Introduction
We have seen there are environmental problems associated with fossil fuels, and to a lesser extent alternative energy. While renewable energy is an attractive prospect, it must still compete economically with fossil fuel, and we will now consider if this is the case. But it is not just cost—a way of dealing with the intermittency of renewable sources might also be needed.
Energy Calculations
The key energy measurement unit as far as the end-user is concerned is the kilowatt-hour (kWh) or unit of electricity. It represents the consumption of 1,000 J of energy every second (1 kW) for an entire hour. Because there are 3,600 seconds in one hour, 1 kWh is equivalent to 3.6 MJ of energy.
For an energy producer, this is too small a unit to use. If the primary source of energy is oil, then one tonne of oil (toe) contains potentially 42 GJ of chemical energy. Dividing by 3.6 MJ, this is equivalent to 11,666 electricity units. Thermal power generation is approximately 40% efficient overall, hence 4,600 units of electricity can actually be generated from 1 toe. A barrel of oil (boe) is equivalent to 0.136 toe, and will generate 625 units of electricity. There are many other units in use, but we will keep with J, W, kWh, toe, boe and multiples of these.
Worked Examples
A car battery is rated at 12 V and has an energy content of 75 Amp-hours. This means the battery will supply 75 Amperes for 1 hour. The energy delivered each second is the voltage times the current, hence the total energy stored in the battery (in Joules) is found by multiplying the voltage by the current by the number of seconds in one hour: E = 12 x 75 x 3600 J = 3.24 MJ. This is equivalent to 0.9 kWh. A lead-acid car battery is about 80% efficient, which means that the energy put in during charging will be 0.9 / 0.8 = 1.125 kWh if the full battery capacity is to be extracted. In contrast Lithium Ion batteries used in mobile phones are 99.9% efficient. The cost to charge a battery is therefore about that of 1 unit of electricity.
It has been estimated that a typical home has an average of 4 devices left on standby each consuming about 3 W. There may also be a PC which if left on all the time will use 35 W typical when idle and the display on standby. This is a total of 0.047 kWh energy consumption. Multiplying by the number of hours in one year (8760), the devices will use 412 units of electricity, equivalent at current prices to £52-60.00 or about £13-15 per quarter.
If a room is illuminated by 8 conventional 40 W spot lamps and the lights are on for an average of 4 hours per day over the whole year, the number of units consumed in the year is 8 x 0.04 x 4 x 365 = 467.2, or a cost of £65 for that room at £0.14 per kWh. If all the lamps were replaced with a 22W compact fluorescent lamp (CFL) or tube (CFT) in the centre of the room, the calculation would become 0.022 x 4 x 365 = 32.1, a cost of £4.50 for the entire year. This is a significant reduction. LED conversion would further reduce this cost.
A fridge freezer will have an energy rating that indicates how much power is being consumed for each litre of storage. This depends on where the freezer is located, how often it is opened and so on. You can check this. If a freezer has a 0.5 kW pump and is on for 3 minutes in every hour then the total energy used is 0.5 / 20 x 24 x 365 = 219 kWh. An modern very efficient 100 litre freezer will consume 200 kWh per year, an older three times this much or more (and should be replaced for economic reasons alone).
The power of a car is normally measured in horsepower (hp). A typical car will weight 1 tonne and have a 100 hp engine. 1 hp is about 0.74 kW hence a typical car running at 50% capacity for 400 hours in the year will consume the equivalent of 0.5 x 400 x 0.74 x 100 kWh = 14,800 units of electricity. This is about 1.5 toe equivalent in primary energy were an engine 100% efficient.
Activity 1
- If the average energy incident on a 2 m2 solar panel is 80 W m-2; how many units of energy will be generated each year?
- If the car in example 5 above is 25% efficient and 1 litre of diesel has a primary energy content of 39 MJ (and weighs 0.85 kg), how much fuel is used in one year?
