WO2012169902A1

WO2012169902A1 - System for supplying electricity

Info

Publication number: WO2012169902A1
Application number: PCT/NO2012/050107
Authority: WO
Inventors: Richard ESPESETH; Harry TOBIASSEN
Original assignee: Hydrogenpartner As
Priority date: 2011-06-10
Filing date: 2012-06-08
Publication date: 2012-12-13
Also published as: NO333040B1; NO20110847A1

Abstract

A system for supplying electricity in remote areas, the system including: - a primary solar cell farm (1) consisting of a number of panels of individual solar cells, the primary solar cell farm being directly connected to - a converter (2) adapted to convert a DC voltage from the primary solar cell farm (1) into an AC mains voltage for delivery to a consumer network (3), - a secondary solar cell farm (4) consisting of a number of panels of individual solar cells, the secondary solar cell farm (4) being directly connected to - an electrolyser plant (5), - a first storage means (7) for storing hydrogen produced by the electrolyser plant (5), and - a fuel cell (8) adapted to convert hydrogen from the first storage means (7) and air or oxygen into water and electricity, the electrolyser plant (5) being connected to the converter (2) for converting DC voltage from the fuel cell (8) into AC mains and delivering this AC mains voltage to the consumer network (3).

Description

SYSTEM FOR SUPPLYING ELECTRICITY

Field of the invention

The present invention relates to a stand-alone system for supplying electricity in remote areas without access to a main power grid.

Background

Remote lying cottages in the mountains have for years been equipped with solar panels for providing electricity. The solar panel is connected to a battery which is charged during daytime for providing electricity also in the night and on cloudy days when the panel cannot provide enough energy. This is a satisfactory setup for driving a few lamps and a television receiver, but is not feasible to cope with larger demands. Such demands may arise in sparsely populated areas, e.g. certain areas in Africa and Asia, with a reduced infrastructure to provide electricity. In such areas, it has been proposed to use larger solar cell "farms". The "farms" provide electricity to the consumer during daytime, while a part of the electricity is lead to an electrolysis cell producing hydrogen. The hydrogen is stored and subsequently led to a fuel cell producing electricity at night. The hydrogen is used as an intermediate storage medium. Such a system has a much larger storage capacity than battery-based systems and also a larger efficiency, i.e. less energy is lost in the conversions. However, prior art electricity producing systems with buffering based on hydrogen storage has a number of drawbacks, in particular in that complicated controlling systems are needed, the electrolysis cells used may turn out to be a bottleneck limiting the capacity of the system and in that compressors are needed in order to compress the hydrogen for storage, the compressors needing energy on their own to operate, introducing a loss in efficiency. There are known systems of this type using PEM electrolysers (PEM - Proton Exchange Membrane). Such electrolysers have far too small capacity to make a profitable alternative and are costly to produce.

Summary of the invention

It is an object of the present invention to devise a system for providing electricity using solar technology which is simpler to control than prior art solutions, which may be scaled to provide a large capacity and which is cost effective. This is achieved in a system as covered by the following claims.

The system is based on using two separate solar cell farms, one supplying electricity to the consumer during daytime, the other supplying electricity to an electrolytic cell, also during daytime. The electrolytic cell is supplying hydrogen and oxygen at a relatively high pressure rendering the use of compressors unnecessary.

Brief description of the drawings

Further properties and benefits will appear from the following detailed description with reference to the appended drawing, which is a sketch showing the principles of the present inventive system.

Detailed description

As the figure shows, the system includes a primary solar cell farm 1 consisting of a number of individual solar cells connected in series and parallel to develop a predefined DC voltage. The DC electric power from the primary solar cell farm 1 is supplied to a converter 2, the converter converting DC low voltage from the primary solar cell farm 1 into a standard AC mains voltage. The AC mains voltage is fed to the consumer(s) via a local network 3.

The system also includes a secondary solar cell farm 4 with a number of individual solar cells, again connected in series/parallel. The secondary farm is connected to an electrolyser plant 5. The electrolyser 5 is a so-called pressurized alkaline electrolyser producing hydrogen and oxygen at 1-5 MPa (10-50 bar) or more. Other electrolysers, if or when they become available, may replace the pressurized alkaline electrolyser employed in the illustrated embodiment of the invention, but the electrolyser should preferably produce hydrogen and oxygen under pressure. Then, the use of compressors may be avoided, meaning an improved efficiency compared with prior art systems. The electrolyser will produce gases as long as the secondary solar cell farm may produce any significant power. The gases are stored in suitable storage means, such as tanks 6, 7 for oxygen and hydrogen,

respectively. At sunset, the gases will be supplied to a fuel cell 8, to produce electricity during the night. The DC power from the fuel cell is then supplied to the converter 2 for conversion to AC mains. The primary solar cell farm 1 is directly connected to the converter 2, and the secondary solar farm is directly connected to the electrolyser. When using two separate solar cell farms and direct connections, control systems may be avoided altogether, meaning a great simplification of the system. The solar cycle will control the operation of the system.

The electrolyser 5 may run on hydrogen from the tank 7 and oxygen from the ambient air. However, using the oxygen from the electrolyser 5 in the fuel cell 8, instead of air, will improve the efficiency of the fuel cell. The fuel cell combines the supplied hydrogen and oxygen into water, as vapor or steam. The vapor/steam is condensed into water in the collector 9 and stored. The fuel cell will produce water during the night and the water is stored and supplied to the electrolyser for re-use during daytime. The re-use of water is beneficial for several reasons. Firstly, the plant only needs to be filled up with water initially when installed. Later, the system will be a closed process. This is a benefit in arid climates where a constant demand of water may be a problem. The use of water from the collector 9, which is clean and sterile, will prolong the lifetime of the electrolyser.

Claims

A system for supplying electricity,

c h a r a c t e r i z e d i n that said system includes:

- a primary solar cell farm (1) consisting of a number of panels of individual solar cells, the primary solar cell farm being directly connected to

- a converter (2) adapted to convert a DC voltage from the primary solar cell farm (1) into an AC mains voltage for delivery to a consumer network (3),

- a secondary solar cell farm (4) consisting of a number of panels of individual solar cells, the secondary solar cell farm (4) being directly connected to

- an electrolyser plant (5),

- a first storage means (7) for storing hydrogen produced by the electrolyser plant (5), and

- a fuel cell (8) adapted to convert hydrogen from the first storage means (7) and air or oxygen into water and electricity, the electrolyser plant (5) being connected to the converter (2) for converting DC voltage from the fuel cell (8) into AC mains and delivering this AC mains voltage to the consumer network (3).

A system as claimed in claim 1, wherein the electrolyser plant (5) is a pressurized alkaline electrolyser.

A system as claimed in claim 1, further including a second storage means (6) for capturing and storing oxygen produced by the electrolyser plant (5), the oxygen being supplied to the fuel cell (8).

A system as claimed in claim 1, further including a collector (9) for storing water produced in the fuel cell (8), the collector (9) being connected with the electrolyser plant (5) for supplying said water to the electrolyser plant (5).