What Is the Most Efficient and Safest Method to Generate Electricity?

[phinds]

I agree w/ you about the excessive secrecy in government these days. If there were active work going on regarding power collection in space beamed to Earth, I would be surprised if the DOD did not piggyback on the project to get some military aspect done, but the main project would be completely out in the open. That's exactly how it worked with NASA ocassionally putting up secret satellites for the military and the NSA.

 

[mheslep]

...common sense that it would not infringe on Earth's natural resources.

Space based solar? Not a the level of, say, coal combustion, but sure it would have an effect. Large land areas taken up with ground antenna arrays along with possible harm to birds, energy to launch and maintain, minerals mining for SB array.

 

[mheslep]

Resources are running out. Scientific fact.

The fact is that Earth based resources are finite. Whether or not they are "running out" is far more complicated, depending on many factors like demand, the availability of cheaper alternatives, and the feasibility of recycling.

 

[mheslep]

As a geologist I'd say definitely what is used today, natural gas and coal. These are going to be the most efficient for the next half century.

Eliminate the political aspect and nuclear is easily preferable to coal, and outside the US with its cheap shale gas nuclear beats gas too. I think the 24 nuclear reactors under construction in China is a confirmation.

 

[tom aaron]

50yrs is a short term fix, one must look to the next generation, building a power station with only a 50yr life is wasteful in my humble opinion.

It's not wasteful or efficient. It depends on capital investment and operating costs. Thus why nuclear is not feasible in most western nations. Even France is phasing out its percent of nuclear generated electricity. Germany, etc. are going to be replacing imported electricity with fossil fuels.

The majority of new capacity in the world will be what is being built now...as will be built in a decade...coal and natural gas generating stations. Solar, wind, etc. are feel good minor tinkering around the edges. The inefficiencies, capital costs, operating costs of alternative energy make them no more more than a footnote to energy needs.

 

[votingmachine]

It's not wasteful or efficient. It depends on capital investment and operating costs. Thus why nuclear is not feasible in most western nations. Even France is phasing out its percent of nuclear generated electricity. Germany, etc. are going to be replacing imported electricity with fossil fuels.

The majority of new capacity in the world will be what is being built now...as will be built in a decade...coal and natural gas generating stations. Solar, wind, etc. are feel good minor tinkering around the edges. The inefficiencies, capital costs, operating costs of alternative energy make them no more more than a footnote to energy needs.

Solar might be better than you are estimating. It was a year ago that news reports told us that HALF of German electricity was coming from solar power. As the higher capacity has grown, a lot from government incentivized demand, the economics of solar panels have gotten much better. With economies of scale, and better processes, solar panels are not that uneconomical. I think they are under 150% the cost of coal power electricity.

When I've looked at rooftop solar panels, they definitely pay for themselves in my sunny spot in Utah. But the lifetime used is generally 20 years. I believe that they are warrantied to be at 80% of the original capacity at 20 years.

The cost per watt keeps dropping on panels. My understanding is that a very large part of that is simply economies of scale as the factory infrastructure is built and operated at higher capacity. I don't think there is much further to drop, but the cost is fairly competitive now. A lot of the cost side has yet to be fully worked thru, as maintenance and true lifetime power curves are still changing.

 

[russ_watters]

Solar might be better than you are estimating. It was a year ago that news reports told us that HALF of German electricity was coming from solar power.

You misread. Coal is more than half of Germany's electricity production and like pretty much everywhere else, solar is an insignificant source of energy.

 

[zoobyshoe]

I think the "best" way is combined wind, solar, wave, hydro-electric, geo-thermal coupled with a push toward increasingly energy-efficient devices.

As Islands, the UK and Ireland have much more coastline than most countries and it would seem natural to take advantage of the usually windy conditions of coastal areas to take up as much slack as possible for their energy needs. According to Ryan_m_b, however, the British are psychologically resistant to the idea of having a lot of windmills on the landscape. The only thing that will dislodge them from that for certain is the eventual depletion of fossil fuels, but that's a long way away. In the meantime the only scenario that might give it a boost would be if some savagely aggressive, out-of-the-box-thinking person or group began to conceive of alternate energy as way to make money, to put the normal utilities out of business and set themselves up as the energy monarchs. Nice people working for a better environment, a better world, are never aggressive enough to change things. Technology only gets developed when businessmen get the idea they can make a lot of money off it. So, you'd need some kind of alternate energy pirate genius of the caliber of Steve Jobs to see a way it could make him rich, and who had the drive to get it done.