- A home oil-fired central heating system uses 2000 litres of fuel a year (energy 40 MJ l-1, cost £0.48 l-1). What would be the comparative cost of heating with off-peak electricity(£0.065 kWh-1) assuming 55% conversion efficiency (CCPP) , 7% transmission losses (CCPP)?
Solution
a.
| Area of panel (m2) | 2 |
| Energy incident on panel (W m-2) | 80 |
| Total energy per second on whole panel (W) (= 80 x 2) | 160 |
| Total energy produced in 1 hour (J) (= 160 x 3600) | 576,000 |
| Equivalent number of kWh / Units (= 576,000 / 3,600,000) | 0.16 |
| Number of Units in the day (= 0.16 x 24) | 3.84 |
| Number of Units in a year (= 3.84 x 365) | 1402 |
It might seem that that 80 W m-2 is rather low for Scotland, but we are taking into account the energy incident on an array will be much higher if the solar panel tracks the sun, but on the down side, the array only converts a fraction of the solar energy falling on it to electricity. 80 W m-2 would therefore be typical for Scotland. For 20 year payback, the panel purchase and installation cost should be no more than £2,800. It is actually much more than this even with grant support, and you also have to figure out how to track the sun.
b.
| Energy required by the engine in 1 second (J) (= 740 x 100 x 0.5) | 37,000 |
| Energy required by the engine in 1 hour (J) (= 37,000 X 3,600) | 133,200,000 |
| Energy required by the engine in 1 hour (MJ) (= 133,200,000 / 1,000,000) | 133.2 |
| Energy required by the engine for 1 year use (MJ) (= 133.2 x 400) | 53,280 |
| Primary energy required (MJ) (= 53,280 * 4) | 213,120 |
because the engine only turn 25% or a quarter of the primary energy in the fuel into useful work
| Energy in 1 litre of diesel (MJ) | 39 |
| Number of litres of diesel a year (=213,120 / 39) | 5,465 |
| Weight of oil (tonnes) (=5,465 x 0.85 / 1000) | 4.64 |
| Equivalent toe (= 4.64 x 1.01) | 4.69 |
From [https://en.wikipedia.org/wiki/Tonne_of_oil_equivalent] (1t diesel = 1.01 toe)
| Equivalent carbon dioxide (tonnes) (= 4.69 x 44 / 12) | 17.2 |
| Miles travelled per year @ 60 miles per hour (= 60 x 400) | 24,000 |
| Cost per year @ £1.30 per litre (£) (=5,465 x 1.30) | 7,104.5 |
| Cost per month (£) (= 7,104.5 / 12) | 592 |
| Miles per litre (= 24,000 / 5465) | 4.391 |
| Miles per gallon (= 4.391 * 4.546) | 19.96 |
The carbon footprint of this car is very high. A 100 hp car is just the engine in a large family car. Why is the performance and economy so poor? Why is the miles per gallon figure not nearer 50? Clearly the initial assumptions are incorrect. It is really a question of how much of the power of this big engine is used at any time. The car is not run at 50% full power on average. For most of the time a car moves under its own momentum. The full power of the engine is really only used for sharp acceleration
Note that the quoted power of the engine is the mechanical power and it can be measured from the acceleration: If a 1 tonne car will go from 0 to 60 mph in 10 seconds at full (constant acceleration), the force applied is 1 tonne x 60/10 (F = ma) which in SI units is 2,683 N. The distance travelled is 1/2 at2, or 134 m. The work done each second is Fd/t, or 35,900 W, equivalent to 48.6 hp. A car that can reach the same speed in 5 seconds (same weight) has an engine power of 97.3 hp.
c.
