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On Tesla Battery Bottom Line: $3,500 For a 10 Kilowatt-Hour System


Here are more complete calculations:

Some folks are claiming one could buy low-cost energy during off-peak hours, store it in a wall-mounted, TESLA battery pack, and use the energy during high-cost, on-peak hours. Multiple units could be used.

At 90% AC to DC inverter efficiency, and allocating half of the 8% DC-to-DC loss to the charging side (the TESLA unit has a round-trip DC-to-DC efficiency of 92%, per spec sheet), it would take 7/(0.9 x 0.96) = 8.10 AC kWh of off-peak grid energy to charge 7 DC kWh into the unit.

During on-peak hours, one would get back 7 x 0.96 x 0.90 = 6.05 AC kWh to use in the house. A big percent loss of energy!!

The INSTALLED cost of the 7 kWh TESLA unit = $3,000 + S & H + Contractor markup of about 10 percent + $2,000 for an AC to DC inverter + Installation by 2 electricians, say 16 hours @ $60/hr = $6,500.

In Southern California, base rates are $0.11, off-peak, and $0.46, on-peak; which likely is THE best-case scenario in the US. But this rate ratio is only for 6 months. 

The 8.10 AC kWh, off-peak, would cost $0.89. The avoided cost of 6.05 AC kWh, on-peak, would be $2.78, for a profit of $1.89/day, or $691/yr, for a SIMPLE payback of about 10 years.

Adjusting for the rate differential being for 6 months, the SIMPLE payback would be about 10 x 2 = 20 years, not counting:

- The cost of financing, PLUS

- Any costs for O&M, PLUS

- Any capacity degradation due to deep cycling.

The TESLA warrantee is for only 10 years (for manufacturing defects, not performance!), and during these 10 years, there would be 3,650 deep discharge cycles, which far exceeds what such batteries are designed for, meaning there would be capacity degradation that would further lengthen the SIMPLE payback period.

NO battery exists that can be repeatedly discharged 100%, i.e., charching and discharging would likely be at most 50% of capacity (which decreases over the years) to keep degradation to a reasonable level. 

See Note 4a, 4b, 4c of this article for further explanation.




May 23, 2015    View Comment    

On The Fossil Fuel Subsidy Red Herring


That tipping fee would also apply to the build outs of RE systems with about 78% fossil fuel on a worldwide basis.

What about a fee on RE energy for requiring many of the OTHER generators to operate more inefficiently? See my above comment to Joris.

As more such variable energy exists on the grid, more capacity of OTHER generators is required to deal with it.

May 20, 2015    View Comment    

On The Fossil Fuel Subsidy Red Herring


You are exactly right. Variable wind and solar energy cannot exist, unless the OTHER generators are adequate in capacity, MW, and flexibility to deal with that variable energy. 

That requires many of these OTHER generators to operate at partial output and ramp up and down, which is inefficient, i.e., increases their Btu/kWh, and their CO2/kWh.

On the Irish grid, it has been proven with real-time 15-minute data from each generator that at 17% wind energy on the grid, only 58% of the reductions that wind was supposed to reduce is actually being reduced.

Eirgrid denied the results of several reports for years, until a few months ago, and informed the EU commission in Brussels of the fact.

May 20, 2015    View Comment    

On The German 'Energiewende' - Finally One Step Too Far?


It makes sense to put solar where the sun shines best and wind where the wind blows most.

Anything else is national chauvinism, a.k.a., lunacy.

Is not global warming a GLOBAL problem which has nothing to do with national borders. Duh!

I am surprised it took the EU 20 years to catch on.

Here are the numbers of what has and will be spent on the ENERGIEWENDE. The numbers likely are UNDER-ESTIMATED.

May 18, 2015    View Comment    

On The German 'Energiewende' - Finally One Step Too Far?


That will take about 2 decades, because of legacy costs being part of the RE mix, as I show in my article.


May 17, 2015    View Comment    

On Increased Wind Energy Versus Increased Canadian Hydro Energy in New England


You are right.

With more minute-to-minute, variable wind and solar energy on the grid, there needs to be a certain quantity of rotational inertia to maintain voltage and frequency.

There are other ways that can be done, all of which are very expensive. Borrowing inertia is much less expensive.

Germany has been borrowing intertia by tying into nearby grids and importing/exporting at the same time.

The exporting usually is at very low, or negative wholesale prices, after subsidizing that ENEGIEWENDE energy at a legacy cost of about 20 eurocent/kWh!!

Read this article. You will have a lot of fun.

Several rather complicated articles involving non-linear control theory, have been written on the subject of rotational inertia. Most commentators have not a clue what is involved, but comment with inanities anyway.

To provide that rotational inertia, more generator capacity, MW, will need to be kept in synchronous mode, not to produce power, but to provide inertia and stability.

