Energy Technologies

China’s manufacturing sector generates 61% of the country’s CO2 emissions, nearly three-quarters of which is related to industrial process heating. To meet China’s climate targets and attain a zero-carbon industrial sector, decarbonizing these industrial heating processes is a necessity. If China’s electricity grid is similarly decarbonized, direct electrification is the most practical means of supplying this heat efficiently at the required scale. In addition to reducing greenhouse gas emissions, industrial electrification would help reduce conventional pollution that was responsible for 1.85 million premature deaths in China in 2019, and it would improve China’s energy security, as the country imported 85% of its petroleum products and crude oil as well as 46% of its natural gas in 2021. Direct electrification would also help Chinese firms avoid volatile fossil fuel prices and future carbon pricing costs, and ensure competitiveness when selling products to environmentally-conscious buyers and governments that may use carbon border adjustment mechanisms or similar efforts to encourage the procurement of cleaner materials. Two electrified technologies stand out as means for China to decarbonize its industrial process heating: industrial heat pumps and thermal batteries. Heat pumps can be the most efficient and cost-effective method to supply clean, low-temperature heat for industrial processes. They can achieve efficiencies several times higher than other electrical technologies because they do not convert their input electricity into heat. Instead, heat pumps move heat from a low-temperature to a high-temperature area, operating much like a refrigerator or air conditioner. Industrial heat pumps can extract heat from a source (such as the air, ground, or waste heat from another industrial process) and output heat at temperatures up to 165 °C. Heat pumps that raise temperature by 40 to 60 °C typically have efficiencies of 300-400%. Notably, no other heating technology can generate heat at an efficiency beyond 100%; this exceptional efficiency makes heat pumps a particularly cost-effective electrification route. For higher temperature processes, thermal batteries can provide up to 1,700 °C, making them a viable option for supporting over two-thirds of China’s manufacturing sector’s process heating needs. Thermal batteries contain thermal storage material with a high specific heat capacity that resists chemical breakdown at high temperatures. The storage material is enclosed in a highly insulated shell to minimize heat loss, losing as little as 1% a day in some systems. Electrical resistance heaters inside the battery convert their electricity to heat that is absorbed by the storage material and can then be extracted when the industrial facility is ready to use the heat. The storage capability of thermal batteries means that they can provide steady-state heat in both on- and off-grid configurations. Off-grid batteries would be able to procure electricity at wholesale prices from dedicated renewables projects, smoothing over the variability of day-night cycles or lulls due to weather conditions. Similarly, for grid-connected batteries, energy can be purchased during the cheapest times of day and banked for future use. While many Chinese manufacturing firms are located in the eastern provinces where there may be limited land for creating new off-grid renewables projects, grid-connected thermal batteries offer firms and utilities the benefits of price-hunting and optimization. Additionally, by reducing industrial electricity demand when electricity is in short supply, direct electrification with thermal batteries could aid in grid regulation, help the grid integrate variable renewables, and cut peak demand, lowering the required grid-related capital costs of transitioning to clean industry. Performing a techno-economic comparison of these two electrified heating technologies and their alternatives in China, we found that for temperatures under 100 °C, industrial heat pumps were the second-cheapest heating option with a levelized cost of $38/MWhth (¥260/MWhth), remaining competitive with combined heat and power (CHP) variants and considerably cheaper than natural gas or electric boilers (Figure ES-1). While coal-fired boilers currently offer the lowest levelized cost of heat production, when incorporating a 2030 estimated carbon cost, industrial heat pumps become the lowest-cost option for low-temperature heat. For temperature ranges of 100-165 °C, industrial heat pumps cost about $58/MWhth (¥391/MWhth), but are broadly competitive with natural gas, and may improve in terms of costs and efficiency with additional research and development. Industrial thermal batteries are costed in-between the two heat pump variants at $46/MWhth (¥314/MWhth) and can support far higher temperatures. Relative to coal-fired technologies, heat pumps were found to achieve significant reductions in five pollutants (CO2, NOx, SOx, PM10, and PM2.5) and thermal batteries in three pollutants (SOx, PM10, and PM2.5), accounting for the pollutant emissions associated with the electricity they use. As China’s grid increasingly shifts to zero-emissions electricity sources, electrified technologies’ pollutant emissions will decline, ultimately reaching zero if China’s grid becomes fully decarbonized. Smart policy is necessary to overcome the barriers to industrial electrification in China. Fossil fuel prices are considerably lower in China than the cost of electricity for industrial energy buyers. Limited availability of electrified equipment, especially high-temperature industrial heat pumps and industrial thermal batteries, also presents a current hurdle. Additionally, upgrading and electrifying existing industrial equipment can be technically challenging, and doing so outside of the equipment’s natural replacement cycle can incur additional costs. Policymakers can incentivize the transition using equipment rebates, retooling grants, and access to low-interest financing mechanisms to offset the capital expenditures related to adopting these technologies. Enhancing existing energy-efficiency standards, emissions standards, and green public procurement programs can likewise encourage the transition to direct electrification. China’s research laboratories, such as those operated by the Chinese Academy of Sciences, can collaborate with private industry on research and development (R&D) programs to move these early-stage technologies forward. Grant funding is not limited to supporting laboratory-scale R&D but can also fund pilot or demonstration plants that provide proof-of-concept and encourage industrial players to transition. Creating a competitive landscape between coal and electricity is also important and can be achieved by carbon pricing or by subsidizing the cost of clean electricity and the cost of upgrades to support electrification. Inter-provincial electricity trading and optimization of China’s Green Electricity Certificate system can help facilitate access to clean electricity. Direct electrification of industrial process heating in China has the potential to reduce greenhouse gas emissions immensely and would yield massive benefits to the country and the globe. While existing technologies offer a path forward, China must incentivize their adoption by creating a supportive environment for industrial decarbonization through the right policy approaches. Given the country’s large industrial capacity, China has the potential to lead in clean industrial technology while achieving its climate targets.