| Total energy for heating p.a. (MJ) (= 2,000 x 40) |
80,000 |
| Tonne of oil equivalent (toe) (= 2 x 0.98) | 1.96 |
1 m3 diesel fuel oil = 0.98 toe and 1,000 litres = 1 m3
| CO2 produced by oil (tonnes) (=1.96 x 44 / 12) | 7.18 |
| Cost to heating with oil p.a. (£) (= £0.48 x 2,000) | 960 |
| Number of kWh (Units) (= 80,000 / 3.6) |
22,222 |
| Cost to heat by electricity (£) (=22,222 X 0.065) |
1,444 |
|
Toe assuming 55% conversion efficiency (CCPP) , 7% transmission losses (CCPP), (= 1.98 / 0.55 / 0.93) |
3.87 |
|
CO2 produced by make electricity (tonnes) (=3.87 x 44 / 12) |
14.2 |
The figures are skewed because about 10% of the energy in oil domestic heating systems is lost in the flue gases and the carbon cost of transportation is not included. The electricity could also be renewable or nuclear generated. Generally speaking though oil or gas are an environmentally better way of heating the home.
Oil is not 100%, some heat is lost in the flue (10%).
Generation Methods and Costs
We will now look at the cost of generating one unit of electricity by different methods and how economics is likely to change as the cost of fossil fuels rise.
All power plant works on the same basic principle. A working fluid is used to move the blades of a turbine, or push the piston of a reciprocating engine such as found in small diesel power stations
The working fluid gains its thermal and kinetic energy by a variety of means: the combustion of fossil fuel; a nuclear reactor; natural energy in the environment (wind, wave, tides, geothermal); water pressure (hydro).
Fig. 1 shows a block diagram illustrating the cycle for different types of energy.
In thermal power stations, the working fluid is heated in a controlled manner. The vast majority of thermal power plants use pressurised steam as the working fluid with the energy in the steam producing rotational motion (mechanical work) in the turbine.
The turbine will then drive a generator to produce electricity (Fig. 2). In a gas turbine, hot gas from the combustion of natural gas is used to directly turn the turbine blades (steam is not used). A gas turbine will respond faster than a steam turbine and is suited to balancing, i.e. adapting to quick changes on the load (the end-user electricity demand), but the electricity produced is more costly because of the lower efficiency of the process.
A steam engine is much more efficient than a reciprocating engine. The different generation methods are categorised in Table 1.
| Working Fluid | Turbine | Piston |
| Water | Hydro, Tidal, Wave | |
| Steam | Nuclear, Coal, Geothermal, (oil, gas) | |
| Hot Gas | Gas turbine |
Diesel/Petrol engines |
| Cold Gas | Wind |
Table 1 Different methods of power generation.
Figure 1: Modular block overview of a power station. Dashed lines show special additions like combined cycle and cogeneration or optional storage [source (CC BY-SA 4.0)]
Figure 2: Typical coal-fired power station [source]
Thermal power stations can only turn a fraction of between 35% - 60% of the energy available in the primary fuel into work because of the limitations imposed by the laws of thermodynamics and losses at each step in the process (friction etc). However, the waste heat may be recovered and used for purposes other than electricity generation to improve the plant overall energy economy.
We are concerned here only with large scale generation, and the comparative cost of generating a unit of electricity by fossil fuels, nuclear power and renewable energy is shown in Fig. 3. It shows the maximum and minimum cost for the different types of generation; renewables tend to have a large variation in price, while fossil fuels are small. Fossil fuels and nuclear tend to remain around or below 100USD/MWh, while the alternative developing renewables sit above this mark.
Figure 3: The cost of electricity generation in 2020 in USD/MWh [source used under fair dealing.]
However, the rapid deployment of renewable power generation technologies, combined with high learning rates, has driven down costs. This trend is projected to continue making renewables increasingly competitive with fossil fuels in countries across the world, and the least-cost option in a growing number of markets. Utility-scale solar PV, onshore wind, and hydropower can all now provide electricity competitively compared to fossil fuels.