 

[votingmachine]

I think the news reports I read look like a snapshot, and it was misleading. They met half of demand with solar, but it was a low demand time. It is a bit difficult (apples to oranges) to compare power plant maximum capacities and what is being run. My impression is that Germany has been the leading installer of solar capacity, and once installed, Solar is used at full capacity available, and other plants are idled.

The yellow line for solar does show the story of increased installation. And you absolutely have to build capacity for peak demand, and the coal/nuclear plants will remain the main backstop for that peak. It looks like for the last decade, the only significant capacity they are adding is in Wind, Solar, and Other (hydroelectric?). The German goal is 80% of electricity from renewable sources. It may be that they will have a surplus coal plant capacity remaining idle.

I would say the electricity from solar in Germany is NOT insignificant. If you look at power capacity, it is still a very small fraction of the installed power production infrastructure. But it is used at 100% capacity available, which actually makes it more significant than you might otherwise expect.

The economics are definitely improved though. If given a purely economic choice between building a coal plant with 100 MW capacity, or solar installations at 100 MW capacity, the coal wins the business decision. But the gap has been getting smaller, as solar panel manufacture has moved to higher capacity, and has advanced technologically. THis curve shows some of the staggering progress in manufacturing costs of PV modules. And I think the drop has continue, and is now closer to $1 per Watt. Still higher than coal and natural gas, but surprisingly close.

 

[jim hardy]

I think the news reports I read look like a snapshot, and it was misleading. They met half of demand with solar, but it was a low demand time.

What ? The news was spun ?

Eternal vigilance is the price of truth.

Being generous
solar insolation might be 5 kwh/day.meter^2
http://www.nrel.gov/gis/images/eere_pv/national_photovoltaic_2012-01.jpg

5kwh is 17,060 BTU's
which is the heat co10 ntent of 1.7 pounds of coal - about one sockful.

A coal plant might be 40% efficient ,
and a solar cell 10 % efficient?

So, to make 5kwh a day takes 50 ten square meters of solar cell (a twenty-three ten foot square array, size of a two car garage roof)
or 4¼ pounds of coal, maybe one shovel full.Next time you have to wait at a railroad crossing for a coal train, think about it. Just to heat the water for 100 million morning showers is over a quarter mile of coal cars.

You can't beat steam. At Earth's population density we don't have a replacement for it.

I do like the idea of rooftop solar for heating water,
and whoever comes up with a solar airconditioner will sell zillions of them in our sunbelt.
That'd save a lot of coal and natural gas for our grandkids.

 

[votingmachine]

5kwh is 17,060 BTU's
which is the heat content of 1.7 pounds of coal - about one sockful.

A coal plant might be 40% efficient ,
and a solar cell 10 % efficient?

So, to make 5kwh a day takes 50 square meters of solar cell (a twenty-three foot square array, size of a two car garage roof)
or 4¼ pounds of coal, maybe one shovel full.

Next time you have to wait at a railroad crossing for a coal train, think about it. Just to heat the water for 100 million morning showers is over a quarter mile of coal cars.

You can't beat steam. At Earth's population density we don't have a replacement for it.

I do like the idea of rooftop solar for heating water,
and whoever comes up with a solar airconditioner will sell zillions of them in our sunbelt.
That'd save a lot of coal and natural gas for our grandkids.

PV efficiency is a little higher now ... more like 15%.

My rooftop in Utah can hold enough solar panels to equal my electric consumption total, using the grid and "net metering" as de facto storage. The hottest sunniest days are exactly when the air conditioner runs the most.

I don't really care about volumetric comparisons. I care about the economic comparison. Coal is much cheaper to build the equipment for ... but solar generally is almost ALL upfront costs, and then almost free to operate. Coal is very economical. Natural gas is very economical. Solar is one where the costs have been coming down so rapidly, that a lot of people don't realize the economics.

