Natural Gas Vehicle Technology Forum 2014 Meeting Summary

Natural Gas Vehicle Technology Form (NGVTF) logo

The 2014 Natural Gas Vehicle Technology Forum (NGVTF) meeting was held Jan. 14–15 at Brookhaven National Laboratory in Upton, New York. Following is a summary of the meeting.

Welcome and DOE Update

Mark Smith, U.S. Department of Energy; and Margo Melendez, National Renewable Energy Laboratory

Mr. Smith and Ms. Melendez welcomed attendees to the NGVTF and discussed the purpose of the meeting. The National Renewable Energy Laboratory (NREL) hosted the meeting in partnership with the U.S. Department of Energy (DOE) and the California Energy Commission (CEC) to bring together a diverse group of stakeholders to discuss technical challenges and opportunities facing natural gas vehicles. It has been many years since NGVTF was held on the East Coast, and it presents a great opportunity to gather input from this critical audience.

NYSERDA Overview

Richard Drake, NYSERDA

Mr. Drake provided an overview of the New York State Energy Research and Development Authority (NYSERDA), a public benefits corporation that seeks to improve energy and environmental performance. Total funding is about $600 million for 2013 and will be close to $700 million in 2014. Most of NYSERDA's efforts are focused on the electric power sector with transportation representing about $25 million. A newly established green bank will be funded at $1 billion over 5 years, which may have the impact of decreasing transportation efforts.

In the transportation space, NYSERDA supports development and adoption of technologies related to alternative fuel vehicles, alternative fuel infrastructure, emission control equipment, and transportation research and development more broadly. They have three current competitive programs: advanced transportation product development, infrastructure, and a demo of technologies that enable electric vehicles.

Most of NYSERDA's natural gas deployment has been for medium- and heavy-duty vehicles. NYSERDA will make $3.5 million available in the spring for public compressed natural gas (CNG) stations ($300,000 to $500,000 per station depending on match). There is also a truck voucher program that is currently being administered that will be discussed in more detail by CALSTART. NYSERDA has also funded a CNG engine dynamometer, outreach events around New York, case studies, and policy studies on liquefied natural gas (LNG) infrastructure and renewable natural gas (RNG) market development.

NGV Global Overview

Alex Lawson, NGV Global

Mr. Lawson discussed the global conversation around natural gas vehicles, including adoption rates, vehicle to infrastructure rations, and technical topics. There are approximately 18 million NGVs worldwide where growth is tracking an S-curve.

Europe has a number of dual-fuel systems for light-duty vehicles, which extends up to heavy-duty vehicles (dual fuel is classified as a compression engine, except methane hydrocarbons, which are spark ignited). On the infrastructure side, Europe's Ten-T project will have nine corridors with CNG every 150 kilometers and 400 kilometer for LNG.

In India, the natural gas vehicle industry is struggling with infrastructure expansion due to space limitations in populated areas. While this has created some strain on expansion, a number of innovative approaches have been introduced, such as mounting compressors on the roof. The industry is now working on low-pressure fuel storage and skid-mounted CNG stations as another means to alleviate infrastructure constraints.

There are a number of non-road natural gas applications being employed around the world as well. Europe is encouraging LNG as a marine fuel, particularly in shipping. Thirty carriers make about 200 shipments a year, and it is expected that 25% of motive power for marine applications will be generated through natural gas by 2016. On the passenger side, Viking Line operates an LNG ferry.

Canada and Russia are increasingly looking at LNG in rail applications. Kamaz has introduced a 12-liter CNG engine in Russia. Russia also now claims the record for the largest load by a natural gas–powered locomotive (generating 8,300 kilowatts and requiring a 17-ton LNG fuel tank, which is equivalent to 170 rail cars). The potential fuel savings is in the millions for operators.

NGV Global's technical committee has identified cylinder mounting, transparency in reporting incidents, and valve and regulator incidents as pressing topics that NGV Global is prioritizing. Relatedly, Honda R&D has introduced a proposal for a worldwide CNG fuel to address concerns about variations in fuel quality and specifications.

