How Green Technologies Will Increase Demand on the Power Grid

As energy efficient and environmentally friendly technologies capture a larger market, the obvious conclusion seems to be that they will decrease power grid demand. However, according to a report on smart power published by the National Infrastructure Commission, emerging technologies will actually raise peak demand.

• Heating and transportation consume significant amounts of energy. However, most of it is consumed directly in the form of fossil fuels – most vehicles run on gasoline or diesel, and plenty of heaters still run on oil or gas. All of this energy consumption contributes toward the carbon footprint of modern societies, but happens entirely outside of power grids.

• The latest transportation and heating technologies – electric vehicles and heat pumps – run on electric power. As these technologies reach the mainstream market, the total energy and carbon footprint of society will decrease, but demand on the power grid in particular will actually increase.

which occurs during the coldest days of winter. If electric vehicles and heat pumps become mainstream, and energy consumption continues to be managed as usual, this value is expected to double, reaching up to 117 gigawatts. Of course, the impact of increased peak demand can be greatly diminished with measures such as energy storage and demand-side management.

Figure 1. Future demand if the power grid is not optimized (Source: National Infrastructure Commission)

If this scenario unfolds, it may be more difficult to decarbonize the grid. If peak demand is not mitigated, it can only be met effectively with gas-fired power plants or hydroelectricity, and hydroelectricity is not always feasible because it requires specific site conditions.

Adoption of Heat Pumps for Water and Space Heating

At a glance, a heat pump may not seem very different from a typical resistance heater, since it draws electric power and provides heat. However, the way in which both devices produce their heating output is very different:

• A resistance heater operates with a one-to-one ratio between heating output and electric power input. In other words, one watt of electricity is needed for each watt of heating.

• On the other hand, a heat pump runs with an inverse refrigeration cycle, and in fact many models offer reversible operation to provide air conditioning if needed. Older heat pumps provide around 2.5 watts of heat per watt of electricity consumed, and newer high-performance models may provide over 4 watts of heat per watt of electricity.

This ratio between heating output and electric power input is called coefficient of performance (COP). If the heating output is reported in BTU per hour instead of watts, the ratio used is the heating seasonal performance factor (HSPF). To convert from the HSPF value to the COP, it just has to be divided by 3.412.

When a heat pump is used to replace an electric resistance heater, there is a reduction of power grid demand; for example, replacing a 3000-watt resistance heater with a heat pump having a COP of 3.0 brings down power consumption to 1000 watts: the heat pump delivers three watts of heat per watt of electricity. On the other hand, if an oil or gas boiler is replaced with a heat pump, electric demand actually increases even though the carbon footprint is reduced.

The adoption of heat pumps will be driven strongly by the Renewable Heating Incentivefrom Ofgem, which provides cash payments for all heating that comes from eligible technologies. In the residential sector, the RHI applies for both air-source and ground-source heat pumps, as well as biomass and solar heating. For the larger scales of the commercial and industrial sectors, geothermal heating is also feasible and eligible for the incentive.

Electric Vehicles

Advances in battery technology are expected to reduce the cost of electric vehicles, allowing them to capture a larger market. EVs are superior to gas vehicles in terms of both energy efficiency and carbon footprint:

• A conventional gas car normally has an efficiency of under 20%, while electric vehicles exceed 80%.

• If an electric vehicle is charged with energy generated by renewable sources, it can operate with zero carbon emissions throughout the entire value chain.

• Even if the energy for the EV is generated at a coal or gas power plant, the total emissions are reduced – power plants burn fossil fuels more efficiently than gas cars, and then the resulting electric power is used efficiently by electric vehicles.

If the demand for electric vehicles is increased, there will also be a larger market for new wind and solar farms – in fact, it might eventually make sense to build them specifically to power the electric vehicle fleet.

However, before all of that energy can be used by an EV, it must be transported through the power grid. This will combine with the increase in power demand due to heat pump adoption, reducing the total carbon emissions across all energy sources, but also creating new challenges in power grid management.

The Role of Energy Storage and Demand-Side Management

If energy consumption is not actively managed, the peak demand on the UK power grid can be expected to double with the adoption of heat pumps and electric vehicles. However, there are viable measures that can be deployed with both technologies:

• Heat pumps can be complemented with thermal energy storage – basically, a highly insulated tank to store hot water. They can be instructed to store hot water whenever there is surplus production from variable renewable sources or when the total power grid demand is low. The stored hot water can then be used exactly when peak demand is expected to occur, and the use of radiant heating system allows it to provide space heating as well.

• The same principle can be used with electric vehicles, using smart home batteries that work with the same rules as thermal storage: energy is drawn from the grid when there is oversupply, and used whenever an electric vehicle must be charged during peak demand hours. If there is no vehicle to charge, that same energy can be used to power home appliances and also achieve the same effect of peak demand reduction.

Both of these measures require a system that is capable of evaluating operating conditions in real time and deciding the best course of action: storing energy, drawing energy directly from the grid to power heat pumps or charge vehicles, or supplying previously stored energy.

Logic Energy has a decade of experience supplying monitoring systems and software solutions for applications such as renewable sources, energy efficiency and weather research. We combine expertise in both hardware and software to provide integrated solutions that are custom-tailored according to the needs of each client.