Current Projects

Department of Energy
Advancing Wood Heater Innovation

In collaboration with Brookhaven National Laboratory, this project aims to accelerate wood heater innovation and commercialization by developing rapid, cost-effective, performance test methodologies (measurement methods and operating protocols) for biomass-fired space heaters, central hydronic heaters, and warm-air furnaces. The simplified methodologies are designed to reduce research and development (R&D) cycle times and enable rapid performance testing that simulate real operating conditions. This will also assist with conducting field measurements and evaluating their performance.

Department of Energy
Feedstock to Function tool

This project aims to develop the foundation for an adaptive computational tool that predicts bioproduct and biofuel properties for validation and certification, and determines the cost, benefits, and risk of promising new and uncertified pathways and their blending effects. The ‘Feedstock to Function’ tool will incorporate supervised machine learning to predict desired properties of high-potential biobased molecules early in technology validation and certification process. Coupled with a lightweight technoeconomic and life-cycle assessment model, this tool will enable bioproduct and biofuel developers and researchers to streamline bioproduct and biofuel scale-up, overcome experimentally and kinetically derived property bottlenecks, identify cost and emissions bottlenecks, and potentially de-risk investments needed to scale up fuel production for the technology certification process. 

Lawrence Berkeley National Laboratory
Low-emission Burner for Residential Appliances

Building from the California Energy Commission funded project developing a residential cooktop burner (see below), we have partnered with industry to evaluate the performance of the burner in a commercial appliance. If successful, this burner will be integrated into a their new line of technology.

Boston Children's Hospital & Global Newborn Solutions
Infant Warmer for Preventing Neonatal Hypothermia

In collaboration with a team from Boston Children’s Hospital, we advancing an infant warmer design that can be used globally in resource-limited locations to prevent neonatal hypothermia, which causes about 40% of global neonatal deaths. A first iteration of the infant warmer has been field tested with success in Rwanda. Based on user feedback, we are further improving the design to ensure it can be reused up to 100 times, remains non-electric and easy to clean, and can be produced at low cost. At full rate production, the cost of the improved infant warmer will be 75% less than competing designs, yielding a cost per use of well under $1. More information can be found at Global Newborn Solutions

California Energy Commission
Low-Cost High-Reliability Thermoelectrics for Waste Heat Conversion

This project aims to develop a novel and cost effective process for creating advanced thermoelectric (TE) materials constructed from Si Nanowires (Si-nw) arrays, and to demonstrate, with a prototype device, its performance and ability to scale to mass-production for heat-to-electricity conversion. Constructing TE materials from Si-nw arrays increases operating temperature (up to 800°C) and allows them to be implemented where the heat-to-electricity conversion efficiency is high. Additionally, implementing Si-nw will create a cost effective waste heat recovery system capable of achieving a heat-to-electricity conversion efficiency of at least 10% (~2.5 times more than market TE). These improvements will attract a large variety of California industries, including petroleum refining, and enable access multi-billion dollar global markets.

Past Projects

Department of Energy
Biomass Cookstoves Project

In this project, substantial progress will be made towards a technological breakthrough that leads to major emission reductions and performance improvements in biomass cookstoves. These breakthroughs will align with DOE goals of helping reduce emissions from biomass cooking by 90% and fuel usage by 50%, and facilitate the GACC’s goal of 100 million homes adopting clean and efficient stoves by 2020. Additionally, the design will be economically and aesthetically attractive, safe, and culturally appropriate. Knowledge gained during design, development, and testing will be transferred to the cookstoves research community, by means of publications, conferences, and training, to spur innovation, a key component of the BioEnergy Technology Office’s mandate, and support the standardization of laboratory testing protocols.

Related publications and material:


For the ARPA-E GENSETS program, we are providing a robust, scalable, and fuel flexible burner and heat exchanger system for state-of-the-art Stirling engine power generation systems. The team at LBNL will leverage its low-swirl burner technology developed for a gas turbine engine and adapt it for use with a Stirling engine heater head. This engine heater head will provide ultra-low emissions while improving heat transfer efficiency to the working fluid of the engine.

California Energy Commission
Demonstration of industrial systems with real-time response to fuel stock 

This project aims to demonstrate, in a commercial boiler installed at a water treatment plant, a low-emissions combustion system capable of switching from biogas, a renewable fuel, to a conventional gaseous fuel (natural gas or propane) in real-time without disrupting the boiler’s operation. Fuel-switching combustion systems will incentivize small to medium facilities, e.g. hospitals, hotels, and large supermarkets, to use their waste streams to fulfill their energy needs. This technology benefits California by promoting a larger renewable energy portfolio and improving air and water quality. The development involved advancements in burner, fuel sensing, and control technologies. Based on laboratory tests that showed the capability of these technologies to perform real-time fuel switching with ultra-low emissions, a fully-functional pre-commercial burner system and control was design and installed to the boiler. Regrettably, the demonstration could not proceed due to time and administrative constraints coupled with host-site availability. The results and knowledge from the developments have clearly shown the technical feasibility of deploying real-time fuel-switching system in industrial settings.

