GB2449102A

GB2449102A - Urban power generation platform for use on street lampposts

Info

Publication number: GB2449102A
Application number: GB0708993A
Authority: GB
Inventors: Clive Nicholas Jordan
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-05-10
Filing date: 2007-05-10
Publication date: 2008-11-12
Also published as: GB2449102A9; GB0708993D0

Abstract

A platform can be mounted on a street-lamp such that the platform can be used as the base for mounting various modular power generation or utility designs. Solar power or micro-wind turbine modules may be mounted on the platform and can utilise existing street-lamps, which may becomes a low-voltage DC network enabling the lamps within the street-lamps to be replaced by high efficiency solid state devices such as LED's. Several power generating street-lamps may be connected together in a DC island and their combined output may be passed through an inverter and connected to the national grid network. A back-feed may be provided from the grid to ensure supply when power is not being generated. Wireless internet routers/antennas, WAN, cameras or other modular devices may be mounted on the platform and any data generated modulated over the DC network and connected to the internet via a suitable gateway.

Description

URBAN POWER GENERATION PLATFORM

Using Street-Lighting Infrastructure for Power Generation

Background

In order to reduce the amount of fossil-fuels consumed for electricity generation, it is necessary to both increase the number of alternative energy power generation units and use a diverse range of energy sources to generate power suitable for putting back into the National Grid.

Large wind-turbines require air that is not disturbed by local topography, often requiring

green-field or remote installation.

The availability of affordable solar panels and so called micro-wind turbines' has opened up the possibility of moving alterative-energy power generation back towards more-populated areas, where the power is needed most. These solutions typically produce small amounts of power (usually less than 500 Watts), but if used in sufficient numbers, could make a worthwhile contribution to overall energy production.

Despite the hype, mounting a small wind-turbine (<2m wingspan) on a residential house roof will produce very little power. There is too much turbulence this low to the ground and the noise and vibration transmitted through the building may be unacceptable. To reach the wind, the turbine needs to be above the roof-line, or in special cases, located where buildings funnel' wind, something that is evident in several large cities. Solar panel siting is less demanding but still need mounting away from overshadowing buildings.

In addition to the issues of siting alternative energy generators, there is the additional problem of converting the energy to a usable form. The most useful solution is to push the extra power back onto the National Grid. Solar panels typically generate DC voltage and are often connected in such a way to produce outputs of 12, 24, or 48 volts. Small Wind Generators usually produce AC volts (usually at the frequency of rotation) somewhere in the same range, namely 12-48 volts. In order to feed the output of these devices onto the National Grid, a mechanism is needed to convert their various outputs to 240V AC Single Phase or 440V AC, 3 Phase.

Turning our attention briefly to street lighting, there are millions of street lights around the UK, many large stretches of road in relatively remote areas as well as built-up ones.

These often use neon or argon gas and although more efficient than incandescent bulbs, they do not produce natural light, but usually an orange tinted light. Power Light Emitting Diodes (LED) are now being produced that are starting to approach the efficiency of fluorescent lights and as time goes on, more efficient LEDs will emerge, making them the light-source of choice for efficient lighting. One of their other key benefits is they

I

produce pure white light (or other colours depending on the manufacturing process).

LEDs are low-voltage devices that are best suited to DC applications.

My proposal is to take all these factors to not only reduce energy consumption, but also to use the existing street-lighting infrastructure as a backbone to house a large number of small alternative-energy power generators. The street-light bulbs' themselves could be replaced by low-voltage LEDs and the existing wiring could be used as a low-voltage DC network between lampposts which each generator could feed. A group of lampposts could then be pooled and connected via an inverter (or similar) back onto the National Grid. Depending on cost efficiencies, many generation islands' can feed the grid via its own inverter allowing for resilience and diversity of power generation. To this end, the goals are: (1) Use existing lamppost infrastructure.

(2) Replace aging street-lights with lower energy alternatives.

(3) Create a low-voltage lighting network using existing wiring.

(4) Push excess power generation back onto the grid using one inverter per generation island.

(5) Install generic platforms' that can be easily mounted on lampposts to host a variety of power-generation or utility devices (eg wifi receivers).

Even in built-up areas, street-lighting offers the perfect platform for mounting solar panels which are high off the ground and usually free from overshadowing obstacles. One particularly useful area would be motorways with their miles of large double-armed lamp posts. Utilizing this dead-space by deploying solar-cells along their length could produce substantial amounts of power. Some more rural locals may benefit from mounting small wind-turbines on the lampposts if local conditions suit. Again, lampposts provide a mounting site high above the ground, out of harm's way, and where the wind is cleaner.

Although perhaps requiring a higher maintenance overhead, having a diversity of generating sources ensures a continuity of supply. Since the lamppost infrastructure already exists, it should be possible to deploy these generators in locations where cost would have previously been prohibitive and by being geographically spread should ensure a high average power-generation total.