Relative Safety Risks Posed by Spark-Ignited Natural Gas Vehicles at Fueling Depots

Ira Pearl, Mansfield

Mr. Pearl discussed Mansfield Oil and the Clean Vehicle Education Foundation's (CVEF) work on spark-ignited (SI) engines at fuel distribution terminals (fuel racks). For the past 30 years, SI engines have not been used as transport vehicles for fuel because of safety concerns about SI engines as an ignition source, high exhaust temperatures, potential leaks from CNG and LNG tanks, and risks of faulty retrofits.

Mansfield and CVEF set out to examine the risk of SI engines versus compression-ignited (CI) engines. They began with a literature review of both SI and CI engine exhaust temperatures to determine their values relative to auto ignition points for natural gas and diesel. They found that SI engines have higher exhaust temperatures than the auto ignition point for natural gas but only under fully loaded operations (full capacity on an incline), which is an unlikely scenario at a fuel depot. Real-world auto-ignition rates for natural gas were much higher than those found in the literature, and the heat/distance gradient was relatively high. The study's overall conclusions were that safety risks posed by SI natural gas–powered engines are similar to that of diesel CI engines. The study also found that conversion kits and installation quality still pose a risk for natural gas vehicles.

National Conference of Weights and Measures Issues

Jeff Clarke, NGV America; and Doug Horne, Clean Vehicle Education Foundation

Mr. Clarke and Mr. Horne provided an overview on weights and measures issues that either currently are or have the potential to affect the natural gas vehicle industry, highlighting two issues in particular: energy equivalent taxation for CNG and LNG, and gasoline gallon equivalence (GGE) for CNG.

The taxation of CNG and LNG is occurring in the United States at different levels as there are a variety of mechanisms that states employ to collect fuel taxes on CNG and LNG. Some states charge excise taxes, others use decals, some charge a sales tax, and others make CNG and/or LNG tax exempt. Mr. Clarke noted that even where there are common methods of levying fuel taxes, different weights and measures create a patchwork of rules. In particular, there are only 10 states using the national standard of a gasoline gallon equivalent (GGE) of CNG, which is defined as 5.66 pounds of natural gas. Furthermore, without a proper conversion factor, LNG is often overtaxed in the context of energy equivalency because it is not as energy dense as diesel fuel. Mr. Clarke stated that the industry is addressing these challenges on a state-by-state basis. A number of states passed legislation in 2013 to address this issue, and 11 states are considering bills in 2014.

The National Conference on Weights and Measures (NCWM) develops national standards for dispensing CNG and GGE definitions. While these standards are set by NWCM, they ultimately need to be adopted by states. The National Institute of Standards and Technology (NIST) Handbooks 44 and 130 contain relevant standards for CNG dispensing and GGE equivalence. NCWM had a meeting in January 2014 in Albuquerque, New Mexico, where the definitions of a diesel gallon equivalent (DGE) were discussed. While DGE is a discussion item, it must be a voting item to be changed. The earliest this could happen is summer 2014. Colorado has already promulgated new standards by regulation.

Producer's Perspective of Market Barriers and Opportunities for NGVs

Curtis Reuter, Noble Energy

Noble Energy is a global oil and gas production company with its headquarters in Houston, Texas. For LNG, Noble is currently using the fuel for drilling rigs (4 dual-fuel rigs) and is in the process of building an LNG plant in Colorado. Noble chose to build its own plant to ensure a secure supply of LNG and obtain environmental and economic benefits. The project initially went out to bid, but Noble decided to do it in house. The capacity of the facility will be about 8.3 million standard cubic feet per day.

Noble sees fleets with quick (1- to 2-year) payback as leading the move to CNG. These are primarily medium-duty vehicles. The light-duty segment of the market is seeing slower adoption and faces a number of market barriers, including limited OEM makes/models, various regulatory policies, a focus of after-market solutions for pickup trucks, limited fueling opportunities, and limited economic savings potential compared to larger vehicles. Smaller and plug-and-play infrastructure solutions present cost reduction opportunities, and there is quite a bit of work going into low-cost, high-performance home refueling solutions.

Compressed Natural Gas Cylinder Safety

John Dimmick, Clean Vehicle Education Foundation

Mr. Dimmick stated that NGVs have become a viable market choice, yet NGV codes and standards are still in "conversion mode" reflecting a new technology and market. The fact that the United States is also one of few countries with multiple dispensing pressures also creates challenges in regulating to the lowest common denominator.

