Models of syngas concentrations five minutes after a leak with the original (top) and final (bottom) ventilation designs. The pink areas are the zones where the concentration is immediately dangerous due to CO toxicity.
Last summer, the RePower team began evaluating the proposed ventilation system for the Blue Lake Rancheria (BLR) biomass energy facility. Each phase of the BLR gasification process involves a dangerous gas. First, biomass is processed into a syngas rich in hydrogen and carbon monoxide. This syngas is then processed into pure hydrogen and a waste gas rich in carbon monoxide. In normal operation, the syngas and hydrogen are fully contained, and the waste gas is safely burned in a flare. However, an accidental leak in the system could pose an immediate toxic or explosive danger. The ventilation system must give personnel enough time to safely exit, and must clear hazardous gases from the building after the gasifier system shuts down.
To test different system designs, the RePower team used a software package from the National Institute of Standards and Technology to model contaminant flow in 3-D. We simulated various leak scenarios and examined how the placement of exhaust fans and intake vents affected the removal of toxic and flammable gases. We were able to improve on the original system design and create a more responsive, and robust system. The final design uses a combination of ceiling fans, wall fans, and floor vents to provide optimum ventilation. Following installation, the ventilation system will undergo a smoke test to validate the model results. Completion of this work will ensure a safe operating environment for the biomass facility.
Contractors installs one of the two heat pump units at Blue Lake Elementary school.
In our last update we mentioned that SERC is working with the Redwood Coast Energy Authority to install and test heat pump systems at Blue Lake Elementary School. We hope to determine how well such systems work in our local climate and whether or not they can save money as well as reduce greenhouse gas emissions compared to conventional systems.
Completed installation of the outdoor unit on top of the covered walkway in front of the classroom.
In July, the project moved out of the planning phase and into hands-on implementation when HVAC contractor Crystal Air of Weaverville installed two Daikin mini-split units at the school. These systems consist of an outdoor compressor unit connected via insulated refrigerant lines to an indoor, wall mounted head (or air handler) which distributes the conditioned air throughout the classroom.
Data loggers with a USB cable for downloading the data to a laptop.
SERC installed a battery of monitoring sensors and data loggers on each of the heat pumps, as well as on the existing natural gas furnaces in two other classrooms. The information collected by the test equipment is being used to determine the amount of heat energy delivered to each of the classrooms as well as the total energy consumed by each of the systems in the process. In the case of the heat pumps, this consists entirely of electricity, while the gas furnaces (as the name implies) rely mostly on natural gas, but also require a moderate amount of electricity for the fan and other electrical components.
Following a shakedown period in which various problems were discovered and rectified, the system is now reliably collecting data around the clock. Preliminary results show that the heat pump systems are consuming less electricity than the conventional furnaces. However, the weather has been so mild up until recently that none of the systems have been used extensively. In addition, the colder it is outside, the more difficult it is for heat pumps to absorb enough energy from the outdoors to heat a room. The true test will come when outdoor temperatures are much lower and heat demand is correspondingly higher.
Biochar unit with instrumentation installed for testing.
In late July, Marc Marshall, Mark Severy, and I traveled to Pueblo, Colorado to conduct testing on a biochar production machine manufactured by Biochar Solutions Incorporated (BSI). The purpose of our three-week trip was to collect experimental data for use in evaluating stand-alone operation (i.e. without an external source of energy to power the process) of the biochar unit as part of the BRDI project.
Infrared image of biochar unit flare during operation.
Biomass conversion technologies (BCTs), such as the BSI biochar machine, can create higher market-value products in near-woods environments, justifying the transport of these products to market. This in turn could allow fuels reduction and forestry residual management projects to be implemented in greater numbers thereby reducing greenhouse gas emissions and the risk of catastrophic wildfires. One of the goals of the BRDI project is to explore whether stand-alone operation of BCTs improves the economic and environmental benefits of removing slash and other woody residues from the forest.
