But the Sun doesn't shine at night...

[Bob Wallace]

(I'm going to be traveling for a while.  Wanted to get this up before I leave.)

A common concern about renewable energy is that the Sun doesn't shine 24/365, neither does the wind blow continuously.  Surely we couldn't build a real grid on nothing but wind and solar with some storage.  At least not a grid that would give us affordable electricity.

Recently a new study was published which tackles this concern head on.

The authors took on the question of whether it would be possible to run a real world grid on only wind, solar and storage and do it for a reasonable price.  They found that they needed to include a tiny bit  (0.1%) of natural gas to keep it affordable.

Researchers at University of Delaware used four years of weather and electricity demand/load data in one minute blocks to determine 1) if a combination of wind, solar and storage could meet 99.9% of demand and 2) the most cost effective mix of each to meet demand.

The data for 1999 through 2002 came from the PJM Interconnection, a large regional grid that services all or part of 13 states from New Jersey west to Illinois, from Pennsylvania south into Tennessee and North Carolina.  This is the world's largest competitive wholesale electricity market, serving 60 million customers, and it represents one-fifth of the United States' total electric grid.

They used currently available technology and its projected price in 2030.  They included no subsidies for wind and solar in their calculation.  They did not include hydro, nuclear, tidal or other possible inputs.  They also did not include power sales to and purchases from adjacent grids.  They used three existing storage technologies - large scale batteries, hydrogen and GIV (grid integrated vehicles).

They found that by 2030 we could obtain 99.9% of our electricity from renewable energy/storage and the remainder 0.1% from fossil fuels for about what we currently pay “all-in” for electricity.  The all-in price of electricity includes coal- and oil-produced health costs currently paid via tax dollars and health insurance premiums.

During the four year period there were five brief periods, a total of 35 hours, when renewables plus storage were insufficient to fully power the grid and natural gas plants came into play.  These were summer days when wind supply was low and demand was high.  The cheapest way to cover these ~7 hour events was to use existing natural gas plants rather than to build additional storage.  (Adding in hydro, tidal, etc. would further reduce this number.)

After 28 billion simulations using differing amount of wind, solar, storage and fossil fuels they found the best solution was to over-build wind and solar and at times simply "throw away" some of the produced power.  Building "too much" wind and solar turns out to be cheaper than building more storage given the storage solutions we have at this time.  Finding markets for the extra production, selling electricity to offset natural gas heating for example,  further reduced costs.

Budischak, Sewell, Thomson, Mach, Veron, and Kempton   Cost-minimized combinations of wind power, solar power and electrochemical storage, powering the grid up to 99.9% of the time  Journal of Power Sources 225 (2013) 60-74

https://docs.google.com/file/d/1NrBZJejkUTRYJv5YE__kBFuecdDL2pDTvKLyBjfCPr_8yR7eCTDhLGm8oEPo/edit

Remember, this is a "worst case" study.  Add in hydro, tidal, geothermal, and residual nuclear and the price drops because less storage will be needed.  The same happens when there is exchange of power between grids.

And those 2030 wind and solar prices?  The authors used somewhat dated (2010) projections.  Current prices have already brought the cost of wind down to their projected 2030 level and solar is already cheaper.  We almost certainly will have better/cheaper storage than they used in their study.

So, yes, we can have a renewable grid that gives us electricity when we want it.  And it's very likely that our electricity will cost less then than it does now.

[Artful Dodger]

Hi Bob,

Good topic. One of the legacy problems we face is that the present grid has not been optimized for availability, it as been optimized for profit. Enron is infamous for ordering power plants to shut down to create artificial shortages, and hence huge spikes in wholesale electricity cost.

Only regulation has been (partially) effective in reining in the profit motive in public utilities. IMHO, that's the progress we need going forward.

Cheers,
Lodger

[Jim Hunt]

Thanks for the link Bob. The paper will make an interesting read when I have a bit more time to spare. Maybe I'll have read it properly by the time you get back from your travels?

A couple of initial thoughts though. Apropos our conversation next door, minimising cost where that includes all the "externalities" of fossil fuels isn't exactly the way the energy markets work at the moment. Unfortunately?

