The ‘Human’ Office

A challenging proposal by Battle McCarthy, has recently been selected by the University College of London for funding under it’s EngD in Urban Sustainability & Resilence programme.

The proposal entitled “The Human Office” initiative will seek to analyse the practical and commercial opportunities for harnessing ‘human’ energy to power electrical devices within the modern office environment.

The research will be carried out by UCL with Battle McCarthy acting as it’s industrial partner.

Context:

In 1992, the UK signed the Kyoto protocol committing it and other nations to cut emission of various greenhouse gases, especially CO₂. London consumes more energy than the whole of Ireland. For London to make a difference, it must not only save energy, but also produce it from renewable sources. Taking the lead from national targets, London has set its own target in the London Plan which should lead to a reduction in London’s CO₂ emissions by 23% by 2016.

Though there are many renewable energy systems available to the building services engineer, many of these systems require an investment into sourcing, and/or producing biomass sourced fuels in one form or another. Solar, hydro, wind and wave derived energy being one of the few exceptions where the ‘fuel’ source is readily available for conversion into useful energy.

Notwithstanding the above, the primary focus of this research would be to carry out an in-depth review and analysis into another form of ‘un-tapped’ energy that can potentially be harnessed from the metabolic energy contained within all of us, i.e. ‘Human Energy’.

There are many examples of technologies that can harness and convert the metabolic energy produced by human beings into other forms of energy. Many of these technologies rely on the conversion of kinetic or mechanical energy into electrical energy using, transducers or dynamos. Used in combination with super-capacitors or batteries, this energy can be stored for later use.

Aims:

To reduce the reliance on grid sourced, fossil fuel dependant, energy to power to modern commercial buildings by substituting it with energy derived from ‘human’ activities within and around the building(s).

To identify and develop appropriate technologies to harness, convert, store and distribute the metabolic energy of human beings to power modern commercial buildings, e.g. piezoelectric materials, pedal driven generators, heel-strike generators, revolving doors, sliding windows and doors, etc.

To analyse the potential energy yields from the different types of systems and processes that have been identified.

Method:

The project will use a combination of quantitative and qualitative research techniques to develop an integrated building solution to harness, convert, store and distribute energy derived from ‘human’ activity.

Outcomes:

To develop ‘human powered’ energy systems that offer good efficiencies, cost effectiveness, reliability and resilience.

Through Battle McCarthy’s experience and contacts, we will jointly be able to promote this research within the industry from a local and global front, and encourage its implementation as part of overall sustainable engineering solution.

The 10 Big Energy Myths

There has never been a more important time to invest in green technologies, yet many of us believe these efforts are doomed to failure. What nonsense, writes Chris Goodall of the Guardian.

Click here for more on this article.

Fuel Cells – An Overview

How A Fuel Cell Works

A fuel cell is an electrochemical device that combines hydrogen fuel and oxygen from the air to produce electricity, heat and water. Fuel cells operate without combustion, so they are virtually pollution free. Since the fuel is converted directly to electricity and heat, a fuel cell’s total system efficiency can be much higher than internal combustion engines, extracting more energy from the same amount of fuel. The fuel cell itself has no moving parts, making it a quiet and reliable source of power.

A fuel cell system typically comprises of three distinct parts, i.e. a Fuel Processor (Reformer), a Fuel Cell Stack & a Power Conditioner.

The Fuel Processor reforms the fuel (natural gas) to hydrogen gas to feed the Fuel Cell Stack. Note that the fuel cell can utilize hydrogen from a number of hydrocarbon fuels including natural gas, methanol, propane, biomass, and gasoline. In principle, any hydrogen compound will do. The emissions from reforming these various hydrocarbon fuels would still be cleaner than those from a combustion process. It is also possible to obtain hydrogen by separating water in an electrolyzer, or by extracting it from a compound that contains no carbon, such as ammonia or boron compounds.

Inside the Fuel Cell Stack, hydrogen gas and air are combined in an electrochemical process that produces Direct Current (DC) power, pure water and heat. The by product water is utilized in the operation of the power plant. The usable heat is available for meeting other facility energy requirements (e.g. hot water, space heating, air conditioning and cooling).

The Power Conditioner takes the DC power provided by the Fuel Cell Stack and conditions it to provide high quality Alternating Current (AC) power output.

Inside The Fuel Cell

The fuel cell is composed of an anode (a negative electrode that provides electrons), an electrolyte in the centre, and a cathode (a positive electrode that accepts electrons).