Solar has a huge disadvantage in that it doesn't work at all at night, and at lower power production as the energy of the sun is diminished. Current storage is too expensive ... although again, costs are improving.

My preference would be to use nuclear steam supply systems as the energy backstop, for peak handling and for when other sources are at lower capacity. Use solar, wind, geothermal, and hydroelectric at as high a capacity as possible, with the electric grid as backstop.

I see the economics of solar, living in Utah. I see solar panels going up on roofs all over, and I've attended some seminars for cost information. I have neighbors who put in panels and have a Nissan Leaf, that they drive completely charged by rooftop solar.

That 4¼ pounds of coal, maybe one shovel full, has immense value in portability. I don't want to move 50 square meters of panels around. But I have 3-4 times that as roof that gets good sun. To me it is strictly an economic proposition, with trade-offs for portability and infrastructure compatibility.

The news from Germany was not terribly misleading ... I was mistaken when I saw that Germany supplied half of the daily electric demand with solar, in generalizing that. They supplied half of one day, with low demand, and bright sunshine. That is still remarkable. It is also still true that the majority of electrical generating capacity in Germany is coal plants. They really are on track towards 80% of electric supply from renewables, with solar an important part of that.

I don't accept that you can't beat steam. It is an economic proposition. If the cost of photovoltaic modules drops enough, then they beat steam. Currently, the economics are great for homeowners who can replace buying kW-hrs with solar panels. They more than pay for themselves in sunny locations. Boiling water with fossil fuels is cheaper currently, but if it isn't in the future ... use the cheaper energy.

I think solar panels will play a growing role in energy production. Coal will continue to be important, as the infrastructure of coal fired power plants that exists is valuable and economically viable. I would say that the true cost of coal might be higher, if the impact of global warming is factored in.

 

[mheslep]

A coal plant might be 40% efficient ,
and a solar cell 10 % efficient?

So, to make 5kwh a day takes 50 square meters of solar cell (a twenty-three foot square array, size of a two car garage roof)
or 4¼ pounds of coal, maybe one shovel full.

10 sq m per 5kwh per day w 10% PV. 18% is common, with 20% available.

 

[jim hardy]

Well , i stand corrected on PV efficiency. In my day they were 2% and i'd heard of 25% panels for NASA.

Given the low consumption of LED lights and consumer electronics, a modest solar can provide that energy need.

It's my opinion electricity is just too convenient (hence precious) to be wasted heating water.. Those BTU's should be collected directly from sunshine. .
Hot water and refrigeration are the two biggest household loads . If they could be made non-electric it'd relieve much of the need for residential grid.
But Western lifestyle is energy centered , we expect to have as much of it as we want whenever we want it at the flip of a switch.
I don't really have to plan ahead to run my welder or air compressor, or even get the gas to drive 2500 miles across the country.

Look what we've done to the humble fishing skiff..

Gonna be some societal changes as we adapt to limited energy.

 

[rootone]

Strapping several outboards together like that (above pic) is I think likely to be very fuel inefficient.
Each propeller will have below optimum water flow over the blades due to interference of the flow caused by the adjacent propeller(s)
Maybe two spaced well apart might be good, but five?

 

[jim hardy]

Conspicuous consumption, that...
This plant uses solar collectors to preheat feedwater for its steam boiler saving around 10% fuel in good daylight..
The advantage is this plant still makes power at night, just a little less of it.
The aerial photo shows the convenience of fossil fuel. All that solar for 10% ?

 

[jim hardy]

10 sq m per 5kwh per day w 10% PV.

Oops - THANKS ! fixed it..

 

[mheslep]

All that solar for 10% ?

If that's the http://www.energydigital.com/renewables/2926/Worlds-First-Hybrid-Natural-Gas-Solar-Power-Plant-Premiers-in-Florida, the solar attachment supposedly will save http://weblogs.sun-sentinel.com/business/realestate/housekeys/blog/2011/01/fpls_estimates_on_solar_costs.html in fuel costs(30 yrs), and reduce emissions a bit. With regards to the gas share of infrastructure for the plant there's a lot we don't see in the photo (which solar doesn't need), including some hundreds of miles of gas pipeline, gas storage, and of course several of these below for just the one plant (I calculate 1882 - 100 Mcf/day gas wells for one 1150 MW plant @50% eff):

 

[zoobyshoe]

The aerial photo shows the convenience of fossil fuel. All that solar for 10% ?

