[semi-extrinsic]

The interesting question for solar power is not "When will stand-alone solar power be cheaper than coal/gas?". It is "How high can we push the fraction of solar power / total power before the power distribution grid fails?". You need base power generation to augment solar/wind, there's not a serious scientist in the world denying that, and the numbers I've heard quoted say you can't average much more than 50-60% solar and wind combined.

Right now, Germany is charging ahead on solar. Their current peak record is 50.4% of total power from solar, on a sunny midsummer day with low power usage. Meanwhile, all of their neigbouring countries to the east are doing massive overhauls/reconfigurations of their power distribution grids just to be able to supply Germany with enough base power, mainly from nuclear.

[ghshephard]

The "We can't do everything with solar" was what everyone was saying (correctly) in 2005-2010. But, the entire point of the Powerwall product is that, today (not next year, today), in parts of Australia and Hawaii, it is now less expensive, and more efficient, to go 100% solar. As the prices of batteries drop, and solar becomes more efficient, the number of places where that is true will only increase.

From the perspective of watching trends back in 2005, this wasn't supposed to happen until 2025, so it's arriving 10 years early.

There's nothing that would prevent a good storage system + wind + power from supplying 100% of the power requirements reliably. You just need to scale your Storage system to handle the periods in which solar/wind aren't driving power.

Regarding the Germany Scenario - Let's see how much nuclear they are going to require after they add a few Terrawatt-Hours worth of battery storage to their grid.

Finally, commenting on your "so Serious Scientists" - there are a lot of them that have done the calculations and have come to the conclusion that only a solar solution will supply the world with the power it requires so that everyone can have an first-world lifestlye. In particular, check out Nate Lewis's introduction to Solar Energy - https://itunes.apple.com/WebObjects/MZStore.woa/wa/viewPodca... ,He "provides a beginner's overview of the concepts behind solar energy generation as well as the current state of the art and its potential role in future energy production."

It's eye opening - even nuclear power plants don't stand a chance versus solar (which, to be honest, is just harvesting the output of a really, really, really big fusion generator)

The missing component has always been storage, and Elon has jumpstarted that conversation. The powerall is interesting, the gigafactory is more interesting, but the fact that he realizes Tesla is only going to be a tiny, tiny element of a much larger industrial transition, is, in my mind, the most important part of this story.

[semi-extrinsic]

Sorry, that's just missing the mark. In northern latitudes, where most of the world's energy consumption is currently located, the seasonal variation in solar influx means a 100% solar solution needs to do energy storage for months at a time. Continuing with the Germany example, the monthly-average production of solar power in January is ~ 1/15th the production in July.

And I don't believe we will ever be able to get the whole world up to current western consumption levels. More to the point, we really shouldn't, as current consumption levels in the west are clearly unsustainable.

[ghshephard]

Not sure who downvoted you (I leveled you up) - I spent about 30 minutes researching seasonal variation of solar power in northern climates (http://www.reuters.com/article/2012/10/16/us-column-wynn-ren...) and your numbers check out. "For example, aggregate solar power generation in the first week of January was only 7 percent of peak production in the final week of May

The northern climates, then, are a challenge for solar, even with lots of storage. Fair point, and something to think about.

But, as to your second point, about how we shouldn't get the whole world up to current western consumption levels - I don't know about you, but I like hot water in the morning, air conditioning on a hot day, clean clothes from the washing machine, baked goods at home, and and a warm house on a cold winters day. I agree that efficiency is important (all of those things can be delivered more efficiently - same value with less energy), but I certainly wouldn't suggest that everyone in the world shouldn't have access to them, and more.

[semi-extrinsic]

(I'm not able to reply to ghshephard, so I put it here.)

My point about not getting everyone up to western consumption levels isn't mainly about the things you mention. It's more about the use-and-throw-away culture, plus the general inability of people to make stuff themselves. Imagine the impact if people started mending stuff and clothes, cooking their own food, taking the bicycle with a trailer to the local market to do the weekly shopping, etc. Not just on reducing direct and (mainly) indirect energy consumption, but on public health and general happiness levels! There's so much of our energy consumption that doesn't improve our lives in any meaningful way.

[ghshephard]

I won't argue about how we live in a terribly consumer-fixated culture - totally agree with you. Ironically, at this exact moment, I'm writing a review on Amazon, about how much I like my 15 year old Kaito KA007 hand-cranked radio. It's never seen a single battery, yet I've had it with me on camping, business trips, burning man - everywhere. 60 seconds on the crank gets me 20 minutes of radio. I hope to have it with me another 15 years.

Likewise, my Mountain Equipment Co-Op Backpack that I've had for 18 years - I've had that with me every single day for 19 years, it's my laptop case, my tool case, my document holder - In the Amazon Jungle, Luxembourg, and with Network Engineers in London, Dubai and Singapore. I've used the heck out of it - and it's still going strong.

So, I'm totally on board with having a very few things, that you take good care of, and last a long time.

But - this is a separate conversation (somewhat) from energy usage. Heat, Pumping/Processing water, cooling - they all have some physical minimum amounts of power. And even if you are living a hyper-efficient 40 gallons/day life style (Northern California, see http://www.nytimes.com/interactive/2015/04/01/us/water-use-i... ) versus the rest of the world (See: http://www.data360.org/dsg.aspx?Data_Set_Group_Id=757) - there are some physical limits as to how little energy you can use and still maintain a comfortable lifestyle. We can only be efficient so far - eventually we're going to have to find a way to provide lots, and lots, and lots of power to everyone in the world, if they want to live a comfortable lifestyle.

Thankfully, much of that comes from having warm homes, and hot water - something that Solar does an admirable job of providing (bringing it all back to the original thread).

[semi-extrinsic]

I agree wholeheartedly with all of this. But I think reducing consumption is probably the most significant thing a person can do to lower their CO2 footprint. My rule of thumb (which is fairly good across a surprising range of goods for ones that I've tested) is that at least 500g of CO2 is emitted for every dollar you spend, whether that's on electricity with our current typical fuel mix or on a cheeseburger or a plane journey. So if your electricity bill is say 5% of your monthly expenditures, electric energy usage is just responsible for 5% of your total CO2 emissions. This is very ballpark, but you get the idea.

[Someone]

"There's nothing that would prevent a good storage system + wind + power from supplying 100% of the power requirements reliably. You just need to scale your Storage system to handle the periods in which solar/wind aren't driving power."

Nothing, except for costs. Those are going down and are becoming competitive for many parts of the world, but costs will be prohibitive for some climates for quite a while. For example, if you have lots of snow and strong winds in winter, you may need to have _weeks_ of power storage to get reliable power.

Keeping a grid connection for those cases will help, but if lots of people do this, the price of power in those peak periods may surge a lot as your electricity supplier will have to recoup the costs of keeping its plant on standby year round in a few weeks.

That seems fixable by connecting solar/wind systems over large distances, but we have to work on getting a grid that is fed by thousands of suppliers and in which the direction power flows can vary more.

But yes, I think solar and wind are the future and even the near future, even in the less sunny parts of the world.