Particularly given your headline, I'm slightly surprised there's no mention of CSP and hence thermal storage. No deserts in the North East I suppose?

Finally I'm not at all sure that "assuming perfect transmission within PJM" to "centralized storage" is a reasonable one.

Much to ponder!

[Bob Wallace]

You've got over a month.  ;o)

I'll be checking in but working from the cramped keyboard of a netbook and sometimes with slow connections.  And a lot of distractions.
--

We really need to face up to what we actually pay for energy.  To pretend that coal-electricity is cheap is foolish.  It may take a carbon tax to make the market recognize the real cost of coal.
--

There's stuff not in the article.  This was not an attempt to design the best possible grid, but to deal with the criticisms of wind and solar being intermittent.  It is very much a 'worst case' study - a 'could we if all we had was?' look.
--

Thermal solar probably won't be a player in the northeast US.  Not unless the cost comes down significantly.  At this point thermal solar with storage barely (if at all) works in very sunny places.

Enhanced/hot rock geothermal may become a major.  We've had two very good developments this last year.  One company was able to fracture rock using CO2 - no nasty fracking chemicals. 

Another company, AltaRock used a biodegradable fracking compound and was able to create fractured rock fields at multiple levels in a single well.  This would be a major cost improvement - multiple hot rock zones from a single bore.  And boring the big hole is where the expense is with geothermal.

If this pans out (and we should know this year) then it's likely hot rock will become an important source of electricity.  Normal wet rock geothermal has a LCOE of 4 to 14 cents (median 6 cents) per kWh but is geographically limited.  Hot rock is possible in a high percentage of the world.

[Artful Dodger]

It is a common misconception that the Sun does not shine at night. Indeed it continues to convert hydrogen to helium and energy even as the world turns it face away from individual nation states.

The key is, how do we connect local grids to that continuous stream of energy? Three large solar farms, displaced 8 time zones apart, could power the entire world from solar energy. 50 square miles of solar array in the deserts of each of Arizona, the Sahara, and the Australian Outback would provide the entire planet with a continuous abundant supply of solar energy.

So then how to connect these solar farms to the grid?

High voltage direct current (HVDC) transmission lines are superbly efficient, losing less that 1% of the energy transferred for each 1,000 km of transmission line. Manitoba Hydro already operates such a HDVC line. There is no technology to invent, only political hurdles to overcome.

On the practical side, the Earth is already far more controlled by large multinational corporations than individual Governments, so once the profitability of such a global array is established, the deployment will follow quickly.

All that's missing is a price on carbon.

[Bob Wallace]

Even better is UHVDC (ultra high voltage).  Crank the voltage up even higher and you can ship more power over the same size wire.  Some UHVDC lines are now being built.

Powering the world with solar by shipping power around the globe - could be done but the cost might be prohibitive.

What is more reasonable, and somewhat likely, is that Europe will end up with a system (Desertec) that ties Europe from Iceland to Bulgaria to North Africa and the Middle East.

The Sun comes up early in Saudi Arabia.  It could supply early morning demand in Europe and the Saudis have to money to build the system.  They could start to transition from oil exporters to electricity exporters.

And the Sun goes down late-ish in Spain, Portugal and Morocco.  There is already power transmission between Morocco and Europe.  It carries power to Morocco, but install a bunch of solar and Morocco could sell power northward.  (The Canaries, the Azores - sunny or cloudy?)

That would give Europe a long solar day and Europe's wind/hydro/geothermal could help out North Africa/Middle East cut their storage needs.

[Artful Dodger]

Unfortunately, the Desertec initiative appears to be collapsing, with several of the major players recently withdrawing from the plan.

It was never a solution anyway, with Spain/Algeria @ UTC+1 and Saudi Arabia @ UTC+3, it potential spanned only 45º of longitude, which is less than a 3 hour extension to the solar day.

Only a globally integrated grid spanning all 24 time zones addresses the underlying problem that begins at local sunset, and also waxes and wanes with the seasons. It was always pointless to try to build anything less.

Nonetheless, 150 sq miles of desert solves our problem of how to decarbonize the electrical grid, without relying on dirty, unreliable nuclear fission.

[Bob Wallace]

I suspect the problems in North Africa - the Arab Spring events - have pushed most of NA's involvement off into the future.   I wouldn't want to say 'never'.  I expect Morocco will go ahead with their solar plans and since transmission is already in place their systems should serve as a good testing/proving ground for other NA countries.

Increasing the solar day by three hours can be significant.  What's happening now in Germany is that a modest amount of solar on their grid has knocked the midday peak wholesale power price down to where late night power sells.  That leaves a fairly high early morning and late afternoon peak.  There will be money to be made knocking those peaks down.

Solar is on the way to becoming cheap.  Sending power to Europe for early morning demand, and on winter days when Europe's panels are not producing a lot could be valuable.  Especially if SA could take back power and lower their storage requirements.  There's huge value in spreading your energy harvesting nets widely.  Input variability and storage needs drop.

[Artful Dodger]

Increasing the solar day by three hours can be significant.  What's happening now in Germany is that a modest amount of solar on their grid has knocked the midday peak wholesale power price down to where late night power sells.

Agreed, Bob. 3 hrs is quite valuable. I just don't see Desertec causing Germany to cancel new coal-fired generation to replace their retiring nuclear fleet.

To mitigate rising CO2, we must first quit burning coal. Nothing else we do matters, if we can't do that.

A global grid would achieve that. And cancel plans for new coal in India, and China, and South Africa. And lead to the retirement of coal everywhere else. It'd simply be too expensive to build a local coal plant when cheap, abundant, reliable power is available globally.

No? Just ask yourself how you feel when you're away from the internet. We ALL want to be connected, to be cool. 

[gfwellman]

As you noted, Hydro was left out of that study.  Hydro (where available) is the perfect night-time power source because it can be turned up and down by opening and closing gates/valves.  Heck, in Niagara, Canada they already run full bore at night and much less in the day so as to leave more water for the tourists at the Falls.  But any hydro plant can be run with that cycle, basically saving up gravitational energy during the day and spending it at night.

[Bob Wallace]

My understanding is that Germany's new coal burning plants are replacing (not adding to) the older plants that either have been or will soon be decommissioned.   And that the new burners were planned and construction started before the decision to close nuclear reactors.

By 2020, 18.5 gigawatts of coal power capacity will be decommissioned, whereas only 11.3 gigawatts will be newly installed.  That would be a net decrease of about 40% in coal capacity.

Furthermore those plants will be more efficient, releasing less CO2 per unit electricity produced than are the ones they are replacing.  Overall Germany may be cutting their coal CO2 by well over 50%.

Germany gets its natural gas from Russia.  It would be politically dangerous to build their fossil fuel component around an undependable supply. 

We just can't go from heavy fossil fuel use to no fossil fuel use overnight.  We've got to find routes that get us there while not disrupting our economies.  Even if some of us think the dangers of climate change are so great we should drastically cut fossil fuels and learn to live with less energy, there's not the widespread support to allow that.

[Bob Wallace]

As you noted, Hydro was left out of that study.  Hydro (where available) is the perfect night-time power source because it can be turned up and down by opening and closing gates/valves.

Yeah.  They intentionally left out other energy sources because they wanted to deal with the two energy sources which get the most banged around by renewable energy skeptics.

If it is possible to build a grid powered by nothing but wind, solar and storage then every other source that's not overly expensive makes it easier and cheaper. 

Hydro, rather than a great nighttime source is probably best looked at as a great fill-in source.  Hydro is highly dispatchable, turbines can be kept spinning without load (and wasting little water) until power is needed.  They can produce the power needed by the grid almost instantly.

Hydro is a great trade off for storage.  It isn't 'lossy' like batteries and pump-up hydro.  No electricity is used to "charge" the system.  The Sun does that work by evaporating moisture which then rains down and fills the reservoir.

Wind tends to produce a lot of power at night.  Use wind when the wind blows, fill in with hydro when it doesn't.

(There is 'run of the river' hydro which isn't dispatchable.  The river needs to run and/or water needs to flow for other reasons.  Run of the river will be 'always on' generation.)

[andrewdoddsuk]

I've seen that study posted elsewhere..

The big problem I had with it was that they only get the economics anywhere near viable by use of EV battery storage; personally I regard this as a non-starter.   The very time of day when storage facilities will be wanted most (dark winter mornings) is also the time when you want your EV to be 100% charged.

The authors of the study have an interest in V2G, as noted in the study.

The other proposed storage solutions are much more expensive.  Essentially huge centralized battery stacks. 

[Jim Hunt]

Andrew - Here in the UK I believe dark winter evenings are even worse than the mornings. In the US they use a lot more air conditioning than we do however!

As luck would have it I have a personal interest in V2G, as well as low cost storage. What do you make of "pumped heat" thermal storage?

Bob - In the video you'll note that (with the approval of our glorious Chancellor!) the UK is investing in R&D into low cost storage distributed around primary substations specifically to try to address "the real issue of avoiding the cost of having to upgrade our distribution network for electricity". That's one reason why I'm none too happy with Budischak et. al's "perfect transmission" assumption. Perfect != "Worst Case" in the real world!

[Neven]

Talking about centralised: I believe what makes the energy revolution really exciting is that it deconstructs the old power (in the literal and figurative sense) structures, where only huge companies have the ability to build the power production facilities, and thus in a sense control the market. Things like Desertec or huge off-shore wind parks basically keep that structure in place.

Isn't it much better, though perhaps less efficient (democracy isn't efficient) to decentralize power production as much as possible? No need for mega-infrastructure like ultraHVAC.

Let me also state my personal interest here. I'm planning on building a house this summer with annual energy needs of around 4000 kWh. That's for all energy, heating, hot water and electricity. Putting 4 kWp of solar panels would essentially make the house energy neutral, except that the electricity I produce during peak hours when the Sun is shining is priced at 6 cents per kWh, whereas the electricity I consume from the net at night and during winter costs me around 20 cents per kWh.

Now, there's a very interesting and recent development in Germany going on because the government all of a sudden decided to reduce the feed-in tariff much faster than anticipated (which is a huge problem for companies that sell large PV solar parks). The effect is that it is now much more interesting to store some of the energy that is collected for personal use instead of selling it to the power company.

I'm interested in this myself too. A 4-5 kWp solar panel array combined with a 4-5 kWh battery storage system would essentially mean I am energy independent for 10 months of the year. I've been reading a lot about it in the past 2-3 weeks, and with recent developments in battery technology (like Lithium-Iron-Yttrium-Phosphate) and dropping prices, my investment would pay off in around 20 years. But that's without subsidies and counting on stable energy prices. Including the subsidies, the system pays for itself in around 10-15 years (provided the batteries last that long, which no one knows exactly because they haven't been around for that long).

Complicated stuff though, the whole PV business. I still don't understand how one would set up such a system (inverter, battery management system, controllers, switches).

But I digress. If at all possible, I would prefer decentralized power production over the usual stuff.

[Bob Wallace]

Andrew, the authors used three different storage solutions.  EV batteries were only one of them.

If it turned out that EV batteries were the best choice for economic reasons we would probably end up installing outlets in parking lots.  People would plug in at home and then plug in again when they got to work/school.

Personally I doubt this is how we'll store electricity. 

[Jim Hunt]

Neven - I may well be teaching my granny how to suck eggs here, but are you aware of the Centre for Alternative Technology in Wales?  If so have you heard of their new "Energy democracy through open source technology" course?

The jury here doesn't seem too keen on V2G, but there's always V2H (or V2µG) to consider. I don't suppose a Passiv家 in Japan is on your shopping list at the moment though?

[Neven]

Hi, Jim. I knew about the CAT, but only visited their website once or twice when contemplating a move to Wales.

That's an interesting course they're offering, but I actually need to find some spot where people discuss the exact thing I'm looking for, which is still slightly exotic, but will gain traction in the coming months in Germany because of the feed-in tariff dropping below the price of electricity.

It's pretty cool stuff, reminds me of the time I built low-power computers. You want an intelligent system that knows exactly when to put PV power through to appliances, feed the surplus to the battery, or to the net when the battery is full, of before that to the hot water boiler. I will have to train my wife when to use the dishwasher and the washing machine. "Honey, it's sunny outside, can I bake my bread now?" 

I'm reading a lot on a big German PV forum right now. I will ask them. The Germans know everything.

[Bob Wallace]

I think you'll find it easy to decide when to run the big appliances and bake bread.

You need two pieces of data - a rough idea of what the weather is going to be and the charge state of your batteries.  If it's a sunny morning, there's no storm rolling in, and your batteries are about 90% charged (easy to read from the meter) then burn some electrons.

In the winter when I have a mix of sunny and cloudy days I'll look ahead at the weather and make a decision along the lines of "Going to be sunny tomorrow.  I'll do a load of laundry and vacuum the bedroom.".  Then 'tomorrow' I'll wait until by meter gives me a 90% charge reading and take a quick look at the sky to make sure rogue clouds haven't snuck in.

[Doc Snow]

Hey, Neven, how about posting some of the bibliography someplace?  Or maybe emailing to those interested?

Of course, knowing your language skills, there's a good chance bunches of it might be not so useful to those of us with only one really strong working language!

[Neven]

Hey, Neven, how about posting some of the bibliography someplace?  Or maybe emailing to those interested?

Sure, Doc, but which bibliography specifically? The books on PV power aren't that good I'm afraid (one in German, the other in English). They're both outdated and don't have enough examples, at least not the one I'm interested in: solar panel array combined with batteries that is still connected to the main grid.

Haven't asked the Germans yet either, but I have a friend here in Austria that has a similar set-up, albeit smaller and he doesn't feed his surplus power into the main grid.

[Artful Dodger]

They're both outdated and don't have enough examples, at least not the one I'm interested in: solar panel array combined with batteries that is still connected to the main grid.

Hi Neven,

The keywords you'll want to search are:

Hybrid Solar Electric Grid Tie Battery Backup Systems

https://www.google.com/search?q=Hybrid+Solar+Electric+Grid+Tie+Battery+Backup+Systems

Your system should have a two-way electricity meter, and should automatically detach itself from the grid when it detects a power failure.

BTW, Chinese solar panels are cheap, cheap right now. You'll save money by installing the system yourself, less the grid connection which must be done by a certified trades person.

Good luck!

[Neven]

Thanks, Lodger!

[Artful Dodger]

Thanks, Lodger!

De nada, Neven. We're all following your plans eagerly. 

I don't want to jack this thread, but this IS related to the OP's topic: what to do when the sun sets, and during winter's long nights.

Combined Heat and Power (CHP) is an excellent alternative for new builds (as opposed to refits), in locations where Natural Gas is available for use as a home heating fuel. CHP can be up to 92% efficient in converting the energy of CNG to electricity, and heat for domestic hot water, and space heating.

http://en.wikipedia.org/wiki/Micro_combined_heat_and_power#Overview

It's great during Winter, as it provides more electricity when more heat is needed, and less when the sun is high and days are long. That's why the cheap solar cells are such a great compliment in this system. As a bonus, you can even fuel you vehicle with CNG.

Here's just one example of a company that sells CHP systems in Austria:

http://www.viessmann.com/com/en/service/kontakt/international/oesterreich.html

[Artful Dodger]

Here's an interesting blog post on "Putting a Power Plant in the Basement: Residential CHP":

http://blog.wegowise.com/blog2/bid/131021/Putting-a-Power-Plant-in-the-Basement-Residential-CHP

[Neven]

I know the CHP principle. Unfortunately we don't have any CNG near our building plot.

I was thinking about buying a wood stove of which 70% for the energy is used for heating water, and 30% for heating air. Now, if you have a 500 Liter boiler that also has an electrical  unit for heating the water, you can heat your water with electricity during summer and use a bit of wood during winter to do the same.

The problem with a wood stove for our situation, I fear, is that our house will be relatively small (85-90 square metres, which is about 900-950 square feet) and very well insulated, which means that temperatures would shoot up and we'd have to open windows, effectively heating the outside air. The problem with wood is that you need a minimum amount, which can already be too much.

That'd be a waste. And besides, I don't like burning stuff. Wood can be put to much better uses.

But if our house would've been bigger and less well-insulated, this would probably be the best way for us to go.

[Artful Dodger]

Neven, Oxy-fuel with wood chips is the place to start. CHP would be awesome, as some of the electricity would be needed to produce the O² for the burner. 

+"Oxy-Fuel" +"wood chips" +"micro CHP"

The advantage of a wood-burning Oxy-fuel setup is that it would allow you to burn green (wet) wood. Most oxy-fuel setups require flue-gas recirculation to cool combustion temps enough to not melt steel! Green waste wood chips with 30-50% water content would probably be ideal

I hope this isn't too experimental though. I have not looked for a commercially available implementation of this scheme

Don't neglect Solar hot water heating, either. Nothing is more cost-effective. Ground source heat pump could be good too once you're making your own power. Many, many clean alternatives!

When will you start your "Neven's New House" thread?

[Neven]

When will you start your "Neven's New House" thread?

As soon as I'm sure it's going to get built. 

[ghoti]

I have had a solar domestic hot water system for years. I am very happy with it and how it greatly reduces the amount of natural gas I burn to provide hot water. It doesn't, however, make economic sense since the cost of heating water with high efficiency natural gas heaters is almost zero in the current NG price environment. I choose to use the sun to heat water not to save money but to reduce the CO₂ I produce.

Similar issues apply to ground source heat pumps for heating. They are much more "energy and CO₂ efficient" at heating than fossil fuel alternatives but are much less "cost efficient" given the current ratio of electricity to natural gas costs plus the enormous cost of the installation or ground source heat pumps.

[gfwellman]

In discussion of ground source heat pumps, don't ignore air source - you get most of the benefit with a fraction of the cost (and they can be easily retrofitted in places where ground source is an impossible retrofit).  A good air source heat pump delivers about half (perhaps a bit better) the efficiency of a ground source version.  But relative to no heat pump that means you get most of the savings.  For example, here in a mild climate, my ASHP probably uses 25-30% the energy that resistive heat would.  A GSHP could push that down to 15%.  But relative to original costs, that's a small gain.  The difference in installation cost (even if GSHP was possible here) is better spent on insulation.

Something that is really great is what I call "actively managed passive solar".  I'm lucky to have large south-facing windows.  I installed double-honeycomb insulating blinds on those windows.  When it's sunny and I want heating, I open the blinds.  When it's not sunny and on those occasional summer days I don't want any heating, I keep them closed.  It makes a big difference.

[Edheler]

In discussion of ground source heat pumps, don't ignore air source - you get most of the benefit with a fraction of the cost (and they can be easily retrofitted in places where ground source is an impossible retrofit).  A good air source heat pump delivers about half (perhaps a bit better) the efficiency of a ground source version.  But relative to no heat pump that means you get most of the savings.  For example, here in a mild climate, my ASHP probably uses 25-30% the energy that resistive heat would.  A GSHP could push that down to 15%.  But relative to original costs, that's a small gain.  The difference in installation cost (even if GSHP was possible here) is better spent on insulation.

It really depends on where you live. If your outside temperatures on average are below freezing in the winter a geothermal HVAC can be a significant win. Not only because of efficiency but from saving your equipment from freeze/thaw cycles. A heat pump in my area would have an expected lifetime of 12-18 years where my geothermal heat pump is expected to last for about 30.

[TerryM]

An air source heat pump loses any efficiency gains at 40F - 4.5c due to the energy requirements of de-icing the condenser coil.

If a swimming pool is on the property simply diverting the filter pump line through a water source condenser. It heats the pool as you cool your house at a huge savings in cash and electricity. Dropping a coil into a septic tank will do the same job.

It's hard to beat gas at current prices, but solar preheaters for hot water systems can be hacked together very inexpensively.

In low humidity locals nothing beats a swamp cooler for cooling a house. Low humidity outflow systems where the chilled high humidity air is passed through a heat exchanger keeping inside humidity constant works well too.

Terry

[Artful Dodger]

Topics included:

• air source heat pump
• swimming pool vs septic tank
• solar preheaters
• swamp cooler/heat exchanger

Terry, awesome list!! We need at least some links, better yet an overview of these topics! 

[OldLeatherneck]

...................In low humidity locals nothing beats a swamp cooler for cooling a house. Low humidity outflow systems where the chilled high humidity air is passed through a heat exchanger keeping inside humidity constant works well too.

Terry

I lived in Southern Arizona for almost 15 years, with nothing more than swamp cooling.  Eventually, I added a second swamp cooler and during times of low humidity (10+ months/year) it was possible to keep the indoor temperature ~20 degrees (F) below the outside temperature.

[TerryM]

Topics included:

• air source heat pump
• swimming pool vs septic tank
• solar preheaters
• swamp cooler/heat exchanger

Terry, awesome list!! We need at least some links, better yet an overview of these topics! 

Ouch!

I'd started a reply that after a while began looking like a grotesque, bloated how to manual.

These were all systems I built for myself or friends over the years when I was living in the American South West. Swamp cooler is the local name for an evaporative cooler. They bring inside air down to very close to wet bulb temps - but add humidity as they do so. By adding an air to air heat exchanger the indoor humidity problem can be solved.

By precooling the air passing through the condenser on an AC by using something like a swamp cooler savings are possible. More savings are incurred if a water source is used to precool the freon going to the condenser by using swimming pool or septic tank water - in the 1st case run the water to the AC, in the second run the freon to the septic tank.

A solar water heater feeding your existing tank water heater just provides hot water going into the tank. The existing heater works just as before to keep the water heated but it no longer has to heat the incoming water. With an electric heater the results are very noticeable on your first electric bill. With gas you just assume you're doing your part to reduce consumption.

Air source heat pumps rely on passing ambient air over what at that time is the evaporative coil. The problems occur when more energy is expended defrosting the coil than is saved. That's why air/air heat pumps are not efficient where cold winters occur. If there is an available source of water that remains above freezing the heat from that can be extracted for heating and it will act as a heat sink when cooling - the best of both worlds!

Most of the stuff I was playing with was intended to deal with high daytime temperatures in very dry climates & worked well under those conditions. The best system I ever saw was a reverse chimney that required no power, relying instead on the relative weight of sinking cold air drawing more air through a damp pad at the top of the structure. I think they're still being used at highway rest areas in Arizona.

Some of these schemes require playing with refrigerant & since the ozone hole scare a certification is required to purchase it. Today I'd assume you'd have to make friends with an adventurous HVAC contractor who would be willing to work with you.

The straw bail homes being built in OldLeatherneck's part of the world have amazing R values. Building codes in different areas are the main stumbling blocks as I understand it, although the local Architectural School just completed a student designed and built straw bail student housing project & managed to get it by the local inspectors.

The fountains the Evil Knirval used to leap over were originally designed to cool the water used by the AC system at Caesar's Palace - very similar to the swimming pool system i was using a few miles away.

Terry

[gfwellman]

That's a good summary.  I would note that a modern air source heat pump uses sensors and logic to determine when defrosting is necessary, so while defrosting definitely cuts down on efficiency, it's still generally better than a non heat pump.  Luckily where I live I only see mine defrosting a few days each year.

If you're designing a home from the ground up, another topic to consider is "thermal inertia", e.g. http://www.beodom.com/en/education/entries/using-thermal-inertia-for-better-comfort-and-heat-savings

[ghoti]

I really love the idea behind the Coolerado cooling system but unfortunately it is much too humid in the summer where I live and their pricing is rather huge in my opinion. I never turned our air conditioning on again after the massive 2003 power outage that hit Ontario and much of the US north east. Somehow we manage okay without air conditioning.

[Artful Dodger]

Ouch!

Oi, mate!

I was hoping for something from the Life of Terry. You didn't disappoint.

[Artful Dodger]

Returning to the OPs thesis that "the Sun doesn't shine at night", there has been serious study done of the feasibility of collecting solar energy in orbit, and beaming the power down to the Earth via either microwave or laser transmitters. This is an interesting solution to the problem of sunset, and the polar night.

Space-based solar power from Wikipedia.

[ghoti]

Except that storing solar power for use at night is already feasible and much less expensive to do than to launch huge numbers of rockets.

