I've read through the thread and I can see where there is a disconnect between the ideas
@KI4MVP and
@Brandname are putting forward and the contrary points
@MalTalm and Q-Tip are making.
I think a few points made however are scientifically inaccurate, and just want to offer my opinion on that.
1)
@MalTalm; you can't look at solar PV total energy conversion as being "inefficient" in the same way as one might look at fossil fuels. In other words, assigning total efficiency a net value at the right end of your equation as you did ("11%") is not mathematically sound
if the goal is to use this for comparative purposes with other forms of electricity generation.
While PV solar energy conversion is a generally inefficient process on small scales, the energy (kJ) stored in a given area(m^2)/time(s) is relatively large. More importantly, it is essentially free and in many places of the world, it is predictable with generally high availability.
What this means is that on small scales, like the roof of your home, solar PV panel efficiency is of extreme importance. In fact, it's the most important factor, but space and cost are the most limiting factors. However,
@KI4MVP and
@Brandname are talking about solar power generation on large scales, where these factors are
far less important. For commercial power generation, simply scaling the area of collection completely removes PV panel efficiency as a bottleneck for competitive costs; which is why KI4MVP has and continually uses the cost of generated electricity from power plants, and not from home installations.
In this sense, he is absolutely correct. According to most estimates, solar power (again, generated by plants and not homes) will reach a national average cost of $0.056/kWh within the next 4.5 years. That's far below the national average and for high populated areas like California, would be highly beneficial.
2) Fossil fuels are more efficient carriers of energy. This statement is true with current technologies (it is not true on the whole though); thus, for a given area, there is more potential energy stored electrochemically in say a given volume of, gasoline, than there is in a given area of sunlight at sea-level.
However, if we consider the fact that gasoline is a finite and
costly resource, not only to extract oil but to find it,
then extract it, refine it, and finally transport it, and then we contrast that paradigm with the fact that land area for solar collection, horizontally, is inexpensive and the area vertically above that land is essentially free, then solar power becomes a
much more
cost efficient means of extracting energy over longer periods of time.
The key point here is longer periods of time. Fuels, in general, are great ways to transport energy in small volumes and store them efficiently. Gasoline is great for what it does, better than a battery with present technology. But this doesn't mean that coal is a superior energy source for electricity generation than solar.
Under technologies of the past, sure; but at present, no way.
3) Describing DC->AC conversion as being inefficient and thus preventing solar power on large scales is an inaccurate way of describing the problems facing solar power generation
on large scales. This simply is
not true, again, within the confines of a power plant.
High current VDC inverters operate at 95% efficiency. Again, the generally fixed % loss here is easily compensated by increasing total collection area to maintain a predictable a fixed total power output.
With that said there are large solar power plant inefficiencies in general, but many of these inefficiencies are present across technologies, solar or otherwise.
In general, modern plants can operate at high levels of efficiency, and again, since solar power is a free and infinite resource, the finite restraint is land area (avg. seasonal kWh/m^2 for a given geographical location) and initial investment - which in many cases is cheap, and subsidized, respectively.
4) That solar means, invariably DC power. This isn't true either. Solar power plants can generate AC power via turbines. There are numerous forms of solar based power generation, not simply the most rudimentary PV installations.
5) That solar power means improving battery technology. This one, again, is really more to do with home use of solar power and not large scale power plants that would be built as part of a national initiative. Commercial solar power plants may use similar techniques to store power as do other power plants including using molten salts to store thermal energy. Both PV and solar thermal energy can be utilized simultaneously in many plant designs.
6) That the national grid, using AC power, is an impediment to solar power. This simply isn't true,
again, with respect to solar
power plants.
7) That fusion is the future of power on Earth and we should wait for it. I actually have mixed feelings about this since I started my academic career in particle physics particularly relating to fusion power before eventually moving on to cosmology and astrophysics. However, again, I have to say I don't think this is true and for quite a few reasons.
That is to say, if given two competing near-term technologies, nuclear fusion, or space based solar power; which do I think would be the most advantageous for the future of a given society (or mankind on the whole)? I think the answer is definitely solar power over fusion.
The reasons for which are somewhat beyond the scope of this conversation, I think; however, the main points are easy to understand:
(a) solar power is
practically infinite, extremely large and readily available very large scales of solar-based energy will outlast the Earth itself;
(b) once the infrastructure is established, it is essentially only as costly as the maintenance for such infrastructure;
(c) we actually
already have the technology, it is simple, and while there would be some engineering hurdles, SBSP requires no new advances in theoretical science;
(d) fusion still produces radioactive byproducts for most reactions, and for those that don't (like He-3) the materials required are rare on Earth thus proposing even larger hurdles for mining these materials in space;
And I could actually continue to go on, and on...
The point is that I think some folks in here are looking at the problems of solar power for the home, solar PV panels installed on the roof of a house and then attempting to scale those unique and particular problems up to national scales. This does not work, for the aforementioned reasons as well as others.
Nationally, ground-based solar turbine and PV does work, is cheap, and is an efficient way to deliver power to specific regions of the country.
That being said, I don't think we can migrate our energy power generation completely to ground based solar; for many reasons. I do think the near-future should include this on much larger scales than that which are currently planned. I also think we should reinvest much of our efforts into nuclear energy. We could cut national energy consumption of fossil fuels dramatically by embracing these two technologies.
Long-term yet still well within our lifetimes, space based solar power is almost assuredly the answer for 90% of our energy use (if not more); barring some major change in the cost and power output of fusion reactors.
I say that simply because it is the one and only available power resource that can scale nearly-infinitely without consideration for a practically finite resource (like He-3, uranium, thorium, etc).
It's also the only power source that makes sense for man's expansion into space, for environments that haven't the resources to use clean energy, like developing countries who can purchase power from the country that develops space based solar, and for nations that would prefer a cleaner energy solution and are not strategically opposed to the nation that is selling SBSP power.
I wanted to leave any liberal bias or my personal views on what the country should do with respect to taxes, etc, for a different post. I just wanted to tackle the scientific and engineering challenges for a national solar power initiative of a similar scale to say McCain's 50 nuclear plants in 20 years proposal (a proposal I supported btw).
While I don't think solar is a complete solution in the next 20 years, that is only by choice. The technology does exist to nearly completely replace our electricity generation with solar power in that time period, but it would take a
monumental effort. The United States could do it, but it isn't likely going to happen for reasons that I think should be left for a different post.