As urban energy systems become decarbonized and digitalized, buildings are increasingly interconnected with one another and with the industrial and transportation sector. Transformation strategies to cost-effectively integrate distributed energy sources, and to increase load flexibility and efficiency, generally increase complexity. This complexity causes challenges that the industry is unprepared to deal with. Today's simulation programs, and the processes in which they are used, have not been developed to meet the challenges of decarbonization. Nor have they been designed for, or do they keep pace with, the energy system digitalization. Modeling, simulation and optimization tools, and the processes in which they are used, need to undergo an innovation jump. We show a path to more holistic tools and workflows that address the new requirements brought forward by the increased complexity. Without concerted actions, the building simulation community will fall short of supporting the 2050 decarbonization targets declared by many governments.

Burners and cooking activities are both major sources of air pollutants in many residences. Mechanical kitchen ventilation can effectively reduce cooking- related indoor air pollution but the knowledge about kitchen ventilation device performance and usage in real homes remains limited. We reviewed recent lab, field and survey studies that investigated the performance and occupant use patterns for mechanical kitchen ventilation devices. We have found the following three major issues. Firstly, in-home performance is lower than what was certificated in laboratory testing. In several recent field studies, researchers investigated 125 US single family homes and 23 apartments and found 82 homes had range hoods or over-the-range microwaves (OTR) certificated by Home Ventilating Institute (HVI) that had working airflows greater than 100 cfm. However, the field measurements showed only 44 of them had installed airflow that matched the rated, with the average ratio of installed versus rated flow of 0.76. The lower installed airflows were due to high air flow resistance of duct venting systems, incorrect installation and dirty hood inlets. Second, the knowledge of range hood performance for pollutant removal before mixing into the room (i.e. capture efficiency) is very limited. We found the capture efficiency was only measured for 57 hoods in 9 studies in the US, either in the lab or in the field. The measured capture efficiency ranged from 10% to 100%, generally increasing with the airflows. The capture efficiency can be influenced by the burner location, hood airflow, range hood geometry and test conditions. The main reason for limited capture efficiency data was the difficulty in conducting field measurements. Third was that the actual usage of the kitchen ventilation during cooking is low. Occupants often do not use their range hood due to the lack of awareness of the benefits of kitchen ventilation. A large survey study in Canadian homes showed that 30% of households reported regularly using their range hood. After being informed of the benefits of kitchen ventilation, the overall willingness to use the range hood was significantly higher. Field data from California showed range hoods were only used for 36% of cooking events in houses and 28% in apartments, though the occupants claimed they used them more frequently.

An archetypal electric vehicle (EV) driver has emerged in the public consciousness. This archetype can generally be characterized as a high-income, highly-educated, urban-dwelling, married, middle-aged white male who owns his home and values the latest technology and/or the environment. For those who see the widespread market for EVs as an important element of transportation decarbonization, this archetype has pluses and minuses. A plus is that if one follows the aphorism, “you can tell a lot about a person by the car they drive,” EVs are now widespread enough to have something to say about the identities of their drivers. Potential minuses include “false dichotomies” associated with the demographic characteristics of this archetype, with associated unintentional exclusionary effects for prospective EV drivers and unintended biases in analyzing latent EV demand. This report revisits the demographic and values characteristics of the EV driver and the vehicle shopper who might become an EV driver, in the context of the dramatic changes in the vehicles offered for sale in the U.S. in recent years. After a short overview of some of the changes in model year 2016-23 battery electric and plug-in hybrid electric vehicle offerings in the U.S. market – by body style, range, and price – the bulk of the report focuses on how the vehicle shopper relates to the changing supply of EVs. We start with reflections on what it means for someone to “own” an EV over this time period and on the importance of body style preferences for all U.S. vehicle shoppers during this time period. We then explore how consumer purchase and consideration of PEVs has evolved over this period, as structured by the demographic characteristics of income, geography, gender, age, race, and to a lesser extent, education and home ownership. We also discuss some of what is known about the values associated with the EV owner and consider how these values relate to consumer shopping criteria and reasons why uninterested consumers “reject” PEVs. The report concludes with a discussion that recaps the main findings in our exploration and considers their implications for the archetypal EV driver and the broader market for PEVs in the U.S.