Levelized Cost of Electricity (LCOE) is an economic measure used to compare the lifetime costs of generating electricity across various generation technologies. The lifetime costs for generation can be categorized into the following groups:
Capital Costs: up-front costs to construct a power plant
Operation and Maintenance (O&M) Costs: costs incurred to run a power plant. These costs can be sub-categorized into fixed and variable costs. Fixed O&M costs are incurred regardless of the plant generating electricity; they are comprised of personnel salaries, security costs, insurance, etc. Variable O&M costs are directly linked to the generation of the power project. Fuel costs for conventional plants also vary with output.
Disposition Costs: costs typically incurred at the end of the useful life.
Activity 2
- List Advantages and Disadvantages for Reciprocating Engine, Gas Turbine, Fuel Cell, and Steam Turbine?
- Explain the purpose of cooling towers for energy generation?
Solution
a.
Reciprocating Engine
Advantages
- Start-up process is quick.
- Low pressure gas fuel.
- Electricity efficiency levels are high.
- Can work on partial loads with high efficiency levels.
- High grade heat (exhaust).
Disadvantages
- Emissions levels are quite high.
- If the heat produced is not used, the engine must be cooled.
- Engine cooling produces low grade heat.
- Relative maintenance costs are high.
Gas Turbine
Advantages
- Very reliable.
- Low emissions levels.
- Low amounts of cooling needed.
- High grade heat (exhaust).
Disadvantages
- Performance declines over time.
- Medium pressure gas fuel.
- Efficiency levels for part loads is low.
- Output lowers as ambient temperature rises
Fuel Cell
Advantages
- Modular design.
- No NOx emissions.
- Low pressure gas fuel.
- Noise levels are low.
- Electrical efficiency is high over load range.
- No direct air emissions.
Disadvantages
- Durability is low.
- Very high relative capital cost in relation to £/kW.
- Performance declines over time.
- If the heat produced is not used, the fuel cell must be cooled.
- Low grade heat.
- Gas fuel requires processing.
- Power density levels are very low.
Steam Turbine
Advantages
- Compact in size.
- High levels of thermal efficiency possible.
- Very reliable.
- Runs on heat instead of fuel.
- Configuration is quite versatile.
Disadvantages
- Units of a smaller size are quite high cost.
- Electrical conversion levels are low.
b.
All thermoelectric power plants that use heat to make steam to drive a turbine generator need a system to cool water. The majority use a once-through cooling system, where water is drawn from a lake, river or reservoir and is circulated within the plant to condense the steam from the turbine back into water. Cooling towers provide an energy efficient and environmentally friendly way of removing heat from this circulating water before it is returned to its source.
One of the most common misconceptions surrounding cooling towers is that the "cloud" leaving the top of a cooling tower – which is often visible from miles away and can create a trail up to two miles long from taller towers – is smoke. It is, of course, clean water vapor that results from the cooling process. It contains no pollutants, and it is not radioactive – the nuclear process takes place inside a secure containment building, not the cooling tower.
Conventional Power Distribution and Energy Storage
Power stations tend to be located away from the main sources of population and in the UK the energy is distributed on a shared network called the National Grid that runs down the backbone of the country (Fig. 4). Note that the links stop far short of areas to the north and north-west of Scotland (and the isles) that have been identified as prime locations for marine and wind energy, and the grid would have to be extended to make large-scale renewable projects viable.
Extending the grid is hard because the infrastructure is so invasive on the landscape making the planning process very difficult. Power is distributed at voltages of 132, 275 or 400 kV in order to keep power losses due to cable resistance to a minimum (Fig. 5).
If the overhead wire resistance (or more accurately impedance) is 0.01 Ohm per km and we need to deliver 1 MW over 100 km on a single wire:
| Volts (V) | Amps (I) | Heat(I2R) | Loss |
| 1 kV | 1 kA | 10 MW ! | 100% |
| 10 kV | 100 A | 100 kW | 1% |
| 100 kV | 10 A | 1 kW | 0.01 % |
| 1 MV | 1 A | 10 W | 0.0001% |
Figure 5: Transmission line energy loss calculations. Energy is lost because the current heats the wire. The losses reduce dramatically with increasing voltage (lower current).