The research knowledge on tank safety is 20 years old. Root causes of cylinder failure include primarily concentrated fire exposure, overfilling as a result of component malfunction, physical impact chemical damage, damage from inappropriate brackets, cylinder removal, defueling, and disposal.

More specifically, the change from demo fleets to high-fuel users exposed shortcomings in how range was considered when developing cylinder safety standards. Periodic detailed inspection and end-of-life (EOL) dates do not correlate with potential causes of root failure. In fact, cylinder replacement at end of life has unexpected hazards not reflected in EOL standards.

CNG Cylinder End of Life Outreach and Education

Mark Smith, DOE; and Alex Schroeder, NREL

Mr. Schroeder discussed the work that NREL is performing for the U.S. Department of Transportation on compressed natural gas cylinder end-of-life requirements. CNG vehicles are different from most other vehicles in that the CNG fuel storage cylinders have a pre-determined lifetime that may be shorter than the expected life of the vehicle. The end-of-life date for a cylinder is based on construction and test protocols, and is specific to the construction and material of each cylinder. The end-of-life date is important because it provides a safe margin of error against catastrophic cylinder failure or rupture. The end-of-life dates range from 15 to 25 years from the date of manufacture.

NREL worked to develop outreach materials to increase awareness of cylinder end-of-life dates, has provided technical support for individual efforts related to cylinder safety and removal, and also worked with CVEF to document best practices for cylinder removal or inspection after an accident.

Mr. Smith discussed the engagement of the DOE Clean Fleets Partners, which were surveyed to identify best practices on managing cylinder inventories and approached to provide initial data on cylinder age in a fleet environment. Both DOE and NREL will continue to engage these fleets and other stakeholders to determine how to best address this issue moving forward.

Modeling CNG and LNG Releases in Maintenance Facilities

Chris LeFleur, Sandia National Laboratories

Mr. LeFleur provided an overview of maintenance for LNG and CNG vehicles focused on informing actions with risk assessments. He also discussed codes and standards for fueling facilities. Sandia National Laboratories is working on improving codes and standards for gaseous fuel vehicle maintenance facility design and operation to reflect advances in transportation technologies. They are also developing guidelines for modifying and constructing maintenance facilities.

Status of Natural Gas Engine Research and Development

Brad Zigler, NREL

Mr. Zigler provided an overview of natural gas vehicle engine options that are or expected to be available commercially in the United States. The light-duty market is powered by spark-ignited original equipment manufacturer (OEM) vehicles and conversion solutions based on gasoline engines. For medium-duty vehicles, there is a gap in 6- to 8-liter engine availability. The California Energy Commission is working with Cummins Westport to develop a 6.7-liter engine that will fill that void (see next section). The heavy-duty vehicle market is composed of spark-ignited CNG and LNG engines or dual-fuel LNG and CNG engines that use diesel fuel to produce the necessary spark. Specifically, Cummins Westport provides an 8.9-liter ISL engine, and Doosan has 11-liter lean-burn engine. Moving into larger engines, Cummins Westport is working to address the 11- to 12-liter size range, and Southwest Research Institute is working with Doosan to upgrade its 11-liter engine. Volvo is expected to introduce a dual-fuel engine in mid-2014.

The increased activity in engine development is in large part due to input received at NGVTF, which has been critical in identifying research gaps in engine technologies. However, opportunities for advancement exist beyond engine design and include the following opportunities and possible solutions:

  • Reduced fuel efficiency penalty relative to diesel
    • Improved fuel injection systems
    • High dilution – exhaust gas recirculation (EGR)
    • High boost
    • Improved ignition
    • Reforming for syngas – hydrogen to extend ignition limits
    • Low-temperature combustion strategies
  • Reduced emissions from natural gas vehicles
    • Refined and updated lifecycle analysis
    • Identifying unregulated emissions, such as ammonia
  • Cold-start and low-temperature catalysts
  • Additional after treatments for natural gas vehicles

Cummins Westport 6.7L and ISX 11.9L

Stephen Ptucha, Cummins Westport

Cummins Westport and the Gas Technology Institute were awarded $1 million through CEC to support the design of a 6.7-liter natural gas engine. The engine will be certified by both EPA and California Air Resources Board Standards as well as 2017 GHG standards. The engine is expected to demonstrate a peak rating of 260 horsepower at 660 pounds per foot and a 5% to 10% improvement in fuel economy versus the 5.9-liter SI engine, and it will be built on the same architecture as the ISL G and ISX12G

Cummins Westport is also working on demonstration and deployment of the ISX12G, which is an 11.9-liter natural gas engine. Funding for this project was provided by NREL and CEC (via AB118). The engine was launched in 2013 with full production in August. To date, it has been the most successful natural gas engine launch in Cummins Westport and Cummins history.

