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A compression ratio of 2 is possible (and sometimes more) but unless the motive steam is at a reasonably high pressure (say, 16 bar g - 250 psig - or more), the motive steam consumption will be in the range of 2 kg per kg of suction vapors. A higher compression ratio means a smaller heat exchanger, and a reduced investment cost.
The following table shows a range of estimates of the levelized costs of gray, blue, and green hydrogen, expressed in terms of US$ per kg of H 2 (where data provided in other currencies or units, the average exchange rate to US dollars in the given year are used, and 1 kg of H 2 is assumed to have a calorific value of 33.3kWh).
The cost of hydrogen production by reforming fossil fuels depends on the scale at which it is done, the capital cost of the reformer, and the efficiency of the unit, so that whilst it may cost only a few dollars per kilogram of hydrogen at an industrial scale, it could be more expensive at the smaller scale needed for fuel cells.
At an electricity cost of $0.06/kWh, as set out in the Department of Energy hydrogen production targets for 2015, [73] the hydrogen cost is $3/kg. The US DOE target price for hydrogen in 2020 is $2.30/kg, requiring an electricity cost of $0.037/kWh, which is achievable given recent PPA tenders for wind and solar in many regions. [ 74 ]
Per-kilogram prices of some synthetic radioisotopes range to trillions of dollars. ... per mass of element contained. This implicitly puts the value of compounds ...
For a given steam velocity work done per kg of steam would be maximum ... modern steam turbines are simple and incur low costs (typically around $0.005 per kWh); ...
Seattle Steam was founded in 1893 as the Seattle Steam Heat and Power Co. It owns 18 miles of pipes under the streets of Downtown. Its average winter output is 250,000 to 300,000 pounds (110,000 to 140,000 kg) of steam per hour; this drops to less than 100,000 pounds (45,000 kg) in the summer.
L.D. Porta gives the following equation determining the efficiency of a steam locomotive, applicable to steam engines of all kinds: power (kW) = steam Production (kg h −1)/Specific steam consumption (kg/kW h). A greater quantity of steam can be generated from a given quantity of water by superheating it.