Overview The key to the system is to produce a generic platform that is capable of being fitted to a variety of existing lamppost designs and is modular in design so it can be used for multiple purposes and also to reuse as much of the existing mechanical and electrical infrastructure. For example: -Allow the bolting-on of a standard' solar panel design.

-Have receptacles/bolt-holes to install a small extension tower suitable for mounting a small wind-turbine.

-Allow bolt-on of a standard' environmental-senor module. This could be used to monitor wind-speed, temperature, sunshine hours etc and would be typically used to see if a particular location was suitable for wind/sun power generation, orjust for collecting meteorological data. Real data about average wind-speed etc is limited in urban areas making it difficult to assess a site's suitability for power generation.

-Allow other modular devices to be added easily. One such example is a wireless access point. It would be possible to allow public access to the internet via WiFi, using the electricity network rather than the telephone network. This would remove the BT local-loop from the equation and bring cheap free internet to a larger part of the population.

Apart from being modular, there are several other factors that must be taken into account: Safety This is paramount. Obviously, the platforms must be secure and nothing should fall off even in adverse weather conditions.

Environment/Structural The platform must be capable of handling large snowfalls, not produce icicles and withstand extremes of heat, rain etc. The platform must not compromise the structural integrity of' the post on which it is mounted. Steps must be taken to prevent them becoming desirable roosting perches for birds.

Minimize maintenance The design of anything mounted on the platform should be done so as to minimize maintenance. Where routine maintenance may be required, it is desirable to make access at ground level rather than on the platform itself. It is better to run extra cables down the lamppost rather than require a cherry-picker to fix something at the top of the pole.

Inverter Several power-generating lamp posts will be connected together in a low-voltage network and fed into an inverter (or similar voltage-converter) to step the voltage back up to grid AC, typically 240v. Each inverter will be mounted at ground-level and the number of power-generating lampposts connected to one inverter will be dependant on costs and efficiency studies made on the generators and inverters. For example, if each pole produces 500 Watt of power, 100 connected together will produce 50kW which could then be put through one inverter. In Europe, this is enough to power about 10 domestic houses.

A mechanism must be put in place to ensure the low-voltage grids are powered from the grid during times when the lamp-posts are not generating power to ensure the lamppost perform their primary function of lighting the streets. A solar-powered network will need an external feed at night.

Transmission Losses Direct Current is not the most efficient mechanism for transmitting power so the exact voltage/current generated and sent over the low-voltage network would be selected carefully. U may prove more efficient to use a 48 volt network in preference to a 12 or 24 volt one. This will be weighed off against the type and efficiency of commercially available inverters (converting 48VDC -> 24OVAC is probably more efficient than converting I2VDC -> 240 VAC).

The size of the low-voltage islands' will need analysis both for efficiency and cost-effectiveness. The more generators connected together in an island, the less inverters are needed although each inverter will require to be larger. Transmission losses over large islands may be considerably more than those on small islands.

Through Life Costs Everything has a usable lifespan. Solar cells are no different. Currently they have a approximate lifespan of 25 years after which their generated output will gradually drop-off. With this in mind, the construction of the solar panels and their attachment to the generic platform should make them easy to replace and recycle. As many parts of the solar panel should be capable of being harvested for recycling with minimal cost.

Replacing solar-panels on a 25 year cycle will still be considerably less expensive (and more environmentally friendly) than having to decommission a nuclear plant and as time progresses, the lifespan of solar panels should become extended with technological advances.

National Grid Impact If this proposal was adopted on a very large scale, there will be an impact on the National Grid as more power is put into it at specific times (eg daylight) while the demand will still be required at other times. More mechanisms for storing excess energy rather than generating it may be required. Pumping stations such as the one at Port Dinorwic are more desirable than other fossil fuel/nuclear options.

Wind Turbine Safety The power generated from the wind rises as the cube of the wind-speed. In very high winds, turbines need to be braked or furled to prevent them overheating or rotating excessively fast. Larger turbines adjust the pitch of the blades but smaller micro-turbines will require a simpler tail-furling mechanism with less moving parts/motors. The aim is to keep the design as simple and maintenance-free as possible. Wind turbines will require more maintenance than solar panels due to moving parts but provided brushless designs are chosen, they can still be kept very simple. Safety should be kept in mind at all times and designs should be such that turbine blades are robust enough not to break and fall off.

Wind turbines will probably be better suited to more rural areas rather than urban ones where human traffic is less dense.