As hydrogen flows into the fuel cell anode, a catalyst layer on the anode helps to separate the hydrogen atoms into protons (hydrogen ions) and electrons.

The electrolyte in the centre allows only the protons to pass through the electrolyte to the cathode side of the fuel cell.

The electrons cannot pass through this electrolyte and therefore must flow through an external circuit in the form of an electric current. This current can power an electric load.

As oxygen flows into the fuel cell cathode, another catalyst layer helps the oxygen, protons and electrons combine to produce pure water and heat.

Individual fuel cells can be combined into a Fuel Cell “Stack” to increase the total electrical output.

Fuel Cell Types

Fuel cells are a family of technologies. Fuel cell types are characterized by their electrolytes and temperature of operation. Though there are many other types of fuel cells being developed, the following list seeks to identify the better known types of fuel cells currently available. With this wide array of technologies and applications possibilities, fuel cells are poised to revolutionize the way use energy today and in the future.

Proton Exchange Membrane fuel cell (PEM) – These fuel cells have a solid polymer membrane as an electrolyte. They operate at relatively low temperatures (60 -100°C), but new developments have produced higher temperature PEMs (up to 200°C). As platinum is the most chemically active substance for low temperature hydrogen separation, it is used as the catalyst. Hydrogen fuel is supplied as hydrogen gas or is reformed from methanol, ethanol, natural gas or liquefied petroleum gas and then fed into the fuel cell. The power range of existing PEMs is about 50W to 150KW with up to 50% electrical efficiency for the fuel cell itself and over 85% total efficiency when waste heat is captured for small scale space and water heating (combined heat and power or CHP).

PEM fuel cells have low weight and volume with good power-to-weight ratios, low temperature operation and quick start with full power available in minutes. These advantages make PEMs well suited for use in buildings, light duty specialty vehicle applications and potentially for much smaller applications such as replacements for rechargeable batteries. Quick-starting PEMs can also provide back-up power to telecommunications and other sites requiring uninterrupted power supplies (UPS).

Several challenges face PEMs. This type of fuel cell is also sensitive to fuel impurities and platinum catalysts are expensive and also subject to CO poisoning from hydrocarbon fuels, so membranes more resistant to chemical impurities, catalyst improvements, non-precious metal catalysts and other alternatives are also being developed.

Phosphoric Acid fuel cell (PAFC) - Phosphoric acid fuel cells are commercially available today. PAFCs are typically used for medium to large-scale stationary power generation and hundreds of fuel cell systems have been installed in several countries – in hospitals, nursing homes, hotels, office buildings, schools, utility power plants, airports, landfills and waste water treatment plants.

PAFCs use liquid phosphoric acid as an electrolyte with a platinum catalyst.  Anode and cathode reactions are similar to PEMs, but operating temperatures are slightly higher (150 – 200°C) making them more tolerant to reforming impurities.  PAFCs use hydrocarbon sources such as natural gas, propane or waste methane. It also has the added advantage in that it can use impure hydrogen as fuel and can tolerate a CO concentration of about 1.5%, therefore broadening the choice of fuels that can be used. The power range of existing PAFCs is 25KW to 250KW with up to 45% electrical efficiency and 85% total efficiency with co-generation of electricity and heat. However, if several units are linked together, PAFCs can achieve a combined power output greater than 1 MW (an 11 MW PAFC power plant is currently operating in Japan).

Direct Methanol fuel cell (DMFC) – These cells are similar to the PEM cells in that they both use a polymer membrane as the electrolyte. However, with DMFCs, the anode catalyst itself draws the hydrogen from unreformed liquid methanol rather than hydrogen, therefore eliminating the need for a fuel reformer. DMFCs operate at slightly higher temperatures than PEMs (120 – 190°C) and achieve around 40% electrical efficiency. DMFCs are directed toward small mobile power applications such as laptops and cell phones, using replaceable methanol cartridges with power ranges of 1-50 W.

Molten Carbonate fuel cell (MCFC) – Molten carbonate fuel cells use an electrolyte composed of a molten carbonate salt mixture suspended in a porous, chemically inert matrix, and operate at high temperatures (600 – 750°C). They require carbon dioxide and oxygen to be delivered to the cathode. The power range of existing MCFCs is 75KW to 250KW with up to 60% electrical efficiency and 85% total efficiency with co-generation of electricity and heat.

To date, MCFCs have been operated on a variety of fuels including hydrogen, carbon monoxide, natural gas, propane, landfill gas, marine diesel, and simulated coal gasification products. MCFCs are primarily targeted to electric utility applications.

