Renewable Energy Systems Final

What is the “trias energetica”?

1.) Minimize demand for fossil fuels. 2.) Use sustainable energy. 3.) Use fossil fuels as efficiently as possible

Primary vs final energy

Energy created vs energy transported to consumer. Changing states always means a loss of some energy

Energy consumption formula

(wattage x time (minutes is a decimal))/1000 = use per day

What is the history of renewable energy?

Low generation compared to fossil fuels, but show signs of exponential growth. Solar has experiences a 99.6% drop in electricity production cost. Wind has dropped by 70% in the last 10 years.

Which countries have recently been deploying the most renewables?

Nepal (EV’s), Pakistan & India (solar)

How has wind grown in capacity?

0.5 MW in 1990. 21 MW in the EU and 26 in China in 2025.

What are the capacity factors of wind turbines?

What is Betz law?

Betz law keeps maximum energy efficiency at 59.3%. If downstream wind molecules are stopped completely, then no new air molecules can enter the system upstream to move it (think of a crowd)

What is the capacity factors of wind turbines?

average power generated/peak capacity

What is the energy output of a wind turbine?

capacity factor x nameplate capacity x hours of use per year

How are wind turbines reducing sound?

Biomickery, replicating owl’s wings

What is the danish model of wind energy?

Half of investors are from the community. They get money made from the wind turbine

What is the difference between solar photovoltaic and solar thermal?

Solar photovoltaic transform solar radiation into energy. Solar thermal heats up insulated pipes with solar rays (warm enough for showering, not for cooking)

How has solar photovoltaic’s energy efficiency developed?

Most recent models have produced 360 W, with an efficiency of 20.8%, from 15.3 (250 W)

How does orientation effect solar panels?

In the Northern hemisphere, panels must be a south-facing surface (E or W) and vice versa. 90 angle is best orientation.

Where should solar panels be placed?

Commercial over residential, and abandoned development over fields.

How much energy is lost during combustion

60-70 percent. Roughly one third of energy is gathered (fossil fuels and coal)

What are possible uses of electricity when production is greater than consumption?

Selling it to other grids (countries) or converting the energy into chemical storage

What are the pro and cons of hydrogen power?

Hydrogen is very efficient and powerful. It it is hard to contain (leaks easily) and high explosive