How should electricity from wind turbines and solar panels be evaluated? Should it be evaluated as if these devices are stand-alone devices? Or do these devices provide electricity that is of such low quality, because of its intermittency and other factors, that we should recognize the need for supporting services associated with actually putting the electricity on the grid? This question comes up in many types of evaluations, including Levelized Cost of Energy (LCOE), Energy Return on Energy Invested (EROI), Life Cycle Analysis (LCA), and Energy Payback Period (EPP).
I recently gave a talk…As you might guess, my conclusion is that the current methodology is quite misleading. Wind and solar are not really stand-alone devices when it comes to providing the kind of electricity that is needed by the grid. Grid operators, utilities, and backup electricity providers must provide hidden subsidies to make the system really work.
This problem is currently not being recognized by any of the groups evaluating wind and solar, using techniques such as LCOE, EROI, LCA, and EPP. As a result, published results suggest that wind and solar are much more beneficial than they really are. The distortion affects both pricing and the amount of supposed CO₂ savings.
One of the questions that came up at the conference was, “Is this distortion actually important when only a small amount of intermittent electricity is added to the grid?” For that reason, I have included discussion of this issue as well. My conclusion is that the problem of intermittency and the pricing distortions it causes is important, even at low grid penetrations….
This means that if we really expect to scale wind and solar, we probably need to be creating packages of grid-quality electricity (wind or solar, supplemented by various devices to create grid quality electricity) at an acceptably high EROI. This is very similar to a requirement that wind or solar energy, including all of the necessary adjustments to bring them to grid quality, be available at a suitably low dollar cost–probably not too different from today’s wholesale cost of electricity. EROI theory would strongly suggest that energy costs for an economy cannot rise dramatically, without a huge problem for the economy. Hiding rising energy costs with government subsidies cannot fix this problem.
Distortions Become Material Very Early
If we look at recently published information about how much intermittent electricity is being added to the electric grid, the amounts are surprisingly small. Overall, worldwide, the amount of electricity generated by a combination of wind and solar (nearly all of it intermittent) was 5.2% in 2016. On an area by area basis, the percentages of wind and solar are as shown in Figure 1.
Figure 1. Wind and solar as a share of 2016 electricity generation, based on BP Statistical Review of World Energy 2017. World total is not shown, but is very close to the percentage shown for China.
There are two reasons why these percentages are lower than a person might expect. One reason is that the figures usually quoted are the amounts of “generating capacity” added by wind and solar, and these are nearly always higher than the amount of actual electricity supply added, because wind and solar “capacity” tend to be lightly used.
The other reason that the percentages on Figure 1 are lower than we might expect is because the places that have unusually high concentrations of wind and solar generation (examples: Germany, Denmark, and California) tend to depend on a combination of (a) generous subsidy programs, (b) the availability of inexpensive balancing power from elsewhere and (c) the generosity of neighbors in taking unwanted electricity and adding it to their electric grids at low prices.
As greater amounts of intermittent electricity are added, the availability of inexpensive balancing capacity (for example, from hydroelectric from Norway and Sweden) quickly gets exhausted, and neighbors become more and more unhappy with the amounts of unwanted excess generation being dumped on their grids. Denmark has found that the dollar amount of subsidies needs to rise, year after year, if it is to continue its intermittent renewables program.
One of the major issues with adding intermittent renewables to the electric grid is that doing so distorts wholesale electricity pricing. Solar energy tends to cut mid-day peaks in electricity price, making it less economic for “peaking plants” (natural gas electricity plants that provide electricity only when prices are very high) to stay open. At times, prices may turn negative, if the total amount of wind and solar produced at a given time is greater than the overall amount of electricity required by customers. This happens because intermittent electricity is generally given priority on the grid, whether price signals indicate that it is needed or not. A combination of these problems tends to make backup generation unprofitable unless subsidies are provided. If peaking plants and other backup are still required, but need to operate fewer hours, subsidies must be provided so that the plants can afford to hire year-around staff, and pay their ongoing fixed expenses….