"All that solar" just refers to some space taken up by the collectors. Show us the whole coal story: the pile of coal, the coal mines, the truck that haul it, the men that dig it, all that.

 

[jim hardy]

show us the whole coal story: the pile of coal, the coal mines, the truck that haul it, the men that dig it, all that.

well, in this case it'd be natural gas by pipeline.

 

[zoobyshoe]

well, in this case it'd be natural gas by pipeline.

Same problem, though. There's a whole natural gas infrastructure that isn't being shown in that pic compared to "all that solar."

 

[jim hardy]

Same problem, though. There's a whole natural gas infrastructure that isn't being shown in that pic compared to "all that solar."

quite so.

And solar doesn't replace that infrastructure or relieve its necessity if we're to have power outside the five hours per day of good sunshine.

 

[zoobyshoe]

And solar doesn't replace that infrastructure or relieve its necessity if we're to have power outside the five hours per day of good sunshine.

True, but 'solar doesn't work at night' is a different objection than "all that solar," by which you mean the large area required by solar collectors.

Fossil fuel is basically millions of years of stored solar energy, and there's no way we'll ever be able to compete with that once it's depleted. Eventually we'll have to collect solar directly as it hits the Earth as best we can. The more we do that now, the better we'll become at it and avoid a sharp, forced learning curve down the road.

 

[votingmachine]

Conspicuous consumption, that...
This plant uses solar collectors to preheat feedwater for its steam boiler saving around 10% fuel in good daylight..
The advantage is this plant still makes power at night, just a little less of it.
The aerial photo shows the convenience of fossil fuel. All that solar for 10% ?

View attachment 85665

I'm not sure why you keep harping on land use efficiency. It seems irrelevant. We all see that the most compact power source is nuclear, and solar can only harvest a portion of the solar constant (IIRC about 1.3 watts per square meter). In an area where the solar surface area is high priced, don't buy that surface area as an economic proposition.

Costs need to be considered. If they bought an acre of what looks like rural/agricultural land, and put a solar array on it, then you have to account for that opportunity cost.

You keep presenting power compactness as the definitive reason that fossil fuels are superior and that just doesn't matter as much as you portray it. Fossil fuels are cheaper. THAT matters. If solar gets cheaper, THAT matters.

As was pointed out, that solar field vs the power plant also ignores the amount of surface area dedicated to strip mining, or fossil fuel collection. There might be another photo with the collected areas of the fossil fuel collection ... that might be larger than the field where the solar sits.

There are cost-benefit analysis with every electric generating process. I think the cheapest in the US right now is natural gas. We should use the heck out of that. Cheaper is great. But it is important to notice that the PV module supply has been growing, getting cheaper, and while producing more efficient panels. The largest part of that economic improvement has been a result of German government subsidies for installations, which drove market demand, which drove producer investment. It was one of those chicken-and-egg situations, industrial investment in panels needed demand, and demand needed lower prices, and lower prices needed industrial investment, and so on. There is still an open question as to what the eventual price will drop to. Demand is now growing in ordinary consumer markets ... as I said, I am considering a home installation for economic reasons.

In that home installation, I will put roof surface area, ordinarily acting as environmental isolation of the home interior, to a second use. The surface area is basically free. Other than I am waiting to time solar installation after a new roof installation, as my roof is about 19 years old ... the economics have to include not throwing away 10% of roof life.

I think costs have to be evaluated and benefits have to be evaluated. If surface area is important, then it has to be considered. I tend to think it is an unimportant part in most cases. The picture you show does not really tell us the value of the land they used. Maybe the installation was purely a show, maybe the installation was a well reasoned economic investment.

 

[jim hardy]

True, but 'solar doesn't work at night' is a different objection than "all that solar," by which you mean the large area required by solar collectors.

