My research is primarily focused on the design and assessment of 100% renewable energy plans. These can be local, national or international energy plans. For example, in the past I have worked on the following projects at different geographical scales:
- Local Energy Plans:
- Limerick-Clare, Ireland
- Ballerup, Denmark
- Copenhagen, Denmark
During these projects, there is often a focus on a few particular challenges in the transition to a 100% renewable energy system. As a result, my research has been focused on a number of key areas, which are:
- The integration of intermittent renewable energy such as wind, wave, tidal, and solar. My latest research demonstrates how more than 80% of our electricity demands can be supplied from these resources.
- District heating, in particular 4th generation low-temperature district heating. This involves a wide range of issues such as identifying the potential for district heating expansion, analysing the impact of district heating on the rest of the energy system, developing policies which can support district heating, and improving district heating technology to fit with the future energy system. For more information, please visit the 4DH Research Centre I am involved in.
- Producing synthetic fuels for trucks, ships, and aeroplanes. I strongly support the electrification of private cars and rail, but it is unlikely that batteries will have sufficiency energy densities to provide power for larger vehicles such as trucks. In the research projects, CEESA, SOEC1, and SOEC2, we developed new pathways for the production of synthetic fuels such as methanol, dimethyl either, and methane. These energy dense fuels can be used in vehicles which require high-density fuels such as trucks, ships, and aeroplanes.
- Electricity storage: the main topic of my PhD dissertation was the role of electricity storage for integrating wind power. During this work, I commercialised a new software tool (in collaboration with Atlas Computers Ltd.) to find potential sites for constructing pumped hydroelectric energy storage, I analysed the profit viable on various electricity grids, and I quantified the amount of additional wind power that can be added to the Irish electricity system when utilising electricity storage. My key conclusion was that electricity storage can increase the amount of wind power on the electricity grid, but there are cheaper alternatives.
In summary, based on my research, I have constructed the key technological steps to transition from today’s energy system to a 100% renewable energy system. The impact of these steps has been quantified in my Green Plan Ireland study and these steps are:
- Implementing energy efficiency measures to reduce the demand for electricity, heat, and transport. Typically the total heat demand (space heating and hot water) should be reduced by 30-50% and after this, it is usually cheaper to supply heat sustainably than to continue with reductions. The transport demand is likely to increase in the future, so maintaining existing levels (for example, by expanding public transport) is likely to be difficult.
- Converting the heating systems in urban areas to district heating. This saves money since it allows you to utilise surplus heat from power plants and by sharing the heating system, the individual consumer pays less for their heating unit. Sources of surplus heat include power plants, waste incinerators and surplus heat from industry. In addition to surplus heat, a district heating network also makes it possible to utilise new renewable resources such as large-scale solar thermal and direct geothermal heat. Finally, district heating increases the comfort levels for the end-user, since you the consumer no longer needs to maintain an individual heating unit in the home and hot-water is available on demand.
- Adding individual and large-scale heat pumps. By adding individual heat pumps in the rural homes and large-scale heat pumps to the district heating networks, it is possible to add more intermittent renewable energy, while also reducing the total costs of the energy system. Heat pumps are very efficient (~300%) and they use electricity, so it is possible to provide a decarbonised heating solution while reducing the overall costs.
- Reducing the grid regulations in place for maintaining the operation of the electricity grid. Today, most electric grids only use large power stations and hydro power to keep electricity grids operating reliably. However, in the future there are a lot of other suppliers and consumers that can contribute to this. For example, decentalised CHP plants in Denmark have already started to help with the stable operation of the Danish electricity grid. Similarly, electric boilers and heat pumps on district heating networks can also contribute to this.
- Replacing existing cars with electric cars. Electric vehicles are around 3-4 times more efficient than conventional petrol and diesel cars. Therefore, if batteries continue to develop as expected and a charging infrastructure is put in place, it is likely that approximately 70% of private cars can be converted from oil to electricity without increasing the costs. Since we now have a new electricity demand and batteries on the network, it will also be possible to add more intermittent renewable energy.
- The most uncertain piece so far is the final step, which is the production of synthetic fuels. There is not enough bioenergy available to convert our existing demand for oil in the transport sector over to biofuels without impacting food production. Synthetic fuels are the combination of carbon and hydrogen together to form new liquid and gaseous fuels for the transport which cannot be electrified. The hydrogen can be produced from electrolysers (primarily using electricity from wind power), while the carbon can be obtained from a variety of sources such as biomass, industry (such as cement), and carbon trees. Using this process, it is possible to produce liquid fuels such as methanol and dimethyl either (DME) or gas fuels such as methane. These can use existing infrastructure to replace oil in trucks, ships, and aeroplanes. Some key technology developments are required in electrolysis, biomass gasification, and carbon capture to develop this industry, even though some demonstration plants have already been completed.
Other technologies which have not been mentioned explicitly here, but will also play a minor role are smart meters (fro reducing the grid regulations), solar thermal on individual buildings for heat, biomass boilers in areas with easy access to bioenergy. Also the intermittent renewable resources will primarily be onshore wind, offshore wind, and solar power, although there will be other smaller contributors such as wave power, tidal power, and geothermal power.
This is of course only on mix of technologies that can economically enable us to transition to 100% renewable energy. We will continue to develop more alternatives so that the debate on how we reach 100% renewable energy can be explored further. These changes will also need to be supported by strong and long-term policies, which is likely to prove even more challenging than developing the technologies themselves.