Figure 4: The national electricity grid [source (public domain)]
Air is used for insulation, consequently the cables hang far above the ground on tall pylons. The distribution system is effective and roughly 1% (about 850MW) of the energy carried is lost in the wire. Energy is also lost through coronal discharge, and at the substations connecting into the grid that eventually drop the voltage to the 240V that reaches the home, with the result that the mean accumulated loses associated with distribution is 7%, still relatively low. You can use an interactive diagram developed by https://www.ukpowernetworks.co.uk/losses/ to determine where losses are located at different stages of distribution. The National grid has a cable capacity of 80 GW, well above the peak demand of 63 GW (https://en.wikipedia.org/wiki/National_Grid_(Great_Britain))
Keeping the load balanced is important. The generation capacity should match the demand. This can be achieved using hydroelectricity and gas turbines to manage rapid fluctuations, and assigning larger stations that have a slower response to match the very predictable overall daily demand curve. Any excess generation can be ’moped up’ using pump-storage, i.e. running a hydro plant in reverse, to soak up the difference.
Another problem is that if an intermittent source such as a large wind farm is connected into the grid, it is very hard to compensate for variation, and rapid changes over a few seconds can cause instability. And is not just keeping the supply stable — if we are heavily reliant on renewable energy as a nation, what happens if there is no wind for several days. Where would excess produced on windy days be stored for use when there is no wind? Pump storage has insufficient capacity. Do we just keep all the existing power stations on line ready for times of no wind? The argument has been made that over the entire UK there will never be a time when there is no energy available from renewable sources, but this remains to be demonstrated. Extensive deployment of renewable energy with no conventional generation backup should really be accompanied by a high-capacity storage system to smooth out variation.
The National Grid is Great Britain’s electricity transmission network, distributing the electrical power generated in England, Scotland, and Wales, and transferring energy between Great Britain and Ireland, France, and the Netherlands. There are various website which enable the public to view the live national grid status. A selected few are https://www.gridwatch.templar.co.uk/ and https://grid.iamkate.com/. Obtained data involves; Demand, Frequency; contributions from CCGT (Gas), Nuclear, Biomass, Wind and others.
Activity 3
- Why do the pylons have to be so high off the ground?
- What determines the maximum line power capacity?
- How can different stations add power to the same line, how do they keep track of whose power is being used? Can renewable energy be put on the grid?
- What happens if the demand is greater than supply?
- Are there times when renewable energy sources really are unavailable? Is there really a problem just relying on fossil fuel or nuclear at times of energy drought?
Solution
a.
High tension lines have to be off the ground so there is no possibility of something like an extended digger arm being able to reach. Also, there is a potential difference between the lines and the ground (and between individual wires). A 400 kV line 20 metres up produces an electric field underneath of 20 kV m-1; if 100 m high the field is reduced to 4 kV m-1.
Even the lower field strength is sufficient to light an unconnected fluorescent tube placed vertically under a power line. Air is a good insulator but will ionise and begin to conduct if the electric field exceeds 800 kV m-1, but considerably less for wet air. Power lines are arranged to keep the field strength well below the limit; this is more difficult when there are different phases on the lines resulting in a horizontal potential difference.
Note that huge voltage gradients are obtained routinely in the home and causes the spark of an electrical mains switch. The electrical breakdown of air generates ozone.
b.
The maximum transmission line capacity is determined by the current flow. As the current increases, the energy losses become greater and the cable heats up. This is a big problem with underground cables as there is limited natural cooling.
For distribution lines (lower voltage, usually 3 horizontal wires or three vertical wires), there is a voltage drop along the wire equal to the current flow times the resistance of the wire. As the current increases the voltage drop increases until the final voltage received by the end-user is below acceptable limits.
Transformers that step voltages up and down also have strict current limits. Increasing the current increases the amplitude of electromagnetic radiation (EMC/EMI/EMF), with distinct problems. Only a varying current will produce low frequency (50 Hz) electromagnetic radiation.
