How natural gas is fueling the renewable energy boom

Posted by Robin Guster via RealClearEnergy,

Solar and wind energy are expanding rapidly in the US Today they account for about 19 percent of energy production, and their volume can reach more than 40% by 2030. This clean energy will quickly replace coal, and many expect it to simply replace natural gas as well. But this is a mistake: in fact, solar and wind power will depend on gas for decades.

Today, solar and wind energy are relatively inexpensive, and prices are likely to fall further. But they’re not like fossil fuels—they’re called variable renewable energy (VRE), meaning they only produce electricity when the sun is shining or the wind is blowing.

Sometimes this change is predictable. For example, solar energy does not produce electricity at night and generates less energy in the winter. But some variations are unpredictable; Cloudiness or wind droughts can last for weeks. This “VRE shortage” is not a problem as long as wind and solar make up a small percentage of electricity production. But as they become dominant, how do we fill the gaps when VRE supply is low?

Electric utilities are now adding a lot of short duration (4 hour) lithium-ion batteries. to eliminate daily and hourly variations, ensuring sufficient power in the evening when demand is high. The Department of Energy expects this trend to accelerate, but while these batteries are reliable and can be turned on with the flick of a switch, they only address VRE shortages for a few hours at a time.

Another issue is the longer VRE shortage. What happens when a shortage lasts for weeks or months? How do we keep the lights on? Detailed research, such as that carried out by the UK’s Royal Society, shows that there can be prolonged periods of bad weather leading to annual energy deficits of up to 20% of total grid electricity production (in a fully decarbonised grid).

Right now, when demand spikes or supply is disrupted, we turn primarily to “peaker plants”—gas-fired plants that operate on a single cycle and drive turbines to produce electricity. These power plants are less efficient than combined cycle gas turbine (CCGT) plants and their energy is more expensive, so they are kept in reserve and paid to provide backup power, ensuring that sufficient emergency power is always available. Typically, grid operators pay about 15% of peak energy demand as reserve power. If less, there may be power outages. Any more and the money will be wasted. Although VRE use is relatively modest, peaking power plants can cover the VRE shortfall.

But as VRE becomes a larger and larger share of the overall energy system, the impact of adverse weather events will become more severe and supply will become more volatile. A grid with 40% VRE will need a lot more insurance to ensure the lights stay on.

There are alternatives to gas power, technologies that can store energy for very long periods of time and deliver it on demand on a large scale – particularly hydrogen, hydropower and compressed air. Hydropower is cheap to operate, is a mature and proven technology, and its generators last for decades. But we are tearing down more dams than we are building, and the US has no desire to build the dozens of huge new dams that might be needed. Conversely, green hydrogen has very low efficiency.100 kWh of green electricity is required to provide 40 kWh of dispatchable stored electricity.— and its production and storage are very expensive, and its transportation is also expensive and can cause serious emissions. Moreover, hydrogen will not suddenly and quickly become cheaper, like wind and solar energy. Currently, compressed air operates at about 50% efficiency. Significant improvement would require cooling and then reheating the air, which is expensive if the air is stored for a long time. And the electrochemical batteries currently being added to the grid will not provide the necessary combination of long life, enormous scalability and low costs.

This leaves us with gas.

To enable a VRE-dominated energy system, natural gas must be used as a hedge against VRE shortages. This is why the Department of Energy predicts that power plant peak output will actually increase during the clean energy transition, and why it also does not predict a significant reduction in CCGT output.

However function gas energy will change. Today, CCGT power plants are used primarily as a guaranteed base load, an energy source used 100% of the time, with additional power available from peaking power plants. As the green energy transition gets underway, CCGT power plants will move from producing base-load electricity to providing insurance against supply disruptions, just as peaking power plants do today.

Ultimately, we can hope to achieve a green, zero-emission grid.. In this world, gas emissions will eventually be completely reduced. Perhas gas will be replaced by new fuel sources such as geothermal or even nuclear fusion, carbon capture could eliminate gas-fired power plant emissions, and scalable storage technologies may finally mature to become the energy insurance policy of tomorrow. Overall, however, it is clear that we do not have all the technologies we need and that we need to put much more effort into improving these critical technologies, many of which are still not ready for full commercial deployment.

Meanwhile, we must understand that in the United States, gas will be critical tool that promotes wind and solar power, providing grid reliability that wind and solar power alone cannot provide. If we are serious about decarbonization, then this is what is needed: a realistic view of the near to medium term, a huge financial commitment to developing critical technologies that will provide cheap and reliable energy, and a realistic understanding of the changing but still important role of gas in the decarbonization network, where it will be needed for decades to come.

Robin Guster is research director at the Information Technology and Innovation Foundation (USA).ITIF).

Author: Zerohedge.com

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