This article first appeared in the May 2016 issue of Business Energy.
Given that energy sustainability and energy economics are top-of-mind among business leaders, politicians, and the public these days, hydrogen fuel cells may be viewed as a savior technology. If that statement seems hyperbolic, there is plenty of statistical evidence to support the growth of fuel cell use for both stationary and transportation applications. The growth in both application categories bodes well for business owners who seek to reduce their reliance on the electrical grid and reduce emissions from operations.
In its “Fuel Cell Technologies Market Report 2014,” the US Department of Energy (DOE) reports that the fuel cell industry grew by almost $1 billion in 2014, reaching $2.2 billion in sales, up from $1.3 billion in 2013. Major increases were seen in North America and Asia Pacific revenues, spurred by fuel cells for the US material-handling market, large-scale stationary power sales by US companies, and the residential market in Japan.
The DOE report also provides an overview of how fuel cells work. Types of fuel cells include molten carbonate, solid oxide, phosphoric acid, direct methanol, and low- and high-temperature proton exchange membrane. The devices electrochemically combine hydrogen and oxygen to produce electricity, water, and heat. Unlike batteries, fuel cells continuously generate electricity as long as a source of fuel is supplied. And, unlike other energy processes, fuel cells do not burn fuel, which makes them quiet, pollution-free, and two to three times more efficient than combustion. When hydrogen is produced from nonpolluting sources, a fuel cell system is a truly zero-emission source of electricity.
The DOE identifies three market categories for fuel cell technology: stationary power, transportation, and portable power. Stationary power is defined as any application in which the fuel cells are operated at a fixed location for primary power, backup power, or combined heat and power (CHP). Transportation applications include power for passenger cars, buses and other fuel cell electric vehicles (FCEVs), specialty vehicles, material handling equipment, and auxiliary power units for off-road vehicles. Portable power applications utilize fuel cells that are not permanently installed or are in a portable device.
That hydrogen serves as an energy carrier for fuel cells, i.e., as energy from another source is used to generate hydrogen, which stores the energy until it is used to power a fuel cell, points out the DOE. In many fueling technologies, fuel cells integrate with a fuel processor to produce a hydrogen-rich gas from a hydrocarbon-based fuel such as natural gas or propane. It is also possible to store high-purity hydrogen directly in the fuel cell.
Stationary Power, Including CHP
The DOE subdivides the stationary fuel cell market category into several sizes and sectors: large-scale systems for prime power, backup power or CHP, small systems for micro-CHP (m-CHP) that suit residential or commercial operations, and prime and backup systems for remote or essential applications (e.g., data centers and telecommunications towers). Systems can range in size from several kilowatts to multiple megawatts.
Jesse Hayes, PureCell product manager for Doosan Fuel Cell, reports that fuel cell technology is well-suited to many commercial, institutional, and industrial applications. Doosan designed its PureCell phosphoric acid fuel cell for stationary power CHP applications. The Doosan PureCell Model 400 is rated for 440 kW with multiple unit installations ranging from 880 kW to 30 MW. The scalability of the Model 400 is a good fit for facilities such as hospitals, data centers, corporate campuses, college campuses, pharmaceutical, and other manufacturing processes. The Model 400 operates on natural gas and generates 440 kW of clean electricity and 1.7 million BTU per hour of usable heat.
Fuel cells offer ultra-low emissions due in part to high-efficiency chemical processes rather than combustion and the use of natural gas fuel—the cleanest fossil fuel resource. Fuel cells are an efficient, continuous-duty, and ultra-low emission distributed energy resource. The PureCell product line is designed to use phosphoric acid fuel cell technology to achieve fast-ramping dispatch capability and the ability to transition to a critical power mode at up to 400 kW in less than five seconds in the event of a utility outage. These two aspects of the Model 400 suit clean technology microgrids. Additionally, fuel cells provide continuous dispatchable power, unlike wind and solar systems, which have intermittency issues.
The development of the Model 400 and its predecessor, the Model 200, focused on durability of the core technology, the cell stack. Doosan’s decision to utilize the medium-temperature phosphoric acid architecture resulted in the Model 200’s five-year stack life, which was subsequently increased to 10 years with the introduction of the Model 400 in 2009.