Solid Oxide fuel cell (SOFC) – Solid oxide fuel cells use a hard, non-porous ceramic compound as the electrolyte, and operate at very high temperatures (800 – 1000°C). High temperature operation eliminates the need for precious metal catalysts and can reduce cost by recycling thee waste heat from internal steam reformation of hydrocarbon fuels. SOFCs are tolerant to CO poisoning, allowing CO derived from coal gas to also be employed as source of fuel. SOFCs produce a power output of 2KW to 100KW and can attain 200KW to 300KW when used in a SOFC/gas turbine hybrid system. Electrical efficiency is approximately 50% with total efficiencies of 85% with cogeneration of waste heat.

SOFCs are well-suited for medium-to-large scale, on-site power generation or CHP (hospitals, hotels, universities), and are also being marketed for telecommunications back up and as auxiliary power units (APUs) for military vehicle on-board equipment.

The challenges to both SOFC and MCFC development include slower start up when compared to other fuel cell types, requirements for strong thermal shielding, and the difficulties in developing durable materials for the higher operating temperatures.

Alkaline fuel cell (AFC) – Alkaline fuel cells use potassium hydroxide as the electrolyte and can use a variety of non-precious metal catalysts at operating temperatures slightly higher temperatures than PEMs (23 – 250°C). Fueled by hydrogen gas, AFCs have a high chemical reaction rate and offer an electrical efficiency of up to 70%. However, they are very susceptible to carbon contamination, so require pure hydrogen and oxygen.

Long used by NASA on space missions, alkaline fuel cells have been used to provide both electricity and drinking water for astronauts since the 1960s. AFCs used in the Space Shuttle missions produce 12KW of power.

Zinc Air fuel cell (ZAFC) – In a typical zinc/air fuel cell, there is a gas diffusion electrode (GDE), a zinc anode separated by electrolyte, and some form of mechanical separators. The GDE is a permeable membrane that allows atmospheric oxygen to pass through. After the oxygen has converted into hydroxyl ions and water, the hydroxyl ions will travel through an electrolyte, and reaches the zinc anode. Here, it reacts with the zinc, and forms zinc oxide. This process creates an electrical potential; when a set of ZAFCs are connected, the combined electrical potential of these cells can be used as a source of electric power. This electrochemical process is very similar to that of a PEM fuel cell, but the refueling is very different and shares characteristics with batteries. ZAFCs contain a zinc “fuel tank” and a zinc refrigerator that automatically and silently regenerates the fuel. In this closed-loop system, electricity is created as zinc and oxygen are mixed in the presence of an electrolyte (like a PEMFC), creating zinc oxide. Once fuel is used up, the system is connected to the grid and the process is reversed, leaving once again pure zinc fuel pellets. The key is that this reversing process takes only about 5 minutes to complete, so the battery recharging time hang up is not an issue. The chief advantage zinc-air technology has over other battery technologies is its high specific energy, which is a key factor that determines the running duration of a battery relative to its weight.

Protonic Ceramic fuel cell (PCFC) – This new type of fuel cell is based on a ceramic electrolyte material that exhibits high protonic conductivity at elevated temperatures. PCFCs share the thermal and kinetic advantages of high temperature operation at 700°C with MCFC and SOFCs, while exhibiting all of the intrinsic benefits of proton conduction in PEMs and PAFCs. The high operating temperature is necessary to achieve high electrical fuel efficiency with hydrocarbon fuels. PCFCs can operate at high temperatures and electrochemically oxidize fossil fuels directly to the anode. This eliminates the intermediate step of producing hydrogen through the costly reforming process. Gaseous molecules of the hydrocarbon fuel are absorbed on the surface of the anode in the presence of water vapor, and hydrogen atoms are efficiently stripped off to be absorbed into the electrolyte, with carbon dioxide as the primary reaction product. Additionally, PCFCs have a solid electrolyte so the membrane cannot dry out as with PEM fuel cells, or liquid can’t leak out as with PAFCs.

Microbial fuel cell (MFC) – Microbial fuel cells use the catalytic reaction of micro organisms such as bacteria to convert virtually any organic material into fuel. Some common compounds include glucose, acetate, and wastewater. Enclosed in oxygen-free anodes, the organic compounds are consumed (oxidized) by the bacteria or other microbes. As part of the digestive process, electrons are pulled from the compound and conducted into a circuit with the help of an inorganic mediator. MFCs operate at relatively low temperatures (20 – 40°C) when compared to other types of fuel cells. MFCs could be capable of an electrical efficiency as high as 50%.

MFCs are potentially suitable for small scale applications such as medical devices fueled by glucose in the blood, or larger applications such as water treatment plants or breweries producing organic waste that could then be used to fuel the MFCs.

Regenerative fuel cell – Regenerative fuel cells are attractive as a closed-loop form of power generation. Water is separated into hydrogen and oxygen by a solar-powered electrolyzer. The hydrogen and oxygen are fed into the fuel cell which generates electricity, heat and water. The water is then re-circulated back to the solar-powered electrolyzer and the process begins again. These types of fuel cells are currently being researched by NASA and others worldwide.

Harnessing wave power

The world’s first commercial-scale wave-power station has gone live off the coast of Portugal.

To view footage about how the 140m-long snake-like devices works click here.

For more on this story click here.

MEP Response to the London Plan

THE LONDON PLAN POLICY 4A.9

In 1992, the UK signed the Kyoto protocol committing it and other nations to cut emissions of various greenhouse gases, the most significant being carbon dioxide.

London is a special case as it consumes in a year as much energy as Greece and Portugal and more than Ireland. In order for London to make a difference, it must not only save energy, but also make it from renewable sources. Taking the lead from the national targets, London has set its own targets in the London Plan which should lead to a reduction in London’s carbon dioxide emissions by 23% by 2016.

To reach these challenging, yet achievable targets, the Mayor has defined an “Energy Hierarchy” to help organisations involved in building new developments contribute towards making London a leading city for sustainable energy. When each stage of the Hierarchy is applied in turn to an activity, it will help ensure that London’s energy needs are met in the most efficient way:

• Be Lean – Use less energy
• Be Green – Use renewable energy
• Be Clean – Supply energy efficiently

The London Plan Policy 4A.9 states that:

“The Mayor will and boroughs should, in their DPDs adopt a presumption that developments will achieve a reduction in carbon dioxide emissions of 20% from on site renewable energy generation (which can include sources of decentralised renewable energy) unless it can be demonstrated that such provision is not feasible”

ASSESSMENT METHODOLOGY

The assessment follows the format set out in the GLA Renewables Toolkit “Integrating renewable energy into new developments: Toolkit for planners, developers & consultants”.

The aim of local and national energy policy is to reduce the consumption of fossil fuels and thereby reduce emissions of carbon dioxide, a major greenhouse gas. Therefore, in common with the calculation methodology applied in the 2006 revision of Approved Document L of the Building Regulations in England and Wales, the GLA methodology assesses site energy consumption, and the contribution of renewable energy systems to reduce energy consumption, in terms of carbon. Where Part L 2006 uses units of kilograms of carbon dioxide per year (kgCO₂/year) the GLA Toolkit uses units of kilogram of carbon per year (kgC/year).

The assessment involves the following steps:

• Calculation of ‘baseline’ carbon emissions for each use on the site, with reference to published benchmark data for annual energy consumption by fuel type per square meter (kWh/m²) – converting into kgC/m² using the carbon emission factor used in Part L 2006, or using GLA Toolkit reference table data for each building type – provided as total annual carbon emissions per square meter.
• Calculation of ‘predicted’ carbon emissions for each use on the site, taking into consideration the extent of energy demand reductions that will be achieved by energy efficiency measures compared to the available benchmark data – to update the benchmarks to reflect the changes to Part L, or where specific energy efficiency measures such as CHP are included.
• Selection of a shortlist of technically feasible renewable energy systems for assessment based on a review of a range of low or zero carbon (LZC) technologies.
• Calculation of contribution of each proposed renewable energy technology to reducing the predicted carbon emissions for the development, using carbon emissions reduction factors provided by the GLA Toolkit reference tables, or where appropriate assessment tools to calculate the potential for carbon emissions reduction for specific renewable energy technologies.
• Calculation of costs of technically feasible LZC technologies, based on benchmark values for the shortlisted technologies.
• Calculation of reduction of predicted carbon emissions, for the development achieved by applying the proposed renewable technologies.
• Inclusion of proposed renewable technologies within the planning application for the development to meet the 20% carbon emissions reduction requirement.

The definition of ‘renewable energy’ used in Planning Policy Statement 22 is:

“those energy flows that occur naturally and repeatedly in the environment – from the wind, the fall of water, the movement of oceans, from the sun and also from biomass. Policies in this statement therefore cover technologies such as onshore wind generation, hydro, photovoltaics, passive solar, biomass and energy crops ,energy from waste (but not energy from mass incineration of domestic waste), and landfill and sewage gas”

This definition has been widened by the UK Government by the use of the term ‘Low or Zero Carbon Energy Technologies’ (LZCs) within the ADL documents. The carbon emissions reduction from applying these technologies when compared to the conventional technologies has also been accepted as ‘renewable energy’ under GLA terminology.

