|
Long Backup Power solutions with a Fuel Cell and Battery combination to a DC/DC cycling even for off-grid
I. Introduction
The globalisation and their consequences leads to more demand on power on a worldwide base. This trend is not stopping on continents or countries and sides where unreliable grids are a normal situation. The demand of having wireless networks available and running is more a must, than a can be. So with clean energy concpts we can solve these problems in bringing up a hybrid solution with Fuel Cells and Batteries, as the best combination to get long Backup power and reduce the H2 consumption.
In the Telecommunication we see this demand since years growing, and different types of hybrid combinations have been tested. The Fuel Cell is a wide spreaded solution with all the benefits of a reliable Backup solution. This is running excellent in countries where H2 is easily available, and comes to its limits in countries where the distribution might be a problem. So the combination on a Fuel Cell with the right Battery can help reducing the consumption of H2 and reduce the OPEX.
II. FC/Battery combination versus Hydrogen only. A typical BTS needs to have a power consumption ap. 2 kWh without AC which needs an add on of ap. 1.5 kWh around 6 hours during the day. The total power is ( 2x24 + 6x1,5) 57 kW/d. The normal used Backup time is between 4 -8 hours, so between 14 and 28 kW. A Fuel Cell running on 3.5 kW per hour needs 1 bottle every 4 hours. (Europe 1 Bottle 200 bar with 50 liters and 8.9 m³). This means we do need every day between 1 and 2 bottles. A bundle of 12 bottles (6 to 12 days) can reduce the distribution first. The use of a hybrid system with Fuel Cells and Batteries can even do more with a DC cycling.
As shown by the graph, the concept behind DC cycling is to allow the FC to oper-ate at its peak efficiency and to shut off during low load demand and let the bat-teries power the load. This saves fuel and maintenance. Also shown is the Fuel Cells fuel reduction as the load decreases due to the variable speed feature of the Fuel Cell. Allowing the FC speed to change and operate at near its most effi-cient power points also reduces the fuel consumption rate. With the right type of a cycling battery we can reduce the runtime by 20 to 25 % and the numbers of starts by more than half.
The power output of a FC can be regulated so we can operate closer to the ideal FC power curve. This saves fuel because we can make use of smaller FC dis-placements. In the chart we show the FC operating at 80 % of its rated power.
III. Installations in the field Backup Power solutions have been installed in the field with small Batteries to reduce the demand of the Fuel Cell coming up on every peak of loss of the grid, and others with high capacity batteries to optimize the fuel consumption especially in long backup power solutions. Off-Grid solutions are coming more into the market and here the H2 consumption is the main cost driver.
IV. Summary The commercial available fuel cell with a combination of the right battery in areas where H2 distribution is an issue, is available and can reduce the consumption of H2 in the field but can offer a very good combination for long Backup Power which is being used in the off-grid solutions.
Hoppecke Batterien GmbH (Power from Innovation) (www.hoppecke.com)
Department: Key-Account-Manager Telecom/IT, Head of Department
Mr. Michael Tausch (michael.tausch@hoppecke.com) |