May 16, 2015    View Comment    

On Increased Wind Energy Versus Increased Canadian Hydro Energy in New England


"What the German experience shows is that wind power is a bonus for NG plant operators and France's load-following nukes and a problem for poorly dispatchable antiquated coal plants."

You make good points, each of which would take an article to respond to.

In Germany, some of the most efficient CCGT plants are on life support. Owners are demanding capacity payments. Gas is very expensive.

It is not a bonus to not operate their plants in a base-loaded mode, but instead in inefficient, variable-output mode, because subsidized wind and solar energy are crowding their energy off the grid.

Germany is building load-following, rapid-ramping coal plants (low-cost domestic fuel) to replace most of its gas plants (high-cost, from Russia fuel).

May 16, 2015    View Comment    

On Dismal Economics and Increased CO2 of Montpelier District Heating Plant


I agree with you regarding burning biomass that could be used as food, such as the US corn-to-ethanol program and burning wood chips that are 45% water. See this article.

Biomass heating plants usually have drying ovens to dry the chips before burning. The drying is usually done by using the heat of the furnace flue gases. Dryed wood chips provide more stable burning conditions at lower heating demand.

My objective was not to discuss the burning of biomass as an ethical issue.

My main objective of the article was to show the dismal economics of the project, and that it does not reduce CO2 emissions.

Claims made in press releases, which I knew to be wrong, based on about 30 years of past experience.

I had completed the front end of the article, when, out-of-the-blue, came these fuel consumptions and CO2 claims for the partial heating season.

I used those values to make the same analysis, which indicated my initial assumption of 15% fuel oil, 85% wood chips, and building Btu/sq ft/hr were close to the mark.

May 15, 2015    View Comment    

On Dismal Economics and Increased CO2 of Montpelier District Heating Plant



Capital 47.4

O&M 14.5

Fuel 39.5

Total 101.4

Wood chips Btu/kWh =  $55/ton x 1 ton/7.6 million Btu x 1 kWh/3413 Btu x 1/0.25 power plant efficiency  = 9.88 c/kWh

The EIA numbers in New England are way off. 

May 15, 2015    View Comment    

On Dismal Economics and Increased CO2 of Montpelier District Heating Plant


If the increase in biomass took place, then it may act to reduce global warming, and should get credit for it in climate computer programs.

May 15, 2015    View Comment    

On Dismal Economics and Increased CO2 of Montpelier District Heating Plant


You can be sure the article changed for the better.

As a result of your comments and of others, I made changes/refinements to better illuminate the pitfalls of this project.

May 15, 2015    View Comment    

On Storage Not Needed to Accommodate Higher Levels of Wind Energy


You are right, storage is not required to integrate variable energy, such as wind energy, to the grid, BUT, as has been PROVEN in Ireland with 15-minute Eirgrid operating data and by Wheatley, using even more accurate date for each generator on the grid, at about 17% wind energy on the grid, the OTHER gas-fired generators are operated so inefficienctly (more Btu/kWh, more CO2/kWh), that that extra fuel and CO2 offset about 50% of what wind energy was supposed to save, as claimed by the AWEA, et al. 

What you may not yet know, the interesting development in the past few months is that Eirgrid has, after many years of obfuscation, PUBLICLY admitted that this is indeed the case, and informed the EU in Brussels of that fact.

Government officials and wind energy promoters, such as the EWEA, BWEA, etc., usually claim one MWh of “clean” wind energy offsets one MWh of “dirty” fossil fuel energy, which is true regarding energy, but not regarding CO2 emissions, because of the inefficient operation of the other generators on the grid due to wind energy.

Below is summary of wind energy CO2 emission reduction effectiveness versus annual wind energy percent, for various grids:

1.0 at 0% wind energy on any grid.

0.97 (my assumption) at 1.0%, New England grid.

0.70 (calculated by Dr. LePair) at 3.36%, the Netherlands grid; based on at least 10 years of actual fuel and production data.

0.706 (calculated by Dr. Udo) at 12.6%, Ireland grid; based on deficient EirGrid data.

0.526 (calculated by Wheatley) at 17%, Ireland grid; based on SEMO data of individual generators, including increased start/stop CO2 emissions, and increased capacity and hours of spinning plant CO2 emissions, i.e., better than Eirgrid data.

Wind energy CO2 reduction effectiveness of Irish Grid = (CO2 intensity, metric ton/MWh, with wind)/(CO2 intensity with no wind).

Ireland = (0.279, 17% wind)/(0.53, no wind) = 0.526, based on SEMO data.

If 17% wind energy, promoters typically claim a 17% reduction in CO2, i.e., 83% is still left over.

If 17% wind energy, actual performance data of the Irish grid shows, 0.526 x 17% is reduced = 8.94%, id est, 91.06% is still left over.

May 15, 2015    View Comment