# Tag Info

Accepted

### Could a mainspring be used to generate train acceleration during starting-up from the kinetic energy stored during its slowing down?

I found that on some Spanish lines, the kinetic energy during braking is converted to electricity and used by other trains from the same line (research paper), but why not keeping the mechanical ...
• 8,229
Accepted

### Why does compressed air energy storage use intercoolers?

Not just CAES system, intercooling is desired for multi stage compressors in general, if you checked this diagrams of isentropic, polytropic and isothermal compression processes between the same ...
• 2,149

### Can the Sabatier reaction power a vehicle?

According to Wikipedia: It [Sabatier reaction ] involves the reaction of hydrogen with carbon dioxide at elevated temperatures (optimally 300–400 °C) and pressures in the presence of a nickel ...
• 2,149

### Could a mainspring be used to generate train acceleration during starting-up from the kinetic energy stored during its slowing down?

On the London Underground, many stations use gravity. The line runs uphill into the station, and then departs downhill. This gives a large amount of energy storage, for free, with no additional moving ...
• 406
Accepted

### What causes rechargeable batteries to age? What can be done to extend life of these batteries?

One of the problems that plagued older rechargeable batteries (e.g. Nickel Cadmium ($\text{NiCad}$) and Nickel Metal Hydride ($\text{NiMH}$)) was the memory effect. The memory effect occurs when a ...
• 2,485

### Could a mainspring be used to generate train acceleration during starting-up from the kinetic energy stored during its slowing down?

Note also that springs are subject to eventual (and very sudden) failure as they develop cracks with age and a very sudden 5.6MJ energy release inside a railroad car would be exceptionally dangerous!

• 206
Accepted

### Storage losses of a heat storage tank

Heat loss due to conductivity of the walls of your container assuming the ambient outside temperature, $$\frac{\Delta Q}{\Delta t*A}=-k \frac{\Delta T}{\Delta x} =C_{constant}$$ In the above ...
• 21k

### Working hours of power plant generators

There isn't a single answer that covers large power plants around the world. There's way too much variation in generation plant, and way too much variation in the way that plant is used. Some plants ...
• 3,701

### Can the Sabatier reaction power a vehicle?

Algo has given you a good answer about the detail. There is a much broader, more widely-applicable, kind of answer. Converting any form of energy to heat introduces huge inefficiencies. It is the ...
• 3,701
Accepted

### Heat transfer coefficient of a cylindrical hot water storage tank depending on its size

In a tank with no fluid movement and no heat source with steady ambient temperature, the temperature of fluid are layered strata roughly in onion layers but favoring the top of the tank, meaning the ...
• 21k
Accepted

### Does a fully mechanical heat pump make sense?

Virtually every possible way of doing this is already out there. For bolt-ons, you can find propshaft pto chain drives and belt drives, hydraulic and mechanical engine pto systems, and front of block ...
• 3,425

### Is compressed air energy storage economically viable in the home?

The existing answers do a pretty good job of explaining the sizing and the economics, but surprisingly for an engineering site, skip over the equipment. And that's where this becomes totally ...
• 762

### Is compressed air energy storage economically viable in the home?

I'm going to do some naïve math. So while charging your setup at night, you take in $x$ kilowatt-hours per hour. Multiply this by 7 hours, and you've taken in $7x$ kilowatt-hours. At a cost of \$\frac{...
• 2,485

### Can large capacitors allow power plants to run at full load and store excess electricity?

Capacitors typically store power over short periods of time, seconds or minutes. This is too short to be useful for the electrical power grid. Typically peak power demand occurs during the day, ...
• 236
Accepted

### Working hours of power plant generators

There isn't currently any practical means of storing electrical energy on a large scale. There are technologies which can store energy for specific applications but certainly nothing which would have ...
• 15k

### Working hours of power plant generators

A typical conventional power plant may consist of multiple generating units rather than one big huge unit. By having multiple units, the plant is better able to respond to changes in demand during ...
• 302