Bethany Frew

Low-cost solution to the grid reliability problem with 100% penetration of intermittent wind, water, and solar for all purposes

Significance The large-scale conversion to 100% wind, water, and solar (WWS) power for all purposes (electricity, transportation, heating/cooling, and industry) is currently inhibited by a fear of grid instability and high cost due to the variability and uncertainty of wind and solar. This paper couples numerical simulation of time- and space-dependent weather with simulation of time-dependent power demand, storage, and demand response to provide low-cost solutions to the grid reliability problem with 100% penetration of WWS across all energy sectors in the continental United States between 2050 and 2055. Solutions are obtained without higher-cost stationary battery storage by prioritizing storage of heat in soil and water; cold in water and ice; and electricity in phase-change materials, pumped hydro, hydropower, and hydrogen. This study addresses the greatest concern facing the large-scale integration of wind, water, and solar (WWS) into a power grid: the high cost of avoiding load loss caused by WWS variability and uncertainty. It uses a new grid integration model and finds low-cost, no-load-loss, nonunique solutions to this problem on electrification of all US energy sectors (electricity, transportation, heating/cooling, and industry) while accounting for wind and solar time series data from a 3D global weather model that simulates extreme events and competition among wind turbines for available kinetic energy. Solutions are obtained by prioritizing storage for heat (in soil and water); cold (in ice and water); and electricity (in phase-change materials, pumped hydro, hydropower, and hydrogen), and using demand response. No natural gas, biofuels, nuclear power, or stationary batteries are needed. The resulting 2050–2055 US electricity social cost for a full system is much less than for fossil fuels. These results hold for many conditions, suggesting that low-cost, reliable 100% WWS systems should work many places worldwide.

Features of a fully renewable US electricity system: Optimized mixes of wind and solar PV and transmission grid extensions

A future energy system is likely to rely heavily on wind and solar PV. To quantify general features of such a weather dependent electricity supply in the contiguous US, wind and solar PV generation data are calculated, based on 32 years of weather data with temporal resolution of 1h and spatial resolution of 40×40km2, assuming site-suitability-based and stochastic wind and solar capacity distributions. The regional wind-and-solar mixes matching load and generation closest on seasonal timescales cluster around 80% solar share, owing to the US summer load peak. This mix more than halves long-term storage requirements, compared to wind only. The mixes matching generation and load best on daily timescales lie at about 80% wind share, due to the nightly gap in solar production. Going from solar only to this mix reduces backup energy needs by about 50%. Furthermore, we calculate shifts in FERC (Federal Energy Regulatory Commission)-level LCOE (Levelized Costs Of Electricity) for wind and solar PV due to differing weather conditions. Regional LCOE vary by up to 29%, and LCOE-optimal mixes largely follow resource quality. A transmission network enhancement among FERC regions is constructed to transfer high penetrations of solar and wind across FERC boundaries, employing a novel least-cost optimization.

The United States can keep the grid stable at low cost with 100% clean, renewable energy in all sectors despite inaccurate claims

