Category: Publications

Among the many challenges of the COVID-19 pandemic is the need to provide testing in regions with little to no access to an electrical grid. The most common approach for COVID-19 diagnostic testing involves collecting samples that must be kept cool or frozen until they reach centralized test facilities. In remote areas, transporting these samples can take several days. This spring, the Lighting Global program at the World Bank asked our off-grid research team to develop an initial assessment of the energy needs required for sample screening, clinic storage, and transportation to test laboratories.

For this project, Meg Harper, Tyler Bernard, and Arne Jacobson from our off-grid team collaborated with Amy Sprowles, Associate Professor of Cellular and Developmental Biology at Humboldt State University. As a biomedical scientist with collaborators at the Stanford, UCSF and UC Davis medical schools, Dr. Sprowles contributed insight on screening and laboratory processes for COVID-19, including temperature requirements for sample storage and transport. We also reviewed the available literature on COVID-19 testing protocols, and guidelines from the World Health Organization (WHO) for vaccine refrigeration.

Our recommendations are included in a new technical guidance note jointly published by the Schatz Center, the Energy Sector Management Assistance Program (ESMAP), and Lighting Global. This document aims to help energy and health professionals select best fit solar appliances and module installations for COVID-19 screening. The publication is one piece of a broader effort by the World Bank and other development agencies to improve health care delivery in regions without stable access to an electrical grid.

• Download the technical guidance note on energy needs for off-grid COVID-19 screening
  

UPDATE 3/17/20

The North Coast Offshore Wind Workshop scheduled for April 28 has been postponed. Our team is investigating options for sharing our initial findings, while maintaining clarity, accessibility, and community engagement. Please RSVP (see below) if you would like to receive information directly on these events.

Original post

The North Coast Offshore Wind Workshop will present initial findings about the opportunities and challenges associated with offshore wind energy in the Humboldt Bay region. This workshop is free and open to the public, and is being hosted by the California Ocean Protection Council and the Schatz Energy Research Center at Humboldt State University.

The all-day event will be held on Tuesday, April 28, at the Wharfinger Building in Eureka, CA.

• If you plan to attend, please RSVP. A recording will be made available to the public following the workshop. We are also currently exploring remote participation options.
• Each session will include a presentation of findings and a panel discussion, followed by a Q&A.
• Lunch and snacks will be provided by the Schatz Center for participants.
• For additional information or to request accessibility accommodations, please contact the Schatz Center at (707) 826-4345 or by email.

Learn more about the Schatz Center’s offshore wind feasibility studies. These studies are being funded by the California Ocean Protection Council, the California Governor’s Office of Planning and Research, and the Bureau of Ocean Energy Management.

Note: agenda details are subject to change. Please RSVP or visit this page again for schedule updates.

Charles Chamberlin, David Carter, and Arne Jacobson recently authored an article on measuring residence time distributions of wood chips in a screw conveyor reactor. A screw conveyor or auger makes use of a rotating helical blade inside of a tube or trough to move wood chips, sawdust, flour, or other granular materials through a reactor — such as a dryer, heater, cooler, gasifier, or torrefier. How much change in the materials takes place in such reactors depends on the average residence time and how variable that residence time is.

This paper compares three alternative methods for measuring the residence time distribution of wood chips in a screw conveyor reactor using experimental results from a pilot scale torrefier:

• addition of material to an empty reactor (step-up),
• halting addition of material to a reactor under steady flow, (step-down), and
• addition of a pulse of labelled material (i.e., a tracer) to a reactor under steady flow.

We found that all three methods yield residence time distributions that are approximately symmetrical and bell-shaped, but the distribution estimated from the pulse input of tracer exhibited a long trailing tail that was not detectable in either the step-up or step-down results. Second, we demonstrated that a normal probability plot provided a useful way to display and analyze the distributions obtained in the tracer experiments. Finally, we observed that all three methods yielded mean residence times that consistently differed from the nominal values, with the step-up method averaging 8% shorter, the pulse addition of tracer averaging 7% longer, and the step-down averaging 60% longer.

The article appeared in the August 2018 issue of Fuel Processing Technology.

The Lighting Global Quality Assurance Program works to ensure that solar products sold around the globe meet established quality standards for product durability, representation of product performance, and warranty. To obtain quality verification, manufacturers may submit products for testing at laboratories in the Lighting Global network.

Pico-solar products include lanterns and simple systems with a peak PV module power up to 10 watts. These small systems encompass 85% of the global cumulative sales of off-grid solar devices. Although more than 30 million quality assured off-grid solar products have been sold globally over the past eight years, the sales numbers for products that do not undergo quality verification (hence are “non-QV”) is even higher. Field observations and customer experiences indicate that non-QV products typically underperform compared to the standards established by Lighting Global.