We spent the first week in Pueblo installing instrumentation on the machine and setting up the data acquisition system. During the second and third weeks, we conducted experiments producing biochar with various biomass feedstocks.The variations in feedstock included tree species, particle size, anatomical distribution, percent contamination, and moisture content. Additional experiments led to design changes in the feedstock drying system and the air injection system for the flare.
The machine generates significant heat while operating (see photo at right). Some of this thermal energy is used for drying feedstock and some is used to preheat fresh air that is injected into the flare for complete combustion. Beyond the heat used for those purposes, there is a significant amount of high quality thermal energy that could potentially be used to generate electricity to power the machine at a forest landing site. Over the coming months, we will analyze the data and evaluate technologies that could be paired with the biochar machine to generate process electricity for stand-alone operations in near-woods environments.
For the past five years, SERC has helped lead the development of the Lighting Global quality assurance framework for small, solar-powered lights sold in countries ranging from Kenya to India. In 2009, a team of researchers from SERC, working with sponsorship from the Lighting Africa program (Lighting Global and Lighting Africa are associated programs of the World Bank Group), found that solar lamps represented a single-digit fraction of the off-grid lights available in markets in selected Kenyan towns. A follow-up visit in 2012 found that solar lamps had expanded to about a third of market share in these towns. This year when we returned to the same Kenyan towns, we discovered that solar products now represent a large majority (over 70%) of the total sales volume of off-grid lights in the market. Given that kerosene wick lamps and cheap, dry-cell battery flashlights had dominated the off-grid lighting market, the shift toward solar-powered LED lights represents a huge step forward in improving energy access for the rural poor.
SERC alum Peter Alstone (front) and UC Berkeley graduate student Dimitry Gershenson (back) interview retailers in Kericho, Kenya.
In partnership with the Energy Resources Group at UC Berkeley, the team broadened the scope of the research to include mapping the supply chain for solar lights in Kenya and investigating the growing potential for pay-as-you-go financing for solar home systems and small solar lights. Through dozens of meetings with distributors, micro-finance institutions, private companies, and NGOs in Nairobi, we were able to observe the positive impact of Lighting Africa’s engagement with key market stakeholders. The biggest decision-makers in the off-grid lighting supply chain are now dealing almost exclusively with products that meet the Lighting Global minimum quality standards. Looking forward, there is still much work to do. For example, many retailers still sell substandard off-grid lighting products, and there is a need to engage with these vendors and their customers to ensure they have information about product quality and performance when they look to buy an off-grid lighting product.
The design and procurement phases of the BLR Biomass to Energy Project are in full swing and the project team is involved in a flurry of activity. A group of engineers from SERC, as well as staff from Serraga Energy, LLC at the Blue Lake Rancheria (BLR) project site, are meeting weekly to discuss design decisions and move the effort forward. Frequent interactions are also taking place with our technology partners: Proton Power (gasifier), Xebec Adsorption (PSA gas cleanup unit), and Ballard Power Systems (fuel cell). Below is a list of key activities currently underway:
- site layout is largely completed
- fire marshal review – first phase is complete
- site work has begun and will ramp up significantly over the next few weeks
- gasifier is being fabricated – witness testing will occur in late July with delivery in August
- PSA design and fabrication are underway – delivery is expected in late August
- syngas compressor requirements have been specified and quotes have been obtained – orders will be placed in the next couple of weeks
- fuel cell is on site – installation is slated for July or August
- central control and monitoring system – design is underway
- ventilation system – design analysis is underway
- fuel storage and processing – design is underway
- electrical service (auxiliary power supply and fuel cell generator/utility interconnection) – electrical engineer and contractor team are working on design, procurement, and the utility interconnect application with Pacific Gas & Electric
Neil Harris (far right) with electrical and construction experts implementing site design at Blue Lake Rancheria. Photo credit Serraga Energy, LLC.
The next phases of the project will include component installation (summer and early fall 2014), system integration and commissioning (fall 2014), and system operation, data collection, analysis and reporting (late fall and winter 2014/15). Stay tuned for additional updates in upcoming newsletters.
