Tuesday 14th November 2017 – ‘Don’t buy an electric car’
Professor Averill Macdonald, University of Southampton
Professor Macdonald apologised for the absence of her co-presenter, Professor Alun Vaughan who was not able to attend.
She opened her talk by stating that she had nothing against electric cars and saw them as a very attractive proposition for reducing pollution levels in towns. However if everyone bought an electric car, far from being a benefit to our environment, there would be serious consequences for the UK’s electricity supply.
The majority of the UK’s electricity is still generated from fossil fuels (coal and gas) as shown opposite. In showing this picture, our speaker did accept that most of the visible emissions from the cooling towers are steam, but obviously the plume from the chimneys adds to pollution. As the majority of present day electric cars require charging from the grid, we effectively shift the source of pollution from the road to the power station.
The electric car isn’t quite the clean option we like to think, particularly when we take into account the materials and processes required to build the car and, particularly, the battery itself.
There are also proposals to install rapid chargers providing 125 A and giving 80% charge in 30 minutes, which could be useful if away from home with a partially discharged battery. One problem for people without off-road parking is that it isn’t possible to trail a cable from your house to your car parked in the road, so specialised charging points will have to be installed in areas where cars have to be parked in the road. Even if these charging problems can be overcome, the major problem is the effect that large numbers of electric vehicles would have upon the grid.
Professor Macdonald then presented the calculation opposite, showing that currently the national grid is capable of providing approximately 1KW of electrical power per person. In the UK there are around 32 million cars on the roads. If only a third of us bought electric cars, equating to about 10 million vehicles requiring charging, the majority overnight on a 32A charger, the connected load would be on average say 80 GW.
During the summer our lowest demand is about 40GW, but on a winter’s night we currently need 55 GW. We would have to substantially raise the grid’s reserve generating capacity to find another 80GW for all these electric vehicles.
The most popular electric car, the Nissan Leaf, shown opposite, has a claimed range of 124 miles and a practicable range of about 90 miles before the driver experiences ‘Range Anxiety’. In cold weather the achievable range can be even less. Once discharged the battery requires 6 – 8 hours charging at 3kW from a standard 13A plug. This is known as slow charging.
Fast charging can be achieved from a special outlet providingvehicles, 75A allowing a full charge in 3 hours (the connector to be installed professionally at a significant cost to the user).
A further problem arises with the cables under our roads. The current we draw to run everything in our houses is transmitted along underground cables. When the national grid (shown opposite) was put in in the 1960’s, houses had far fewer electric gadgets. Typically the cables in the road can carry 100kW for 10 houses (10 kW maximum demand expected per house). If half of those houses bought electric cars and recharged them using a 32A supply, then the demand would be 5 cars x 8 kW on average = 40kW. Add this to the current level (10 houses x 10 kW ) + (5 cars x 8 kW) = 140kW.
So the cables under the roads would need to carry far higher currents than they were designed to do. If many of us bought electric cars, then the cables under the roads would have to be replaced – with all the inconvenience and cost that that entails.
The speaker accepted that with sufficient investment and time these problems could be overcome.
However the reason we want electric cars is to reduce pollution and our reliance upon fossil fuels. But cars and transport are only a small fraction of our total energy usage. An important additional contributor is heating for houses: at present, 84% of homes have gas central heating and use 300GW of power for heating in winter. If we were to rely totally on electric heating, it would cost c. £15k per house to convert them, and we would need to convert one house every second to complete the work by 2050, with a total cost of £300bn.
As an individual you currently use about 100 kWh energy in total each day, of which about 20kWh is electricity. The forecast is that you will use about 140kWh energy each day in the future.
So for every person in the UK we need to plan to be able to provide 140kWh of clean energy, probably by electricity generated from renewable sources. In order to do this, we would need:
Just looking at the need for 60,000 wind turbines averaging 2MW by 2025, implies putting up 15 turbines per day –> 1 per hour!
To go green – being able to provide all our energy needs from sustainable sources – we will need to spend lots of money building the generating capacity and ‘rewiring’ the grid to transmit the energy to our homes and to charge our cars.
60,000 wind turbines – most of them offshore
Half of all the roof area in the country covered with solar panels 5 new nuclear power stations
1000km of wave machines along the coast
Re-insulate almost all the nation’s homes
Flood the Severn Estuary…and
Give over about 25% of the UK’s food-producing land over to
So can we do it? Well there are a number of hopeful signs:-
We know how to generate electricity
We are installing more wind turbines
The efficiency of photovotaics is rising
The second generation of smart meters should enable the power companies to control demand
China is planning to build 100 nuclear reactors by 2030 to very similar specifications, a process that will benefit
them hugely due to economies of scale. Perhaps in the future China will be one of the dominant players in
nuclear energy and we can buy some affordable nuclear power stations from China?
The concept of ‘localised energy’, or moving the generation, storage, and distribution of electricity down the chain
to towns and communities is gaining popularity, partly due to subsidies that used to be given out to those who installed solar panels on their homes. Companies like Solar City, and arguably Tesla with their ‘supercharger’ network, are attempting to become distributed utilities, taking the load off the national networks.
One of the more futuristic possibilities is an international electricity grid enabling countries to trade power over, so that we can generate vast amounts of solar energy in the Sahara Desert, wind energy in the North Sea, hydro- electric power in the mountains of Scandinavia, and so on. This would require cables capable of carrying tens of gigawatts of power, over thousands of miles, almost certainly using High Voltage DC transmission.
So we might be able do this, but it’s going to be very expensive and will take far longer that current plans allow. Are there alternatives?
Attempting to predict the future is always difficult, but currently one possibility that is gaining support is to move over to a hydrogen economy.
Hydrogen can be produced in a number of ways: currently the dominant technology for direct production is steam reforming from hydrocarbons, but other methods are known including electrolysis.
Hydrogen can power cars, and some hydrogen powered vehicles are currently in operation, but much work is still needed before hydrogen could become a viable means of powering cars, not least on the infrastructure where in the whole of the UK we only have a handful of hydrogen ‘filling’ stations. Other countries, including Germany and Japan, are far more advanced than we are. The Toyota Mirai hydrogen car is currently in production (with some 2 dozen sold so far in the UK). It is also understood that Hyundai’s ix35 is also in production, and the Honda Clarity is promised for later in the year. All of these hydrogen-powered cars use fuel cells to convert the hydrogen fuel into electrical power as opposed to burning the hydrogen in an internal combustion engine.
Hydrogen can also heat the home by relatively minor modifications to conventional gas boilers. In fact before we had North Sea gas, ‘town’ gas was 50% hydrogen. The UK is particularly well placed to ‘re-purpose’ its extensive gas supply network to distribute hydrogen.
There are a number of city busses, airport vehicles, and a demonstrator train that run on hydrogen. The Leeds Citygate project describes converting a whole town to hydrogen.
Hydrogen can also be seen as a rival to batteries for storing surplus grid power. It has been suggested that abandoned salt mines could be used to store hydrogen.
This was a very thought provoking talk attracting a large audience and considerable discussion.
Tuesday 14th November 2017 – ‘Don’t buy an electric car’