In order to ascertain the actual performance of these devices, Lighting Global laboratories recently tested 17 pico-solar non-QV products that are top-sellers in Ethiopia, Kenya, Myanmar, Nigeria and Tanzania. Products were purchased direct from market retailers.

Key results:

All 17 evaluated products failed to meet the Lighting Global Quality Standards for pico-PV products.

• 94% of the tested products fail to meet the Standards due to one or more deficiency that
  affects product durability.
• 88% of the tested products inaccurately advertise product performance.
• 88% of the tested products do not include a consumer-facing warranty.
• 76% of the tested products would require significant changes to product design and
  components to meet the Quality Standards.

The Lighting Global Quality Assurance team issued the report this August as part of the Technical Notes series. Chris Carlsen (a Schatz Center alumnus) led the effort in collaboration with team members from CLASP, the Schatz Center, World Bank Group regional lighting programs, and the Lighting Global network of test labs.

Read the complete report on the Lighting Global website…

We recently completed work on the Waste to Wisdom project that examined the entire supply chain of converting forest waste residues into bioenergy and wood products. The Center’s role was to evaluate equipment that produces biochar, torrefied biomass, electricity, or densified wood briquettes using forest residues as the input feedstock. Collaborators from Humboldt State’s Forestry Department analyzed the upstream collection of forest biomass, and experts from the U.S. Forest Service conducted a lifecycle assessment and economic analysis of the supply chain.

Data collected by the Schatz Center during field tests of biomass conversion equipment were used to:

• identify optimal process conditions,
• specify feedstock limitations,
• measure emissions,
• evaluate product quality, and
• recommend design improvements to equipment manufacturers.

Results and conclusions from the entire project are presented in a special issue of Applied Engineering for Agriculture, published in February 2018. Four principal investigators, including Schatz Center Director Arne Jacobson, summarized the project’s objectives and major conclusions in the introduction article to the special issue. Engineers from Schatz authored four papers, on biochar production, torrefaction and briquetting, and gasification of forest residues:

• Performance and Emissions Control of Commercial-Scale Biochar Production Unit. Results are presented for the performance and emissions characteristics of two biochar machines. Our analysis of biochar quality shows that high levels of moisture and ash content in the woody biomass feedstock reduces the carbon sequestration potential of biochar as a soil amendment.
• Utilization of Wet Forest Biomass as both the Feedstock and Electricity Source for an Integrated Biochar Production System. This paper demonstrated how biochar machines can be integrated into a complete production facility without the use of fossil fuels. We built and reported on a demonstration plant that recovered waste heat from a biochar machine to dry incoming feedstock and used a small fraction of biomass in a gasifier to produce enough electricity to power the entire operation.
• Demonstration of a Pilot-Scale Plant for Biomass Torrefaction and Briquetting. The torrefaction process, which improves the properties of biomass as an energy fuel, was studied in a continuous-flow, mobile, demonstration-scale facility that produced densified torrefied biomass using a dryer, torrefier, and briquetter. This work identified optimal operating conditions that produce torrefied briquettes with higher energy density and greater durability that briquettes produced from raw biomass.
• Performance Analysis of a Biomass Gasifier Genset at Varying Operating Conditions. Small biomass gasifier generators can be used as an alternative to diesel generators to provide electricity to biomass conversion equipment at remote field sites. The performance and emissions from a 20 kW biomass gasifier generator set were analyzed under varying load conditions to determine its suitability to power biomass conversion equipment.

Collaborators at the U.S. Forest Service and the Consortium for Research and Renewable Industrial Materials (CORRIM) used the results collected from testing activities to conduct economic and environmental life cycle analyses of biomass conversion technologies. Field measurements from the Waste to Wisdom project will also be included in our current California Biopower Impacts project, which is evaluating the environmental impacts associated with utilization of forest-derived woody biomass for electricity generation.

This work could not have been completed without close collaboration between our primary industry partners: Biochar Solutions, Inc., Norris Thermal Technologies, and Pellet Fuels Institute, who provided the testing equipment. Other partners that provided key support include the Green Diamond Resource Company, the Redwood Forest Foundation, Inc. (RFFI), All Power Labs, Bear Mountain Forest Products, Colorado Biochar Resources, Pueblo Wood Products, California Redwood Company, North Coast Air Quality Management District, RUF Briquetting Systems, and OMNI Test Labs.