Figure 8: A lightning strike on the Eiffel tower in 1902. Example of air breaking down and conducting electricity. [source]
c.
If two supplies are at the same voltage, they will not interfere with one another. A voltage difference is needed before current can flow from one into the other. The end-user, the load, will draw power from the line though there is no way of determining where the power came from (diagram right).
A renewable energy device putting power on the grid has merely to match the voltage and phase of the line and cut out if the mains supply fails.
© UHI
d.
If the demand exceeds supply, the voltage drops to reduce the current drain and the frequency drifts. Power generation stops (or some of the load is actively switched off supply) if this happens. In a large connected system, variation may not be easy to control, and local instability can trigger a catastrophic domino effect such as occurred in the U.S. in 1983.
e.
There is no real problem with keeping power stations on standby because the amount of fossil fuel used is much reduced, but there are running costs which makes the renewable energy more expensive than were there to be an economical buffering mechanism (e.g. hydrogen). It is a very reasonable option and by strategically placing renewable energy around the UK (or even Europe), it is possible to optimise the location of resources to avoid time of no energy generation. The UK is ‘fortunate’ in that there is wide weather variation along its length and rarely is the weather uniform.
The Hydrogen Economy
The existing electricity distribution system is very efficient, but it is not the only way of transporting energy. Fossil fuels are effectively moved around the country in solid, liquid and gaseous states, though the distribution costs are more significant, particularly for remote communities.
Could excess energy generated by renewable means not be converted into some tangible form and stored for use in times of energy drought? Yes, it is relatively easy to produce hydrogen (Fig. 10) using electricity by electrolysing water.
The hydrogen is then collected and stored. The process is not subject to the restrictions of a thermodynamic cycle and is potentially close to 100% efficient. The hydrogen can later be burnt when all the energy is recovered, or a fuel cell can be used to reverse the electrolysis process and produce electricity from hydrogen. In this context, hydrogen is an energy carrier, not a source of energy. A sustainable future world where cars and buildings run off piped hydrogen produced using clean energy is the idea of a hydrogen economy emerging from the ashes of the present oil age.
Figure 10: Chemical properties of Hydrogen [source (CC BY-SA 3.0)]
This is the ultimate in clean technologies, the only ‘waste’ product from the combustion of hydrogen is pure water. There is an alternative process called Blue Hydrogen derived from natural gas, but Green Hydrogen uses a cleaner renewable process (Fig. 11).
Figure 11: Blue vs Green Hydrogen flow diagram [source (CC BY-NC-SA 2.0)].
The hydrogen economy is theoretically feasible but realisation meets with a number of technical difficulties such as significantly raising the efficiencies of electrolysers and fuel cells, finding ways to store huge quantities of hydrogen as it is very hard to compress to liquid form when designing a car that will run a reasonable distance, say 400 miles, on a ‘tank full’ of hydrogen. There is also a public perception that hydrogen is unsafe (because of the hydrogen bomb and airship disasters) - hydrogen gas burns in air at concentrations ranging from 4 to 75%. Of course the fear can be alleviated by educating people (even at school age) in the production, handing and use of hydrogen with a sensible regard for safety as it is a highly flammable fuel.
Another difficulty shared with renewable energy generation is the huge cost of building up an infrastructure for production, storage and distribution from scratch. All the basic components: fuel cells, electrolysers, and electronics to manage the load and for grid connectivity, are very, very expensive. For example; Precious metals such as platinum and iridium are typically required as catalysts in fuel cells and some types of water electrolyser, which means that the initial costs can be high.
The advantages of hydrogen fuel cells as one of the best renewable energy sources are evident, however there are still a number of challenges to overcome to realise the full potential of hydrogen as a key enabler for a future decarbonised energy system.