Natural Gas Engine and Vehicle Research, Development, and Demonstration

Mark Walls, Southwest Research Institute

Southwest Research Institute is working to develop a dedicated Doosan natural gas engine that costs less and produces near-zero emissions without sacrificing efficiency or performance compared to the 2010 engine.

Engine calibration is 90% complete, and durability testing has started. The formal certification process will begin after durability testing is complete. The final parts have been selected, and the operating software is ready for production.

Testing has revealed a tradeoff between NOx and ammonia emissions but has also shown a 2% gain over the CWI 8.9-liter engine (40.9%), greater torque and power, and generally lower emissions. Future plans will look at a dedicated EGR (up to 33%).

California Energy Commission Natural Gas for Transportation R&D Work

Rey Gonzalez, California Energy Commission

Mr. Gonzalez provided an overview of the California Energy Commission, its charter, and interest in natural gas for transportation. CEC has long been involved in NGVTF and will be hosting the next meeting in California.

CEC's previous funding mechanism for natural gas transportation research and development, Public Interest Energy Research (PIER), will be phasing out in 2015, but final program funding has already ended. The Electric Program Investment Charge (EPIC) program is taking its place and should be launched in 2014. There are three areas of transportation focus supported under the EPIC program: electric drive (vehicle-to-grid and vehicle-to-building smart charging), natural gas vehicles (engine development, vehicle integration, fueling infrastructure, and on-board storage), and renewable natural gas.

Additionally, CEC will update its Natural Gas Vehicle Research Roadmap (NGVRR) this year. The NGVRR will develop a new baseline and identify barriers to deployment. Stakeholder participation will be key to the roadmap. CEC aims to have a final draft to share by the next NGVTF meeting, which will be followed by a public workshop in December 2014 and publication in February 2015.

Natural Gas Successes in Energy Assuredness

Mark Smith, DOE

DOE is working to identify lessons learned from Hurricane Sandy on alternative fuels and their role in aiding disaster recovery. Specifically, the Jitney transit service in New Jersey was able to provide key logistical support because they used natural gas to fuel their vehicles. Mr. Smith showed a MotorWeek video that provided an overview of the story.

Based on feedback from Clean Cities coordinators, fleets, and other stakeholders involved in Sandy recovery efforts, DOE is working to include information on alternative fueling stations with backup power as part of is station locator. A participant from the audience noted they had success with biodiesel vehicles during Sandy recovery efforts because the fuel was readily available in an on-site storage tank.

Analytical Tools for Fleets

Andy Burnham, Argonne National Laboratory

Mr. Burnham discussed AFLEET, which is an Excel-based tool that looks at economic and environmental costs and benefits of alternative fuel vehicles. The tool was developed after a number of Clean Cities coordinators sought to lay the groundwork for a Green Fleet certification program and provide consulting on the costs and benefits of alternative fuels. The model looks at a number of factors to make estimates of these impacts and combines a number of existing models into an Excel tool.

Renewable Natural Gas

Joanna Underwood, Energy Vision

Energy Vision is a New York City–based environmental organization that sees CNG and LNG as the most promising fuels for medium- and heavy-duty diesel fleets. According to the Gas Technologies Institute, renewable natural gas has the highest ratio of energy in to energy out compared to any biomass-based fuel. Ms. Underwood continued to provide an overview of the benefits and production process of RNG, noting that 11 projects in the United States are currently operating.

New York State Alternative Fuel Truck Program

Alycia Gilde, CALSTART; and Susan McSherry, New York City Department of Transportation

Ms. Gilde and Ms. McSherry detailed incentives looking at technology advancement. The program recently launched in New York State is aimed at OEMs, fleets, and technology vendors by providing a point-of-sale incentive for electric vehicles, alternative fuel vehicles, and diesel emissions reduction technologies. The point-of-sale "voucher" program was launched on August 9, 2013, and is available to both private and non-profit fleets for the purchase of dedicated alternative fuel vehicles. Additionally, it is expected that funding for CNG infrastructure will be available in January 2014.

