- A bucket grain elevator is powered by a 150 kW electric motor. Determine its efficiency if it can lift grain to a height of 60 m at a rate of 900 m3/h. Assume the elevator is lifting wheat with a density of 770 kg/m3.
- Write something else.
- Write something different.
- Write something completely different.
The United States in a humongous machine. Energy comes in, energy goes out, and work is done. Every year since 1976 (and a for a few years before that), the Lawrence Livermore National Laboratory (LLNL) has released annual flowcharts that illustrate the production and consumption of energy for the whole of the United States. Primary energy sources are on the far left (petroleum, natural gas, coal, nuclear, biomass, wind, hydro, solar, geothermal) Energy consumption sectors are on the near right (transportation, industrial, residential, commercial) with electricity generation as an intermediate step. Ultimately, all energy winds up on the far right as useful energy (energy services) or rejected energy (lost energy).
The images below link to a copy of every LLNL energy flowchart I could find. Use the information in these flowcharts to create four time series graphs for the US machine and comment briefly on each one. The overall trend in one graph may shock you.
- energy consumption vs. year
- useful energy vs. year
- rejected energy vs. year
- efficiency vs. year