Environmental and Risk Assessment
The third phase of the project was determining the potential Environmental Impacts of the Suggested technologies. As Hydrogen is an emerging gas technology, within a city centre an in depth Risk assessment was also necessary.
Environmental Impact Assessment of WSHP
The key environmental impacts of the Water Source Heat Pump (WSHP) from the river Clyde are illustrated in figure 1, where the larger the orange bubble, the larger the magnitude of the impact.
Figure 1- Illustration of the Key Environmental Impacts Associated with the WSHP at the River Clyde, the larger the orange circle the larger the impact Significance.
Due to the large area of construction, the environmental impact of the construction phase must be considered. The optimal route that the pipe will take is 1.4km in distance, this route will travel up high street, along George street to be connected to the heat pump. The pipe route has the potential to cause numerous disruptions, the largest disruption is to the public and traffic. Table 1 below shows the impacts and the proposed mitigations for the construction phase of the WSHP system.
The second part of the Environmental impact focused on the operational side of the heat pump system. Due to the heat pump being water source and open loop there will be impacts on wildlife, biodiversity and the embankment these have to mitigated. Table 2 below shows the impacts and the proposed mitigations for the operational phase of the WSHP.
KEY for table 1
Table 1- Identified Impacts of the Construction Phase, Assigned Magnitude and Significance and Mitigation provided.
Table 2- Identified Impacts of the Operational Phase, Assigned Magnitude and Significance and Mitigation provided.
KEY for table 2
Environmental Impact Assessment of Hydrogen CHP
The Key environmental impacts identified for scenario 2 are illustrated in figure 2, where the larger the orange bubble, the larger the magnitude of the environmental impact. Construction phase impacts are identified on the left of the illustration and operational on the right. Electrolysis requires large volumes of water and electricity to produce the hydrogen needed, it is important to consider not only the environmental impacts of this, but also the strain on the grid and resources. Waste production is identified as a significant but in fact positive impact as the waste product is oxygen, which has the potential be sold and create a revenue of income for the University.
Figure 2- Illustration of the Key Environmental Impacts Associated with the Hydrogen Fuelled CHP (and Boilers), the larger the orange circle the larger the impact Magnitude.
Where Impacts are deemed significant, mitigations have been provided as illustrated in tables 3 and 4, detailing impacts and mitigations for construction and operational phases respectively.
Table 3- Identified Impacts of the Construction Phase, Assigned Magnitude and Significance and Mitigation provided.
KEY for table 3
Table 4- Identified Impacts of the Operational Phase, Assigned Magnitude and Significance and Mitigation provided.
KEY for table 4
While there are small emissions associated with the construction phase and with the electrical grid, the carbon emissions of the proposed scenarios are far lesser than that of the current system.
Carbon Emission Savings Analysis
The key environmental consideration of the project is the aim to decarbonise. An analysis of the potential operational Carbon Emission savings of switching to the proposed scenarios, compared to the current natural gas system was undertaken. The graph in figure 3 depicts the potential accumulated savings up to the year 2050. The savings per year can be seen in the boxes to the right of the graph, showing that the water source heat pump shows the highest potential of savings, followed by CHP & boilers with hydrogen and finally, the dual scenario. These are based upon a carbon emission factor for the grid assumed to be 0.03kg/CO2e/kWh in 2021 and the carbon emission factor of Natural gas to be 0.18 kg/CO2e/kWh. (Department for Business, Energy & Industrial Strategy, 2019) For full methodology of calculating the emissions please refer to methodology section of website.
The carbon emission factor of hydrogen combustion is 0, so all emissions are as a result of the electricity grid. In a situation of a carbon free grid, savings of up to four hundred and 78 thousand tonnes of CO2 could be made by 2050.
Figure 3- Projected Accumulated Carbon Emission savings from 2020 to 2050, for the switch from the Current System to all 3 proposed systems. Carbon savings in one year highlighted in boxes to the right of graph, in descending order of most savings to least.
Risk Assessment of Hydrogen
Every new technology has its own risks and associated hazards, which in turn require their own prevention measures. Similarly, hydrogen as a fuel is an emerging technology, so risk analysis needs to be carried out. Particularly with the circumstance of the Powerplant being located within Glasgow City Centre. Some of the significant hazards, consequences and mitigation measures associated with the production of H2 by the Polymer Electrolyte Membrane (PEM) electrolysis method, use of hydrogen fuel in a Combined Heat and Power (CHP) plant and hydrogen fuel are shown below in tables 5, 6 and 7 respectively. This section does not include the probability of hazards or carry out any analysis such as Fault tree analysis and Event tree analysis, as these were outside the scope of the project.
Table 5- Hazards, Consequences and Mitigation measures of PEM Electrolsysis. Information sourced from Hotellier and Becker, 2013)
Table 6- Hazards, Causes of Hazard and Mitigation measures of CHPs. Information sourced from (Santon, 1997)
Table 7- Hazards, Causes of Hazard, Consequences and Mitigation measures of Hydrogen Fuel. Information sourced from (The health and Safety Executive, 2018)
