathrm {avg} }=\lim _{\Delta t\to 0}{\frac {\Delta W}{\Delta t}}={\frac {dW}{dt}}.} When power P

980-465: Is the product of the torque τ and angular velocity ω , P ( t ) = τ ⋅ ω , {\displaystyle P(t)={\boldsymbol {\tau }}\cdot {\boldsymbol {\omega }},} where ω is angular frequency , measured in radians per second . The ⋅ {\displaystyle \cdot } represents scalar product . In fluid power systems such as hydraulic actuators, power

1029-523: Is the rate at which electrical work is performed when a current of one ampere (A) flows across an electrical potential difference of one volt (V), meaning the watt is equivalent to the volt-ampere (the latter unit, however, is used for a different quantity from the real power of an electrical circuit). 1   W = 1   V ⋅ A . {\displaystyle \mathrm {1~W=1~V{\cdot }A} .} Two additional unit conversions for watt can be found using

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1078-541: Is therefore considered one of the most important heating plants in Iceland. It is connected to the wider Icelandic electrical grid through Reykjavík. Svartsengi has also produced spin-offs; one of these side products is one of Iceland's most popular bathing resorts, the Blue Lagoon , and another is the first renewable methanol plant, Carbon Recycling International . In the beginning of 1976, Svartsengi power station

1127-530: Is used to quantify the rate of energy transfer . The watt is named in honor of James Watt (1736–1819), an 18th-century Scottish inventor , mechanical engineer , and chemist who improved the Newcomen engine with his own steam engine in 1776. Watt's invention was fundamental for the Industrial Revolution . When an object's velocity is held constant at one meter per second against

1176-408: The International System of Units , the unit of power is the watt , equal to one joule per second. Power is a scalar quantity. Specifying power in particular systems may require attention to other quantities; for example, the power involved in moving a ground vehicle is the product of the aerodynamic drag plus traction force on the wheels, and the velocity of the vehicle. The output power of

1225-414: The fundamental theorem of calculus , we know that P = d W d t = d d t ∫ Δ t F ⋅ v d t = F ⋅ v . {\displaystyle P={\frac {dW}{dt}}={\frac {d}{dt}}\int _{\Delta t}\mathbf {F} \cdot \mathbf {v} \,dt=\mathbf {F} \cdot \mathbf {v} .} Hence

1274-424: The mechanical advantage of the system (output force per input force) is given by M A = F B F A = v A v B . {\displaystyle \mathrm {MA} ={\frac {F_{\text{B}}}{F_{\text{A}}}}={\frac {v_{\text{A}}}{v_{\text{B}}}}.} The similar relationship is obtained for rotating systems, where T A and ω A are

1323-461: The 1973 Eldfell eruption. The water cooling capacity was subsequently increased. Both an increase in height of the barriers and water cooling strategies had to be applied, in attempts to protect local infrastructure including the power station, in later eruptions. Megawatt The watt (symbol: W ) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m ⋅s . It

1372-470: The above equation and Ohm's law . 1   W = 1   V 2 / Ω = 1   A 2 ⋅ Ω , {\displaystyle \mathrm {1~W=1~V^{2}/\Omega =1~A^{2}{\cdot }\Omega } ,} where ohm ( Ω {\displaystyle \Omega } ) is the SI derived unit of electrical resistance . The watt

1421-421: The average power P avg over that period is given by the formula P a v g = Δ W Δ t . {\displaystyle P_{\mathrm {avg} }={\frac {\Delta W}{\Delta t}}.} It is the average amount of work done or energy converted per unit of time. Average power is often called "power" when the context makes it clear. Instantaneous power

1470-583: The beginning and end of the path along which the work was done. The power at any point along the curve C is the time derivative: P ( t ) = d W d t = F ⋅ v = − d U d t . {\displaystyle P(t)={\frac {dW}{dt}}=\mathbf {F} \cdot \mathbf {v} =-{\frac {dU}{dt}}.} In one dimension, this can be simplified to: P ( t ) = F ⋅ v . {\displaystyle P(t)=F\cdot v.} In rotational systems, power

1519-415: The combined capacity of Svartsengi power station is 75 MW in electrical power and 150 MW in thermal power. Energy Plant 1 , with its two back-pressure turbines of 1 MW each, was constructed in 1977–1979. It consisted of four thermal energy circuits, which produced 40 L/s of heating water and 50 MW electricity for its own power needs, but today it is mostly out of action and only two circuits are in use, so

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1568-399: The earthquakes. Pressure readings from boreholes associated with the power station have proved to be useful in giving minutes warning at least of the eruptions. However, the main road leading to Svartsengi was engulfed by lava on 8 February 2024 and a section of the hot water pipe leading from it was also destroyed, leading to a heating crisis in parts of the peninsula for a few days until

1617-515: The energy company Ørsted A/S uses the unit megawatt for produced electrical power and the equivalent unit megajoule per second for delivered heating power in a combined heat and power station such as Avedøre Power Station . When describing alternating current (AC) electricity, another distinction is made between the watt and the volt-ampere . While these units are equivalent for simple resistive circuits , they differ when loads exhibit electrical reactance . Radio stations usually report

1666-611: The force is variable over a three-dimensional curve C , then the work is expressed in terms of the line integral: W = ∫ C F ⋅ d r = ∫ Δ t F ⋅ d r d t   d t = ∫ Δ t F ⋅ v d t . {\displaystyle W=\int _{C}\mathbf {F} \cdot d\mathbf {r} =\int _{\Delta t}\mathbf {F} \cdot {\frac {d\mathbf {r} }{dt}}\ dt=\int _{\Delta t}\mathbf {F} \cdot \mathbf {v} \,dt.} From

1715-523: The formula is valid for any general situation. In older works, power is sometimes called activity . The dimension of power is energy divided by time. In the International System of Units (SI), the unit of power is the watt (W), which is equal to one joule per second. Other common and traditional measures are horsepower (hp), comparing to the power of a horse; one mechanical horsepower equals about 745.7 watts. Other units of power include ergs per second (erg/s), foot-pounds per minute, dBm ,

1764-731: The maximum performance of a device in terms of velocity ratios determined by its physical dimensions. See for example gear ratios . The instantaneous electrical power P delivered to a component is given by P ( t ) = I ( t ) ⋅ V ( t ) , {\displaystyle P(t)=I(t)\cdot V(t),} where If the component is a resistor with time-invariant voltage to current ratio, then: P = I ⋅ V = I 2 ⋅ R = V 2 R , {\displaystyle P=I\cdot V=I^{2}\cdot R={\frac {V^{2}}{R}},} where R = V I {\displaystyle R={\frac {V}{I}}}

1813-460: The maximum power output it can achieve at any point in time. A power station's annual energy output, however, would be recorded using units of energy (not power), typically gigawatt hours. Major energy production or consumption is often expressed as terawatt hours for a given period; often a calendar year or financial year. One terawatt hour of energy is equal to a sustained power delivery of one terawatt for one hour, or approximately 114 megawatts for

1862-414: The path C and v is the velocity along this path. If the force F is derivable from a potential ( conservative ), then applying the gradient theorem (and remembering that force is the negative of the gradient of the potential energy) yields: W C = U ( A ) − U ( B ) , {\displaystyle W_{C}=U(A)-U(B),} where A and B are

1911-488: The power of their transmitters in units of watts, referring to the effective radiated power . This refers to the power that a half-wave dipole antenna would need to radiate to match the intensity of the transmitter's main lobe . The terms power and energy are closely related but distinct physical quantities. Power is the rate at which energy is generated or consumed and hence is measured in units (e.g. watts) that represent energy per unit time . For example, when

1960-427: The produced capacity is 25 MW of thermal power. Energy Plant 2 was built in 1980 and it produces, with its three thermal energy exchange systems, 225 L/s (3 × 75 L/s) of 90 °C (194 °F) hot water and 75 MW (3 × 25 MW) of power. Energy Plant 3 , with its 6 MW counter-pressure steam turbines, is especially used for producing electricity. Each second 40 kg of 160 °C (320 °F) steam passes through