LNG Infrastructure Development

Steve Zilonis, Dresser-Rand

Mr. Zilonis discussed Dresser-Rand's modular LNG system (LNGo), which is capable of producing 6,000 gallons per day of LNG. The unit is aimed at tackling some of the challenges around LNG availability and the capital costs of large-scale liquefaction facilities.

LNG Tank Design, Life Expectancy, and LNG Safety Aspects

Peter Murray, Chart Industries

Mr. Murray discussed on-board storage for LNG, providing an overview of the technology as well as the certification process that tanks undergo. Mr. Murray stated he believes LNG makes sense for about 20% of the heavy-duty vehicle market, which is not insignificant, but also does not represent a wholesale transformation. This portion of the market is where their company is focusing its efforts.

On-board LNG fueling systems have 3 core technology components that determine performance:

  • Efficient fueling and capacity utilization
  • Super insulation and hold times
  • Auto-refrigeration

Regarding the first attribute of efficient fueling, Mr. Murray stated that pressure vessel standards for LNG are well understood and field-tested. Chart Industries' technology also allows for a hold time of 7 to 10 days, which is the amount of time a tank can hold LNG without venting (5 days is the standard required by California law). Finally, the refrigeration element of an LNG tank primarily consists of a vacuum and a barrier. Their work has shown that durability of the vacuum is more important than initial performance.

In addition to these performance attributes, LNG tanks also undergo a variety of safety tests, including pressure tests, drop tests, fire tests, vibration tests, G-load tests, and component tests to ensure the tanks are robust. Relating back to the discussion on CNG cylinder lifetimes, there is no set lifetime for LNG tanks, and most are replaced after suffering some type of damage. Within the LNG tank system, the average lifespan for plumbing components is 5 to 10 years and less than 8 years for insulation. Connector seals are the item that typically requires the most maintenance.

OEM Roundtable: Maintenance and Training

Dick Kauling, General Motors; Butch Gosline, Ford; and Dan Bowerson, Chrysler

Participants were asked to describe the natural gas vehicle maintenance procedures that they have in place with their respective dealerships as well as how that information is communicated and updated. The following is a summary of the responses of the panelists to this question.

General Motors (GM)

Mr. Kauling began his presentation by noting that GM has numerous programs and mechanisms in place to get feedback from the field that are likely very similar among automakers and vehicle and fuel types. Specific to the conversation held the previous day, GM has a standard procedure that it uses to remove natural gas cylinders from service and will then drill a hole in them after removal if the cylinder has passed its end of life date.

Regarding future barriers and opportunities, Kauling suggested that new or revised codes and standards that are data driven are increasingly needed and possible. He noted that automakers are increasingly asked to identify and address issues that come from the customer (e.g., refueling accuracy, fuel quality) and dealerships and that education across all users and service providers will be of continued importance.


Ford has sold over 26,000 CNG-prep vehicles in the last 3 years. Annual sales have grown from approximately 3,000 units per year to around 13,000 units per year since 2010. As an outreach and marketing tool, Ford publishes an alternative fuel buyer's guide annually and uses its own qualified vehicle modifier (QVM) service to upfit CNG vehicles. Building from the comments made by GM, Mr. Gosline stated dealership facilities need to be retrofitted to accommodate CNG as the current designs accommodate gasoline (and perhaps more relevantly, a liquid fuel). Ford estimates the retrofit cost between $200,000 and $500,000 per shop and states that these capital expenses can be a non-starter for certain dealerships.


Chrysler is a relatively recent entrant in the production of light-duty CNG vehicles in the United States, launching its RAM 2500 in 2012. All of the engineering and design of this vehicle, which is a bi-fuel configuration, was done in-house. Chrysler stated that its service protocol is almost identical to what GM presented.


Q: How many Ford prep vehicles get converted?

A: There is no real way to track but likely less than 50%.

Q: Did Ford add any QVMs?

A: No, Ford actually has one less QVM equipment supplier with BAF and Westport merging.

Q: What is the cost of training technicians?

A: Ford will vary by QVMs. GM offers a 4-hour Web-based CNG and LPG overview. Chrysler will do hands-on training with the vehicle and also offers Web-based follow-up.

Q: What is the industry doing to get a better sense of how many natural gas vehicles are on the road?