In order to achieve the goal of reducing carbon emissions by 20%, a combination or all of the following types of technologies could be integrated as part of the building’s environmental and engineering systems:

• Solar Photovoltaic (PV) panels
• Solar Thermal Systems
• Ground Source Heat Pump
• Bio-diesel fuelled CHP plant
• Wind Turbines

SOLAR PHOTOVOLTAIC PANELS

Solar photovoltaics (PVs) convert energy from daylight into electricity using a semiconductor material such as silicon. When light hits the semiconductor, the energy in the light is absorbed, ‘exciting’ the electrons in the semiconductor so that they break free from their atoms. This allows the electrons to flow through the semiconductor material producing electricity.

Solar PV panels are best mounted at an incline with a southerly orientation, although orientations between south-east and south-west are viable.

PV panels are expensive, and hot water heating is usually a more cost effective option. There exist ways to cut the relative cost of PV panels by using Building Integrated PV panels (BIPV).

SOLAR WATER HEATING

Solar water heating systems convert solar radiation to heat carried by water for use in space heating or the provision of domestic hot water. Solar water heating systems normally operate with a back-up source of heat, such as gas condensing boilers. The solar water heating pre-heats the incoming water, which is topped-up by the back-up heat source when there is insufficient solar energy to reach the target water temperature.

Solar water heating systems are best mounted at an incline facing south, although orientaions between south-east and south-west are acceptable. Solar Hot Water Panels are far more efficient than photovoltaic and could provide the development with a better return on investment.

GROUND SOURCE HEAT PUMP

Ground source heating takes advantage of the stable ground temperatures of 12ºC to heat either air or water to provide energy efficient heating (and optional comfort cooling) to a building. The energy flow is driven by the temperature difference between the ground and the circulating fluid which can be used to deliver heating (and optional cooling) to the building.

The direct bore hole type of installation requires a number of boreholes with an average depth of 100m with a minimum centreline distance of 6m separating each bore hole. This is the type of system that will require close scrutiny by the Environment Agency.

Alternatively, closed loops can be installed along the piles or pad foundations to take advantage of the foundation excavations to maximise the earth-connectivity of the system. The drawback for this option is that an indirect system requires a great deal of surface area to be in contact with the earth and is usually more cost effective in non-urban sites where more land area is available in which to place the earth-connected piping loops.

Proposals to install a Closed Loop Ground Source Heat Pump and/or a direct bore hole system to satisfy a large percentage of the heating demand for the development could be a cost-effective option. This system also offers the option of providing ‘free-cooling’ to its occupants via the use of the constant 12ºC deep-earth temperature.

BIO DIESEL BOILER

A boiler that works on natural gas provides an efficient system, but as it utilises a non-renewable source of energy, it does not contribute towards the 20% requirement. If the source of energy is switched to boi-diesel fuel, the boiler system becomes a highly cost-efficient method to meet the London Plan. The bio-diesel boiler system would use conventional diesel engines running on ‘bio-diesel’ fuel to generate heat for the development. At the moment the choice of liquefied boi-fuels is methanol, ethanol, and vegetable oils (such as rape seed oil). The US Department of Energy tests in 2001 showed that bio-diesel blends of B30 and below (30% or less) can be used as replacement fuel without significant risk – typically a B20 blend is used in place of conventional fuel oil. Too rich a blend can lead to problems of corrosion of rubber seals, so pure bio-diesel has not been commercially used.

The installation of a bio-fuel boiler may require additional approval form the relevant emissions authorities for the exhaust and flue discharge.

WIND TURBINE

Wind turbines are modern, high technology descendants of the old technology windmills that have been around for centuries. The difference is that now the kinetic energy of the wind is used to turn a turbine to generate electricity as opposed to moving water or turning a grist mill wheel. There are two types of wind turbine, one being the three bladed type (the horizontal-axis variety) which faces up-stream or down-stream of the wind and where the rotational movement of the blade is connected to a generator to create electricity. The other type is the vertical-axis design, which is by far the most flexible type of wind turbine and is best suited for the more urban sites as it is more cost effective and operates in any wind direction.

One of the big issues with wind turbines is the available wind speed. Apart from direction, approximately 4.0 m/s wind velocity is required as a minimum before the turbine will begin to generate electricity.