Department of Energy
Fuel-Engine Co-Optimization

The Co-Optima project will identify improved fuels that in combination with new engine designs will reduce petroleum reduction through a) greater overall efficiency and b) substitution of lower-GHG-lifecycle fuels for current market fuels. The Co-Optima project is a collaborative project between nine national laboratories, multiple universities, and industries. Our aim was to provide rapid feedback of measured fundamental thermodynamic and combustion properties to enable metabolic engineering and process optimization for quality assurance, thus streamlining the process for creating and producing a viable, sustainable biofuel for advanced property testing and engine testing conducted by other national laboratories. We initiated this process by measuring laminar flame speed of biofuels identified by the Optima Low Greenhouse Gas Fuels Team. Laminar flame speed is a low-volume, fundamental combustion property that has translational value across multiple fuels and is applicable to multiple engine platforms and scales. It is used to predict turbulent flame speed as well as validate and expand combustion models for multiple engine platforms, thus supporting understanding and interpretation of engine combustion performance.

New York State Energy Research and Development Authority
Low NOX, high turndown burner for on-demand water heater 

Current state-of- the art on-demand (tankless) water heaters are expensive due to multi-stage burner banks that require complex controls. This project aims to develop an efficient, cost-effective, ultra-low emissions natural gas on-demand (tankless) water heater for commercial and residential buildings. The new design will have higher efficiency and lower manufacturing costs than current tankless water heaters. The enabling technology is the low swirl burner (LSB), developed at Lawrence Berkeley National Laboratory (LBNL). The LSB is simple, robust, and fuel-flexible; it offers high-performance (30:1 turndown) with ultra low emissions while requiring less control hardware. Integrating the LSB to tankless water heaters will circumvent the complicated burner staging practices used in current state-of- the-art tankless water heaters.

Related publication:

California Energy Commission
Low emissions, residential cooktop burner

This project adapted the Lawrence Berkeley National Laboratory (LBNL) Ring-Stabilizer Burner combustion technology for residential and commercial natural gas fired cooking appliances (such as ovens, ranges, and cooktops). LBNL originally developed the Ring-Stabilizer Burner for a NASA funded microgravity experiment. This natural draft combustion technology reduces NOx emissions significantly below current SCAQMD emissions standards without post combustion treatment. Additionally, the Ring-Stabilizer Burner technology does not require the assistance of a blower to achieve an ultra-low emission lean premix flame. The research team evaluated the Ring-Stabilizer Burner and fabricated the most promising designs based on their emissions and turndown.

Related publication:

California Energy Commission
Effects of gas composition on water heater emissions

As a part of a larger effort to evaluate the potential air quality impacts of using liquefied natural gas in California, this project investigated the effects of effect of varying natural gas blends and associated Wobbe number (a measure of the energy delivery rate for appliances that use orifice- or pressure-based fuel metering) on pollutant emissions from residential water heaters in controlled laboratory experiments. Experiments were conducted on eight storage water heaters, including five with “ultra low-NOX” burners, and four on-demand (tankless) water heaters, all of which featured ultra low-NOX burners. Pollutant emissions were measured for carbon monoxide (CO), nitrogen oxides (NOX), nitrogen oxide (NO), formaldehyde and acetaldehyde as the water heaters were operated through defined operating cycles using fuels with varying Wobbe number.

Related publication:

California Energy Commission
Combustion safety for engergy efficient residential buildings

This project aims to improve energy efficiency while maintaining occupant health and safety by reducing the combustion appliance barrier to increased air tightening. The project combines measurements and simulations to produce improved test methods, guidelines, and standards that facilitate air tightening by better diagnosing potential combustion safety issues. Air sealing of homes to reduce the uncontrolled entry of outdoor air is typically among the most cost-effective home retrofit measures to reduce energy consumption and associated greenhouse gas emissions. However, tighter homes more readily depressurize when exhaust equipment is operated, making combustion appliances more prone to backdraft and spill harmful exhaust gases into the living space. Several test methods are available for assessing the potential for depressurization-induced backdrafting and spillage, but the reliability of these tests is unresolved and the mitigation objectives are not clearly defined.

Related publications:

© 2020 by Vi H. Rapp

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