In today’s Electrek Green Energy Brief (EGEB):

  • UN: A decade of renewables quadruples capacity — and it’s led by solar.
  • The advantages and challenges of super-tall wind turbine towers.
  • Extreme weather is driving battery-powered energy storage.
  • Crops under solar panels is a win for both.

EGEB: A daily technical, financial, and political review/analysis of important green energy news.

According to the United Nations’ “Global Trends in Renewable Energy Investment 2019” report, “Global investment in new renewable energy capacity over this decade — 2010 to 2019 inclusive — is on course to hit USD $2.6 trillion, with more gigawatts of solar power capacity installed than any other generation technology.”

This investment will have nearly quadrupled renewable energy capacity (excluding large hydro) from 414 GW at the end of 2009 to just over 1,650 GW by the end of 2019.

Solar power will have drawn half — USD $1.3 trillion — of the USD $2.6 trillion in renewable energy capacity investments made over the decade. Solar alone will have grown from 25 GW at the beginning of 2010 to an expected 663 GW by the close of 2019 — enough to produce all the electricity needed each year by about 100 million average homes in the US.

The global share of electricity generation accounted for by renewables reached 12.9%, in 2018, up from 11.6% in 2017.

And costs have come down, too: “The levelized cost of electricity (a measure that allows comparison of different methods of electricity generation on a consistent basis) is down 81% for solar photovoltaics since 2009; that for onshore wind is down 46%.”

However, global power sector emissions have risen about 10% over this period. So we’re heading in the right direction, but we have to keep up the momentum.

Super-tall wind turbines in the US

The American Wind Energy Association (AWEA) reports that the average hub height of US utility-scale wind turbines jumped from 190 feet (58 meters) to 288 feet (88 meters) from 2000 to 2018, according to Greentech Media.

The benefit of taller wind turbines is a stronger, more consistent wind. According to a new National Renewable Energy Laboratory (NREL) report on tower heights for land-based turbines:

Across large portions of the country, average annual wind speeds increase by 0.5 to 1 meters per second with a jump from 80- to 110-meter towers, and by 1 to 1.5 meters per second when moving from 80- to 160-meter towers.

But the challenge is that manufacturers must figure out ways to reduce costs for towers that are 459 feet (140 meters) or higher.

Super-tall wind turbines are still rare in the US: As of the first half of 2019, there were only 19 turbines that exceeded 361 feet (110 meters). The tallest is currently a 427-foot (130-meter) turbine installed in 2018 at West Texas A&M University.

Manufacturing options are currently “rolled tubular steel (the most common today), concrete, lattice steel, or hybrid designs that combine these methods,” but there isn’t consensus yet on the best material for the towering turbines.

Extreme weather = energy storage boom

When bad storms or weather disasters are about to strike, residents have typically purchased or pulled gas-powered diesel generators out of the garage to keep their fridges, AC, and gadgets running. But the diesel generators pollute, they’re loud, and sometimes even cause deaths due to carbon monoxide poisoning.

Michael Colvin, director of California Energy, points out on the Environmental Defense Fund’s website that there is a sharp rise in energy storage involving battery technology in areas prone to extreme weather. For example, installations in Puerto Rico have doubled since Hurricane Maria.

When properly designed, electric energy storage can not only provide additional grid resilience, it can further minimize greenhouse gas and local air emissions compared with the conventional gas generators.

In the US, 15 states have made it more affordable to invest in energy storage. And “analysts expect such investments to soar by $620 billion globally over the next two decades.”

Right. It’s hurricane season, and I’m in Florida. Now to sort out battery technology energy storage for our house.

Solar + crops = a happy pairing

The University of Arizona’s Greg Barron-Gafford, associate professor of biogeography and ecosystem science, has figured out that plants and solar panels can coexist quite happily. He focused on the US Southwest’s arid climate in his studies.

As Arstechnica explains:

To test this, the researchers set up three plots for the summer months: one only solar panels, one with only crops, and one with both. The solar panels, in this case, were built to stand a little over 3 meters off the ground—higher than a typical solar array. All three plots were irrigated the same, and temperatures, humidity, and soil moisture were tracked. Cherry tomatoes, jalapeños, and chiltepin peppers were chosen as the crops to test.

The results showed that combining things did alter temperatures, as expected. Air temperatures stayed a little over 1°C cooler during the day, on average, but they also stayed about 0.5°C warmer overnight. The temperature of the solar panels, though, was about 9°C cooler during the day because of the growth beneath them. The air was also a little less dry under the solar panels, and the soil dried out more slowly between waterings.

The vegetable result: The amount of chiltepin peppers tripled under the panels, the jalapeños missed the sunlight but became much more water-efficient, and the cherry tomatoes produced twice as much fruit while using the same amount of water.

And for the solar panel output, “the researchers calculated that the cooler temperatures should increase electricity generation by about 3% over the summer months, averaging out to a 1% gain for the whole year.”

Everybody wins.


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