Getting real with renewable energy 

Electricity generation uses a variety of power sources which have different roles in the fuel mix:

• Nuclear power is the bedrock of generation, which typically provides 4 MW of baseload power, 24 hours a day and seven days a week. It provides about 30 percent of electricity used and is the largest source of clean low-carbon energy in New England.

• Renewables including wood, refuse and wind make up about 9 percent of energy generated. The wood and refuse are typically the majority of the mix, and are a fairly stable source of power. Wind though is highly variable and is more difficult to integrate into the power grid.

• Hydropower provides about 7 percent of the generated power. It is a mix of stored hydro that can be dispatched and varied throughout the day, and run-of-the-river hydro which is available based on the river flow. Additional hydro is imported from Hydro-Quebec and even more could be available when new high voltage DC transmission lines are installed to transmit power to southern New England.

• Natural gas provides about 50 percent of the energy. It is the most versatile source since the generators can be used to provide baseload power; ramp up fast to respond to demand; or vary output as needed to help regulate the grid. Natural gas generators are needed for maintaining grid reliability and reserve power. Over the past 15 years natural gas has helped displace most use of coal and oil, which has resulted in large reductions in pollution and CO2 emissions.

Wind power is variable renewable energy that is forecast to increase throughout New England. There is a practical upper limit to the contribution variable renewable energy can make to the overall energy sourcing. The wind variability and the highly variable electrical demand, ends up limiting the ability of variable renewable energy to provide energy to the grid. The difficulty in New England is that the windier time of the year is in the winter, which also has much less demand for electricity than the summer.

From an environmental perspective, the primary role of wind power is to displace the burning of natural gas to reduce CO2 emissions. An increase of wind power is limited to the point where wind generation would displace most natural gas generation on the windiest day of the year with the least demand for electricity. In 2016 this occurred on Dec 25. If the current installed wind power was six times greater than it actually was in 2016, then all of the natural gas generation would have been displaced on that day. Adding more wind power beyond that would not be economical, since it would then frequently need to be curtailed under similar conditions. Even with a hypothetical six-fold increase in wind power, the energy produced by wind would only be 14 percent of total generation and all renewable energy produced would be 28 percent of total generation.

There are physical and economical limits to renewable energy generation in the real world. A vision of 100 percent renewable energy is a denial of the physics and engineering of the electrical grid. It is like climate change denial because it ignores the empirical evidence and replaces it with a desired world instead. It is dangerous because it creates a false sense of what is achievable, leading to support for policies than can’t work.

The grid should generate as much renewable energy as possible – but what is possible for New England is closer to 30 percent, than is is 100 percent. For sure, “30 percent renewables” is not nearly as ambitious as a goal. But it is actually technically feasible and is not magical thinking. A 30 percent renewables generation target, when combined with additional renewable hydro from Hydro-Quebec, can achieve a path to economic decarbonization in New England.

References

ISO New England real-time data: https://www.iso-ne.com/isoexpress/

ISO New England Daily Generation by Fuel Type
https://www.iso-ne.com/isoexpress/web/reports/operations/-/tree/daily-gen-fuel-type

The Breakthrough, A Look at Wind and Solar Part 2: Is There An Upper Limit To Intermittent Renewables?
http://thebreakthrough.org/index.php/voices/energetics/a-look-at-wind-and-solar-part-2