Researchers at SERC are studying alternative pathways for biomass energy to displace fossil fuels in existing high-efficiency power plants. Chemical reactions can harness waste heat to convert biomass into a hydrogen-rich syngas, displacing fossil fuel consumption. Modeling work at SERC estimates that integrated systems can produce between 5% and 100% of a power plant’s fuel requirement from biomass, depending on the quality of the waste heat resource. If applied to internal combustion engine power plants, blending hydrogen-rich syngas with natural gas additionally reduces untreated nitrogen oxide (NOx) emissions by up to 95% and increases engine efficiency by up to 25%.
Over the past year, SERC’s Dr. David Vernon led a research team to study aqueous phase reformation (APR) of plant-derived sugars to produce a hydrogen-rich syngas. This project, funded by the California Energy Commission, investigated the potential to use this low temperature reformation process to recover waste heat from natural gas power plants. SERC engineers designed, built, and tested a benchtop chemical reactor to convert aqueous sorbitol (C6H14O6) into an energy-rich gas consisting of hydrogen, carbon dioxide, and methane. Sorbitol, a sugar alcohol, was selected as the feedstock because it is easily produced from glucose, a biomass derivative, and reforming sorbitol produces hydrogen at a faster rate than reforming glucose.
Testing was completed in April. Our results showed that APR is able to convert up to 94% of the input sorbitol into a hydrogen-rich gaseous fuel. By synthesizing our own catalysts at SERC, we were able to produce a gas containing 64% hydrogen by volume. Furthermore, the output liquid and gas were found to contain 46% more chemical energy than the input feedstock.
Based on these promising results, we conclude that it is feasible to use APR in waste heat recovery applications. We have applied for additional funding to continue this work. Next, we plan to use crude glycerol, a byproduct of biodiesel production, as the feedstock. Our economic models predict that converting crude glycerol will significantly reduce the lifecycle costs of the system, making this process more cost competitive than other waste heat recovery technologies such as organic Rankine cycles.
Dana Boudreau of RCEA displays air flow measuring equipment that will be used in the heat pump study.
Numerous SERC staff are busy working on the RePower Humboldt with Community Scale Renewable Energy project. Most of our recent efforts have been focused on the design of the biomass gasification to fuel cell project at the Blue Lake Rancheria. We also met recently with Redwood Coast Energy Authority staff at the Blue Lake Elementary School to scope out the installation and testing of a mini-split heat pump system. The RePower Humboldt Strategic Plan indicated that use of heat pumps could be a cost effective way to utilize local renewable energy resources to meet heating demands while reducing greenhouse gas emissions. However, heat pump performance can vary significantly in different climates, so the strategic plan recommended conducting a heat pump pilot study to examine performance characteristics in the Humboldt climate. Blue Lake Elementary will receive one or two heat pump systems to be installed in individual classrooms. These systems will be equipped with monitoring instruments. At the same time, we will measure the energy consumption and performance of the small natural gas furnaces that currently provide heat to these classrooms. This will allow us to evaluate the energy efficiency, cost-effectiveness, and greenhouse gas impacts associated with the heat pump systems compared to conventional heating systems. This information can then be used to inform decisions about the potential future installation of heat pump systems throughout the county.
As we reported previously, SERC is collaborating with Renewable Fuel Technologies (RFT) to assess performance of RFT’s biomass torrefier. The torrefier converts wood waste from logging or forest thinning, roasting it to make a renewable energy product that can replace coal in power plants. The testing is funded by a grant from the California Energy Commission. The goal of the assessment is to determine whether waste heat from the torrefier can be used to make the device self-powered for off-grid use at timber harvest sites. Such use could make recovery of waste material at these sites more cost-effective.
This past fall, SERC engineers made multiple trips to RFT’s abrication and testing facility in Hayward, CA. We first procured about three tons of tanoak wood chips in Humboldt County and delivered them to RFT. Tanoak is of special interest because it is abundant in northwest California but considered of low value as a timber species.
An array of torrefied wood chips shows the effects of varying temperature and processing time. The raw biomass is shown in the column on the right.