Fossil fuel is basically millions of years of stored solar energy, and there's no way we'll ever be able to compete with that once it's depleted. Eventually we'll have to collect solar directly as it hits the Earth as best we can. The more we do that now, the better we'll become at it and avoid a sharp, forced learning curve down the road.

Good. Now we're in agreement. Extrapolating to the extreme mankind will someday have to get through every day on what energy he can eke out of the sun.

Utility scale solar and wind exist in US today only because of tax incentives.
In some quarters people gripe about corporate tax breaks , but you just explained why they exist - to get a technology or enterprise going. There's a premise that gov't will share in your development cost with anticipation of sharing in your future profits.

The question "What's the best way to generate electricity" has to be considered at two levels - utility scale and homeowner scale.

Utility scale i'd rank
1 Hydro, 2 Steam, followed by wind and solar where they're plentiful.

Homeowner scale i'd rank
1.Reduce consumption of electricity by direct solar heat collection for space and water heating, on premise not using electricity in the first place it is as good as making it..
2. Rooftop solar PV at latitudes where it makes sense, windmills where they make sense

If we're to keep our mechanized society and lifestyle i do not see the electric grid going away. Nuclear steam will replace fossil as carbon resources dwindle, buying a century or two to get fusion up and running.

 

[mheslep]

(I calculate 1882 - 100 Mcf/day gas wells for one 1150 MW plant @50% eff)...

Apparently ~7000 Mcf/day is more typical for a gas well brought online in the last few years, so 26 wells are enough for a 1150 MW plant at 50%.

 

[mheslep]

Fossil fuel ... no way we'll ever be able to compete with that once it's depleted.

Nuclear?

 

[mheslep]

1 Hydro, 2 Steam,

Jim - Don't need steam for gas fired electricity (Brayton cycle). More efficient and no large water supply required. US has 121 GW of such turbines (though only 3% of power as of 2012 - its rising).

 

[votingmachine]

At one point the Tennessee Valley Authority was looking at a storage idea where they used a mountain reservoir. Pump water up at low demand and then hydroelectric down when there is peak demand. I don't know if anything ever came of the idea, but I recall that there was one impressive claim of 90% efficiency of recovery.

It is only practical where there is an existing geographical feature to provide the elevation ... I would think building a supported tank would add to much cost. But if you could take advantage of natural geography, the pipes and pumps are pretty cheap. You might even be able to use the power turbines as pumps.

I agree that the inevitable backstop for the foreseeable future should shift to nuclear fission. Hydroelectric and geothermal are geography dependent, but make sense in places. I think nuclear should be much more cost efficient than it currently is. There should be much more standardization across nuclear plants. Standard, pre-approved designs would improve the construction economics considerably.

 

[jim hardy]

Jim - Don't need steam for gas fired electricity (Brayton cycle). More efficient and no large water supply required. US has 121 GW of such turbines (though only 3% of power as of 2012 - its rising).

Gas turbine powered generator?

My utility began installing them early 1970's when the nuke plant was late and they needed a few hundred megawatts online quickly.
Early ones had a terrible heat rate and there was a learning curve to stumble up, we were not jet engine mechanics.

They've come a long way but i spent hardly any time around them. When one recovers their exhaust heat by tacking a small boiler behind the gas turbine, their efficiency beats a conventional steam boiler/turbine.

Our system guys were ecstatic with heat rates of 6,000 BTU/KWH which is around 56% efficient.

http://www.energy.siemens.com/us/en/sustainable-energy/power-generation.htm?stc=usccc021878&s_kwcid=AL!462!3!44427756700!b!g!combined%20cycle%20power%20plants&ef_id=UpUo0gAABR99gZzO:20150708165315:s

It's the improvements in gas infrastructure that enabled them in Florida. When i started working there in 1969, we burned low grade oil brought in on huge barges.. 40,000 barrels a day of the gooey stuff. Our heat rate was around 9,000.

 

[mheslep]

they used a mountain reservoir. Pump water up at low demand and then hydroelectric down when there is peak demand. I don't know if anything ever came of the idea

See Pumped-storage hydro. Supposedly 128 GW of capacity worldwide, which runs on the order of hours. The largest facility in the world (by power output) is in Virginia.

https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity