Excess Renewable Energy Research Articles

A comparative study of demand-side energy management strategies for building integrated photovoltaics-battery and electric vehicles (EVs) in diversified building communities

This study compares four developed energy management strategies for a grid-connected photovoltaic-battery (PVB) system in a district energy system comprising four diverse building communities: campus, residential, office, and commercial. The proposed demand-side energy management scenarios include maximizing photovoltaic self-consumption, cost minimum strategy under time-of-use and two peer-to-peer (P2P) strategies (a Mid-Market Rate (MMR) and a novel demand response (DR) based P2P strategies). Besides, Monte Carlo integrated Markov Chain simulation method was applied to calculate the load distribution of integrated electric vehicles in diversified building communities, and P2P price was generated considering dynamic supply-demand ratio. In term of dynamic energy flow, energy cost and grid interaction, dispatch results of proposed management strategies were simulated and compared in detailed. The results demonstrate that compared to the mainstream MSC and TOU operation strategies, P2P strategies, especially the DR based P2P strategy, effectively alleviate pressure on the utility grid by actively responding to peak electricity demand and utilizing excess renewable energy generation from other communities. It is worth noting that the choice of strategy depends on the role of the building community, whether as a consumer or a prosumer. This study offers insights for decision-makers and stakeholders in managing grid-connected PVB district energy systems in diverse building communities.

Green hydrogen production using proton membrane electrolysis of clean drinking water

With the EU’s green strategy and its member countries making a conscious effort to move away from fossil fuels and cut greenhouse gas emissions, there has been an uptick in technologies that produce green energy. Power-to-X has become an important topic in recent times, due to the so-called emission-free process of creating hydrogen from excess renewable energy. This research investigated this claim of being emission-free by analysing the method of obtaining extremely clean (pure) drinking water to produce hydrogen. A linear equation was produced that determines the carbon dioxide (CO2) intensity per kilowatt-hour of electricity used in producing a kilogram of water used to produce hydrogen. It was found that carbon dioxide emissions were produced by small-, medium- and large-capacity projects based in Denmark. Indicatively, for a 1 GW project facility, it was calculated that such a plant can produce 160 161 kg of carbon dioxide per year, so apparently, nothing comes without a cost.

Can bitcoin mining empower energy transition and fuel sustainable development goals in the US?

The transition to renewable energy in the US, vital for Sustainable Development Goals (SDGs) 7 and 13, faces economic obstacles, leaving a knowledge gap regarding potential innovative solutions to accelerate this shift. Simultaneously, the energy-intensive nature of blockchain applications like bitcoin mining is a cause for climate concerns. This work addresses the previously unanswered research question of whether bitcoin mining can be strategically used to harness surplus renewable energy from forthcoming clean energy installations, bridging the gap between economic viability and SDGs. Specifically, we conduct a comprehensive analysis, comparing the economic returns of bitcoin mining with three alternative chemical-based energy storage systems, including hydrogen, ammonia, and methanol, all powered by planned renewable sources. Mixed-integer linear programs were formulated to determine the maximum profits that can be obtained based on power utilization from planned renewable installations using varying alternatives. Results suggest that bitcoin mining is profitable in 80 out of 83 examined planned installations, generating a maximum profit of $7.68 million and harnessing 62% of the available renewable energy. Therefore, integrating bitcoin mining with planned renewable installations offers a dual solution of bolstering investments in the renewable energy sector while addressing climate concerns associated with conventional mining operations.

Evaluating the efficiency of a proton exchange membrane green hydrogen generation system using balance of plant modeling

A system model of a proton exchange membrane green hydrogen generation system is developed with the intent of demonstrating the dynamic interactions of the system with varying inputs such as electrolyzer current density and hydrogen pressure. The model includes physics-based modules that are validated with available experimental data for the power electronics, electrolyzer stack, pressure swing adsorption dryer, hydrogen compressor, and cooling circuit components of the system. A single electrolyzer system and multi-electrolyzer system are evaluated with varying operating conditions and multi-stack system operating strategies. Increasing electrolyzer cathode pressure results in an overall increase in specific energy consumption but may allow the use of low-pressure storage without the need for a hydrogen compressor. For a theoretical case study of excess renewable energy generation in Texas, the system achieves an overall efficiency of 46.5 % defined as the efficiency of converting electricity into an equivalent energy content of the produced hydrogen.

Particle Swarm Optimization for an Optimal Hybrid Renewable Energy Microgrid System under Uncertainty

Microgrids can assist in managing power supply and demand, increase grid resilience to adverse weather, increase the deployment of zero-emission energy sources, utilise waste heat, and reduce energy wasted through transmission lines. To ensure that the full benefits of microgrid use are realised, hybrid renewable energy-based microgrids must operate at peak efficiency. To offer an optimal solution for managing microgrids with hybrid renewable energy sources (HRESs) while taking microgrid reserve margins into account, the particle swarm optimisation (PSO) method is suggested. The suggested approach demonstrated good performance in terms of charging and discharging BESS and maintaining the necessary reserve margins to supply critical loads if the grid and renewable energy sources are unavailable. On a clear day, the amount of electricity sold to the grid increased by 58%, while on a partially overcast day, it increased by 153%. Microgrids provide a good return on investment for their operators when they are run at peak efficiency. This is because the BESS is largely charged during off-peak hours or with excess renewable energy, and power is only purchased during less expensive off-peak hours.

Dynamic exploration of a 1 MW molten carbonate electrolyzer: A modeling study approach

The reversible use of a commercially available molten carbonate fuel cell (MCFC) as a molten carbonate electrolysis cell (MCEC) is an appealing prospect for both storing surplus renewable energy and converting CO2 into valuable syngas (H2 and CO). This work aims to explore the dynamic aspects of this type of electrolyzer. The study investigates the dynamic behavior of the MCEC, involving dynamic model development, degradation analysis, and cold start-up evaluation. The findings revealed that cell degradation results in a 0.8 % decrease in H2 and a 1.5 % decrease in CO at a 1 % degradation rate, rising to 7.9 % H2 and 14.3 % CO decrease at a 10 % degradation rate, necessitating an increase in the current to maintain the same production. Additionally, the study identifies the most energy-efficient cold start-up heating process for the MCEC. These insights emphasize the importance of addressing degradation issues and optimizing start-up procedures for real-world applications.

Renewable Energy Trading Platform using Blockchain

As the demand for renewable energy grows, there is a need for efficient and transparent mechanisms to facilitate renewable energy trading. This research presents a novel Renewable Energy Trading Platform (RETP) that leverages blockchain technology to enable secure and decentralized energy trading. The platform utilizes distributed ledger technology to record and verify energy transactions, ensuring transparency and immutability. Smart contracts are employed to automate trade execution and settlement, eliminating the need for intermediaries and reducing transaction costs. The RETP integrates renewable energy data from various sources, such as smart meters and IoT devices, to enable accurate tracking and verification of energy production and consumption. Through the implementation of the RETP, energy producers can directly sell excess renewable energy to consumers, promoting the adoption of green energy and enhancing energy grid efficiency. A comprehensive evaluation of the platform demonstrates its efficiency, scalability, and security. The proposed RETP has the potential to revolutionize the renewable energy market by fostering peer-to-peer energy trading, empowering energy communities, and accelerating the transition to a sustainable energy future.

Chemistry of the iron-chlorine thermochemical cycle for hydrogen production utilizing industrial waste heat

This research presents an inventive thermochemical cycle that utilizes a reaction between iron and HCl acid for hydrogen production. The reaction occurs spontaneously at room temperature, yielding hydrogen and a FeCl2 solution as a by-product. Exploring the thermal decomposition of the FeCl2 by-product revealed that, at conditions suitable for utilization of low-temperature industrial waste heat (250 °C), chlorine gas formation can be circumvented. Instead, the resulting by-product is HCl, which is readily soluble in water, facilitating direct reuse in subsequent cycles. The utilization of low-temperature industrial heat not only optimizes resource utilization and reduces operational costs but also aligns with environmentally sustainable production processes. From the kinetic studies the activation energy was calculated to be 45 kJ/mol and kinetics curves were constructed. They showed significant kinetics at room temperature and above but rapid decrease towards lower temperatures. This is important to consider during real-scale technology optimization. The theoretical overall energy efficiency of the cycle, with 100% and 70% heat recuperation, was calculated at 68.8% and 44.8%, respectively. In practical implementation, considering the efficiency of DRI iron reduction technology and free waste heat utilization, the cycle achieved a 41.7% efficiency. Beyond its energy storage capabilities, the Iron-chlorine cycle addresses safety concerns associated with large-scale hydrogen storage, eliminating self-discharge, reducing land usage, and employing cost-effective storage materials. This technology not only facilitates seasonal energy storage but also establishes solid-state energy reserves, making it suitable for balancing grid demands during winter months using excess renewable energy accumulated in the summer.

Electrochemical reconstruction of non-noble metal-based heterostructure nanorod arrays electrodes for highly stable anion exchange membrane seawater electrolysis

Direct seawater electrolysis for hydrogen production has been regarded as a viable route to utilize surplus renewable energy and address the climate crisis. However, the harsh electrochemical environment of seawater, particularly the presence of aggressive Cl−, has been proven to be prone to parasitic chloride ion oxidation and corrosion reactions, thus restricting seawater electrolyzer lifetime. Herein, hierarchical structure (Ni,Fe)O(OH)@NiCoS nanorod arrays (NAs) catalysts with heterointerfaces and localized oxygen vacancies were synthesized at nickel foam substrates via the combination of hydrothermal and annealing methods to boost seawater dissociation. The hierarchical nanostructure of NiCoS NAs enhanced electrode charge transfer rate and active surface area to accelerate oxygen evolution reaction (OER) and generated sulfate gradient layers to repulsive aggressive Cl−. The fabricated heterostructure and vacancies of (Ni,Fe)O(OH) tuned catalyst electronic structure into an electrophilic state to enhance the binding affinity of hydroxyl intermediates and facilitate the structural transformation into amorphous γ-NiFeOOH for promoting OER. Furthermore, through operando electrochemistry techniques, we found that the γ-NiFeOOH possessing an unsaturated coordination environment and lattice-oxygen-participated OER mechanism can minimize electrode Cl− corrosion enabled by stabilizing the adsorption of OH* intermediates, making it one of the best OER catalysts in the seawater medium reported to date. Consequently, these catalysts can deliver current densities of 100 and 500 mA cm−2 for boosting OER at minimal overpotentials of 245 and 316 mV, respectively, and thus prevent chloride ion oxidation simultaneously. Impressively, a highly stable anion exchange membrane (AEM) seawater electrolyzer based on the non-noble metal heterostructure electrodes reached a record low degradation rate under 100 μV h−1 at constant industrial current densities of 400 and 600 mA cm−2 over 300 h, which exhibits a promising future for the non-precious and stable AEMWE in the direct seawater electrolysis industry.

Extended power to hydrogen operations for enhanced grid flexibility in low carbon systems

Power-to-hydrogen (P2H) systems are increasingly recognized as a promising solution to expedite the integration of Renewable Energy (RE) in various energy sectors. P2H in Hydrogen Consuming Industries (HCIs) can serve hydrogen demands and the much-needed flexibility for power system operations. However, consideration of these systems for significant industrial and power sector use cases requires modelling fidelities for exact operational and economic reflections. P2H operational modelling for flexibility focuses on excess renewable energy evacuation and storage only while often oversimplifying their models by using constant efficiency models or neglecting specific Hydrogen Electrolyzer (HE) overvoltage components. Under variable operations and downstream HCI demands, this can lead to inaccurate assessments, undermining existing flexibility quantum from HCIs. Another prevalent issue with P2H adoption is its costs, which are directly linked with P2H operating ranges. These systems are presently modelled with constrained operations, leading to increased costs and limited ability to provide grid services. Therefore, appropriate modelling of HCIs considering P2H device working characteristics and its inherent flexibilities is essential. It can allow cost-effective operations and the exchange of accurate flexible margins with electrical grids. In this regard, this work proposes a comprehensive extended electro-chemical HE model for HCIs allowing high current density working through the extended operation of P2H. The considered model inherits intrinsic working characteristics of electrolyser operation, i.e., variable current, nonlinear efficiency, and loading, to cater to the hydrogen demands of HCI. The effect of high current density operations is elucidated through device operations under reaction kinetics. The results highlight that the proposed model integrated with the electrical grid provides actual operational costs and flexibility margins. A comparison of various modelling approaches and their effect on adjustable margins demonstrates a considerable difference in P2H loading, working efficiency, operating costs, and adjustable margins with the proposed model.

Hybrid electrical energy generation from hydropower, solar photovoltaic and hydrogen

The global concern to reduce greenhouse gas emissions and increase the use of renewable sources has led Brazil to stand out as a promising nation in this context, with a large portion of its energy capacity coming from renewable sources. However, renewable sources have the disadvantage of intermittency and seasonality, which has prompted the search for solutions to these challenges. This study assesses the feasibility of integrating hydro and solar power with a Hydrogen-based Electrical Energy Storage System (H2EESS) at the Serra da Mesa hydroelectric Brazilian power plant. Hydrogen would be produced through water electrolysis, taking advantage of the available excess renewable energy, and subsequently converted back into electricity through fuel cells. The integration of hydro and solar power with H2EESS resulted in an increase of 11.10 % in the energy produced compared to conventional hydroelectric generation, with 36.06 % of this increase coming from H2EESS. Additionally, there was a 9.71 % increase in the utilization of substation capacity. These results highlight the feasibility and benefits of integrating hydro and solar power with H2EESS. This approach allows for maximizing renewable energy generation, reducing greenhouse gas emissions, and better utilizing available resources without the need for significant infrastructure investments.

Assessment of thermally activated inner building components or a high temperature stone storage system to utilize surplus renewable electrical energy

In electrical grids with high renewable percentage, the production is less demand-driven, but more dependent on weather conditions. Usually there are periodical weather patterns in the winter period with substantial amounts of wind energy production. Sometimes this results in a shut-off of the wind turbines due to the inability of the grid to use the produced power (overproduction). This paper assesses two thermal storage systems to service space heating and domestic hot water that exploit the overproduction of electricity and thereby bridge periods of lower electricity production. The first system utilizes inner walls and ceilings with a thermally activated building system (TABS) to store and dissipate heat. The second system is a stand-alone high temperature stone storage system (HTSS). Models to simulate such systems within a whole building simulation framework are introduced and the verification with measured data from field measurements is presented. Both models are used to assess the systems with regard to the speed of loading and the potential to bridge time periods without additional heating in high-performance buildings. It is shown that both systems can provide heating and domestic hot water (DHW) up to 13 days without substantial additional electricity.

Novel insight from in‐/ex‐situ investigation toward intercalated water in high‐performance oxygen evolution electrocatalysts and their mechanisms

AbstractHydrogen is a green energy source with zero carbon emissions and renewable properties. Green hydrogen, produced via water electrolysis, can efficiently harness excess renewable energy during peak periods, making it a key player in grid stabilization through processes like power‐to‐gas. Consequently, there is a pressing need to develop catalysts with high activity, stability, and cost‐effectiveness in the energy sector. The development of electrochemical (EC) water splitting, a promising path to meet alternative energy demands, however, is hindered by two main challenges that persist in water splitting: the anodic oxygen evolution reaction (OER) catalysts still need lower overpotential, and they must have enough stability with high catalytic activity. Both factors determine water electrolysis reactions' overall energy consumption and commercialization potential. This article introduces several significant parameters for assessing catalyst performance; three primary OER mechanisms are also briefly reviewed. Thereby, numerous electrocatalysts for OER are categorized by their composition and morphology. Furthermore, we generalize a common phenomenon that occurs at the surface of catalysts during the OER process. It is deduced that the surface transformation from as‐prepared to an activated state, that is, the surface‐environment change of the active site due to redox‐induced dissolution and re‐deposition, plays a critical role in OER. On the other hand, generating a layered structure leads to the accommodation of intercalated water molecules, which may enhance the activity and robustness via hydrogen bonds and dominate the absorption energy of oxygen species on the metal site. Lastly, we enumerate several in‐/ex‐situ methodologies that can discriminate the real active sites of the bulk, near‐surface region, interface, and intermediates adsorbed on the electrocatalyst surface. Further investigation is needed to unveil the interaction between active sites and embedded water molecules in EC catalytic processes. This paper provides a novel perspective of the intercalated water for future development of OER electrocatalysts, simultaneously considering performance and stability.

Optimal scheduling of hydrogen blended integrated electricity–gas system considering gas linepack via a sequential second-order cone programming methodology

In the context of increasing global environmental pollution and constant increase of carbon emission, hydrogen production from surplus renewable energy and hydrogen transportation using existing natural gas pipelines are effective means to mitigate renewable energy fluctuation, build a decarbonized gas network, and achieve the goal of “carbon peak and carbon neutral” in China. Existing gas network modeling with hydrogen blended is divided into steady-state and dynamic. The steady-state modeling oversimplifies the physical process, while the dynamic modeling is computationally intensive. Thus, a quasi-steady-state modeling method of a hydrogen blended integrated electricity–gas system (HBIEGS) considering gas linepack is developed in this paper. The gas linepack refers to the gas stored in natural gas pipelines due to the compressibility of the gas. As a form of gas energy storage, linepack can enhance system flexibility by coping with wind power uncertainty. In the face of nonlinear gas flow equations in HBIEGS, conventional relaxation or approximate methods cannot provide a sufficiently feasible optimal solution. Therefore, a sequential second-order cone programming (S-SOCP) method is proposed to solve the developed model. It can effectively strike a balance between solution speed and the quality of the solution obtained. Finally, the modified IEEE-24-node power system and 12-node natural gas system are used to validate the effectiveness of the developed model and the proposed method. The optimization results show that the proposed method improves the computational efficiency by 91% compared with a general nonlinear solver.

Power Flow Optimization with Energy Storage - Sal Island Case Study

The correlation between energy costs and the country's economic competitiveness is an unquestionable reality also responsible for the improvement of the population's life conditions. In the past Cape Verdean electric power system (EPS), expansion was based on fossil-fuel power plants, nowadays it shifted to renewable energy (RE) which is abundant in the Cape Verde archipelago. However, no reduction in the electricity tariffs occurred, due to renewable curtailment and other pendent questions related to power transmission losses in the EPS. This paper presents an approach, that supports an implementation of a distributed electric energy storage system (ESS) on the Sal Island of Cape Verde archipelago, as a solution to increase the RE integration and power Transmission congestion relief. Thus, a power flow optimization is only achievable by storing excess RE as near as possible to consumption buses that can reduce overall transmission losses. The most advantageous allocation of ESSs along the EPS buses is combinational which faces a maximization of transmission loss reduction and minimization of ESS investment capital. The proposed tool to manage the “trade-off” between cost and avoided losses, is based on a genetic algorithm (GA) that is broadly applied to multi-objective problems like this.

Recovery of Phosphorus and Metals from the Ash of Sewage Sludge, Municipal Solid Waste, or Wood Biomass: A Review and Proposals for Further Use

This review provides an overview of methods to extract valuable resources from the ash fractions of sewage sludge, municipal solid waste, and wood biomass combustion. The resources addressed here include critical raw materials, such as phosphorus, base and precious metals, and rare earth elements for which it is increasingly important to tap into secondary sources in addition to the mining of primary raw materials. The extraction technologies prioritized in this review are based on recycled acids or excess renewable energy to achieve an optimum environmental profile for the extracted resources and provide benefits in the form of local industrial symbioses. The extraction methods cover all scarce and valuable chemical elements contained in the ashes above certain concentration limits. Another important part of this review is defining potential applications for the mineral residues remaining after extraction. Therefore, the aim of this review is to combine the knowledge of resource extraction technology from ashes with possible applications of mineral residues in construction and related sectors to fully close material cycle loops.

Effects of geological heterogeneity on gas mixing during underground hydrogen storage (UHS) in braided-fluvial reservoirs

Hydrogen, as an energy carrier, is at the centre of research attention for its potential advantages over electricity to transport and store excessive renewable energy at the GW scale as part of the energy transition. To store energy at such a large scale and in a seasonal manner, energy storage technologies such as compressed air storage and high-temperature aquifer thermal storage are proposed, where Underground Hydrogen Storage (UHS) in porous reservoirs may be an important technology for hydrogen economy. Research studies suggest the necessity of using alternative gas to hydrogen as cushion gas due to the very low density at reservoir conditions and the high production cost of hydrogen. In addition, the potentially lower development cost of UHS in existing depleted natural gas reservoirs or former sites for underground gas storage compared to that of saline aquifers makes gas mixing a real possibility for future UHS operations. However, this topic is rarely studied, let alone its geological governing factors. In this study, we focus on the most likely geological settings for early UHS projects (Depleted gas fields in high permeability braided fluvial reservoirs) to understand the potential impacts of geological heterogeneity on project economics.To quantify the possible gas mixing induced by macro-scale heterogeneity and find the dominant factors that affect storage performance, in this study, we start by building synthetic high permeability water-gas reservoir model with geological characteristics of braided-fluvial systems often encountered in the oil and gas industry. Then we examine the effects of structural and litho-facies heterogeneity on gas mixing processes during typical UHS projects (10 mol% hydrogen-methane mixture as stored gas) via compositional numerical simulation. Homogeneous cases with different injection/production rates are also part of the sensitivity analysis. The cumulative days hydrogen fraction in produced stream is used as the metric for quantifying gas mixing during this process. Our results show that, compared to the homogeneous cases, macro-scale geological heterogeneity will intensify gas mixing and degrade the hydrogen fraction in the produced stream, affecting up to 15.8% of the recovery in 10 years (6% more than the homogeneous cases). Geological structure (reservoir dip angle and closure area) is a first-order determining factor above facies heterogeneity (braided channel dimensions). It determines the level of methane breakthrough during UHS projects in all the test cases, leading to contrasting gas mixing behaviors. Our study hereby provides a systematic method for evaluating gas mixing in UHS projects and facilitates future UHS techno-economic analysis.

The effects of catalyst conductivity and loading of dielectric surface structures on plasma dynamics in patterned dielectric barrier discharges

Dielectric barrier discharges (DBDs) are promising tools for air pollution removal and gas conversion based on excess renewable energy. Catalyst loading of dielectric pellets placed inside the plasma can improve such processes. The effects of such metallic and dielectric catalyst loading on the discharge are investigated experimentally. A patterned DBD is operated in different He/O2 mixtures and driven by a pulsed rectangular voltage waveform. Hemispherical dielectric pellets coated by different catalyst materials at different positions on their surface are embedded into the bottom grounded electrode. Based on phase resolved optical emission spectroscopy the effects of different catalyst materials and locations on the streamer dynamics are investigated. The propagation of cathode directed positive volume streamers towards the apex of the hemispheres followed by surface streamers, that move across the structured dielectric, is observed for positive applied voltage pulses. Coating the apex with a conducting catalyst results in attraction of such streamers towards the apex due to charging of this surface, while they avoid the apex in the presence of a dielectric catalyst. Surface streamers, that propagate across the hemispheres, are stalled by conducting catalysts placed on the embedded pellets as rings of different diameters, but propagate more easily across dielectric coatings due to the presence of tangential electric fields. Reversing the polarity of the driving voltage results in the propagation of negative streamers across the patterned dielectric and attenuated effects of catalytic coatings on the streamer dynamics.

Technological advances of ammonia as energy storage solution

The renewable energy is playing an important role in transitioning to the decarbonization of the entire energy value chain. But how will the global energy industry accelerate this transition? Renewables and electrification of energy could be a perfect solution. However, intermittency of renewable energy production is the single biggest challenge faced by renewable energy sources, which can be mitigated when it is coupled with an appropriate energy storage system. First, you need to generate electricity from renewable sources and then store it so that it can be extracted whenever there is a demand. There are several energy storage systems that can be coupled with renewables such as fossil fuel storage, mechanical storage, thermal storage, electrochemical storage, and chemical storage. Studies have shown that chemical storage technologies provide clear advantage in terms of storage time and range of power it can store over other similar technologies. It also justifies the recent research activities around various new chemical storage technologies. A combination of the above energy systems works very well for most of the abundant and affordable energy. However, one area where there can be a significant improvement is the carbon emissions associated with fossil fuel-based storage systems. As a result, the energy industry is recently interested in the transition to renewables coupled with non-carbon storage of power as a long term solution to environmental issues. So the possible solution is producing chemical storage options from surplus renewable energy which solves both the hurdles of emissions as well as carbon-free energy storage system. This article analyses whether ammonia can be viewed as an efficient and technological solution to the problem of large-scale and long-duration energy storage in the decarbonized energy systems of the future. Throughout the article, references have been drawn from a wide range of resources and author’s academic and industrial experience. It is intended to use the article as a vehicle to share knowledge with a wide range of audience on utilization of ammonia for energy storage.

Detailed evaluation of electric demand load shifting potential of heat pump water heaters in a hot humid climate

Heat pump water heaters (HPWH) are a proven method of reducing water heating energy use over prevailing electric resistance systems (ERWH). Both technologies lend themselves to enhanced control for peak load reduction. Laboratory tests were conducted in Central Florida using the CTA-2045 standard to evaluate load shifting strategies with connected water heaters. Four HPWHs from three manufacturers, including two different tank volumes, were tested alongside an ERWH in a garage-like environment. Tests aimed to shift energy use away from utility peak load periods to off-peak times when excess renewable energy resources are often available. Two load-shifting strategies were shown effective, Shed and Critical Peak, with variation by manufacturer. Beyond draw volume, other factors influenced HPWH load shifting: Florida winter conditions, which increase the energy used per draw, provided the greatest challenges to complete load shift. Inlet water temperature had a large impact on the success of load reduction. Ground temperatures in which water pipes were buried largely determined inlet water temperatures. HPWH efficiency setting: Heat pump water heaters often default to a “hybrid” mode that may use some electric resistance heat to minimize risk of running out of hot water. Operational mode can impact load shifting potential.