[Artful Dodger]

Except that storing solar power for use at night is already feasible and much less expensive to do than to launch huge numbers of rockets.

Storing power is inefficient, expensive, and unnecessary when there is a globally connected grid. Who suggested rockets?

[ghoti]

Silly me to think space based solar would require rockets.

[Bob Wallace]

No rockets.  Use a space elevator.

Now we only need to figure out how to make a space elevator....

[dreater]

No rockets.  Use a space elevator.

Now we only need to figure out how to make a space elevator....

Yeah, if only....

Solve the "gravity well" problem, and lots of things become feasible.

[Artful Dodger]

Silly me to think space based solar would require rockets.

So you didn't look at the Wikipedia article? The part about 'Non-conventional launch methods'? Or 'Building from space'? These technical problems were addressed 40 years ago. Ever hear of the L5 Society? <smh>



The Colonization of Space
by Gerard K. O'Neill
Reproduced with permission from
Physics Today, 27(9):32-40 (September, 1974)

It's been 40 years since Gerry O'Neill showed that a space station could be built in the stable Lagrangian points L4 and L5 with <5% of the raw materials coming from Earth.

[Sigmetnow]

This topic has been quiet for a while, but I still think it's a good one. 

Here’s a recent article on “the largest battery in the world” -- the Bath County Hydro Pumped Storage Facility.  It uses two reservoirs on the Virginia-West Virginia border in the (eastern US) Appalachian mountains.  Good little video, too.

http://thinkprogress.org/climate/2013/08/27/2524501/hydro-pumped-storage-climate-change/

[MOwens]

no sun, no problem!

There is massive potential to expand our global energy use without using fossil fuels - no new technology needed.

...here's another article on pumped hydro that takes a deeper look at the numbers, costs, site location, and lingering misrepresentations.

http://www.fairfaxclimatewatch.com/blog/2013/07/is-pumped-storage-hydro-power-the-answer-to-storing-wind-and-solar.html

China for example has recently identified 247 sites that would have a combined power capacity close to 1/3 of the current grid capacity. Sites are abundant.

And here's an article on nuclear's necessity (or not):

http://www.fairfaxclimatewatch.com/blog/2013/11/hot-topic-hansen-says-global-warming-demands-nuclear-energy.html

[Csnavywx]

http://www.withouthotair.com/

Still the best resource I've seen on renewable energy and its potential, without broad-brushing over the difficult physical realities of the subject.

Possible? Yes. However, running the world on renewables would not be without extreme effort, both from a physical and social aspect.

[Jim Hunt]

Still the best resource I've seen on renewable energy and its potential, without broad-brushing over the difficult physical realities of the subject.

Agreed. More from me on David MacKay:

http://econnexus.org/david-mackay-explains-how-you-can-halve-your-energy-usage/

[ggelsrinc]

Still the best resource I've seen on renewable energy and its potential, without broad-brushing over the difficult physical realities of the subject.

Agreed. More from me on David MacKay:

http://econnexus.org/david-mackay-explains-how-you-can-halve-your-energy-usage/

I'm all for conserving energy in the home, but that's a terrible video to get that point across. Early on David MacKay talks about writing a book about energy and being embarrassed when a friend asked him how much energy he uses in his home and he didn't know. He points out the average person in the UK uses 125 kWh of energy a day, similar to Germany, other developed areas in Europe and Japan, with Canada, the US and Australia being about twice that amount. He points out the average person uses that energy for transporting, heating, electricity and industry. That would mean the average family of four is consuming 500 kWh per day in the UK and 1,000 kWh per day in the US. David MacKay then focuses on what can be done to cut energy consumption in the home.

Twice throughout the video a thermostat is pictured and discussions to lower it when you leave the home or adjust it low enough to just be comfortable are made, but there is a problem with the picture presented. All the pictures of the thermostat (the second time it was shown, even has a quick close up shot) show it being set on 36 degrees C, which is one degree less than normal human body temperature.

Pictures of various Vaillant thermostats:

http://www.bing.com/images/search?q=vaillant+thermostat&qpvt=vaillant+thermostat&FORM=IGRE