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By C. Rhodes, P.Eng., Ph.D.

Fossil fuels such as oil and natural gas inherently provide both energy and power-on-demand. Hence displacement of fossil fuels with non-fossil electricity requires the capacity to provide both energy and power-on-demand. Renewable energy sources provide energy but generally require large amounts of supplementary energy storage to provide power-on-demand. Nuclear power plants provide both energy and power-on- demand. However, nuclear power plants emit additional heat that may be useful in the winter but which must be dissipated in the summer. Typically renewable energy sources require much more transmission than do nuclear power plants.

Energy currently reaches end-use consumers via four routes:
1) Electricity grid;
2) Natural gas pipeline;
3) Liquid fuel (gasoline, oil, propane) tanker trucks;
4) Behind the meter hydro, solar and wind generation.

In the future piped natural gas may be replaced by piped electrolytic hydrogen. However, there is about a 30% energy loss in conversion of electricity into hydrogen. There is about a 50% energy loss in conversion of hydrogen back into electricity. The energy loss in electricity transmission is about 9.2%. Hence, subject to electricity system transmission and distribution capacity limitations, electricity is a much more efficient means of delivering both thermal energy and mechanical energy to customers than is electrolytic piped hydrogen. The advantage of hydrogen lies in its capacity for storing energy.

Electricity has the further advantages that it can be used to directly power customer owned heat pumps and to directly charge lithium ion batteries in electric vehicles. The charge-discharge cycle efficiency of a lithium ion battery is significantly better than the comparable charge-discharge cycle efficiency of hydrogen generation by electrolysis of water, hydrogen compression/liquification and hydrgen chemical energy recovery via a fuel cell or a combined cycle turbine. The advantages of hydrogen as a vehicle fuel as compared to a battery lie in faster vehicle refueling and lower initial vehicle cost. A disadvantage of hydrogen as a vehicle fuel is the initial cost of the required fuel supply infrastructure.

Thus, subject to electricity system transmission/distribution capacity limitations, the most efficient way of delivering thermal and mechanical energy to consumers is via electricity. Piped hydrogen might still be used to mitigate electricity transmission/distribution costs but piped hydrogen will bear an inherent inefficiency burden. There are also significant public safety issues relating to use of pure hydrogen because it burns explosively over a wide range of air-fuel ratios. Metal pipe and pressure vessels containing hydrogen must be kept cool to avoid hydrogen induced cracking.

In order to maximize the energy delivery capacity of the electricity transmission/distribution system the electricity system must be operated at the highest possible load factor. A high load factor can only be achieved by billing customers primarily for peak kW demand or peak kVA rather than for energy. Note that a reduction in peak kW demand or peak kVA reduces the maximum possible energy consumption whereas a reduction in kWh energy consumption at off-peak times does not reduce peak kW demand or peak kVA.

Note that if a nuclear reactor is used to displace natural gas or heating oil via electric resistance heating the thermal capacity of the reactor must be about 3 X the thermal load. If a nuclear reactor is used to generate hydrogen by electrolysis of water and then if the hydrogen is delivered to the load via a pipeline the overall efficiency at heat delivery is about:
.33 (.7)(.85) = .20
meaning that the themal capacity of the reactor must be 5 X the thermal load. Thus delivering heat via hydrogen as compared to delivering heat via electricity increases the required number of nuclear reactors by a factor of (5 / 3) = 1.666. The advantages of using hydrogen for energy delivery lie in its potential for energy storage and its potential for distribution via the existing natural gas distribution piping system to minimize the costs of upgrading electricity transmission/distribution.

According to Statistics Canada (http://www.statcan.gc.ca/pub/57-003-x/2016001/t022-eng.htm) data summarized in a June 1, 2016 presentaion by Ritch Murray of Enbridge Gas Distribution to the PEO, Ontario's primary energy mix is:
41% refined petroleum products (gasoline, diesel oil, fuel oil, jet fuel, etc.);
32% natural gas (95% methane);
20% nuclear and hydro electricity;
5% coke, coke oven gas and coal;
2% natural gas liquids (propane, butane, etc)

If natural gas, natural gas liquids and refined petroleum products are to be overnight replaced by electricity the required annual electricity energy production will be:
(32 + 2 + 41 + 20) / 20 = 4.75 fold.

According to the IESO, during the year 2015 the total electricity usage in Ontario was sourced as follows:
201592.3 TWh36.3 TWh n/a15.4 TWh9.0 TWh0.45 TWh0.25 TWh
2015 (% of total)60%24%n/a10%6%< 1%< 1%

Thus from a delivered electrical energy perspective the increase in functional nuclear reactor capacity required overnight to meet all of Ontario's present electricity energy requirements is:
(92.3 TWh + 36.3 TWh + 15.4 TWh + 9.0 TWh + 0.45 TWh + 0.25 TWh) / 92.3 TWh = 1.6652

From a delivered thermal energy perspective the increase in functional nuclear reactor capacity required overnight to meet the entire Ontario energy load is:
1.6652 X 4.75 fold = 7.9 fold

This energy is:
7.9 X 92.3 TWh / year = 730 TWh / year.

Providing this energy to remote locations from 2000 MWt FNRs operating at a thermal efficiency of 0.3333 and at a capacity factor of 0.900 requires:
[730 TWh / (2000 MWt / reactor X 0.3333 X 8766 h X 0.9 X 1 TWh / 1,000,000 MWh)]
= [730 reactors / (2 X 0.3333 X 8.766 X 0.9)]
= 138.8 reactors

This is an operational reactor quantity increase of:
138.8 / 18 = 7.71 fold

This is an average increase in installed reactor capacity per year between 2015 and 2050 of:
(138.8 reactors - 18 reactors) / 35 years = 3.45 reactors per year

There is a total failure on the part of the government of Ontario to face this nuclear reactor construction reality.

The total energy delivered via the Ontario electricity system must be expanded about five fold in order to fully displace the fossil fuels used in both the transportation and heating sectors. Existing load following fossil fuelled electricity generation must be replaced by load following nuclear electricity generation. Intermittent renewable generation requires extensive energy storage and/or balancing generation support. Renewable generation has the advantage that, unlike nuclear generation, it dissipates no additional heat to the atmosphere.

Financially enabling energy storage requires that marginal electricity rate per kWh be very low to provide an adequate return on investment for the owners of the energy storage systems and to economically displace fossil fuels. The required low marginal rate per kWh is inherent in a Firm Electricity Service (FES) rate primarily based on peak kW or peak kVA during the billing period.

In order to incent use of off-peak electricity for displacement of fossil fuels the marginal cost of electricity per kWh must be less than the marginal cost of the displaced fossil fuel per kWht. The retail electricity rate will need to be about:
$85.00 / monthly peak kVA + $0.02 / kWh. The peak kVA meter must be automatically bypassed at times when the IESO signals that there is an electricity surplus.

This web page last updated November 21, 2016.

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