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By Post Carbon Institute

Post Carbon Institute has released two reports authored by Earth scientist J. David Hughes assessing the U.S. Energy Information Administration's (EIA) most recent projections for domestic tight ("shale") oil and shale gas production.

The reports 2016 Tight Oil Reality Check and 2016 Shale Gas Reality Check evaluate the EIA's increasingly optimistic projections in light of actual production data (through June 2016) and the agency's own previous estimates. The reports raise critical questions about the veracity and volatility of the EIA's estimates, questions that are especially important as the Trump Administration sets its domestic energy policy.

"The EIA kindly provided the play level projections that make up its Annual Energy Outlook reference case forecasts," said Earth scientist and the reports' author J. David Hughes. "This allowed a comparison to the administration's previous projections and my own forecasts, which were based on an analysis of well productivity by subarea within each play and other fundamentals such as the number of available drilling locations and decline rates. I was also able to assess the EIA's most recent projections in light of actual production data from the field. Simply put, when looked at on a play-level, the EIA's forecasts are highly unlikely to be realized."

The Annual Energy Outlook (AEO) published yearly by the U.S. Energy Information Administration is taken by media, policymakers, investors and general public at face value. Yet the EIA's projections for future energy prices and production are very often wrong (like when it revised its own estimate for the Monterey shale downward by 96 percent after just three years) and tend to show a consistent optimism bias.

For example, AEO 2016 has increased estimates of tight oil production through 2040 by 19 percent over AEO 2015 and 31 percent over AEO 2014, while its estimates for shale gas production have been increased by 31 percent over AEO 2015 and 43 percent over AEO 2014. This despite the fact that U.S. tight oil production is already down 13 percent (as of June 2016) from its peak in March 2015 and shale gas production has declined 5 percent from its peak in early 2016. The EIA does not provide an explanation for why it is so optimistic about future production, especially considering that AEO 2016 anticipates lower drilling rates than in 2014 through 2040, when it projects 31 percent higher oil and gas production, and only modest increases in prices. It also does not account for the year-over-year volatility in its estimates of various plays. For example, Marcellus shale gas production estimates through 2040 are now 76 percent higher than they were in 2014 (accounting for 147 percent of the unproved, technically recoverable resource in the play), while Eagle Ford production has been reduced by 36 percent in that same period of time.

"Forty years ago, the EIA was uniquely granted independence from the rest of the federal government in order to ensure that its data collection and analysis would not be politicized. But with that independence comes great responsibility," said Asher Miller, executive director of Post Carbon Institute. "Particularly with an incoming presidential administration that is, by all signs, strongly in favor of expanding fossil fuel production, the American people need to be certain that U.S. energy policy is based on realistic, independently-sourced and transparent analysis rather than wishful thinking."

Key Takeaway/Conclusions

  • The EIA has raised its estimates in 2016 for how much tight oil and shale gas will be produced through 2040 by 19 percent and 31 percent, respectively, over the previous year's projections, despite the fact that production of both has declined by 13 percent and 5 percent, respectively, from peak production levels.
  • The EIA projects tight oil and shale gas production will grow 88 percent from 2014 levels to all-time highs by 2040, while drilling rates remain below 2014 levels through 2040, with only a modest increase in oil price.
  • The AEO forecasts continue to be volatile and trend toward very high, unsubstantiated optimism bias. Tight oil AEO projections of recovery by 2040 in certain plays have been adjusted significantly between AEO 2016 and AEO 2014—ranging from +414 percent (Bone Spring) and +137 percent (Bakken) to -42 percent (Austin Chalk), while shale gas forecasts range between +237 percent (Bakken) to -36 percent (Eagle Ford). The EIA offers no explanation for this volatility.
  • The EIA assumes that tight oil and shale gas production will grow strongly beginning in 2017, that U.S. oil and gas production will reach 2015 highs by 2019 and that production will grow a further 31 percent by 2040—all while also assuming that drilling rates (which are currently 37 percent below peak levels of 2014) will remain below 2014 levels through 2040. This seems highly improbable, considering that all major tight oil plays have peaked except in the Permian Basin and that all major shale gas plays have peaked.
  • The EIA assumes that the major shale gas plays (which account for 75 percent of total projected 2013-2040 production) will recover 132 percent of their "unproved technically recoverable resources" by 2040 but provide no explanation as to why or how they believe this to be possible.

Questions for the EIA:

  • AEO 2016 projects tight oil and shale gas production to grow 88 percent from 2014 levels to all-time highs by 2040. Given that drilling rates are projected to remain below 2014 levels through 2040, with only a modest increase in oil price, what justifies the unprecedented growth?
  • Considering that AEO 2015 and AEO 2016 are just 12 months apart, there is a lot of change in projected production profiles for individual plays and total production between the two. What is the reason for the substantial variation in these projections?
  • The EIA published a more in-depth assessment of the Eagle Ford shale play in 2014 and has subsequently downgraded its projection for tight oil and shale gas production through 2040 by 15 percent and 36 percent, respectively. Has the EIA conducted similar assessments of other plays?
  • Is the EIA's optimism based on the assumption of ever increasing technological improvements, considering that they will not necessarily increase the ultimate recovery of a play? At a constant drilling rate, better technology will allow each well to tap more of the reservoir while reducing the number of drilling locations, and exhaust a play more quickly at a lower cost.
  • If NEMS is truly a robust system for forecasting, why is there so much difference at the play level between AEO 2015 and AEO 2016 when play fundamentals have changed little?
  • How can overall tight oil production increase by 19 percent in AEO 2016 compared to AEO 2015 while assuming oil prices are the same or lower over the 2015-2040 period
  • How can overall shale gas production increase by 31 percent in AEO 2016 compared to AEO 2015 while assuming gas prices are 20 percent lower over the 2015-2040 period?