A: GM has implemented a VIN feature, which will allow them and Polk to determine whether or not a vehicle fills on natural gas.

Q: What is the current thinking on limitations for light-duty CNG platforms?

A: GM said the business case isn't there for certain vehicles such as the Tahoe. Chrysler has no plans for a 3.6-liter engine, but Fiat is creating new opportunities for Chrysler to look at new platforms.

Q: Do OEMs have a process for expired cylinders or materials for dealers to be proactive on cylinder expiration? Will they turn away an expired cylinder?

A: GM has a service bulletin, Tech Tips, and materials for dealers to use, but it's ultimately up to the dealer.

Light-Duty Natural Gas Direct Injection Discussion

John Mitton, Mitton Ventures

Mr. Mitton is the primary investor in a company, Crazy Diamond, that is investigating direct-injection (DI) natural gas engines for light-duty vehicles. DI can provide leaner fuel mixtures, greater efficiency, and higher output per engine volume with better fuel control and lower emissions by putting the injector directly in the combustion chamber. The work follows a general direction toward direct injection, where Mitton cited that just a few years ago, 5 of 92 engines produced by Ford and GM were DI, whereas that number is now 34 of 77. Chrysler has not produced a DI engine yet.

Natural gas poses some similar and different challenges to gasoline DI engines. On the positive side, natural gas allows for a higher compression ratio (due to increased octane), is already atomized, and the engine valves are already hardened (although it is not clear if they are hardened enough). Key challenges are that gaseous fuel injectors are not designed for high-pressure injection, that high pressure can limit driving range, and some engine control strategy modifications are needed. Mitton outlined two approaches to addressing these challenges:

  • A high-pressure DI gas booster on a vehicle maintains 4,200 psi injection pressure.
    Mitton stated this is a good solution for heavy-duty diesel vehicles and provides up to 90% on-board fuel utilization. For light-duty vehicles operating on the Otto cycle, there are difficulties due to weight and space needed, energy loss, thermal effects, component costs, and additional high-pressure injector development needed.

  • A low-pressure direction injector LPDI.
    This is the approach that Mitton is taking, which involves placing the injector interface between the gaseous fuel injector and combustion chamber. The IID valve, part of the fuel injector, is open during the entire intake stroke and most of combustion stroke, and then closes for the end of the compression stroke and the entire exhaust and power strokes. Mitton is currently testing this approach using a GM 2.4-liter engine, 182 horsepower, 11.5 to 1 compression ratio.

Inspections and Out-of-Service Criteria for Natural Gas Commercial Motor Vehicles

Quon Kwan, U.S. Department of Transportation Federal Motor Carrier Safety Administration (FMCSA)

FMCSA recently undertook a project on vehicle inspection procedures and out of-service criteria for natural gas vehicles. The project was completed in May 2013 and consisted of a literature review, consultations, site visits, and a final report.

Out-of-service criteria are established by the Commercial Vehicle Safety Alliance and are used to identify violations that prevent safe vehicle operations. There are 14 safety critical parts in a given vehicle, which range from brakes to windshield wipers. For natural gas vehicles, the current inspection procedures for out-of-service criteria are designed to identify possible leaks of CNG or LNG. FMCSA's final report proposed additional procedures to examine pressure relief devices (PRD) or pressure relief valves (PRV) as well as vent lines inspection (if accessible). Specifically, the report also proposes adding the following procedures.

  • CNG: leak of natural gas, missing/managed PRD, or inoperable shutoff valve
  • LNG: leak, missing/damaged PRV, damaged or misdirected vent lines, or missing shutoff valve

Open Issues and General Discussion

At the end of the meeting, participants provided input on the meeting as well as topics that they would like to see covered at future meetings. The following is a list of topics suggested:

  • Dual-fuel vehicles
  • Vehicle leasing and business models
  • Portable fueling units
  • Codes around home refueling
  • Modification of garages and technologies available to support it
  • ARPA-E update
  • Vehicle fueling variability and options
  • Website overview of the DOE Alternative Fuels Data Center
  • Breakout or working groups to provide for more topics and discussions
  • Emissions regulations, new market drivers, and possible unintended consequences
  • CARB and EPA updates
  • Rail and marine opportunities within the California Energy Commission's roadmap
  • Opportunity for more informal discussion, such as an evening opening reception