The premise and all error claims by Clack et al. (1) in PNAS, about Jacobson et al.’s (2) report, are demonstrably false. We reaffirm Jacobson et al.’s conclusions. Clack et al.’s (1) premise that deep decarbonization studies conclude that using nuclear, carbon capture and storage (CCS), and bioenergy reduces costs relative to “other pathways,” such as Jacobson et al.’s (2) 100% pathway, is false. First Clack et al. (1) imply that Jacobson et al.’s (2) report is an outlier for excluding nuclear and CCS. To the contrary, Jacobson et al. are in the mainstream, as grid stability studies finding low-cost up-to-100% clean, renewable solutions without nuclear or CCS are the majority (3⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓–16). Second, the Intergovernmental Panel on Climate Change (IPCC) (17) contradicts Clack et al.’s (1) claim that including nuclear or CCS reduces costs (7.6.1.1): “ … high shares of variable RE [renewable energy] power…may not be ideally complemented by nuclear, CCS,...” and (7.8.2) “Without support from governments, investments in new nuclear power plants are currently generally not economically attractive within liberalized markets,…” Similarly, Freed et al. (18) state, “…there is virtually no history of nuclear construction under the economic and institutional circumstances that prevail throughout much of Europe and the United States,” and Cooper (19), who compared decarbonization scenarios, concluded, “Neither fossil fuels with CCS or nuclear power enters the least-cost, low-carbon portfolio.” Third, unlike Jacobson et al. (2), the IPCC, National Oceanic and Atmospheric Administration, National Renewable Energy Laboratory, and International Energy Agency have never performed or reviewed a cost analysis of grid stability under deep decarbonization. For example, MacDonald et al.’s (20) grid-stability analysis considered only electricity, which is only ∼20% of total energy, thus far from deep decarbonization. Furthermore, deep-decarbonization studies … [↵][1]1To whom correspondence should be addressed. Email: jacobson{at}stanford.edu. [1]: #xref-corresp-1-1

Alternatives No More: Wind and Solar Power Are Mainstays of a Clean, Reliable, Affordable Grid

Wind and solar photovoltaic (PV) generation, no longer alternative energy sources, have grown rapidly in the United States and worldwide during the last decade. This rapid growth is due to significantly improved technology (power electronics, controls, and physical attributes such as tower heights and blades), plummeting costs, and vast advancements in understanding how to plan and operate reliable regional power systems that have high penetrations of variable renewable resources. Wind and PVs have become mainstays of a clean, reliable, affordable electric grid.

Renewable build-up pathways for the US: Generation costs are not system costs

The transition to a future electricity system based primarily on wind and solar PV is examined for all regions in the contiguous US. We present optimized pathways for the build-up of wind and solar power for least backup energy needs as well as for least cost obtained with a simplified, lightweight model based on long-term high resolution weather-determined generation data. In the absence of storage, the pathway which achieves the best match of generation and load, thus resulting in the least backup energy requirements, generally favors a combination of both technologies, with a wind/solar PV (photovoltaics) energy mix of about 80/20 in a fully renewable scenario. The least cost development is seen to start with 100% of the technology with the lowest average generation costs first, but with increasing renewable installations, economically unfavorable excess generation pushes it toward the minimal backup pathway. Surplus generation and the entailed costs can be reduced significantly by combining wind and solar power, and/or absorbing excess generation, for example with storage or transmission, or by coupling the electricity system to other energy sectors.

Advancing System Flexibility for High Penetration Renewable Integration

This report summarizes some of the issues discussed during the engagement on power system flexibility. By design, the focus is on flexibility options used in the United States. Exploration of whether and how U.S. experiences can inform Chinese energy planning will be part of the continuing project, and will benefit from the knowledge base provided by this report. We believe the initial stage of collaboration represented in this report has successfully started a process of mutual understanding, helping Chinese researchers to begin evaluating how lessons learned in other countries might translate to Chinas unique geographic, economic, social, and political contexts.

Reply to Bistline and Blanford: Letter reaffirms conclusions and highlights flaws in previous research.

Bistline and Blanford’s (1) (hereinafter BB16) comments about Jacobson et al. (2) (hereinafter J15) are incorrect or unsubstantiated, and thus affect no conclusion in J15. However, their remarks highlight the failure of previous decarbonization studies to treat many existing storage options, load reduction upon electrification, accurate wind power, and true nuclear and carbon capture costs. [↵][1]1To whom correspondence should be addressed. Email: jacobson{at}stanford.edu. [1]: #xref-corresp-1-1

Impact of Market Behavior, Fleet Composition, and Ancillary Services on Revenue Sufficiency

This presentation provides an overview of new and ongoing NREL research that aims to improve our understanding of reliability and revenue sufficiency challenges through modeling tools within a markets framework.