We next performed a series of test runs with RFT engineers, in which we varied the moisture content of the feedstock, operating temperature, and residence time of the material in the roaster. We collected operating data such as temperatures, material flow rates, and electric power use during each run. In addition, we collected samples of the raw wood chips used for each run as well as the solid, liquid, and gas outputs from the process for later laboratory analysis. All of these data allowed us to perform a rigorous energy and mass balance for the process, key to determining the feasibility of stand-alone operation.
Our tentative conclusion is that such operation may be feasible, though the design may need further modification to reduce heat loss to the surroundings. We are now working to prepare our final report to the Energy Commission.
Director Arne Jacobson at the TERI grand opening in March. Photo credit Sanjay Kumar.
The Solar Lighting Laboratory of The Energy and Resources Institute (TERI) in New Delhi, India is open and ready for business. Last year, SERC director Arne Jacobson and I traveled to New Delhi to complete a hands-on training for the Solar Lighting Laboratory and have since evaluated the laboratory’s work testing off-grid lighting products. Through SERC’s support and the Solar Lighting Laboratory’s hard work, TERI has established the first Asian laboratory within the Lighting Global Quality Assurance Program test laboratory network.
TERI’s Solar Lighting Laboratory will be evaluating off-grid lighting products using the International Electrotechnical Commission’s standard TS 62257-9-5. The test methods verify products by checking product ratings; measuring key product parameters such as daily hours of operation, lighting output, and solar power production; and evaluating parameters related to product durability such as LED life, shock resistance, and workmanship of electrical and mechanical parts.
In other news, in response to demand from the off-grid lighting market, the Lighting Global program has decided to extend the existing quality assurance framework to include larger solar home system kits. Compared to the lighting products we currently test, these plug-and-play direct current kits can provide more power for lighting as well as other uses, such as mobile phone charging, radios, fans and even TVs. Over the next two years, SERC will partner with the Fraunhofer Institute for Solar Energy Systems to adapt existing test methods and standards to reliably assess and report the quality of these larger systems.
While expanding our scope, we are also working with our wide range of stakeholders to refine our current test procedures and ensure a reliable and rigorous quality assurance framework that can be sustained for years into the future. As part of this process, Arne and other team members presented to stakeholders at the Global Off-Grid Lighting Association quality assurance symposium in Cologne, Germany in April.
We also remain committed to better promoting and communicating information about the products that have met our Quality Standards in the off-grid lighting market. As part of this ongoing effort, we have re-designed the Lighting Global website to enable interested parties to more easily view and compare 48 solar lighting products produced by over 20 different manufacturers that have met the Lighting Global Minimum Quality Standards.
I’ve been leading a new area of research aimed at offsetting natural gas consumption with hydrogen produced from biomass-derived sugars or waste glycerol from biodiesel production. The process utilizes waste heat in the exhaust from internal-combustion-engine power plants to drive chemical reactions that produce hydrogen. The hydrogen can then be blended with the primary natural gas fuel in order to enhance combustion. Hydrogen-enriched combustion can increase efficiency by up to 20% and reduce emissions of NOx by more than 95%.
The current project is focused on understanding the use of catalysts in aqueous phase reformation (APR) processes to speed up chemical reactions so that medium-temperature waste heat can be used to reform a wide range of plant based feedstocks.
Mark Severy recently graduated with a M.S. in Environmental Resources Engineering from HSU. His thesis modeled the waste heat resources available from large internal-combustion-engine power plants like the one at the Humboldt Bay Generating Station. His work demonstrates that, depending on engine type and operating conditions, there is sufficient waste heat to replace a significant portion of the natural gas with hydrogen produced from waste glycerol left over from biodiesel production. His work also shows that water vaporization in APR can consume a significant portion of the recovered waste heat. By raising the APR pressure, this water vaporization could be reduced. We are currently applying for grants to experimentally investigate high-pressure APR.
Waste heat from engine exhaust is used to convert the feedstock into hydrogen rich gas. The hydrogen produced in the reformer will be mixed with natural gas and air in the combustion engine to increase efficiency and reduce emissions.