Introduction - Fuel Cell Descriptions - Step-by-Step Outline - Interactive Guide - Download Spreadsheet

Fuel Cell Information Guide


Introduction
With the growing interest in fuel cell technology and applications, the DoD PAFC Demonstration Program experience offers valuable insights into evaluating and installing fuel cell power plant technology. Below is a brief summary of the approach and concepts utilized in the PAFC Demonstration Program.

The submenu items above point to descriptions of fuel cell technologies, a step by step outline to evaluating a potential fuel cell site, an economic analysis spreadsheet model to download, and an online interactive evaluation tool.

PAFC Demonstration Program Site Selection Criteria

Selection of the thirty DoD fuel cell sites was based on the following criteria:
  1. Geographic diversity
  2. Application diversity
  3. Fuel cell utilization at site
  4. Energy savings
The first two criteria are related more to overall Program goals while the last two criteria are typical for most fuel cell evaluations. It was important that the DoD Fuel Cell Program sites represent a cross section of both bases (including climate) and building applications. It was also important to identify applications where a high percentage of the fuel cell thermal and electrical output could be utilized at the site to demonstrate the greatest possible benefits. Energy savings were less important in this Program than is typical with commercial applications since fuel cells purchased by the DoD were given to Program sites. The economic criteria was for each application to generate at least $25,000 per year in energy savings which would cover annual maintenance costs. This would enable the fuel cell to pay for itself once the responsibility for maintenance was turned over to the base (~ 3 to 5 years).

PAFC Demonstration Program Implementation Approach

The site selection, design and installation of the fuel cell followed the same set of procedures at each site. The approach is briefly described below:

Preliminary screening - Base energy data from the Defense Energy Information System (DEIS) was used to rank sites by utility rates and potential fuel cell energy savings

Site Visits - USACERL and SAIC representatives visited sites, evaluated potential fuel cell application sites and discussed possibilities with site personnel.

Site Evaluation Reports - SAIC prepared a site evaluation report documenting site information, presenting conceptual fuel cell installation plans, estimation of electrical and thermal energy savings and projected energy savings.

Kick-off Meeting - USACERL, SAIC, ONSI and site personnel meet to review the site evaluation report, discuss relevant issues, schedules, etc.

Design Review Meeting - Detailed drawings submitted by ONSI are reviewed by USACERL, SAIC and site personnel. Issues are discussed and schedules for installation planned.

Acceptance Test - once the fuel cell is installed, ONSI is required to perform a number of tests for validation of installation completion. Upon completion, the fuel cell is turned over to the base, but operation and maintenance remains the responsibility of ONSI for three to five years.

Dedication Ceremony - Many sites elected to dedicate the fuel cell with invited guests. Some sites had Generals and State Governors in attendance.

PAFC Demonstration -

Site Evaluation Concepts

The following is a list of the most important issues involved in the evaluating a particular site for a fuel cell. These are discussed in general terms only.

ENERGY UTILIZATION - the best site applications utilize 100% of the thermal and electrical output of the fuel cell. The more site energy that is displaced by the fuel cell, the higher the energy savings and the shorter the pay back period will be for the fuel cell. It should noted that in the DoD Program, only seven sites were estimated to use more than 90% of the fuel cell thermal and electric output. Average estimated thermal utilization for the 30 sites was 58%.

SPACE AVAILABILITY - fuel cell dimensions coupled with spacing requirements dictates how large an area is required for the fuel cell. The PC25C measures 10' x 18' with a 8' spacing requirement on each side. With the cooling module, the fuel cell space requirement was approximately 34' x 38'.

LOCATION - the objective is to minimize piping and wiring runs to reduce costs and energy losses. Proximity to the mechanical room is generally the best location, but is not always available. Since the electrical and thermal building interfaces are not always next to each other, it is generally more important to locate the fuel cell nearest the thermal interface. Drainage paths and sloping terrain must be evaluated for the requirement for new drainage culverts or re-grading and/or retaining wall requirements which can add significantly to installation costs.

ELECTRICAL INTERFACE - in the DoD program, the fuel cell electrical interface was either tied directly into an electrical transformer or into an electrical panel. Since all the DoD facilities own the electrical transmission on each base, concern over fuel cell electrical output going into the grid is not an issue as it would be in a typical utility grid. If the site interface did not have an adequate 480 Volt interface, a step-up or step-down transformer was installed. All the DoD fuel cells were grid connected. Seven fuel cells had grid-independent capability which enabled the fuel cell to power an isolated load up to 200 kW in cases where utility grid power was lost.

THERMAL INTERFACE - design of the thermal interface was generally the most involved requirement of the conceptual design. The temperature of the site application needed to be considered. Ideally, the fuel cell would heat "city" water at a temperature <~55o F (e.g., boiler make-up water, domestic hot water make-up, etc.) and raise it to ~140o F. The cell can not interface with steam. With the high grade heat exchanger option, the fuel cell could deliver up to 250o F hot water.