Tight Oil Play-Specific Questions:

  • Why does Bakken production rise 128 percent from current levels, recover more than twice as much oil by 2040 as the latest USGS mean estimate of technically recoverable resources and exit 2040 at production levels more than double current levels?
  • How can a decades old play like the Austin Chalk increase production 21-fold over current levels, compared to the modest forecast in AEO 2015, and recover twice as much oil by 2040 as it has recovered since the 1940s?

Shale Gas Play-Specific Questions:

  • Why does Marcellus shale gas production rise 48 percent from current levels, recover 47 percent more gas than the EIA's estimate of "unproved technically recoverable resources" and exit 2040 at near all-time high production levels?
  • How can the Haynesville grow 223 percent from current levels and exit 2040 at all-time high production levels after recovering 28 percent more gas than the EIA's estimate of unproved resources?
  • How can an old play like the Barnett be resurrected and exit 2040 at near all-time high production levels after recovering 145 percent more unproved resources than the EIA estimates exist?
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Solar panels allow you to harness the sun's clean, renewable energy, potentially cutting your electric bills as well as your environmental footprint. But do solar panels work on cloudy days, or during seasons of less-than-optimal sun exposure? For homeowners who live outside of the Sun Belt, this is a critical question to consider before moving ahead with solar panel installation.

In this article, we'll go over how solar panels work on cloudy days, whether solar panels work at night, and how to ensure you always have accessible power — even when your panels aren't producing solar energy.

How Solar Panels Work on Cloudy Days

Photovoltaic (PV) solar panels can use both direct and indirect sunlight to generate electrical power. This means they can still be productive even when there is cloud coverage. With that said, solar panels are most efficient and productive when they are soaking up direct sunlight on sunny days.

While solar panels still work even when the light is reflected or partially obstructed by clouds, their energy production capacity will be diminished. On average, solar panels will generate 10 to 25% of their normal power output on days with heavy cloud coverage.

With clouds usually comes rain, and here's a fact that might surprise you: Rain actually helps solar panels work more effectively. That's because rain washes away any dirt or dust that has gathered on your panels so that they can more efficiently absorb sunlight.

Do Solar Panels Work at Night?

While solar panels can still function on cloudy days, they cannot work at night. The reason for this is simple: Solar panels work because of a scientific principle called the photovoltaic effect, wherein solar cells are activated by sunlight, generating electrical current. Without light, the photovoltaic effect cannot be triggered, and no electric power can be generated.

One way to tell if your panels are still producing energy is to look at public lights. As a general rule of thumb, if street lamps or other lights are turned off — whether on cloudy days or in the evening — your solar panels will be producing energy. If they're illuminated, it's likely too dark out for your solar panel system to work.

Storing Solar Energy to Use on Cloudy Days and at Night

During hours of peak sunlight, your solar panels may actually generate more power than you need. This surplus power can be used to provide extra electricity on cloudy days or at night.

But how do you store this energy for future use? There are a couple of options to consider:

You can store surplus energy in a solar battery.

When you add a solar battery to your residential solar installation, any excess electricity can be collected and used during hours of suboptimal sun exposure, including nighttime hours and during exceptionally cloudy weather.

Batteries may allow you to run your solar PV system all day long, though there are some drawbacks of battery storage to be aware of:

  • It's one more thing you need to install.
  • It adds to the total cost of your solar system.
  • Batteries will take up a bit of space.
  • You will likely need multiple batteries if you want electricity for more than a handful of hours. For example, Tesla solar installations require two Powerwall batteries if your system is over 13 kilowatts.

You can use a net metering program.

Net metering programs enable you to transmit any excess power your system produces into your municipal electric grid, receiving credits from your utility company. Those credits can be cashed in to offset any electrical costs you incur on overcast days or at night when you cannot power your home with solar energy alone.

Net metering can ultimately be a cost-effective option and can significantly lower your electricity bills, but there are a few drawbacks to consider, including:

  • You may not always break even.
  • In some cases, you may still owe some money to your utility provider.
  • Net metering programs are not offered in all areas and by all utility companies.

Is Residential Solar Right for You?

Now that you know solar panels can work even when the sun isn't directly shining and that there are ways to store your energy for times your panels aren't producing electricity, you may be more interested in installing your own system.

You can get started with a free, no-obligation quote from a top solar company in your area by filling out the 30-second form below.

FAQ: Do Solar Panels Work on Cloudy Days?

How efficient are solar panels on cloudy days?

It depends on the panels, but as a rule of thumb, you can expect your solar panels to work at 10 to 25% efficiency on cloudy days.

How do solar panels work when there is no sun?

If there is literally no sunlight (e.g., at night), then solar panels do not work. This is because the photovoltaic effect, which is the process through which panels convert sunlight into energy, requires there to be some light available to convert.

However, you can potentially use surplus solar power that you've stored in a battery. Also note that solar panels can work with indirect light, meaning they can function even when the sun is obscured by cloud coverage.

Do solar panels work on snowy days?

If there is cloud coverage and diminished sunlight, then solar panels will not work at their maximum efficiency level on snowy days. With that said, the snow itself is usually not a problem, particularly because a dusting of snow is easily whisked away by the wind.

Snow will only impede your solar panels if the snowfall is so extreme that the panels become completely buried, or if the weight of the snow compromises the integrity of your solar panel structures.

Will my solar panels generate electricity during cloudy, rainy or snowy days?

Cloudy days may limit your solar panel's efficiency, but you'll still be able to generate some electricity. Rainy days can actually help clean your panels, making them even more effective. And snowy days are only a problem if the snow is so extreme that the panels are totally submerged, without any part of them exposed to the sun.

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