DOE Invests $20 Million in Fuel Cell and Hydrogen Research (Part 1 of 2)

In October, the Department of Energy announced an investment of $20 million in fuel cell research and technologies, to be allocated among ten projects. The ten funded projects will focus on fuel cell research ranging from hydrogen production using microbial biomass conversion to optimization of platinum metal catalysts used in the electrodes of fuel cells.

The fuel cell industry has undergone recent, rapid growth, making it one of the most quickly expanding and one of the most promising clean energy industries. The DOE’s 2014 market report on fuel cell technologies notes a number of favorable trends in the fuel cell industry in 2014, during which the industry overall grew to $2.2 billion, from $1.3 billion in 2013. More than 50,000 fuel cells – equating to about 180 megawatts of power – were shipped worldwide in 2014, and fuel cell technology was reportedly used to power facilities, forklifts, data centers, and cell phone towers in 25% of the top hundred Fortune 500 companies.

Additionally, 2014 saw the commercial introduction of fuel cell electric vehicles (FCEVs) in the U.S. and several other countries. Hyundai began leasing FCEVs in southern California starting in late 2014, and Toyota and Honda announced that they will begin selling FCEVs in the U.S. beginning in 2015 and 2016, respectively.

Fig 1

Fig 2.jpb

Number and megawatts of fuel cells shipped worldwide from 2008 to 2014. Image from DOE 2014 Market Report on Fuel Cell Technologies.

Fuel Cells and Hydrogen Production: Brief Background

Why fuel cells? Fuel cells are more efficient than the traditional combustion engine and can produce electricity from the chemical energy of a variety of fuels with efficiency of up to 60% without generating carbon dioxide emissions.

fig 3

A comparison of different methods of generating electricity. Image from Renewable and Sustainable Energy Reviews.

Additionally, fuel cells can be built to a wide range of scales, making them capable of powering a system ranging from the size of a power plant to the size of a laptop, and consequently have the potential to be used for a wide range of applications. Finally, fuel cells are quiet, due to a smaller number of moving parts.

fig 4

Scope of fuel cells. Image from DOE Fuel Cell Technologies Office Fact Sheet.

Fuel cells convert energy stored in chemical bonds to electricity through a series of oxidation-reduction reactions (reactions involving the transfer of electrons). Like batteries, fuel cells consist of an anode (a negative electrode) and a cathode (a positive electrode) separated by an electrolyte (a substance that conducts charged ions but not electrons). However, unlike batteries, fuel cells are able to generate electricity and heat as long as fuel is supplied. The electrodes of fuel cells, which are embedded or coated with a porous layer of a catalyst that facilitates the ionization of the fuel by increasing the rate of oxidation, are not degraded.

Hydrogen is commonly used as fuel for fuel cells. Not only can hydrogen be derived from a wide variety of hydrocarbon sources, but the sole byproducts of a fuel cell using pure hydrogen are water and heat. Hydrogen is supplied to and oxidized at the anode, generating protons and releasing electrons; the protons diffuse through the electrolyte to the cathode. The freed electrons flow through an external circuit, generating an electric current, before ultimately reaching the cathode, where oxygen is subsequently reduced. The ionized oxygen combines with protons at the interface of the cathode and the electrolyte, forming solely water as exhaust.

fig 5

Chemical reactions at anode and cathode (electrochemical half-cell reactions). Image from Renewable and Sustainable Energy Reviews.

fig 6

Fuel cell schematic, with cathode, anode, and electrolyte. Image from AccessScience (McGraw-Hill).

Most hydrogen currently produced in the U.S. comes from the steam reforming of natural gas. However, renewable methods that result in zero greenhouse gas emissions are being explored. In electrolysis, electrolyzers (consisting of an anode and a cathode separated by an electrolyte) split water into oxygen and hydrogen using electricity, but current grid electricity is dependent on energy technologies that result in greenhouse gas emissions. Photolytic processes can utilize sunlight to split water into hydrogen ions and oxygen. Photobiological hydrogen production uses photosynthetic microbes such as microalgae or cyanobacteria to break down organic materials and release hydrogen, but currently, solar-to-hydrogen efficiency is too low for this technology to be commercially viable. Finally, although biomass-derived liquids are a renewable energy source, generating hydrogen from biomass-derived liquids is currently more difficult and more expensive than reforming natural gas, due to the large size of biomass molecules.

 fig 7

An electrolytic cell for the production of hydrogen. Image from the DOE Fuel Cell Technologies Office.

 

Next: Part 2 – An overview of hydrogen production using microbial biomass conversion, one of the research projects funded by the DOE’s $20 million fuel cell research program