Oct 07 2019

Utilities vs Renewable Energy

We are beginning to experience some growing pain with widespread adoption of wind and solar energy. Solar in particular is causing utility companies some heartache because of its distributed design and intermittent energy production. None of the issues raised are fatal problems, but we do need to address them head on.

The basic problem is that we cannot simply look at each piece of energy production in isolation. It’s tempting to think that if you install solar roof panels, that is a pure environmental good because clean energy will be replacing more dirty energy. Initially this may have been largely the case, with very low penetration of distributed solar. However, as the amount of installed solar increases, tensions with utility companies and the complexity of integrating into the power grid are rising.

In 2018 solar was producing 1.6% of total electricity generation in the US (total renewable is 17.1%), but this is projected to rise considerably over the next decade. Solar and wind cause challenges for the grid because they are intermittent sources. For the individual installing solar will likely result in decreased electricity cost. However, if our concern is the overall efficiency and environmental impact, a more complicated evaluation is necessary.

A recent study by Duke Energy highlights this complexity. This is not an objective source – some utility companies are taking a hostile attitude toward distributed energy because of the problems it causes. Here is a quote from Dan Kish, distinguished senior fellow at the Institute for Energy Research, to give you an idea:

“Renewable energy sounds good, but it performs terribly. If you want electricity available when you need it, you don’t want intermittent, unreliable, renewable energy,” Kish said. “It’s like a cancer on an efficient grid, with its ups-and-downs forcing other sources to pick up the slack in the most inefficient ways, which, in some cases, are more polluting.”

What the Duke study found was that as the solar mix increased, CO2 emissions did decrease as expected, mainly from displacing some fossil fuel production, but another pollutant, NOx (nitrogen oxide) increased. The reason for the NOx increase has to do with ramping up and down on-demand energy production in order to compensate for the intermittent nature of solar. The generators are more efficient when they are running at a constant power, including the mechanisms for reducing NOx pollution. The equipment is simply not optimized for this kind of use.

NOx emssions more than doubled due to the introduction of solar. However, the study also showed that if instead of turning the generators off they simply idle them low, NOx emissions could be significantly reduced, although still 44% higher than baseline. Duke is mandated by law to turn their fossil fuel generators off when solar is entering the grid, so they are applying for a licence to idle these generators instead.

Could we solve this problem if more homes had battery backup? Local energy storage has numerous advantages, because it can level off demand, and shift energy produced during the day to peak demand just after sunset. However, there is also a downside to energy storage, it uses up energy itself. Storing solar energy could increase total energy usage by 8-14%. If that extra energy is ultimately coming from fossil fuel generators, this could eat into the environmental benefits of renewable energy.

The fact is, our current energy grid is not really designed for distributed and intermittent energy production. It’s designed for big centralized energy production and distribution. Utility companies are now struggling to deal with the changing mix of energy using a system not designed for, and certainly not optimized for, high penetration of renewables. So what do we do?

The short answer is that we need to redesign our energy infrastructure. We cannot just tack on wind and solar, we need to design the grid to be optimized for clean energy and distributed energy production. At the very least this will require a massive grid upgrade. The grid needs to be designed to handle more people sending energy to the grid when they are producing it, and not just taking energy from the grid. This requires, for example, more transformers (devices that increase or decrease the voltage of the energy).

The grid also needs to have higher capacity and to be designed to share energy across wider areas. Balancing energy production among wind and solar can be done, if the grid is wide enough (the wind is always blowing somewhere).

We also need grid storage. This is perhaps the greatest challenge. This requires a lot of energy storage, and we’re not really sure what the best way to do this is. Batteries may be the best, but they add inefficiency of their own, and to make enough to serve as grid storage may strain our resources. One idea is to repurpose old electric car batteries for grid storage, and this can partially solve the problem, but still this will be a massive challenge of production and recycling. Pumped hydro is probably best, but is limited by geography. Researchers are looking into new technology, like gravity storage using towers of heavy blocks.

And finally, as the Duke study shows, we need to rethink other forms of energy production. They need to be designed with renewables in mind, so that they are optimized for ramping up and down as needed, rather than running at a constant rate or being completely off. Backup energy production needs to be more adaptive.

These challenges are all solvable – but we do need to solve them. We can just keep adding wind and solar and think this will take care of energy needs with clean energy. We need a massive investment in our energy infrastructure, but it is an investment that is worth it and will pay for itself in the long run. While we’re at it, we can harden our energy grid against a coronal mass ejection (CME) – also a worthwhile investment.

It’s frustrating when everyone essentially knows that we need to do something, and that it is a good idea and worth it in the long run, but it still seems difficult to harness the political will to get it done.

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