2009-580: The product of a torque on a shaft and the shaft's angular velocity. Mechanical power is also described as the time derivative of work. In mechanics , the work done by a force F on an object that travels along a curve C is given by the line integral : W C = ∫ C F ⋅ v d t = ∫ C F ⋅ d x , {\displaystyle W_{C}=\int _{C}\mathbf {F} \cdot \mathbf {v} \,dt=\int _{C}\mathbf {F} \cdot d\mathbf {x} ,} where x defines

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2058-488: The pulse length τ {\displaystyle \tau } such that P 0 τ = ε p u l s e {\displaystyle P_{0}\tau =\varepsilon _{\mathrm {pulse} }} so that the ratios P a v g P 0 = τ T {\displaystyle {\frac {P_{\mathrm {avg} }}{P_{0}}}={\frac {\tau }{T}}} are equal. These ratios are called

2107-744: The torque and angular velocity of the input and T B and ω B are the torque and angular velocity of the output. If there are no losses in the system, then P = T A ω A = T B ω B , {\displaystyle P=T_{\text{A}}\omega _{\text{A}}=T_{\text{B}}\omega _{\text{B}},} which yields the mechanical advantage M A = T B T A = ω A ω B . {\displaystyle \mathrm {MA} ={\frac {T_{\text{B}}}{T_{\text{A}}}}={\frac {\omega _{\text{A}}}{\omega _{\text{B}}}}.} These relations are important because they define

2156-506: The turbines with 5 bar pressure. Energy Plant 4 , with its seven 1.2 MW Isopentan Ormat turbines, was built in 1989–1992 to produce power with 105 °C (221 °F) hot excess steam and low pressure steam from the other power plants. Energy Plant 5 was built in 1999 to substitute the old energy plant 1 and to increase the power and hot water, so the demand could be met. It produces with its 30 MW turbines and 75 MW thermal energy exchange system, around 225 GWh per annum. Energy Plant 6

2205-569: The unit of power. In the electric power industry , megawatt electrical ( MWe or MW e ) refers by convention to the electric power produced by a generator, while megawatt thermal or thermal megawatt (MWt, MW t , or MWth, MW th ) refers to thermal power produced by the plant. For example, the Embalse nuclear power plant in Argentina uses a fission reactor to generate 2,109 MW t (i.e. heat), which creates steam to drive

2254-570: The unit within the existing system of practical units as "the power conveyed by a current of an Ampère through the difference of potential of a Volt". In October 1908, at the International Conference on Electric Units and Standards in London, so-called international definitions were established for practical electrical units. Siemens' definition was adopted as the international watt. (Also used: 1 A × 1 Ω.) The watt

2303-622: The work done is defined as W = F ⋅ x {\displaystyle W=\mathbf {F} \cdot \mathbf {x} } . In this case, power can be written as: P = d W d t = d d t ( F ⋅ x ) = F ⋅ d x d t = F ⋅ v . {\displaystyle P={\frac {dW}{dt}}={\frac {d}{dt}}\left(\mathbf {F} \cdot \mathbf {x} \right)=\mathbf {F} \cdot {\frac {d\mathbf {x} }{dt}}=\mathbf {F} \cdot \mathbf {v} .} If instead

2352-562: Was completely liquid-dominated, but it changed into a liquid dominated with a steam cap geothermal system. Today, it consists of 13 production boreholes connected to the six plants, eight of those wells are producing a mixture of steam and brine and the other five are shallow dry steam wells. It also possesses one of the largest supervisory control and data acquisition ( SCADA ) systems in Iceland, with P-CIM monitors and 50 substations, which include hot water / cold water / electricity distribution systems and 11 turbines and generators. Nowadays,

2401-420: Was defined as equal to 10 units of power in the practical system of units. The "international units" were dominant from 1909 until 1948. After the 9th General Conference on Weights and Measures in 1948, the international watt was redefined from practical units to absolute units (i.e., using only length, mass, and time). Concretely, this meant that 1 watt was defined as the quantity of energy transferred in

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