On the positive side, hydrogen fuel cells could offer a fully renewable and clean power source for stationary and mobile applications in the near future. To achieve this there is the need to scale up decarbonised hydrogen production and fuel cell manufacture, and develop the required regulatory framework to clearly define commercial deployment models. Further technological advances to lower the associated costs of extraction, storage and transportation are envisaged, along with further investment in the infrastructure to support it.
Figure 12: The Hydrogen Lab at Lews Castle College, UHI. It is used for training in the production, handling and use of hydrogen. The facility is linked to an electrolyser and a range of renewable energy generation devices.
© UHI
Hydrogen could become the best solution for the future of our energy requirements but this will require political will and investment to achieve. However, as fossil fuels run out hydrogen could be a key solution for our global energy needs.
Activity 4
- List and elaborate the Advantages and Disadvantages of Hydrogen fuel cells?
Solution
Advantages;
- Renewable and Readily Available: Hydrogen is the most abundant element in the Universe
- Hydrogen is a Clean and Flexible Energy Source to support Zero-Carbon Energy Strategies: Clean source of energy, No adverse environmental impact during operation as the by-products are simply heat and water. Doesn’t require large areas of land to produce
- More Powerful and Energy Efficient than Fossil Fuels: High-density source of energy with good energy efficiency. Hydrogen has the highest energy content of any common fuel by weight. High pressure gaseous and liquid hydrogen have around three times the gravimetric energy density (around 120MJ/kg) of diesel and LNG and a similar volumetric energy density to natural gas.
- Highly Efficient when Compared to Other Energy Sources: More efficient than many other energy sources, including many green energy solutions.
- Almost Zero Emissions: Do not generate greenhouse gas emissions as for fossil fuel sources, thus reducing pollution and improving air quality as a result.
- Reduces Carbon Footprints: With almost no emissions, hydrogen fuel cells do not release greenhouse gases, which means they do not have a carbon footprint while in use.
- Fast Charging Times: The charge time for hydrogen fuel cell power units is extremely rapid, where electric vehicles require between 30 minutes and several hours to charge, hydrogen fuel cells can be recharged in under five minutes. This fast charging time means that hydrogen powered vehicles provide the same flexibility as conventional cars.
- No Noise Pollution: Hydrogen fuel cells do not produce noise pollution like other sources of renewable energy
- No Visual Pollution: Some low-carbon energy sources, including wind energy and biofuel power plants can be an eyesore, however, hydrogen fuel cells do not have the same space requirements, meaning that there is less visual pollution too.
- Long Usage Times: Offer greater efficiencies with regard to usage times, with vehicle range similar as those that use fossil fuels (around 300 miles).
- Versatility of Use: As the technology advances, hydrogen fuel cells will be able to provide energy for a range stationary and mobile applications.
Disadvantages;
- Hydrogen Extraction: Needs to be extracted from water via electrolysis or separated from carbon fossil fuels requiring a significant amount of energy to achieve.
- Investment is Required: Needs investment to be developed to the point where they become a genuinely viable energy source. Requires political investment of time and money into development in order to improve and mature the technology.
- Cost of Raw Materials: Precious metals such as platinum and iridium are typically required as catalysts in fuel cells and some types of water electrolyser, which means that the initial cost of fuel cells (and electrolysers) can be high. Such costs need to be reduced in order to make hydrogen fuel cells a feasible fuel source for all.
- Overall Cost: The cost for a unit of power from hydrogen fuel cells is currently greater than other energy sources, including solar panels. This expense also impacts costs further down the line, such as with the price of hydrogen operated vehicles, making widespread adoption unlikely at the moment.
- Hydrogen Storage: Storage and transportation of hydrogen is more complex than that required for fossil fuels. This implies additional costs to consider for hydrogen fuel cells as a source of energy.
- Infrastructure: Because fossil fuels have been used for decades, the infrastructure for this power supply already exists. Large scale adoption requires new refuelling infrastructure to support it.
- Highly Flammable: Hydrogen is a highly flammable fuel source, which brings understandable safety concerns. Hydrogen gas burns in air at concentrations ranging from 4 to 75%.
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