Renewable energy production variability by hour of day, and by season (graph)

– …illustrate the variability of wind and solar generation relative to the comparatively smooth output from other generation sources

– Power produced by geothermal, biomass, biogas, and small hydro generators can be easily dispatched, meaning it can be either increased, decreased, or controlled to remain fairly constant.

– Wind resources are often more available at night.

– Solar power is not generated until the sun comes up, and can increase and decrease quickly as the sun rises, sets, or is blocked by cloud cover. However, much of California’s utility-scale solar capacity is based on concentrating solar technology, which embodies enough thermal storage to continue generating power for a few hours after the sun goes down

– The variability of wind and solar power generation leads to challenges in power system operations and planning.

– The contribution towards total generation from eligible renewable resources also varies seasonally. For the dates charted above, the amount of renewable generation as a percentage of the total generation ranges from 8% on Oct 18, 2011 to 14% on May 9, 2011.

via – Today in Energy, EIA

Apple, Amazon, & Microsoft build data centers around dirty energy

The current explosion in cloud computing offered by major IT companies is driving significant new demand for dirty energy like coal and nuclear power, according to a new report from Greenpeace International.

The report, “How Clean is Your Cloud?” shows a growing split within the tech industry between companies that are taking steps to power their clouds with clean energy, like Google, Yahoo and Facebook, and companies like Apple, Amazon and Microsoft who lag behind by choosing to build their growing fleets of data centres to be powered by coal and nuclear energy.

“When people around the world share their music or photos on the cloud, they want to know that the cloud is powered by clean, safe energy,” said Gary Cook, Greenpeace International Senior Policy Analyst. “Yet highly innovative and profitable companies like Apple, Amazon, and Microsoft are building data centres powered by coal and acting like their customers won’t know or won’t care.”

The report research found that if the cloud were a country its electricity demand would currently rank 5th in the world, and is expected to triple by 2020.

“While many IT companies have made great strides in efficiency, that’s only half the picture – they need to make sure their energy comes from clean sources,” said Gary Cook, Greenpeace International Senior Policy Analyst.

Companies like Google, Yahoo and Facebook are beginning to lead the sector down a clean energy pathway through innovations in energy efficiency, prioritising renewable energy access when siting their data centres, and demanding better energy options from utilities and government decision-makers.

 

keep readingApple, Amazon, & Microsoft choose dirty energy