Using Lamp Lighting Network For Data Transmission If a Wifi access point module is mounted on the platform, it would be possible to modulate the data signal onto the low-voltage network and it could be demodulated at the inverter and a connection made to the internet backbone. Although adding this (comparatively) complex technology to the platform would compromise its simplicity, the benefit of free/cheap internet access for all may well justify the approach. To ease maintenance, it would probably be better to add the modulator circuitry in the base of the lamppost and possibly run extra wires to the platform. This would make maintenance more straightforward and most of it would be at ground-level. Ideally, only the aerial should be mounted on the platform and all the electronics could be put in the base. Metal lampposts will provide good screening from RFI which may make this approach feasible.

Other Uses -Cameras, Radio Masts etc. Having a generic tower-attachment would enable other items such as speed-cameras, radio antennas etc to be added to the platform rather than a wind-turbine. Great cost savings could be achieved if all units had the same mounting mechanism.

Details Figure I gives an overview of the scheme. This shows 3 generic platforms mounted on 3 lampposts. Two have been configured as solar-generators, the third as a wind-generator.

The three posts are connected together using the existing street-lighting wiring as a low-voltage network. Te low-voltage network is converted via an inverter back onto the national grid. Additionally, a will-antenna is used on one platform to piggy-back data over the low-voltage network to the iriverter. Here it is demodulated an connected to the internet back-bone.

The main points that 1 am trying to convey here are: * Simplicity. Use a generic platform that can be fitted to various lamppost designs which can have standard accessories' bolted to It.

* Wiring Reuse. Reuse the existing street-lighting wiring as much as possible, using the 240 v network as a low-voltage network.

* Replace existing street-lamps with high-efficiency, low power DC LEDs.

Simplicity The platform should be easy and cheap to manufacture, strong, long-lasting and if possible, recyclable. I believe steel would probably be the best choice but more details would be needed about street-lamp mechanical design before such a decision could be made. The weight of the platform may be more important than any other factor.

Furthermore, details about the different types of lamppost designs would be needed so that universal mounting arrangements could be devised. The aim is to have one generic platform that fits all. Figure 2 shows simple right-angled mounting lugs although more elegant designs could be produced if required.

The size of the platform is indicated as 2 metres square in Figure 2.

Depending on lamppost design and strength, this may change.

Figure 3 shows a standard' solar panel being bolted onto the platform. Once a generic platform has been decided upon, the mounting dimensions can be standardized and mass-production of rnultiple-sourced solar panels could be undertaken. Easy replacement and recyclability should be key factors in solar-panel design.

Figure 4 shows how the same mounting holes can be used to affix a small wind-turbine. In effect, this is standard' bolt-on tower to which the turbine would be mounted. Such a tower could be used for a radio mast (eg police etc), telephone mast, camera mount or WAN antenna if necessary. Depending on the signal propagation, it may be more beneficial to mount Will antennas underneath the platform rather than (0 above it. Some field trials would be necessary to determine the best siting of such an antenna.

Figure 5 gives a couple of ideas to protect the platform from the environment. Perforating the platform with large holes will assist in reducing snow-buildup and also help reduce the weight of the platform itself. If bolt-lugs are radiated around the platform, thin wires could be threaded through these (over the solar panel) to make it difficult for pigeons/birds to use the platforms as perches. In dire weather conditions the wire could be heated to melt snow and ice that had formed on the platform.

Claims

URBAN POWER GENERATION PLATFORM

Figure I gives an overview of the complete system.

I. A Generic platform with various connection mechanisms that can be mounted on top of a variety of lampposts with receptacles for the addition of various modules which can make use of the existing lamppost wiring infrastructure where possible.
2. Building on claim 1, modular solar panels can be mounted on the platform, the output being fed into the existing wiring used by the lighting. Additional wiring may be required where necessary.
3. Building on claim I, a modular mico wind-turbine can be mounted on the platform, the output being fed into the existing wiring used by the lighting. Additional wiring may be required where necessary.
4. Building on previous claims, the existing wiring would be isolated to become a low-voltage DC power generation/I ighting network.
5. Building on previous claims, replacement of the existing streetlight bulbs with high.

efficiency, low voltage Light Emitting Diode modules.
6. Building on previous claims, the low-voltage network would be divided into power-generation islands' and connected to the national grid via a power inverter, one inverter for N power generation Units.
7. Building on previous claims, a modular WiFi module can be mounted on/under the platform and data piggy-packed onto the power wiring which can be demodulated and connected to the internet either at the inverter or at a separate location. Additional wiring may be required.
8. Building on previous claims, modular surveillance cameras can be mounted on the platform, the output being fed into the existing wiring although additional wiring may be necessary. A modulation/demodulation mechanism could be used (similar to claim 7) to extract data collected from the cameras.
9. Building on previous claims, a modular data collector (primarily meteorological) can be mounted on the platform, the output being fed into the existing wiring although additional wiring may be necessary. A modulation/demodulation mechanism could be used (similar to claim 7) to extract data collected from the cameras. Alternatively, data could be stored within the module and collected when the module was retrieved.