Embodied emissions from the production of building materials account for 17% of Chinas carbon dioxide (CO2) emissions and are important to focus on as China aims to achieve its carbon neutrality goals. However, there is a lack of systematic assessments on embodied emissions reduction potential of building materials that consider both the heterogeneous industrial characteristics as well as the Chinese buildings sector context. Here, we developed an integrated model that combines future demand of building materials in China with the strategies to reduce CO2 emissions associated with their production, using, and recycling. We found that measures to improve material efficiency in the value-chain has the largest CO2 mitigation potential before 2030 in both Low Carbon and Carbon Neutrality Scenarios, and continues to be significant through 2060. Policies to accelerate material efficiency practices, such as incorporating embodied emissions in building codes and conducting robust research, development, and demonstration (RD&D) in carbon removal are critical.

In the transition from fossil fuel to electrified heating, a concerning trend is emerging in certain regions of the US. Owners of buildings with gas-based systems leave them in place after adding heat pumps (HPs). Existing control solutions for these hybrid (dual fuel) systems are rudimentary and fall short of realizing the full carbon reduction potential of these systems. Model predictive control (MPC) is often regarded as the benchmark for achieving optimal control in integrated systems. However, in the case of small-medium commercial buildings (SMCBs), the control and communication infrastructure required to facilitate the implementation of such advanced controls is often lacking. This paper presents a field implementation of easy-to-deploy MPC for a dual fuel heating system consisting of HPs and a gas-fired furnace (GF) for SMCBs. The control system is deployed on an open-source middleware platform and utilizes low-cost sensor devices to be used for real SMCBs without major retrofits. We demonstrated this MPC in a real office building with 5 HPs and 1 GF for 2 months. The test results showed that MPC reduced 27% of cost while completely eliminating GF usage by shifting 23% of the thermal load from occupied-peak time to non-occupied-non-peak times.

Roughly, 50% of primary energy worldwide is rejected as waste heat over a wide range of temperatures. Waste heat above 573 K has the highest Carnot potential ( > 50 % ) to be converted to electricity due to higher Carnot efficiency. Thermoelectric (TE) materials have gained significant attention as potential candidates for efficient thermal energy conversion devices. Silicon nanowires (SiNWs) are promising materials for TE devices due to their unique electrical and thermal properties. In this study, we report the successful fabrication of high-quality double-sided SiNW arrays using advanced techniques. We engineered the double-sided structure to increase the surface area and the number of TE junctions, enhancing TE energy conversion efficiency. We also employed non-agglomeration wire tip engineering to ensure uniformity of the SiNWs and designed effective Ohmic contacts to improve overall TE efficiency. Additionally, we post-doped the double-sided SiNW arrays to achieve high electrical conductivity. Our results showed a significant improvement in the TE performance of the SiNW array devices, with a maximum figure-of-merit (ZT) value of 0.24 at 700 K, fabricated from the single SiNW with ZT of 0.71 at 700 K in our previous work [Yang et al., Nat. Commun. 12(1), 3926(2021)].

This report details modeled energy performance and savings from retrofit packages in prototypical school buildings in climate zones throughout the U.S. The information herein serves as a reference for elementary and secondary schools interested in implementing retrofit packages in their facilities for energy savings as well as health and safety benefits. School models developed for simulating package performance differentiated between rural and urban environments. Simulations were run for 10 distinct climate zones covering a range of climate conditions throughout the U.S. Results include savings estimates for electricity, natural gas, CO2 emissions, and annual utility costs for nine different retrofit packages that combine energy conservation measures, including HVAC controls and equipment upgrades, lighting efficiency upgrades, and electrification technologies such as heat pumps for space conditioning and domestic hot water. Nine additional retrofit packages were also developed for elementary schools and modeled in two climate zones. Appendix B describes the additional retrofit packages and presents savings estimates.

The evolution of the BEV market, to date, reflects a number of developments, including: changing attributes of BEVs (e.g., more diverse models, greater range, nascent ability to provide backup power to homes, etc.) and their complementary charging infrastructure; alterations in consumers’ assessments of the alignment between BEVs and their preferences and travel needs; and the roll-out of new BEV-supportive policies. Considering sales volumes of BEVs to date, the U.S. has passed through the “Innovator” stage of Roger’s diffusion of innovations curve, and solidly into the “Early Adopter” market, with the “Early Majority” on the horizon. This paper attempts to bring the Early Majority into greater clarity, analyzing publicly available data to characterize its potential nature and size. We apply a framework of four related components of electric vehicle acceptance—awareness, access, approval, and adoption. The variables we examine primarily enable the “access” component of acceptance, and include characteristics of individuals and households. We also consider physical and economic/governmental aspects of the social system in which vehicle purchase decisions occur, with a focus on the spatial heterogeneity of both public charging density and laws and incentives. A key finding is that a substantial portion of U.S. households reflect a combination of apparent BEV acceptance enablers as demonstrated by the majority of current BEV adopters. We find that 46.9% of US household own a single-family home with reasonable charging capabilities, making the convenience and savings associated with BEV ownership feasible for nearly half of US households. Furthermore, 28% of those household also earn more than $100k annually, leaving them potentially well-positioned to become part of the Early Majority.