patrick.net

http://physics.ucsd.edu/do-the-math/2011/09/dont-be-a-pv-efficiency-snob/

Long read but worth it. I'm skeptical that solar with supply electricity on Giga or Terra watt scale that the US consumes, but it provide a share.
Also remember that the "front end" of solar (and most other alternative energy sources) is fossil fuel based.
That said we should have a much more aggressive effort involving it.

Rooftop solar continues to improve and has much to commend it, especially considering that half of [update: see below - long line] utility electricity is lost in transmission, but the issue comes down to storage. When battery prices come down, rooftop solar will become much more popular.

Also, the exclusive focus on PV is misplaced. If you want to run lighting and electronics, then PV and LED are ideal, but if you want heat, then you should look at old fashioned solar heating pipes using either water or oil as the heat transfer/storage medium. It is possible to combine both, with the visible light being absorbed by PV panels and the infrared heat going through to pipes underneath. If you can adjust the height of the panel assembly relative to the roof, then it can provide cooling shade in summer and warming insulation in winter.

The utilities seem to finally be a adopting a "if you can't beat 'em, join 'em mentality". Distributed grid regulation provided by solar inverters that can synthesize reactive power -- who knew? And on that front, all the Enphase microinverters (800,000+) on the Oahu were recently upgraded to provide voltage regulation when the grid experiences minor events that might affect the operating voltage or grid frequency. (PS - let's hope the link from the Enphase mothership and the microinverters is really secure).
Batteries, we don't need no stinkin' batteries -- just a HVDC link to Norway. Hmm.. wonder if California could partner with all that hydro in the Pacific Northwest.

curious2 says

considering that half of utility electricity is lost in transmission

If we're talking transmission losses in the United States, I usually see figures of around 7% over all.

Or are you including other sorts of inefficiencies?

curious2 says

the exclusive focus on PV is misplaced

Heat pumps are great for California's temperate climate. The place I occasionally house-sit for has one, and he told me to stop substituting a single-room electric space heater for his whole-house system, since the space heater was actually pulling more power.

Being a zillionaire, he's been able to work every angle of the system wrt subsidies for his rooftop PV and EVs, LOL.

HydroCabron says

If we're talking transmission losses in the United States, I usually see figures of around 7% over all.

Citation please?

HydroCabron says

Or are you including other sorts of inefficiencies?

I was talking about long line transmission, which is typical for consumers considering solar. Some large users install generators on their properties, so they have near zero transmission loss, and likewise NYC has many local substations due to legislation requiring electricity to be generated within the city, and those would bring down the national average. Also I wonder if your 7% includes fuel transport, and if it's even a number that you got from a reliable source. Typical suburban homeowners and city dwellers considering rooftop solar are currently relying on long lines.

curious2 says

HydroCabron says

If we're talking transmission losses in the United States, I usually see figures of around 7% over all.

Citation please?

U.S. Energy Information Administration

EIA estimates that national electricity transmission and distribution losses average about 6% of the electricity that is transmitted and distributed in the United States each year.

Wikipedia quotes the same figure - I'll leave them out, since some do not consider them an acceptable reference.

Sunrun.com, a solar-panel sales and installation firm:

As you can see, long-distance transmission gets messy. On average, 7-8% of the total energy generated is lost during this entire process.

World Bank data: 6%

National Geographic (2010)

7-10%

NEMA (warning - PDF)

Generally speaking, T&D losses between 6% and 8% are considered normal.

That's the reason your contention of 50% losses sticks out for me.

Citation?

Since the 7% figure is generally used to calculate the efficiency of electric cars vs. gasoline, and the numbers show that electric cars, even when charged through the grid, are a more efficient way to use raw feedstocks, these numbers are of some interest. A change from 7% to 50% would probably be enough to put grid-charged electric vehicles behind gas vehicles - not the usual result I have seen.

The worst figure for long-distance losses is around 4%. This jibes with the facts on the ground: for example, New York will often get cheaper power from plants 1000 miles further away than the usual, indicating that long-distance transmission is efficient compared to other considerations.

By the way, the breakdown among the various conversion steps (step-up and step-down transformers plus line losses) seems to break down like this:

1-2% – Step-up transformer from generator to Transmission line
2-4% – Transmission line
1-2% – Step-down transformer from Transmission line to Distribution network
4-6% – Distribution network transformers and cables

The overall losses between the power plant and consumers is then in the range between 8 and 15%.

These guys give the highest total loss estimate I could find, still well below 50%.
See http://blog.schneider-electric.com/energy-management-energy-efficiency/2013/03/25/how-big-are-power-line-losses/

HydroCabron says

Wikipedia quotes the same figure - I'll leave them out, since some do not consider them an acceptable reference.

Well, if you accept Wikipedia as a source, then the simplest citation would be there: "Long-distance transmission of electricity (thousands of kilometers) is cheap and efficient, with costs of US$0.005–0.02/kWh (compared to annual averaged large producer costs of US$0.01–0.025/kWh". In other words, cost of generation and cost of transmission were about the same at the time their source was published, but following the links I found their source was a paper published more than 30 years ago.

Searching further, I found a range of numbers from around the world, e.g. in India: "Not only is too little energy produced, but as much as 60 percent of that energy is lost in transmission and distribution." In America, Schneider estimates, "The overall losses between the power plant and consumers is then in the range between 8 and 15%...This must not be mixed up with the efficiency of power plants like nuclear, coal-fired or natural gas turbine. These technologies are based on a thermodynamic cycle, which efficiency is in the order of 35%... From the energy assessment, it can be concluded that 100 units saved at home can save 300 units saved at the power plant."

My original 50% number came from a documentary I saw years ago. It may have reflected the infrastructure deployed at that time, or combined different percentages from around the world, or conflated generation and transmission losses.

Until the Saudis start to limit production and the price of oil gets back to its normal high, there won't be as much investment in alternative energy generation, in the next few years. I wouldn't be surprised if the coal-to-gasoline facility in West VA gets shelved for another generation.

Does this 3-5X supply still work if CA has to distill more ocean water?