Fuel cell-powered CHP systems provide baseload electric power and heating to a facility; when a fuel source also powers cooling applications, the system is referred to as trigeneration. According to Doosan, combined use of heat and power can deliver 90% system efficiency. In non-CHP applications, nearly two-thirds of the energy used to generate and distribute electric power is wasted in the form of heat discharged to the atmosphere. Most of Doosan’s installed global fleet is made up of CHP applications, Hayes reports.
Using fuel cells for stationary power carries several significant benefits. For one, fuel cells are a clean power source. Doosan’s PureCell systems, for example, operate on low-emissions natural gas and qualify for four to six Leadership in Energy and Environmental Design (LEED) points. The combustion-free electrochemical process that occurs in powering fuel cells results in ultra-low emissions of pollutants such as NOx, SO2, carbon monoxide, volatile organic compounds, particulate matter—significantly below that which occurs in utility-generated power and reciprocating engines.
The system’s emissions fall well below the California Air Resources Board (CARB) 2007 limits for distributed generation. This means that fuel cells are considered such a clean technology that the South Coast Air Quality Management District in Los Angeles has ruled that they do not require clean air permits.
Hayes points out that other technologies used for CHP require air permits, which are sometimes difficult to obtain, and they also need exhaust gas treatments to process unburned hydrocarbons and prevent formaldehyde emissions. “Their exhaust gas cleanup systems take up space, are complex, and have extra moving parts for urea pumps. Tanks and maintenance on those systems is needed. Fuel cells are inherently clean and do not need exhaust gas treatment.”
In addition, fuel cells generate minimal noise pollution. Fuel cells do not have moving parts, e.g., pistons and cylinders, as technologies such as reciprocating engines do. Noise from the PureCell process are limited to fan and pump operation or natural gas flowing through pipes, which generates 60 dBA or less at 10 meters, about the level of normal conversation. Hayes points out that many other technologies require the construction of soundproof enclosures.
Another environmental benefit of using fuel cells is water savings. The PureCell system, for example, is designed to operate in water balance, with no consumption or discharge of water in normal operations. In contrast, central power generation requires a substantial amount of fresh water to cool the turbine generators, resulting in the use of millions of gallons of water at a typical plant.
Providing Control Over Economics
The benefits of fuel cells for stationary power go beyond sustainability and positively impact economics. For one thing, fuel cells provide utility cost control. “If someone purchases a fuel cell system, they take control of their energy costs,” says Hayes. “In places where electricity is five cents per kilowatt-hour, you’re likely burning coal to get that power. Where utilities are pressed to do better with their emissions, increases in costs are borne by the rate payers.” He adds that customers with high electric rates can adopt fuel cells to reduce their reliance on the grid for their power and control their energy costs.
Hayes notes that fuel cells have not yet been produced in mass quantities. When that happens, the economies of scale will help reduce equipment costs. “If we look at the solar industry, there are huge quantities of panels being made and prices are coming down drastically—the same will be true of fuel cells,” he says. Initial investment is a barrier in the Midwest, where coal-fired power plants are plentiful and electricity costs five to six cents per kilowatt-hour.
“With electric rates that low, it’s hard to convince someone to sign off on a project that will make electricity cost 10 cents per kilowatt-hour, even if it’s orders of magnitude cleaner,” he continues. “But, if you look at the handful of more progressive states, they have clean energy portfolio standards or incentive programs, such as net metering, that include fuel cell technologies. I’ll agree that natural gas is not a renewable fuel, but it is the cleanest possible fuel resource, coupled with an ultraclean technology in fuel cells. If you shift the conversation from renewable technologies to ultraclean technologies, one, it addresses the intermittency and non-dispatchability issues of solar and wind, and it allows us to use the right mix of technologies to address a broader energy sustainability need. One of the benefits of our fuel cells is that they have a very high-capacity factor, so we generate roughly six times more energy as an equivalently sized solar panel throughout the course of a year.”