The other major anomaly is the need for a lot of quick “ramp up” and “ramp down” capacity. One time this typically happens is at sunset, when demand is high (people cooking their dinners) but a large amount of solar electricity disappears because of the setting of the sun. For wind, rapid ramp ups and downs seem to be related to thunderstorms and other storm conditions. California and Australia are both adding big battery systems, built by Tesla, to help deal with rapid ramp-up and ramp-down problems.
There is a lot of work on “smart grids” being done, but this work does not address the particular problems brought on by adding wind and solar. In particular, smart grids do not move demand from summer and winter (when demand is normally high) to spring and fall (when demand is normally low). Smart grids and time of day pricing aren’t very good at fixing the rapid ramping problem, either, especially when these problems are weather related…
With the strange demand pattern that occurs when intermittent renewables are added, standard pricing approaches (based on marginal costs) tend to produce wholesale electricity prices that are too low for electricity produced by natural gas, coal, and nuclear providers. In fact, wholesale electricity rates for supporting providers tend to diverge further and further from what is needed, as more and more intermittent electricity is added. The dotted line on Figure 2 illustrates the falling wholesale electricity prices that have been occurring in Europe, even as retail residential electricity prices are rising.
Figure 2. European residential electricity prices have risen, even as wholesale electricity prices (dotted line) have fallen. Chart by Paul-Frederik Bach.
The marginal pricing scheme gives little guidance as to how much backup generation is really needed. It is therefore left up to governments and local electricity oversight groups to figure out how to compensate for the known pricing problem. Some provide subsidies to non-intermittent producers; others do not.
To complicate matters further, electricity consumption has been falling rapidly in countries whose economies are depressed. Adding wind and solar further reduces needed natural gas, coal, and nuclear generation. Some countries may let these producers collapse; others may subsidize them, as a jobs-creation program, whether this backup generation is needed or not.
Of course, if a single payer is responsible for both intermittent and other electricity programs, a combined rate can be set that is high enough for the costs of both intermittent electricity and backup generation, eliminating the pricing problem, from the point of view of electricity providers. The question then becomes, “Will the new higher electricity prices be affordable by consumers?”
The recently published IEA World Energy Investment Report 2017 provides information on a number of developing problems:
“Network investment remains robust for now, but worries have emerged in several regions about the prospect of a “utility death spiral” as the long-term economic viability of grid investments diminishes. The still widespread regulatory practice of remunerating fixed network assets on the basis of a variable per kWh charge is poorly suited for a power system with a large amount of decentralised solar PV and storage capacity.”
The IEA investment report notes that in China, 10% of solar PV and 17% of wind generation were curtailed in 2016, even though previous problems with lack of transmission had been fixed. Figure 1 shows China’s electricity from wind and solar amounts to only 5.0% of its total electricity consumption in 2016.
Regarding India, the IEA report says, “More flexible conventional capacity, including gas-fired plants, better connections with hydro resources and investment in battery storage will be needed to support continued growth in solar power.” India’s intermittent electricity amounted to only 4.1% of total electricity supply in 2016.
In Europe, a spike in electricity prices to a 10-year high took place in January 2017, when both wind and solar output were low, and the temperature was unusually cold. And as previously mentioned, California and South Australia have found it necessary to add Tesla batteries to handle rapid ramp-ups and ramp-downs. Australia is also adding large amounts of transmission that would not have been needed, if coal generating plants had continued to provide services in South Australia.
None of the costs related to intermittency workarounds are currently being included in EROI analyses. They are generally not being included in analyses of other kinds, either, such as LCOE. In my opinion, the time has already arrived when analyses need to be performed on a much broader basis than in the past, so as to better capture the true cost of adding intermittent electricity.
Source: Researchers Have Been Underestimating the Cost of Wind and Solar | Wind Energy Impacts and Issues