Hacker News Reader

Comment by diafygi | Hacker News Reader

You can get to approximately 50% penetration safely without storage[1], then you have to start adding factors that can deal with intermittent sources like wind and solar[2]. It doesn't have to be storage, either. You can used demand response signals to outsource your "storage" by paying people to turn off their electric vehicle charging or ice manufacturing for a period of time. In energy, reducing demand has the same result as increasing supply.

Additionally, in hotter places like the UAE, solar irradiation tends to correlate much more with grid load, since cooling is the primary energy use. So, you could safely push well beyond the 50% penetration point for solar/wind.

[1]: https://people.eecs.berkeley.edu/~vsmith/docs/renewables_sgc...

[2]: https://www1.eere.energy.gov/solar/pdfs/2010ulw_ellis.pdf

View on HN

> solar irradiation tends to correlate much more with grid load.

This is a very interesting remark. Last week, we had relatively high temperatures in Germany and France (above 30°C). In Germany, because the weather was perfect for solar, this reduced the middle of the day spot price where in France, this increased the spot price[0].

[0]: https://www.eex.com/en/ "European Energy Exchange"

In the US, the peaks are in the afternoon, when you have a mix of business and residential use along with lingering high temperatures in summer.[0]

In the UK, meanwhile, peak load is driven by tea kettles and Eastenders.[1]

[0a] http://cleantechnica.com/2014/07/21/utilities-cry-fowl-over-...

[0b] http://businesstech.co.za/news/hardware/86252/new-battery-te...

[0c] https://www.cnet.com/news/a-technology-race-to-curb-peak-ene...

[0d] There's a great NPR viz on power sources around the US, though somewhat dated now: http://www.npr.org/2009/04/24/110997398/visualizing-the-u-s-...

[1] http://www.bbc.co.uk/britainfromabove/stories/people/teatime...

> You can get to approximately 50% penetration safely without storage[1], then you have to start adding factors that can deal with intermittent sources like wind and solar[2].

Keep in mind that this number will vary depending on generation mix. Specifically, it will depend on the response time of your dispatch-able generators. If your primary source of non-renewable generation is big steam turbines with a painfully slow ramp-rate (e.g. coal generation) then you're going to have a bad time.

> If your primary source of non-renewable generation is big steam turbines with a painfully slow ramp-rate (e.g. coal generation) then you're going to have a bad time.

Which is why most coal in the US is being displaced by combined cycle natural gas turbines; ~10-30 minute ramp, depending on load demand.

http://www.utilitydive.com/news/a-users-guide-to-natural-gas...

Reply on news.ycombinator.com